#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/CodeMetrics.h"
#include "llvm/Analysis/LoopAnalysisManager.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Use.h"
#include "llvm/IR/Value.h"
#include "llvm/Pass.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GenericDomTree.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Scalar/SimpleLoopUnswitch.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
+#include "llvm/Transforms/Utils/ValueMapper.h"
#include <algorithm>
#include <cassert>
#include <iterator>
+#include <numeric>
#include <utility>
#define DEBUG_TYPE "simple-loop-unswitch"
STATISTIC(NumSwitches, "Number of switches unswitched");
STATISTIC(NumTrivial, "Number of unswitches that are trivial");
+static cl::opt<bool> EnableNonTrivialUnswitch(
+ "enable-nontrivial-unswitch", cl::init(false), cl::Hidden,
+ cl::desc("Forcibly enables non-trivial loop unswitching rather than "
+ "following the configuration passed into the pass."));
+
+static cl::opt<int>
+ UnswitchThreshold("unswitch-threshold", cl::init(50), cl::Hidden,
+ cl::desc("The cost threshold for unswitching a loop."));
+
static void replaceLoopUsesWithConstant(Loop &L, Value &LIC,
Constant &Replacement) {
assert(!isa<Constant>(LIC) && "Why are we unswitching on a constant?");
}
}
-/// Update the dominator tree after removing one exiting predecessor of a loop
-/// exit block.
-static void updateLoopExitIDom(BasicBlock *LoopExitBB, Loop &L,
- DominatorTree &DT) {
- assert(pred_begin(LoopExitBB) != pred_end(LoopExitBB) &&
- "Cannot have empty predecessors of the loop exit block if we split "
- "off a block to unswitch!");
+/// Update the IDom for a basic block whose predecessor set has changed.
+///
+/// This routine is designed to work when the domtree update is relatively
+/// localized by leveraging a known common dominator, often a loop header.
+///
+/// FIXME: Should consider hand-rolling a slightly more efficient non-DFS
+/// approach here as we can do that easily by persisting the candidate IDom's
+/// dominating set between each predecessor.
+///
+/// FIXME: Longer term, many uses of this can be replaced by an incremental
+/// domtree update strategy that starts from a known dominating block and
+/// rebuilds that subtree.
+static bool updateIDomWithKnownCommonDominator(BasicBlock *BB,
+ BasicBlock *KnownDominatingBB,
+ DominatorTree &DT) {
+ assert(pred_begin(BB) != pred_end(BB) &&
+ "This routine does not handle unreachable blocks!");
+
+ BasicBlock *OrigIDom = DT[BB]->getIDom()->getBlock();
+
+ BasicBlock *IDom = *pred_begin(BB);
+ assert(DT.dominates(KnownDominatingBB, IDom) &&
+ "Bad known dominating block!");
- BasicBlock *IDom = *pred_begin(LoopExitBB);
// Walk all of the other predecessors finding the nearest common dominator
// until all predecessors are covered or we reach the loop header. The loop
// header necessarily dominates all loop exit blocks in loop simplified form
// so we can early-exit the moment we hit that block.
- for (auto PI = std::next(pred_begin(LoopExitBB)), PE = pred_end(LoopExitBB);
- PI != PE && IDom != L.getHeader(); ++PI)
+ for (auto PI = std::next(pred_begin(BB)), PE = pred_end(BB);
+ PI != PE && IDom != KnownDominatingBB; ++PI) {
+ assert(DT.dominates(KnownDominatingBB, *PI) &&
+ "Bad known dominating block!");
IDom = DT.findNearestCommonDominator(IDom, *PI);
+ }
+
+ if (IDom == OrigIDom)
+ return false;
+
+ DT.changeImmediateDominator(BB, IDom);
+ return true;
+}
- DT.changeImmediateDominator(LoopExitBB, IDom);
+// Note that we don't currently use the IDFCalculator here for two reasons:
+// 1) It computes dominator tree levels for the entire function on each run
+// of 'compute'. While this isn't terrible, given that we expect to update
+// relatively small subtrees of the domtree, it isn't necessarily the right
+// tradeoff.
+// 2) The interface doesn't fit this usage well. It doesn't operate in
+// append-only, and builds several sets that we don't need.
+//
+// FIXME: Neither of these issues are a big deal and could be addressed with
+// some amount of refactoring of IDFCalculator. That would allow us to share
+// the core logic here (which is solving the same core problem).
+void appendDomFrontier(DomTreeNode *Node,
+ SmallSetVector<BasicBlock *, 4> &Worklist,
+ SmallVectorImpl<DomTreeNode *> &DomNodes,
+ SmallPtrSetImpl<BasicBlock *> &DomSet) {
+ assert(DomNodes.empty() && "Must start with no dominator nodes.");
+ assert(DomSet.empty() && "Must start with an empty dominator set.");
+
+ // First flatten this subtree into sequence of nodes by doing a pre-order
+ // walk.
+ DomNodes.push_back(Node);
+ // We intentionally re-evaluate the size as each node can add new children.
+ // Because this is a tree walk, this cannot add any duplicates.
+ for (int i = 0; i < (int)DomNodes.size(); ++i)
+ DomNodes.insert(DomNodes.end(), DomNodes[i]->begin(), DomNodes[i]->end());
+
+ // Now create a set of the basic blocks so we can quickly test for
+ // dominated successors. We could in theory use the DFS numbers of the
+ // dominator tree for this, but we want this to remain predictably fast
+ // even while we mutate the dominator tree in ways that would invalidate
+ // the DFS numbering.
+ for (DomTreeNode *InnerN : DomNodes)
+ DomSet.insert(InnerN->getBlock());
+
+ // Now re-walk the nodes, appending every successor of every node that isn't
+ // in the set. Note that we don't append the node itself, even though if it
+ // is a successor it does not strictly dominate itself and thus it would be
+ // part of the dominance frontier. The reason we don't append it is that
+ // the node passed in came *from* the worklist and so it has already been
+ // processed.
+ for (DomTreeNode *InnerN : DomNodes)
+ for (BasicBlock *SuccBB : successors(InnerN->getBlock()))
+ if (!DomSet.count(SuccBB))
+ Worklist.insert(SuccBB);
+
+ DomNodes.clear();
+ DomSet.clear();
}
/// Update the dominator tree after unswitching a particular former exit block.
// dominator frontier to see if it additionally should move up the dominator
// tree. This lambda appends the dominator frontier for a node on the
// worklist.
- //
- // Note that we don't currently use the IDFCalculator here for two reasons:
- // 1) It computes dominator tree levels for the entire function on each run
- // of 'compute'. While this isn't terrible, given that we expect to update
- // relatively small subtrees of the domtree, it isn't necessarily the right
- // tradeoff.
- // 2) The interface doesn't fit this usage well. It doesn't operate in
- // append-only, and builds several sets that we don't need.
- //
- // FIXME: Neither of these issues are a big deal and could be addressed with
- // some amount of refactoring of IDFCalculator. That would allow us to share
- // the core logic here (which is solving the same core problem).
SmallSetVector<BasicBlock *, 4> Worklist;
+
+ // Scratch data structures reused by domfrontier finding.
SmallVector<DomTreeNode *, 4> DomNodes;
SmallPtrSet<BasicBlock *, 4> DomSet;
- auto AppendDomFrontier = [&](DomTreeNode *Node) {
- assert(DomNodes.empty() && "Must start with no dominator nodes.");
- assert(DomSet.empty() && "Must start with an empty dominator set.");
-
- // First flatten this subtree into sequence of nodes by doing a pre-order
- // walk.
- DomNodes.push_back(Node);
- // We intentionally re-evaluate the size as each node can add new children.
- // Because this is a tree walk, this cannot add any duplicates.
- for (int i = 0; i < (int)DomNodes.size(); ++i)
- DomNodes.insert(DomNodes.end(), DomNodes[i]->begin(), DomNodes[i]->end());
-
- // Now create a set of the basic blocks so we can quickly test for
- // dominated successors. We could in theory use the DFS numbers of the
- // dominator tree for this, but we want this to remain predictably fast
- // even while we mutate the dominator tree in ways that would invalidate
- // the DFS numbering.
- for (DomTreeNode *InnerN : DomNodes)
- DomSet.insert(InnerN->getBlock());
-
- // Now re-walk the nodes, appending every successor of every node that isn't
- // in the set. Note that we don't append the node itself, even though if it
- // is a successor it does not strictly dominate itself and thus it would be
- // part of the dominance frontier. The reason we don't append it is that
- // the node passed in came *from* the worklist and so it has already been
- // processed.
- for (DomTreeNode *InnerN : DomNodes)
- for (BasicBlock *SuccBB : successors(InnerN->getBlock()))
- if (!DomSet.count(SuccBB))
- Worklist.insert(SuccBB);
-
- DomNodes.clear();
- DomSet.clear();
- };
// Append the initial dom frontier nodes.
- AppendDomFrontier(UnswitchedNode);
+ appendDomFrontier(UnswitchedNode, Worklist, DomNodes, DomSet);
// Walk the worklist. We grow the list in the loop and so must recompute size.
for (int i = 0; i < (int)Worklist.size(); ++i) {
DT.changeImmediateDominator(Node, OldPHNode);
// Now add this node's dominator frontier to the worklist as well.
- AppendDomFrontier(Node);
+ appendDomFrontier(Node, Worklist, DomNodes, DomSet);
}
}
// one of the predecessors for the loop exit block and may need to update its
// idom.
if (UnswitchedBB != LoopExitBB)
- updateLoopExitIDom(LoopExitBB, L, DT);
+ updateIDomWithKnownCommonDominator(LoopExitBB, L.getHeader(), DT);
// Since this is an i1 condition we can also trivially replace uses of it
// within the loop with a constant.
SplitBlock(DefaultExitBB, &DefaultExitBB->front(), &DT, &LI);
rewritePHINodesForExitAndUnswitchedBlocks(*DefaultExitBB, *SplitBB,
*ParentBB, *OldPH);
- updateLoopExitIDom(DefaultExitBB, L, DT);
+ updateIDomWithKnownCommonDominator(DefaultExitBB, L.getHeader(), DT);
DefaultExitBB = SplitExitBBMap[DefaultExitBB] = SplitBB;
}
}
SplitExitBB = SplitBlock(ExitBB, &ExitBB->front(), &DT, &LI);
rewritePHINodesForExitAndUnswitchedBlocks(*ExitBB, *SplitExitBB,
*ParentBB, *OldPH);
- updateLoopExitIDom(ExitBB, L, DT);
+ updateIDomWithKnownCommonDominator(ExitBB, L.getHeader(), DT);
}
// Update the case pair to point to the split block.
CasePair.second = SplitExitBB;
return Changed;
}
+/// Build the cloned blocks for an unswitched copy of the given loop.
+///
+/// The cloned blocks are inserted before the loop preheader (`LoopPH`) and
+/// after the split block (`SplitBB`) that will be used to select between the
+/// cloned and original loop.
+///
+/// This routine handles cloning all of the necessary loop blocks and exit
+/// blocks including rewriting their instructions and the relevant PHI nodes.
+/// It skips loop and exit blocks that are not necessary based on the provided
+/// set. It also correctly creates the unconditional branch in the cloned
+/// unswitched parent block to only point at the unswitched successor.
+///
+/// This does not handle most of the necessary updates to `LoopInfo`. Only exit
+/// block splitting is correctly reflected in `LoopInfo`, essentially all of
+/// the cloned blocks (and their loops) are left without full `LoopInfo`
+/// updates. This also doesn't fully update `DominatorTree`. It adds the cloned
+/// blocks to them but doesn't create the cloned `DominatorTree` structure and
+/// instead the caller must recompute an accurate DT. It *does* correctly
+/// update the `AssumptionCache` provided in `AC`.
+static BasicBlock *buildClonedLoopBlocks(
+ Loop &L, BasicBlock *LoopPH, BasicBlock *SplitBB,
+ ArrayRef<BasicBlock *> ExitBlocks, BasicBlock *ParentBB,
+ BasicBlock *UnswitchedSuccBB, BasicBlock *ContinueSuccBB,
+ const SmallPtrSetImpl<BasicBlock *> &SkippedLoopAndExitBlocks,
+ ValueToValueMapTy &VMap, AssumptionCache &AC, DominatorTree &DT,
+ LoopInfo &LI) {
+ SmallVector<BasicBlock *, 4> NewBlocks;
+ NewBlocks.reserve(L.getNumBlocks() + ExitBlocks.size());
+
+ // We will need to clone a bunch of blocks, wrap up the clone operation in
+ // a helper.
+ auto CloneBlock = [&](BasicBlock *OldBB) {
+ // Clone the basic block and insert it before the new preheader.
+ BasicBlock *NewBB = CloneBasicBlock(OldBB, VMap, ".us", OldBB->getParent());
+ NewBB->moveBefore(LoopPH);
+
+ // Record this block and the mapping.
+ NewBlocks.push_back(NewBB);
+ VMap[OldBB] = NewBB;
+
+ // Add the block to the domtree. We'll move it to the correct position
+ // below.
+ DT.addNewBlock(NewBB, SplitBB);
+
+ return NewBB;
+ };
+
+ // First, clone the preheader.
+ auto *ClonedPH = CloneBlock(LoopPH);
+
+ // Then clone all the loop blocks, skipping the ones that aren't necessary.
+ for (auto *LoopBB : L.blocks())
+ if (!SkippedLoopAndExitBlocks.count(LoopBB))
+ CloneBlock(LoopBB);
+
+ // Split all the loop exit edges so that when we clone the exit blocks, if
+ // any of the exit blocks are *also* a preheader for some other loop, we
+ // don't create multiple predecessors entering the loop header.
+ for (auto *ExitBB : ExitBlocks) {
+ if (SkippedLoopAndExitBlocks.count(ExitBB))
+ continue;
+
+ // When we are going to clone an exit, we don't need to clone all the
+ // instructions in the exit block and we want to ensure we have an easy
+ // place to merge the CFG, so split the exit first. This is always safe to
+ // do because there cannot be any non-loop predecessors of a loop exit in
+ // loop simplified form.
+ auto *MergeBB = SplitBlock(ExitBB, &ExitBB->front(), &DT, &LI);
+
+ // Rearrange the names to make it easier to write test cases by having the
+ // exit block carry the suffix rather than the merge block carrying the
+ // suffix.
+ MergeBB->takeName(ExitBB);
+ ExitBB->setName(Twine(MergeBB->getName()) + ".split");
+
+ // Now clone the original exit block.
+ auto *ClonedExitBB = CloneBlock(ExitBB);
+ assert(ClonedExitBB->getTerminator()->getNumSuccessors() == 1 &&
+ "Exit block should have been split to have one successor!");
+ assert(ClonedExitBB->getTerminator()->getSuccessor(0) == MergeBB &&
+ "Cloned exit block has the wrong successor!");
+
+ // Move the merge block's idom to be the split point as one exit is
+ // dominated by one header, and the other by another, so we know the split
+ // point dominates both. While the dominator tree isn't fully accurate, we
+ // want sub-trees within the original loop to be correctly reflect
+ // dominance within that original loop (at least) and that requires moving
+ // the merge block out of that subtree.
+ // FIXME: This is very brittle as we essentially have a partial contract on
+ // the dominator tree. We really need to instead update it and keep it
+ // valid or stop relying on it.
+ DT.changeImmediateDominator(MergeBB, SplitBB);
+
+ // Remap any cloned instructions and create a merge phi node for them.
+ for (auto ZippedInsts : llvm::zip_first(
+ llvm::make_range(ExitBB->begin(), std::prev(ExitBB->end())),
+ llvm::make_range(ClonedExitBB->begin(),
+ std::prev(ClonedExitBB->end())))) {
+ Instruction &I = std::get<0>(ZippedInsts);
+ Instruction &ClonedI = std::get<1>(ZippedInsts);
+
+ // The only instructions in the exit block should be PHI nodes and
+ // potentially a landing pad.
+ assert(
+ (isa<PHINode>(I) || isa<LandingPadInst>(I) || isa<CatchPadInst>(I)) &&
+ "Bad instruction in exit block!");
+ // We should have a value map between the instruction and its clone.
+ assert(VMap.lookup(&I) == &ClonedI && "Mismatch in the value map!");
+
+ auto *MergePN =
+ PHINode::Create(I.getType(), /*NumReservedValues*/ 2, ".us-phi",
+ &*MergeBB->getFirstInsertionPt());
+ I.replaceAllUsesWith(MergePN);
+ MergePN->addIncoming(&I, ExitBB);
+ MergePN->addIncoming(&ClonedI, ClonedExitBB);
+ }
+ }
+
+ // Rewrite the instructions in the cloned blocks to refer to the instructions
+ // in the cloned blocks. We have to do this as a second pass so that we have
+ // everything available. Also, we have inserted new instructions which may
+ // include assume intrinsics, so we update the assumption cache while
+ // processing this.
+ for (auto *ClonedBB : NewBlocks)
+ for (Instruction &I : *ClonedBB) {
+ RemapInstruction(&I, VMap,
+ RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
+ if (auto *II = dyn_cast<IntrinsicInst>(&I))
+ if (II->getIntrinsicID() == Intrinsic::assume)
+ AC.registerAssumption(II);
+ }
+
+ // Remove the cloned parent as a predecessor of the cloned continue successor
+ // if we did in fact clone it.
+ auto *ClonedParentBB = cast<BasicBlock>(VMap.lookup(ParentBB));
+ if (auto *ClonedContinueSuccBB =
+ cast_or_null<BasicBlock>(VMap.lookup(ContinueSuccBB)))
+ ClonedContinueSuccBB->removePredecessor(ClonedParentBB,
+ /*DontDeleteUselessPHIs*/ true);
+ // Replace the cloned branch with an unconditional branch to the cloneed
+ // unswitched successor.
+ auto *ClonedSuccBB = cast<BasicBlock>(VMap.lookup(UnswitchedSuccBB));
+ ClonedParentBB->getTerminator()->eraseFromParent();
+ BranchInst::Create(ClonedSuccBB, ClonedParentBB);
+
+ // Update any PHI nodes in the cloned successors of the skipped blocks to not
+ // have spurious incoming values.
+ for (auto *LoopBB : L.blocks())
+ if (SkippedLoopAndExitBlocks.count(LoopBB))
+ for (auto *SuccBB : successors(LoopBB))
+ if (auto *ClonedSuccBB = cast_or_null<BasicBlock>(VMap.lookup(SuccBB)))
+ for (PHINode &PN : ClonedSuccBB->phis())
+ PN.removeIncomingValue(LoopBB, /*DeletePHIIfEmpty*/ false);
+
+ return ClonedPH;
+}
+
+/// Recursively clone the specified loop and all of its children.
+///
+/// The target parent loop for the clone should be provided, or can be null if
+/// the clone is a top-level loop. While cloning, all the blocks are mapped
+/// with the provided value map. The entire original loop must be present in
+/// the value map. The cloned loop is returned.
+static Loop *cloneLoopNest(Loop &OrigRootL, Loop *RootParentL,
+ const ValueToValueMapTy &VMap, LoopInfo &LI) {
+ auto AddClonedBlocksToLoop = [&](Loop &OrigL, Loop &ClonedL) {
+ assert(ClonedL.getBlocks().empty() && "Must start with an empty loop!");
+ ClonedL.reserveBlocks(OrigL.getNumBlocks());
+ for (auto *BB : OrigL.blocks()) {
+ auto *ClonedBB = cast<BasicBlock>(VMap.lookup(BB));
+ ClonedL.addBlockEntry(ClonedBB);
+ if (LI.getLoopFor(BB) == &OrigL) {
+ assert(!LI.getLoopFor(ClonedBB) &&
+ "Should not have an existing loop for this block!");
+ LI.changeLoopFor(ClonedBB, &ClonedL);
+ }
+ }
+ };
+
+ // We specially handle the first loop because it may get cloned into
+ // a different parent and because we most commonly are cloning leaf loops.
+ Loop *ClonedRootL = LI.AllocateLoop();
+ if (RootParentL)
+ RootParentL->addChildLoop(ClonedRootL);
+ else
+ LI.addTopLevelLoop(ClonedRootL);
+ AddClonedBlocksToLoop(OrigRootL, *ClonedRootL);
+
+ if (OrigRootL.empty())
+ return ClonedRootL;
+
+ // If we have a nest, we can quickly clone the entire loop nest using an
+ // iterative approach because it is a tree. We keep the cloned parent in the
+ // data structure to avoid repeatedly querying through a map to find it.
+ SmallVector<std::pair<Loop *, Loop *>, 16> LoopsToClone;
+ // Build up the loops to clone in reverse order as we'll clone them from the
+ // back.
+ for (Loop *ChildL : llvm::reverse(OrigRootL))
+ LoopsToClone.push_back({ClonedRootL, ChildL});
+ do {
+ Loop *ClonedParentL, *L;
+ std::tie(ClonedParentL, L) = LoopsToClone.pop_back_val();
+ Loop *ClonedL = LI.AllocateLoop();
+ ClonedParentL->addChildLoop(ClonedL);
+ AddClonedBlocksToLoop(*L, *ClonedL);
+ for (Loop *ChildL : llvm::reverse(*L))
+ LoopsToClone.push_back({ClonedL, ChildL});
+ } while (!LoopsToClone.empty());
+
+ return ClonedRootL;
+}
+
+/// Build the cloned loops of an original loop from unswitching.
+///
+/// Because unswitching simplifies the CFG of the loop, this isn't a trivial
+/// operation. We need to re-verify that there even is a loop (as the backedge
+/// may not have been cloned), and even if there are remaining backedges the
+/// backedge set may be different. However, we know that each child loop is
+/// undisturbed, we only need to find where to place each child loop within
+/// either any parent loop or within a cloned version of the original loop.
+///
+/// Because child loops may end up cloned outside of any cloned version of the
+/// original loop, multiple cloned sibling loops may be created. All of them
+/// are returned so that the newly introduced loop nest roots can be
+/// identified.
+static Loop *buildClonedLoops(Loop &OrigL, ArrayRef<BasicBlock *> ExitBlocks,
+ const ValueToValueMapTy &VMap, LoopInfo &LI,
+ SmallVectorImpl<Loop *> &NonChildClonedLoops) {
+ Loop *ClonedL = nullptr;
+
+ auto *OrigPH = OrigL.getLoopPreheader();
+ auto *OrigHeader = OrigL.getHeader();
+
+ auto *ClonedPH = cast<BasicBlock>(VMap.lookup(OrigPH));
+ auto *ClonedHeader = cast<BasicBlock>(VMap.lookup(OrigHeader));
+
+ // We need to know the loops of the cloned exit blocks to even compute the
+ // accurate parent loop. If we only clone exits to some parent of the
+ // original parent, we want to clone into that outer loop. We also keep track
+ // of the loops that our cloned exit blocks participate in.
+ Loop *ParentL = nullptr;
+ SmallVector<BasicBlock *, 4> ClonedExitsInLoops;
+ SmallDenseMap<BasicBlock *, Loop *, 16> ExitLoopMap;
+ ClonedExitsInLoops.reserve(ExitBlocks.size());
+ for (auto *ExitBB : ExitBlocks)
+ if (auto *ClonedExitBB = cast_or_null<BasicBlock>(VMap.lookup(ExitBB)))
+ if (Loop *ExitL = LI.getLoopFor(ExitBB)) {
+ ExitLoopMap[ClonedExitBB] = ExitL;
+ ClonedExitsInLoops.push_back(ClonedExitBB);
+ if (!ParentL || (ParentL != ExitL && ParentL->contains(ExitL)))
+ ParentL = ExitL;
+ }
+ assert((!ParentL || ParentL == OrigL.getParentLoop() ||
+ ParentL->contains(OrigL.getParentLoop())) &&
+ "The computed parent loop should always contain (or be) the parent of "
+ "the original loop.");
+
+ // We build the set of blocks dominated by the cloned header from the set of
+ // cloned blocks out of the original loop. While not all of these will
+ // necessarily be in the cloned loop, it is enough to establish that they
+ // aren't in unreachable cycles, etc.
+ SmallSetVector<BasicBlock *, 16> ClonedLoopBlocks;
+ for (auto *BB : OrigL.blocks())
+ if (auto *ClonedBB = cast_or_null<BasicBlock>(VMap.lookup(BB)))
+ ClonedLoopBlocks.insert(ClonedBB);
+
+ // Rebuild the set of blocks that will end up in the cloned loop. We may have
+ // skipped cloning some region of this loop which can in turn skip some of
+ // the backedges so we have to rebuild the blocks in the loop based on the
+ // backedges that remain after cloning.
+ SmallVector<BasicBlock *, 16> Worklist;
+ SmallPtrSet<BasicBlock *, 16> BlocksInClonedLoop;
+ for (auto *Pred : predecessors(ClonedHeader)) {
+ // The only possible non-loop header predecessor is the preheader because
+ // we know we cloned the loop in simplified form.
+ if (Pred == ClonedPH)
+ continue;
+
+ // Because the loop was in simplified form, the only non-loop predecessor
+ // should be the preheader.
+ assert(ClonedLoopBlocks.count(Pred) && "Found a predecessor of the loop "
+ "header other than the preheader "
+ "that is not part of the loop!");
+
+ // Insert this block into the loop set and on the first visit (and if it
+ // isn't the header we're currently walking) put it into the worklist to
+ // recurse through.
+ if (BlocksInClonedLoop.insert(Pred).second && Pred != ClonedHeader)
+ Worklist.push_back(Pred);
+ }
+
+ // If we had any backedges then there *is* a cloned loop. Put the header into
+ // the loop set and then walk the worklist backwards to find all the blocks
+ // that remain within the loop after cloning.
+ if (!BlocksInClonedLoop.empty()) {
+ BlocksInClonedLoop.insert(ClonedHeader);
+
+ while (!Worklist.empty()) {
+ BasicBlock *BB = Worklist.pop_back_val();
+ assert(BlocksInClonedLoop.count(BB) &&
+ "Didn't put block into the loop set!");
+
+ // Insert any predecessors that are in the possible set into the cloned
+ // set, and if the insert is successful, add them to the worklist. Note
+ // that we filter on the blocks that are definitely reachable via the
+ // backedge to the loop header so we may prune out dead code within the
+ // cloned loop.
+ for (auto *Pred : predecessors(BB))
+ if (ClonedLoopBlocks.count(Pred) &&
+ BlocksInClonedLoop.insert(Pred).second)
+ Worklist.push_back(Pred);
+ }
+
+ ClonedL = LI.AllocateLoop();
+ if (ParentL) {
+ ParentL->addBasicBlockToLoop(ClonedPH, LI);
+ ParentL->addChildLoop(ClonedL);
+ } else {
+ LI.addTopLevelLoop(ClonedL);
+ }
+
+ ClonedL->reserveBlocks(BlocksInClonedLoop.size());
+ // We don't want to just add the cloned loop blocks based on how we
+ // discovered them. The original order of blocks was carefully built in
+ // a way that doesn't rely on predecessor ordering. Rather than re-invent
+ // that logic, we just re-walk the original blocks (and those of the child
+ // loops) and filter them as we add them into the cloned loop.
+ for (auto *BB : OrigL.blocks()) {
+ auto *ClonedBB = cast_or_null<BasicBlock>(VMap.lookup(BB));
+ if (!ClonedBB || !BlocksInClonedLoop.count(ClonedBB))
+ continue;
+
+ // Directly add the blocks that are only in this loop.
+ if (LI.getLoopFor(BB) == &OrigL) {
+ ClonedL->addBasicBlockToLoop(ClonedBB, LI);
+ continue;
+ }
+
+ // We want to manually add it to this loop and parents.
+ // Registering it with LoopInfo will happen when we clone the top
+ // loop for this block.
+ for (Loop *PL = ClonedL; PL; PL = PL->getParentLoop())
+ PL->addBlockEntry(ClonedBB);
+ }
+
+ // Now add each child loop whose header remains within the cloned loop. All
+ // of the blocks within the loop must satisfy the same constraints as the
+ // header so once we pass the header checks we can just clone the entire
+ // child loop nest.
+ for (Loop *ChildL : OrigL) {
+ auto *ClonedChildHeader =
+ cast_or_null<BasicBlock>(VMap.lookup(ChildL->getHeader()));
+ if (!ClonedChildHeader || !BlocksInClonedLoop.count(ClonedChildHeader))
+ continue;
+
+#ifndef NDEBUG
+ // We should never have a cloned child loop header but fail to have
+ // all of the blocks for that child loop.
+ for (auto *ChildLoopBB : ChildL->blocks())
+ assert(BlocksInClonedLoop.count(
+ cast<BasicBlock>(VMap.lookup(ChildLoopBB))) &&
+ "Child cloned loop has a header within the cloned outer "
+ "loop but not all of its blocks!");
+#endif
+
+ cloneLoopNest(*ChildL, ClonedL, VMap, LI);
+ }
+ }
+
+ // Now that we've handled all the components of the original loop that were
+ // cloned into a new loop, we still need to handle anything from the original
+ // loop that wasn't in a cloned loop.
+
+ // Figure out what blocks are left to place within any loop nest containing
+ // the unswitched loop. If we never formed a loop, the cloned PH is one of
+ // them.
+ SmallPtrSet<BasicBlock *, 16> UnloopedBlockSet;
+ if (BlocksInClonedLoop.empty())
+ UnloopedBlockSet.insert(ClonedPH);
+ for (auto *ClonedBB : ClonedLoopBlocks)
+ if (!BlocksInClonedLoop.count(ClonedBB))
+ UnloopedBlockSet.insert(ClonedBB);
+
+ // Copy the cloned exits and sort them in ascending loop depth, we'll work
+ // backwards across these to process them inside out. The order shouldn't
+ // matter as we're just trying to build up the map from inside-out; we use
+ // the map in a more stably ordered way below.
+ auto OrderedClonedExitsInLoops = ClonedExitsInLoops;
+ std::sort(OrderedClonedExitsInLoops.begin(), OrderedClonedExitsInLoops.end(),
+ [&](BasicBlock *LHS, BasicBlock *RHS) {
+ return ExitLoopMap.lookup(LHS)->getLoopDepth() <
+ ExitLoopMap.lookup(RHS)->getLoopDepth();
+ });
+
+ // Populate the existing ExitLoopMap with everything reachable from each
+ // exit, starting from the inner most exit.
+ while (!UnloopedBlockSet.empty() && !OrderedClonedExitsInLoops.empty()) {
+ assert(Worklist.empty() && "Didn't clear worklist!");
+
+ BasicBlock *ExitBB = OrderedClonedExitsInLoops.pop_back_val();
+ Loop *ExitL = ExitLoopMap.lookup(ExitBB);
+
+ // Walk the CFG back until we hit the cloned PH adding everything reachable
+ // and in the unlooped set to this exit block's loop.
+ Worklist.push_back(ExitBB);
+ do {
+ BasicBlock *BB = Worklist.pop_back_val();
+ // We can stop recursing at the cloned preheader (if we get there).
+ if (BB == ClonedPH)
+ continue;
+
+ for (BasicBlock *PredBB : predecessors(BB)) {
+ // If this pred has already been moved to our set or is part of some
+ // (inner) loop, no update needed.
+ if (!UnloopedBlockSet.erase(PredBB)) {
+ assert(
+ (BlocksInClonedLoop.count(PredBB) || ExitLoopMap.count(PredBB)) &&
+ "Predecessor not mapped to a loop!");
+ continue;
+ }
+
+ // We just insert into the loop set here. We'll add these blocks to the
+ // exit loop after we build up the set in an order that doesn't rely on
+ // predecessor order (which in turn relies on use list order).
+ bool Inserted = ExitLoopMap.insert({PredBB, ExitL}).second;
+ (void)Inserted;
+ assert(Inserted && "Should only visit an unlooped block once!");
+
+ // And recurse through to its predecessors.
+ Worklist.push_back(PredBB);
+ }
+ } while (!Worklist.empty());
+ }
+
+ // Now that the ExitLoopMap gives as mapping for all the non-looping cloned
+ // blocks to their outer loops, walk the cloned blocks and the cloned exits
+ // in their original order adding them to the correct loop.
+
+ // We need a stable insertion order. We use the order of the original loop
+ // order and map into the correct parent loop.
+ for (auto *BB : llvm::concat<BasicBlock *const>(
+ makeArrayRef(ClonedPH), ClonedLoopBlocks, ClonedExitsInLoops))
+ if (Loop *OuterL = ExitLoopMap.lookup(BB))
+ OuterL->addBasicBlockToLoop(BB, LI);
+
+#ifndef NDEBUG
+ for (auto &BBAndL : ExitLoopMap) {
+ auto *BB = BBAndL.first;
+ auto *OuterL = BBAndL.second;
+ assert(LI.getLoopFor(BB) == OuterL &&
+ "Failed to put all blocks into outer loops!");
+ }
+#endif
+
+ // Now that all the blocks are placed into the correct containing loop in the
+ // absence of child loops, find all the potentially cloned child loops and
+ // clone them into whatever outer loop we placed their header into.
+ for (Loop *ChildL : OrigL) {
+ auto *ClonedChildHeader =
+ cast_or_null<BasicBlock>(VMap.lookup(ChildL->getHeader()));
+ if (!ClonedChildHeader || BlocksInClonedLoop.count(ClonedChildHeader))
+ continue;
+
+#ifndef NDEBUG
+ for (auto *ChildLoopBB : ChildL->blocks())
+ assert(VMap.count(ChildLoopBB) &&
+ "Cloned a child loop header but not all of that loops blocks!");
+#endif
+
+ NonChildClonedLoops.push_back(cloneLoopNest(
+ *ChildL, ExitLoopMap.lookup(ClonedChildHeader), VMap, LI));
+ }
+
+ // Return the main cloned loop if any.
+ return ClonedL;
+}
+
+static void deleteDeadBlocksFromLoop(Loop &L, BasicBlock *DeadSubtreeRoot,
+ SmallVectorImpl<BasicBlock *> &ExitBlocks,
+ DominatorTree &DT, LoopInfo &LI) {
+ // Walk the dominator tree to build up the set of blocks we will delete here.
+ // The order is designed to allow us to always delete bottom-up and avoid any
+ // dangling uses.
+ SmallSetVector<BasicBlock *, 16> DeadBlocks;
+ DeadBlocks.insert(DeadSubtreeRoot);
+ for (int i = 0; i < (int)DeadBlocks.size(); ++i)
+ for (DomTreeNode *ChildN : *DT[DeadBlocks[i]]) {
+ // FIXME: This assert should pass and that means we don't change nearly
+ // as much below! Consider rewriting all of this to avoid deleting
+ // blocks. They are always cloned before being deleted, and so instead
+ // could just be moved.
+ // FIXME: This in turn means that we might actually be more able to
+ // update the domtree.
+ assert((L.contains(ChildN->getBlock()) ||
+ llvm::find(ExitBlocks, ChildN->getBlock()) != ExitBlocks.end()) &&
+ "Should never reach beyond the loop and exits when deleting!");
+ DeadBlocks.insert(ChildN->getBlock());
+ }
+
+ // Filter out the dead blocks from the exit blocks list so that it can be
+ // used in the caller.
+ llvm::erase_if(ExitBlocks,
+ [&](BasicBlock *BB) { return DeadBlocks.count(BB); });
+
+ // Remove these blocks from their successors.
+ for (auto *BB : DeadBlocks)
+ for (BasicBlock *SuccBB : successors(BB))
+ SuccBB->removePredecessor(BB, /*DontDeleteUselessPHIs*/ true);
+
+ // Walk from this loop up through its parents removing all of the dead blocks.
+ for (Loop *ParentL = &L; ParentL; ParentL = ParentL->getParentLoop()) {
+ for (auto *BB : DeadBlocks)
+ ParentL->getBlocksSet().erase(BB);
+ llvm::erase_if(ParentL->getBlocksVector(),
+ [&](BasicBlock *BB) { return DeadBlocks.count(BB); });
+ }
+
+ // Now delete the dead child loops. This raw delete will clear them
+ // recursively.
+ llvm::erase_if(L.getSubLoopsVector(), [&](Loop *ChildL) {
+ if (!DeadBlocks.count(ChildL->getHeader()))
+ return false;
+
+ assert(llvm::all_of(ChildL->blocks(),
+ [&](BasicBlock *ChildBB) {
+ return DeadBlocks.count(ChildBB);
+ }) &&
+ "If the child loop header is dead all blocks in the child loop must "
+ "be dead as well!");
+ LI.destroy(ChildL);
+ return true;
+ });
+
+ // Remove the mappings for the dead blocks.
+ for (auto *BB : DeadBlocks)
+ LI.changeLoopFor(BB, nullptr);
+
+ // Drop all the references from these blocks to others to handle cyclic
+ // references as we start deleting the blocks themselves.
+ for (auto *BB : DeadBlocks)
+ BB->dropAllReferences();
+
+ for (auto *BB : llvm::reverse(DeadBlocks)) {
+ DT.eraseNode(BB);
+ BB->eraseFromParent();
+ }
+}
+
+/// Recompute the set of blocks in a loop after unswitching.
+///
+/// This walks from the original headers predecessors to rebuild the loop. We
+/// take advantage of the fact that new blocks can't have been added, and so we
+/// filter by the original loop's blocks. This also handles potentially
+/// unreachable code that we don't want to explore but might be found examining
+/// the predecessors of the header.
+///
+/// If the original loop is no longer a loop, this will return an empty set. If
+/// it remains a loop, all the blocks within it will be added to the set
+/// (including those blocks in inner loops).
+static SmallPtrSet<const BasicBlock *, 16> recomputeLoopBlockSet(Loop &L,
+ LoopInfo &LI) {
+ SmallPtrSet<const BasicBlock *, 16> LoopBlockSet;
+
+ auto *PH = L.getLoopPreheader();
+ auto *Header = L.getHeader();
+
+ // A worklist to use while walking backwards from the header.
+ SmallVector<BasicBlock *, 16> Worklist;
+
+ // First walk the predecessors of the header to find the backedges. This will
+ // form the basis of our walk.
+ for (auto *Pred : predecessors(Header)) {
+ // Skip the preheader.
+ if (Pred == PH)
+ continue;
+
+ // Because the loop was in simplified form, the only non-loop predecessor
+ // is the preheader.
+ assert(L.contains(Pred) && "Found a predecessor of the loop header other "
+ "than the preheader that is not part of the "
+ "loop!");
+
+ // Insert this block into the loop set and on the first visit and, if it
+ // isn't the header we're currently walking, put it into the worklist to
+ // recurse through.
+ if (LoopBlockSet.insert(Pred).second && Pred != Header)
+ Worklist.push_back(Pred);
+ }
+
+ // If no backedges were found, we're done.
+ if (LoopBlockSet.empty())
+ return LoopBlockSet;
+
+ // Add the loop header to the set.
+ LoopBlockSet.insert(Header);
+
+ // We found backedges, recurse through them to identify the loop blocks.
+ while (!Worklist.empty()) {
+ BasicBlock *BB = Worklist.pop_back_val();
+ assert(LoopBlockSet.count(BB) && "Didn't put block into the loop set!");
+
+ // Because we know the inner loop structure remains valid we can use the
+ // loop structure to jump immediately across the entire nested loop.
+ // Further, because it is in loop simplified form, we can directly jump
+ // to its preheader afterward.
+ if (Loop *InnerL = LI.getLoopFor(BB))
+ if (InnerL != &L) {
+ assert(L.contains(InnerL) &&
+ "Should not reach a loop *outside* this loop!");
+ // The preheader is the only possible predecessor of the loop so
+ // insert it into the set and check whether it was already handled.
+ auto *InnerPH = InnerL->getLoopPreheader();
+ assert(L.contains(InnerPH) && "Cannot contain an inner loop block "
+ "but not contain the inner loop "
+ "preheader!");
+ if (!LoopBlockSet.insert(InnerPH).second)
+ // The only way to reach the preheader is through the loop body
+ // itself so if it has been visited the loop is already handled.
+ continue;
+
+ // Insert all of the blocks (other than those already present) into
+ // the loop set. The only block we expect to already be in the set is
+ // the one we used to find this loop as we immediately handle the
+ // others the first time we encounter the loop.
+ for (auto *InnerBB : InnerL->blocks()) {
+ if (InnerBB == BB) {
+ assert(LoopBlockSet.count(InnerBB) &&
+ "Block should already be in the set!");
+ continue;
+ }
+
+ bool Inserted = LoopBlockSet.insert(InnerBB).second;
+ (void)Inserted;
+ assert(Inserted && "Should only insert an inner loop once!");
+ }
+
+ // Add the preheader to the worklist so we will continue past the
+ // loop body.
+ Worklist.push_back(InnerPH);
+ continue;
+ }
+
+ // Insert any predecessors that were in the original loop into the new
+ // set, and if the insert is successful, add them to the worklist.
+ for (auto *Pred : predecessors(BB))
+ if (L.contains(Pred) && LoopBlockSet.insert(Pred).second)
+ Worklist.push_back(Pred);
+ }
+
+ // We've found all the blocks participating in the loop, return our completed
+ // set.
+ return LoopBlockSet;
+}
+
+/// Rebuild a loop after unswitching removes some subset of blocks and edges.
+///
+/// The removal may have removed some child loops entirely but cannot have
+/// disturbed any remaining child loops. However, they may need to be hoisted
+/// to the parent loop (or to be top-level loops). The original loop may be
+/// completely removed.
+///
+/// The sibling loops resulting from this update are returned. If the original
+/// loop remains a valid loop, it will be the first entry in this list with all
+/// of the newly sibling loops following it.
+///
+/// Returns true if the loop remains a loop after unswitching, and false if it
+/// is no longer a loop after unswitching (and should not continue to be
+/// referenced).
+static bool rebuildLoopAfterUnswitch(Loop &L, ArrayRef<BasicBlock *> ExitBlocks,
+ LoopInfo &LI,
+ SmallVectorImpl<Loop *> &HoistedLoops) {
+ auto *PH = L.getLoopPreheader();
+
+ // Compute the actual parent loop from the exit blocks. Because we may have
+ // pruned some exits the loop may be different from the original parent.
+ Loop *ParentL = nullptr;
+ SmallVector<Loop *, 4> ExitLoops;
+ SmallVector<BasicBlock *, 4> ExitsInLoops;
+ ExitsInLoops.reserve(ExitBlocks.size());
+ for (auto *ExitBB : ExitBlocks)
+ if (Loop *ExitL = LI.getLoopFor(ExitBB)) {
+ ExitLoops.push_back(ExitL);
+ ExitsInLoops.push_back(ExitBB);
+ if (!ParentL || (ParentL != ExitL && ParentL->contains(ExitL)))
+ ParentL = ExitL;
+ }
+
+ // Recompute the blocks participating in this loop. This may be empty if it
+ // is no longer a loop.
+ auto LoopBlockSet = recomputeLoopBlockSet(L, LI);
+
+ // If we still have a loop, we need to re-set the loop's parent as the exit
+ // block set changing may have moved it within the loop nest. Note that this
+ // can only happen when this loop has a parent as it can only hoist the loop
+ // *up* the nest.
+ if (!LoopBlockSet.empty() && L.getParentLoop() != ParentL) {
+ // Remove this loop's (original) blocks from all of the intervening loops.
+ for (Loop *IL = L.getParentLoop(); IL != ParentL;
+ IL = IL->getParentLoop()) {
+ IL->getBlocksSet().erase(PH);
+ for (auto *BB : L.blocks())
+ IL->getBlocksSet().erase(BB);
+ llvm::erase_if(IL->getBlocksVector(), [&](BasicBlock *BB) {
+ return BB == PH || L.contains(BB);
+ });
+ }
+
+ LI.changeLoopFor(PH, ParentL);
+ L.getParentLoop()->removeChildLoop(&L);
+ if (ParentL)
+ ParentL->addChildLoop(&L);
+ else
+ LI.addTopLevelLoop(&L);
+ }
+
+ // Now we update all the blocks which are no longer within the loop.
+ auto &Blocks = L.getBlocksVector();
+ auto BlocksSplitI =
+ LoopBlockSet.empty()
+ ? Blocks.begin()
+ : std::stable_partition(
+ Blocks.begin(), Blocks.end(),
+ [&](BasicBlock *BB) { return LoopBlockSet.count(BB); });
+
+ // Before we erase the list of unlooped blocks, build a set of them.
+ SmallPtrSet<BasicBlock *, 16> UnloopedBlocks(BlocksSplitI, Blocks.end());
+ if (LoopBlockSet.empty())
+ UnloopedBlocks.insert(PH);
+
+ // Now erase these blocks from the loop.
+ for (auto *BB : make_range(BlocksSplitI, Blocks.end()))
+ L.getBlocksSet().erase(BB);
+ Blocks.erase(BlocksSplitI, Blocks.end());
+
+ // Sort the exits in ascending loop depth, we'll work backwards across these
+ // to process them inside out.
+ std::stable_sort(ExitsInLoops.begin(), ExitsInLoops.end(),
+ [&](BasicBlock *LHS, BasicBlock *RHS) {
+ return LI.getLoopDepth(LHS) < LI.getLoopDepth(RHS);
+ });
+
+ // We'll build up a set for each exit loop.
+ SmallPtrSet<BasicBlock *, 16> NewExitLoopBlocks;
+ Loop *PrevExitL = L.getParentLoop(); // The deepest possible exit loop.
+
+ auto RemoveUnloopedBlocksFromLoop =
+ [](Loop &L, SmallPtrSetImpl<BasicBlock *> &UnloopedBlocks) {
+ for (auto *BB : UnloopedBlocks)
+ L.getBlocksSet().erase(BB);
+ llvm::erase_if(L.getBlocksVector(), [&](BasicBlock *BB) {
+ return UnloopedBlocks.count(BB);
+ });
+ };
+
+ SmallVector<BasicBlock *, 16> Worklist;
+ while (!UnloopedBlocks.empty() && !ExitsInLoops.empty()) {
+ assert(Worklist.empty() && "Didn't clear worklist!");
+ assert(NewExitLoopBlocks.empty() && "Didn't clear loop set!");
+
+ // Grab the next exit block, in decreasing loop depth order.
+ BasicBlock *ExitBB = ExitsInLoops.pop_back_val();
+ Loop &ExitL = *LI.getLoopFor(ExitBB);
+ assert(ExitL.contains(&L) && "Exit loop must contain the inner loop!");
+
+ // Erase all of the unlooped blocks from the loops between the previous
+ // exit loop and this exit loop. This works because the ExitInLoops list is
+ // sorted in increasing order of loop depth and thus we visit loops in
+ // decreasing order of loop depth.
+ for (; PrevExitL != &ExitL; PrevExitL = PrevExitL->getParentLoop())
+ RemoveUnloopedBlocksFromLoop(*PrevExitL, UnloopedBlocks);
+
+ // Walk the CFG back until we hit the cloned PH adding everything reachable
+ // and in the unlooped set to this exit block's loop.
+ Worklist.push_back(ExitBB);
+ do {
+ BasicBlock *BB = Worklist.pop_back_val();
+ // We can stop recursing at the cloned preheader (if we get there).
+ if (BB == PH)
+ continue;
+
+ for (BasicBlock *PredBB : predecessors(BB)) {
+ // If this pred has already been moved to our set or is part of some
+ // (inner) loop, no update needed.
+ if (!UnloopedBlocks.erase(PredBB)) {
+ assert((NewExitLoopBlocks.count(PredBB) ||
+ ExitL.contains(LI.getLoopFor(PredBB))) &&
+ "Predecessor not in a nested loop (or already visited)!");
+ continue;
+ }
+
+ // We just insert into the loop set here. We'll add these blocks to the
+ // exit loop after we build up the set in a deterministic order rather
+ // than the predecessor-influenced visit order.
+ bool Inserted = NewExitLoopBlocks.insert(PredBB).second;
+ (void)Inserted;
+ assert(Inserted && "Should only visit an unlooped block once!");
+
+ // And recurse through to its predecessors.
+ Worklist.push_back(PredBB);
+ }
+ } while (!Worklist.empty());
+
+ // If blocks in this exit loop were directly part of the original loop (as
+ // opposed to a child loop) update the map to point to this exit loop. This
+ // just updates a map and so the fact that the order is unstable is fine.
+ for (auto *BB : NewExitLoopBlocks)
+ if (Loop *BBL = LI.getLoopFor(BB))
+ if (BBL == &L || !L.contains(BBL))
+ LI.changeLoopFor(BB, &ExitL);
+
+ // We will remove the remaining unlooped blocks from this loop in the next
+ // iteration or below.
+ NewExitLoopBlocks.clear();
+ }
+
+ // Any remaining unlooped blocks are no longer part of any loop unless they
+ // are part of some child loop.
+ for (; PrevExitL; PrevExitL = PrevExitL->getParentLoop())
+ RemoveUnloopedBlocksFromLoop(*PrevExitL, UnloopedBlocks);
+ for (auto *BB : UnloopedBlocks)
+ if (Loop *BBL = LI.getLoopFor(BB))
+ if (BBL == &L || !L.contains(BBL))
+ LI.changeLoopFor(BB, nullptr);
+
+ // Sink all the child loops whose headers are no longer in the loop set to
+ // the parent (or to be top level loops). We reach into the loop and directly
+ // update its subloop vector to make this batch update efficient.
+ auto &SubLoops = L.getSubLoopsVector();
+ auto SubLoopsSplitI =
+ LoopBlockSet.empty()
+ ? SubLoops.begin()
+ : std::stable_partition(
+ SubLoops.begin(), SubLoops.end(), [&](Loop *SubL) {
+ return LoopBlockSet.count(SubL->getHeader());
+ });
+ for (auto *HoistedL : make_range(SubLoopsSplitI, SubLoops.end())) {
+ HoistedLoops.push_back(HoistedL);
+ HoistedL->setParentLoop(nullptr);
+
+ // To compute the new parent of this hoisted loop we look at where we
+ // placed the preheader above. We can't lookup the header itself because we
+ // retained the mapping from the header to the hoisted loop. But the
+ // preheader and header should have the exact same new parent computed
+ // based on the set of exit blocks from the original loop as the preheader
+ // is a predecessor of the header and so reached in the reverse walk. And
+ // because the loops were all in simplified form the preheader of the
+ // hoisted loop can't be part of some *other* loop.
+ if (auto *NewParentL = LI.getLoopFor(HoistedL->getLoopPreheader()))
+ NewParentL->addChildLoop(HoistedL);
+ else
+ LI.addTopLevelLoop(HoistedL);
+ }
+ SubLoops.erase(SubLoopsSplitI, SubLoops.end());
+
+ // Actually delete the loop if nothing remained within it.
+ if (Blocks.empty()) {
+ assert(SubLoops.empty() &&
+ "Failed to remove all subloops from the original loop!");
+ if (Loop *ParentL = L.getParentLoop())
+ ParentL->removeChildLoop(llvm::find(*ParentL, &L));
+ else
+ LI.removeLoop(llvm::find(LI, &L));
+ LI.destroy(&L);
+ return false;
+ }
+
+ return true;
+}
+
+/// Helper to visit a dominator subtree, invoking a callable on each node.
+///
+/// Returning false at any point will stop walking past that node of the tree.
+template <typename CallableT>
+void visitDomSubTree(DominatorTree &DT, BasicBlock *BB, CallableT Callable) {
+ SmallVector<DomTreeNode *, 4> DomWorklist;
+ DomWorklist.push_back(DT[BB]);
+#ifndef NDEBUG
+ SmallPtrSet<DomTreeNode *, 4> Visited;
+ Visited.insert(DT[BB]);
+#endif
+ do {
+ DomTreeNode *N = DomWorklist.pop_back_val();
+
+ // Visit this node.
+ if (!Callable(N->getBlock()))
+ continue;
+
+ // Accumulate the child nodes.
+ for (DomTreeNode *ChildN : *N) {
+ assert(Visited.insert(ChildN).second &&
+ "Cannot visit a node twice when walking a tree!");
+ DomWorklist.push_back(ChildN);
+ }
+ } while (!DomWorklist.empty());
+}
+
+/// Take an invariant branch that has been determined to be safe and worthwhile
+/// to unswitch despite being non-trivial to do so and perform the unswitch.
+///
+/// This directly updates the CFG to hoist the predicate out of the loop, and
+/// clone the necessary parts of the loop to maintain behavior.
+///
+/// It also updates both dominator tree and loopinfo based on the unswitching.
+///
+/// Once unswitching has been performed it runs the provided callback to report
+/// the new loops and no-longer valid loops to the caller.
+static bool unswitchInvariantBranch(
+ Loop &L, BranchInst &BI, DominatorTree &DT, LoopInfo &LI,
+ AssumptionCache &AC,
+ function_ref<void(bool, ArrayRef<Loop *>)> NonTrivialUnswitchCB) {
+ assert(BI.isConditional() && "Can only unswitch a conditional branch!");
+ assert(L.isLoopInvariant(BI.getCondition()) &&
+ "Can only unswitch an invariant branch condition!");
+
+ // Constant and BBs tracking the cloned and continuing successor.
+ const int ClonedSucc = 0;
+ auto *ParentBB = BI.getParent();
+ auto *UnswitchedSuccBB = BI.getSuccessor(ClonedSucc);
+ auto *ContinueSuccBB = BI.getSuccessor(1 - ClonedSucc);
+
+ assert(UnswitchedSuccBB != ContinueSuccBB &&
+ "Should not unswitch a branch that always goes to the same place!");
+
+ // The branch should be in this exact loop. Any inner loop's invariant branch
+ // should be handled by unswitching that inner loop. The caller of this
+ // routine should filter out any candidates that remain (but were skipped for
+ // whatever reason).
+ assert(LI.getLoopFor(ParentBB) == &L && "Branch in an inner loop!");
+
+ SmallVector<BasicBlock *, 4> ExitBlocks;
+ L.getUniqueExitBlocks(ExitBlocks);
+
+ // We cannot unswitch if exit blocks contain a cleanuppad instruction as we
+ // don't know how to split those exit blocks.
+ // FIXME: We should teach SplitBlock to handle this and remove this
+ // restriction.
+ for (auto *ExitBB : ExitBlocks)
+ if (isa<CleanupPadInst>(ExitBB->getFirstNonPHI()))
+ return false;
+
+ SmallPtrSet<BasicBlock *, 4> ExitBlockSet(ExitBlocks.begin(),
+ ExitBlocks.end());
+
+ // Compute the parent loop now before we start hacking on things.
+ Loop *ParentL = L.getParentLoop();
+
+ // Compute the outer-most loop containing one of our exit blocks. This is the
+ // furthest up our loopnest which can be mutated, which we will use below to
+ // update things.
+ Loop *OuterExitL = &L;
+ for (auto *ExitBB : ExitBlocks) {
+ Loop *NewOuterExitL = LI.getLoopFor(ExitBB);
+ if (!NewOuterExitL) {
+ // We exited the entire nest with this block, so we're done.
+ OuterExitL = nullptr;
+ break;
+ }
+ if (NewOuterExitL != OuterExitL && NewOuterExitL->contains(OuterExitL))
+ OuterExitL = NewOuterExitL;
+ }
+
+ // If the edge we *aren't* cloning in the unswitch (the continuing edge)
+ // dominates its target, we can skip cloning the dominated region of the loop
+ // and its exits. We compute this as a set of nodes to be skipped.
+ SmallPtrSet<BasicBlock *, 4> SkippedLoopAndExitBlocks;
+ if (ContinueSuccBB->getUniquePredecessor() ||
+ llvm::all_of(predecessors(ContinueSuccBB), [&](BasicBlock *PredBB) {
+ return PredBB == ParentBB || DT.dominates(ContinueSuccBB, PredBB);
+ })) {
+ visitDomSubTree(DT, ContinueSuccBB, [&](BasicBlock *BB) {
+ SkippedLoopAndExitBlocks.insert(BB);
+ return true;
+ });
+ }
+ // Similarly, if the edge we *are* cloning in the unswitch (the unswitched
+ // edge) dominates its target, we will end up with dead nodes in the original
+ // loop and its exits that will need to be deleted. Here, we just retain that
+ // the property holds and will compute the deleted set later.
+ bool DeleteUnswitchedSucc =
+ UnswitchedSuccBB->getUniquePredecessor() ||
+ llvm::all_of(predecessors(UnswitchedSuccBB), [&](BasicBlock *PredBB) {
+ return PredBB == ParentBB || DT.dominates(UnswitchedSuccBB, PredBB);
+ });
+
+ // Split the preheader, so that we know that there is a safe place to insert
+ // the conditional branch. We will change the preheader to have a conditional
+ // branch on LoopCond. The original preheader will become the split point
+ // between the unswitched versions, and we will have a new preheader for the
+ // original loop.
+ BasicBlock *SplitBB = L.getLoopPreheader();
+ BasicBlock *LoopPH = SplitEdge(SplitBB, L.getHeader(), &DT, &LI);
+
+ // Keep a mapping for the cloned values.
+ ValueToValueMapTy VMap;
+
+ // Build the cloned blocks from the loop.
+ auto *ClonedPH = buildClonedLoopBlocks(
+ L, LoopPH, SplitBB, ExitBlocks, ParentBB, UnswitchedSuccBB,
+ ContinueSuccBB, SkippedLoopAndExitBlocks, VMap, AC, DT, LI);
+
+ // Build the cloned loop structure itself. This may be substantially
+ // different from the original structure due to the simplified CFG. This also
+ // handles inserting all the cloned blocks into the correct loops.
+ SmallVector<Loop *, 4> NonChildClonedLoops;
+ Loop *ClonedL =
+ buildClonedLoops(L, ExitBlocks, VMap, LI, NonChildClonedLoops);
+
+ // Remove the parent as a predecessor of the unswitched successor.
+ UnswitchedSuccBB->removePredecessor(ParentBB, /*DontDeleteUselessPHIs*/ true);
+
+ // Now splice the branch from the original loop and use it to select between
+ // the two loops.
+ SplitBB->getTerminator()->eraseFromParent();
+ SplitBB->getInstList().splice(SplitBB->end(), ParentBB->getInstList(), BI);
+ BI.setSuccessor(ClonedSucc, ClonedPH);
+ BI.setSuccessor(1 - ClonedSucc, LoopPH);
+
+ // Create a new unconditional branch to the continuing block (as opposed to
+ // the one cloned).
+ BranchInst::Create(ContinueSuccBB, ParentBB);
+
+ // Delete anything that was made dead in the original loop due to
+ // unswitching.
+ if (DeleteUnswitchedSucc)
+ deleteDeadBlocksFromLoop(L, UnswitchedSuccBB, ExitBlocks, DT, LI);
+
+ SmallVector<Loop *, 4> HoistedLoops;
+ bool IsStillLoop = rebuildLoopAfterUnswitch(L, ExitBlocks, LI, HoistedLoops);
+
+ // This will have completely invalidated the dominator tree. We can't easily
+ // bound how much is invalid because in some cases we will refine the
+ // predecessor set of exit blocks of the loop which can move large unrelated
+ // regions of code into a new subtree.
+ //
+ // FIXME: Eventually, we should use an incremental update utility that
+ // leverages the existing information in the dominator tree (and potentially
+ // the nature of the change) to more efficiently update things.
+ DT.recalculate(*SplitBB->getParent());
+
+ // We can change which blocks are exit blocks of all the cloned sibling
+ // loops, the current loop, and any parent loops which shared exit blocks
+ // with the current loop. As a consequence, we need to re-form LCSSA for
+ // them. But we shouldn't need to re-form LCSSA for any child loops.
+ // FIXME: This could be made more efficient by tracking which exit blocks are
+ // new, and focusing on them, but that isn't likely to be necessary.
+ //
+ // In order to reasonably rebuild LCSSA we need to walk inside-out across the
+ // loop nest and update every loop that could have had its exits changed. We
+ // also need to cover any intervening loops. We add all of these loops to
+ // a list and sort them by loop depth to achieve this without updating
+ // unnecessary loops.
+ auto UpdateLCSSA = [&](Loop &UpdateL) {
+#ifndef NDEBUG
+ for (Loop *ChildL : UpdateL)
+ assert(ChildL->isRecursivelyLCSSAForm(DT, LI) &&
+ "Perturbed a child loop's LCSSA form!");
+#endif
+ formLCSSA(UpdateL, DT, &LI, nullptr);
+ };
+
+ // For non-child cloned loops and hoisted loops, we just need to update LCSSA
+ // and we can do it in any order as they don't nest relative to each other.
+ for (Loop *UpdatedL : llvm::concat<Loop *>(NonChildClonedLoops, HoistedLoops))
+ UpdateLCSSA(*UpdatedL);
+
+ // If the original loop had exit blocks, walk up through the outer most loop
+ // of those exit blocks to update LCSSA and form updated dedicated exits.
+ if (OuterExitL != &L) {
+ SmallVector<Loop *, 4> OuterLoops;
+ // We start with the cloned loop and the current loop if they are loops and
+ // move toward OuterExitL. Also, if either the cloned loop or the current
+ // loop have become top level loops we need to walk all the way out.
+ if (ClonedL) {
+ OuterLoops.push_back(ClonedL);
+ if (!ClonedL->getParentLoop())
+ OuterExitL = nullptr;
+ }
+ if (IsStillLoop) {
+ OuterLoops.push_back(&L);
+ if (!L.getParentLoop())
+ OuterExitL = nullptr;
+ }
+ // Grab all of the enclosing loops now.
+ for (Loop *OuterL = ParentL; OuterL != OuterExitL;
+ OuterL = OuterL->getParentLoop())
+ OuterLoops.push_back(OuterL);
+
+ // Finally, update our list of outer loops. This is nicely ordered to work
+ // inside-out.
+ for (Loop *OuterL : OuterLoops) {
+ // First build LCSSA for this loop so that we can preserve it when
+ // forming dedicated exits. We don't want to perturb some other loop's
+ // LCSSA while doing that CFG edit.
+ UpdateLCSSA(*OuterL);
+
+ // For loops reached by this loop's original exit blocks we may
+ // introduced new, non-dedicated exits. At least try to re-form dedicated
+ // exits for these loops. This may fail if they couldn't have dedicated
+ // exits to start with.
+ formDedicatedExitBlocks(OuterL, &DT, &LI, /*PreserveLCSSA*/ true);
+ }
+ }
+
+#ifndef NDEBUG
+ // Verify the entire loop structure to catch any incorrect updates before we
+ // progress in the pass pipeline.
+ LI.verify(DT);
+#endif
+
+ // Now that we've unswitched something, make callbacks to report the changes.
+ // For that we need to merge together the updated loops and the cloned loops
+ // and check whether the original loop survived.
+ SmallVector<Loop *, 4> SibLoops;
+ for (Loop *UpdatedL : llvm::concat<Loop *>(NonChildClonedLoops, HoistedLoops))
+ if (UpdatedL->getParentLoop() == ParentL)
+ SibLoops.push_back(UpdatedL);
+ NonTrivialUnswitchCB(IsStillLoop, SibLoops);
+
+ ++NumBranches;
+ return true;
+}
+
+/// Recursively compute the cost of a dominator subtree based on the per-block
+/// cost map provided.
+///
+/// The recursive computation is memozied into the provided DT-indexed cost map
+/// to allow querying it for most nodes in the domtree without it becoming
+/// quadratic.
+static int
+computeDomSubtreeCost(DomTreeNode &N,
+ const SmallDenseMap<BasicBlock *, int, 4> &BBCostMap,
+ SmallDenseMap<DomTreeNode *, int, 4> &DTCostMap) {
+ // Don't accumulate cost (or recurse through) blocks not in our block cost
+ // map and thus not part of the duplication cost being considered.
+ auto BBCostIt = BBCostMap.find(N.getBlock());
+ if (BBCostIt == BBCostMap.end())
+ return 0;
+
+ // Lookup this node to see if we already computed its cost.
+ auto DTCostIt = DTCostMap.find(&N);
+ if (DTCostIt != DTCostMap.end())
+ return DTCostIt->second;
+
+ // If not, we have to compute it. We can't use insert above and update
+ // because computing the cost may insert more things into the map.
+ int Cost = std::accumulate(
+ N.begin(), N.end(), BBCostIt->second, [&](int Sum, DomTreeNode *ChildN) {
+ return Sum + computeDomSubtreeCost(*ChildN, BBCostMap, DTCostMap);
+ });
+ bool Inserted = DTCostMap.insert({&N, Cost}).second;
+ (void)Inserted;
+ assert(Inserted && "Should not insert a node while visiting children!");
+ return Cost;
+}
+
/// Unswitch control flow predicated on loop invariant conditions.
///
/// This first hoists all branches or switches which are trivial (IE, do not
/// require duplicating any part of the loop) out of the loop body. It then
/// looks at other loop invariant control flows and tries to unswitch those as
/// well by cloning the loop if the result is small enough.
-static bool unswitchLoop(Loop &L, DominatorTree &DT, LoopInfo &LI,
- AssumptionCache &AC) {
- assert(L.isLCSSAForm(DT) &&
+static bool
+unswitchLoop(Loop &L, DominatorTree &DT, LoopInfo &LI, AssumptionCache &AC,
+ TargetTransformInfo &TTI, bool NonTrivial,
+ function_ref<void(bool, ArrayRef<Loop *>)> NonTrivialUnswitchCB) {
+ assert(L.isRecursivelyLCSSAForm(DT, LI) &&
"Loops must be in LCSSA form before unswitching.");
bool Changed = false;
// Try trivial unswitch first before loop over other basic blocks in the loop.
Changed |= unswitchAllTrivialConditions(L, DT, LI);
- // FIXME: Add support for non-trivial unswitching by cloning the loop.
+ // If we're not doing non-trivial unswitching, we're done. We both accept
+ // a parameter but also check a local flag that can be used for testing
+ // a debugging.
+ if (!NonTrivial && !EnableNonTrivialUnswitch)
+ return Changed;
+
+ // Collect all remaining invariant branch conditions within this loop (as
+ // opposed to an inner loop which would be handled when visiting that inner
+ // loop).
+ SmallVector<TerminatorInst *, 4> UnswitchCandidates;
+ for (auto *BB : L.blocks())
+ if (LI.getLoopFor(BB) == &L)
+ if (auto *BI = dyn_cast<BranchInst>(BB->getTerminator()))
+ if (BI->isConditional() && L.isLoopInvariant(BI->getCondition()) &&
+ BI->getSuccessor(0) != BI->getSuccessor(1))
+ UnswitchCandidates.push_back(BI);
+
+ // If we didn't find any candidates, we're done.
+ if (UnswitchCandidates.empty())
+ return Changed;
+
+ DEBUG(dbgs() << "Considering " << UnswitchCandidates.size()
+ << " non-trivial loop invariant conditions for unswitching.\n");
+
+ // Given that unswitching these terminators will require duplicating parts of
+ // the loop, so we need to be able to model that cost. Compute the ephemeral
+ // values and set up a data structure to hold per-BB costs. We cache each
+ // block's cost so that we don't recompute this when considering different
+ // subsets of the loop for duplication during unswitching.
+ SmallPtrSet<const Value *, 4> EphValues;
+ CodeMetrics::collectEphemeralValues(&L, &AC, EphValues);
+ SmallDenseMap<BasicBlock *, int, 4> BBCostMap;
+
+ // Compute the cost of each block, as well as the total loop cost. Also, bail
+ // out if we see instructions which are incompatible with loop unswitching
+ // (convergent, noduplicate, or cross-basic-block tokens).
+ // FIXME: We might be able to safely handle some of these in non-duplicated
+ // regions.
+ int LoopCost = 0;
+ for (auto *BB : L.blocks()) {
+ int Cost = 0;
+ for (auto &I : *BB) {
+ if (EphValues.count(&I))
+ continue;
+
+ if (I.getType()->isTokenTy() && I.isUsedOutsideOfBlock(BB))
+ return Changed;
+ if (auto CS = CallSite(&I))
+ if (CS.isConvergent() || CS.cannotDuplicate())
+ return Changed;
+
+ Cost += TTI.getUserCost(&I);
+ }
+ assert(Cost >= 0 && "Must not have negative costs!");
+ LoopCost += Cost;
+ assert(LoopCost >= 0 && "Must not have negative loop costs!");
+ BBCostMap[BB] = Cost;
+ }
+ DEBUG(dbgs() << " Total loop cost: " << LoopCost << "\n");
+
+ // Now we find the best candidate by searching for the one with the following
+ // properties in order:
+ //
+ // 1) An unswitching cost below the threshold
+ // 2) The smallest number of duplicated unswitch candidates (to avoid
+ // creating redundant subsequent unswitching)
+ // 3) The smallest cost after unswitching.
+ //
+ // We prioritize reducing fanout of unswitch candidates provided the cost
+ // remains below the threshold because this has a multiplicative effect.
+ //
+ // This requires memoizing each dominator subtree to avoid redundant work.
+ //
+ // FIXME: Need to actually do the number of candidates part above.
+ SmallDenseMap<DomTreeNode *, int, 4> DTCostMap;
+ // Given a terminator which might be unswitched, computes the non-duplicated
+ // cost for that terminator.
+ auto ComputeUnswitchedCost = [&](TerminatorInst *TI) {
+ BasicBlock &BB = *TI->getParent();
+ SmallPtrSet<BasicBlock *, 4> Visited;
+
+ int Cost = LoopCost;
+ for (BasicBlock *SuccBB : successors(&BB)) {
+ // Don't count successors more than once.
+ if (!Visited.insert(SuccBB).second)
+ continue;
+
+ // This successor's domtree will not need to be duplicated after
+ // unswitching if the edge to the successor dominates it (and thus the
+ // entire tree). This essentially means there is no other path into this
+ // subtree and so it will end up live in only one clone of the loop.
+ if (SuccBB->getUniquePredecessor() ||
+ llvm::all_of(predecessors(SuccBB), [&](BasicBlock *PredBB) {
+ return PredBB == &BB || DT.dominates(SuccBB, PredBB);
+ })) {
+ Cost -= computeDomSubtreeCost(*DT[SuccBB], BBCostMap, DTCostMap);
+ assert(Cost >= 0 &&
+ "Non-duplicated cost should never exceed total loop cost!");
+ }
+ }
+
+ // Now scale the cost by the number of unique successors minus one. We
+ // subtract one because there is already at least one copy of the entire
+ // loop. This is computing the new cost of unswitching a condition.
+ assert(Visited.size() > 1 &&
+ "Cannot unswitch a condition without multiple distinct successors!");
+ return Cost * (Visited.size() - 1);
+ };
+ TerminatorInst *BestUnswitchTI = nullptr;
+ int BestUnswitchCost;
+ for (TerminatorInst *CandidateTI : UnswitchCandidates) {
+ int CandidateCost = ComputeUnswitchedCost(CandidateTI);
+ DEBUG(dbgs() << " Computed cost of " << CandidateCost
+ << " for unswitch candidate: " << *CandidateTI << "\n");
+ if (!BestUnswitchTI || CandidateCost < BestUnswitchCost) {
+ BestUnswitchTI = CandidateTI;
+ BestUnswitchCost = CandidateCost;
+ }
+ }
+
+ if (BestUnswitchCost < UnswitchThreshold) {
+ DEBUG(dbgs() << " Trying to unswitch non-trivial (cost = "
+ << BestUnswitchCost << ") branch: " << *BestUnswitchTI
+ << "\n");
+ Changed |= unswitchInvariantBranch(L, cast<BranchInst>(*BestUnswitchTI), DT,
+ LI, AC, NonTrivialUnswitchCB);
+ } else {
+ DEBUG(dbgs() << "Cannot unswitch, lowest cost found: " << BestUnswitchCost
+ << "\n");
+ }
return Changed;
}
DEBUG(dbgs() << "Unswitching loop in " << F.getName() << ": " << L << "\n");
- if (!unswitchLoop(L, AR.DT, AR.LI, AR.AC))
+ // Save the current loop name in a variable so that we can report it even
+ // after it has been deleted.
+ std::string LoopName = L.getName();
+
+ auto NonTrivialUnswitchCB = [&L, &U, &LoopName](bool CurrentLoopValid,
+ ArrayRef<Loop *> NewLoops) {
+ // If we did a non-trivial unswitch, we have added new (cloned) loops.
+ U.addSiblingLoops(NewLoops);
+
+ // If the current loop remains valid, we should revisit it to catch any
+ // other unswitch opportunities. Otherwise, we need to mark it as deleted.
+ if (CurrentLoopValid)
+ U.revisitCurrentLoop();
+ else
+ U.markLoopAsDeleted(L, LoopName);
+ };
+
+ if (!unswitchLoop(L, AR.DT, AR.LI, AR.AC, AR.TTI, NonTrivial,
+ NonTrivialUnswitchCB))
return PreservedAnalyses::all();
#ifndef NDEBUG
namespace {
class SimpleLoopUnswitchLegacyPass : public LoopPass {
+ bool NonTrivial;
+
public:
static char ID; // Pass ID, replacement for typeid
- explicit SimpleLoopUnswitchLegacyPass() : LoopPass(ID) {
+ explicit SimpleLoopUnswitchLegacyPass(bool NonTrivial = false)
+ : LoopPass(ID), NonTrivial(NonTrivial) {
initializeSimpleLoopUnswitchLegacyPassPass(
*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<AssumptionCacheTracker>();
+ AU.addRequired<TargetTransformInfoWrapperPass>();
getLoopAnalysisUsage(AU);
}
};
auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+ auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
+
+ auto NonTrivialUnswitchCB = [&L, &LPM](bool CurrentLoopValid,
+ ArrayRef<Loop *> NewLoops) {
+ // If we did a non-trivial unswitch, we have added new (cloned) loops.
+ for (auto *NewL : NewLoops)
+ LPM.addLoop(*NewL);
+
+ // If the current loop remains valid, re-add it to the queue. This is
+ // a little wasteful as we'll finish processing the current loop as well,
+ // but it is the best we can do in the old PM.
+ if (CurrentLoopValid)
+ LPM.addLoop(*L);
+ else
+ LPM.markLoopAsDeleted(*L);
+ };
+
+ bool Changed =
+ unswitchLoop(*L, DT, LI, AC, TTI, NonTrivial, NonTrivialUnswitchCB);
- bool Changed = unswitchLoop(*L, DT, LI, AC);
+ // If anything was unswitched, also clear any cached information about this
+ // loop.
+ LPM.deleteSimpleAnalysisLoop(L);
#ifndef NDEBUG
// Historically this pass has had issues with the dominator tree so verify it
INITIALIZE_PASS_BEGIN(SimpleLoopUnswitchLegacyPass, "simple-loop-unswitch",
"Simple unswitch loops", false, false)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LoopPass)
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
INITIALIZE_PASS_END(SimpleLoopUnswitchLegacyPass, "simple-loop-unswitch",
"Simple unswitch loops", false, false)
-Pass *llvm::createSimpleLoopUnswitchLegacyPass() {
- return new SimpleLoopUnswitchLegacyPass();
+Pass *llvm::createSimpleLoopUnswitchLegacyPass(bool NonTrivial) {
+ return new SimpleLoopUnswitchLegacyPass(NonTrivial);
}
--- /dev/null
+; RUN: opt -passes='loop(unswitch),verify<loops>' -enable-nontrivial-unswitch -S < %s | FileCheck %s
+; RUN: opt -simple-loop-unswitch -enable-nontrivial-unswitch -S < %s | FileCheck %s
+
+declare void @a()
+declare void @b()
+declare void @c()
+declare void @d()
+
+declare void @sink1(i32)
+declare void @sink2(i32)
+
+; Negative test: we cannot unswitch convergent calls.
+define void @test_no_unswitch_convergent(i1* %ptr, i1 %cond) {
+; CHECK-LABEL: @test_no_unswitch_convergent(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+;
+; We shouldn't have unswitched into any other block either.
+; CHECK-NOT: br i1 %cond
+
+loop_begin:
+ br i1 %cond, label %loop_a, label %loop_b
+; CHECK: loop_begin:
+; CHECK-NEXT: br i1 %cond, label %loop_a, label %loop_b
+
+loop_a:
+ call void @a() convergent
+ br label %loop_latch
+
+loop_b:
+ call void @b()
+ br label %loop_latch
+
+loop_latch:
+ %v = load i1, i1* %ptr
+ br i1 %v, label %loop_begin, label %loop_exit
+
+loop_exit:
+ ret void
+}
+
+; Negative test: we cannot unswitch noduplicate calls.
+define void @test_no_unswitch_noduplicate(i1* %ptr, i1 %cond) {
+; CHECK-LABEL: @test_no_unswitch_noduplicate(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+;
+; We shouldn't have unswitched into any other block either.
+; CHECK-NOT: br i1 %cond
+
+loop_begin:
+ br i1 %cond, label %loop_a, label %loop_b
+; CHECK: loop_begin:
+; CHECK-NEXT: br i1 %cond, label %loop_a, label %loop_b
+
+loop_a:
+ call void @a() noduplicate
+ br label %loop_latch
+
+loop_b:
+ call void @b()
+ br label %loop_latch
+
+loop_latch:
+ %v = load i1, i1* %ptr
+ br i1 %v, label %loop_begin, label %loop_exit
+
+loop_exit:
+ ret void
+}
+
+declare i32 @__CxxFrameHandler3(...)
+
+; Negative test: we cannot unswitch when tokens are used across blocks as we
+; might introduce PHIs.
+define void @test_no_unswitch_cross_block_token(i1* %ptr, i1 %cond) nounwind personality i32 (...)* @__CxxFrameHandler3 {
+; CHECK-LABEL: @test_no_unswitch_cross_block_token(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+;
+; We shouldn't have unswitched into any other block either.
+; CHECK-NOT: br i1 %cond
+
+loop_begin:
+ br i1 %cond, label %loop_a, label %loop_b
+; CHECK: loop_begin:
+; CHECK-NEXT: br i1 %cond, label %loop_a, label %loop_b
+
+loop_a:
+ call void @a()
+ br label %loop_cont
+
+loop_b:
+ call void @b()
+ br label %loop_cont
+
+loop_cont:
+ invoke void @a()
+ to label %loop_latch unwind label %loop_catch
+
+loop_latch:
+ br label %loop_begin
+
+loop_catch:
+ %catch = catchswitch within none [label %loop_catch_latch, label %loop_exit] unwind to caller
+
+loop_catch_latch:
+ %catchpad_latch = catchpad within %catch []
+ catchret from %catchpad_latch to label %loop_begin
+
+loop_exit:
+ %catchpad_exit = catchpad within %catch []
+ catchret from %catchpad_exit to label %exit
+
+exit:
+ ret void
+}
+
+
+; Non-trivial loop unswitching where there are two distinct trivial conditions
+; to unswitch within the loop.
+define i32 @test1(i1* %ptr, i1 %cond1, i1 %cond2) {
+; CHECK-LABEL: @test1(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond1, label %entry.split.us, label %entry.split
+
+loop_begin:
+ br i1 %cond1, label %loop_a, label %loop_b
+
+loop_a:
+ call void @a()
+ br label %latch
+; The 'loop_a' unswitched loop.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: br label %loop_a.us
+;
+; CHECK: loop_a.us:
+; CHECK-NEXT: call void @a()
+; CHECK-NEXT: br label %latch.us
+;
+; CHECK: latch.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin.us, label %loop_exit.split.us
+;
+; CHECK: loop_exit.split.us:
+; CHECK-NEXT: br label %loop_exit
+
+loop_b:
+ br i1 %cond2, label %loop_b_a, label %loop_b_b
+; The second unswitched condition.
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br i1 %cond2, label %entry.split.split.us, label %entry.split.split
+
+loop_b_a:
+ call void @b()
+ br label %latch
+; The 'loop_b_a' unswitched loop.
+;
+; CHECK: entry.split.split.us:
+; CHECK-NEXT: br label %loop_begin.us1
+;
+; CHECK: loop_begin.us1:
+; CHECK-NEXT: br label %loop_b.us
+;
+; CHECK: loop_b.us:
+; CHECK-NEXT: br label %loop_b_a.us
+;
+; CHECK: loop_b_a.us:
+; CHECK-NEXT: call void @b()
+; CHECK-NEXT: br label %latch.us2
+;
+; CHECK: latch.us2:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin.us1, label %loop_exit.split.split.us
+;
+; CHECK: loop_exit.split.split.us:
+; CHECK-NEXT: br label %loop_exit.split
+
+loop_b_b:
+ call void @c()
+ br label %latch
+; The 'loop_b_b' unswitched loop.
+;
+; CHECK: entry.split.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: br label %loop_b
+;
+; CHECK: loop_b:
+; CHECK-NEXT: br label %loop_b_b
+;
+; CHECK: loop_b_b:
+; CHECK-NEXT: call void @c()
+; CHECK-NEXT: br label %latch
+;
+; CHECK: latch:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit.split.split
+;
+; CHECK: loop_exit.split.split:
+; CHECK-NEXT: br label %loop_exit.split
+
+latch:
+ %v = load i1, i1* %ptr
+ br i1 %v, label %loop_begin, label %loop_exit
+
+loop_exit:
+ ret i32 0
+; CHECK: loop_exit.split:
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit:
+; CHECK-NEXT: ret
+}
+
+define i32 @test2(i1* %ptr, i1 %cond1, i32* %a.ptr, i32* %b.ptr, i32* %c.ptr) {
+; CHECK-LABEL: @test2(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond1, label %entry.split.us, label %entry.split
+
+loop_begin:
+ %v = load i1, i1* %ptr
+ br i1 %cond1, label %loop_a, label %loop_b
+
+loop_a:
+ %a = load i32, i32* %a.ptr
+ %ac = load i32, i32* %c.ptr
+ br i1 %v, label %loop_begin, label %loop_exit
+; The 'loop_a' unswitched loop.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br label %loop_a.us
+;
+; CHECK: loop_a.us:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[AC:.*]] = load i32, i32* %c.ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin.backedge.us, label %loop_exit.split.us
+;
+; CHECK: loop_exit.split.us:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A]], %loop_a.us ]
+; CHECK-NEXT: %[[AC_LCSSA:.*]] = phi i32 [ %[[AC]], %loop_a.us ]
+; CHECK-NEXT: br label %loop_exit
+
+loop_b:
+ %b = load i32, i32* %b.ptr
+ %bc = load i32, i32* %c.ptr
+ br i1 %v, label %loop_begin, label %loop_exit
+; The 'loop_b' unswitched loop.
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br label %loop_b
+;
+; CHECK: loop_b:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: %[[BC:.*]] = load i32, i32* %c.ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin.backedge, label %loop_exit.split
+;
+; CHECK: loop_exit.split:
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %loop_b ]
+; CHECK-NEXT: %[[BC_LCSSA:.*]] = phi i32 [ %[[BC]], %loop_b ]
+; CHECK-NEXT: br label %loop_exit
+
+loop_exit:
+ %ab.phi = phi i32 [ %a, %loop_a ], [ %b, %loop_b ]
+ %c.phi = phi i32 [ %ac, %loop_a ], [ %bc, %loop_b ]
+ %result = add i32 %ab.phi, %c.phi
+ ret i32 %result
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[AB_PHI:.*]] = phi i32 [ %[[B_LCSSA]], %loop_exit.split ], [ %[[A_LCSSA]], %loop_exit.split.us ]
+; CHECK-NEXT: %[[C_PHI:.*]] = phi i32 [ %[[BC_LCSSA]], %loop_exit.split ], [ %[[AC_LCSSA]], %loop_exit.split.us ]
+; CHECK-NEXT: %[[RESULT:.*]] = add i32 %[[AB_PHI]], %[[C_PHI]]
+; CHECK-NEXT: ret i32 %[[RESULT]]
+}
+
+; Test a non-trivial unswitch of an exiting edge to an exit block with other
+; in-loop predecessors.
+define i32 @test3a(i1* %ptr, i1 %cond1, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test3a(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond1, label %entry.split.us, label %entry.split
+
+loop_begin:
+ %v = load i1, i1* %ptr
+ %a = load i32, i32* %a.ptr
+ br i1 %cond1, label %loop_exit, label %loop_b
+; The 'loop_exit' clone.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_exit.split.us
+;
+; CHECK: loop_exit.split.us:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A]], %loop_begin.us ]
+; CHECK-NEXT: br label %loop_exit
+
+loop_b:
+ %b = load i32, i32* %b.ptr
+ br i1 %v, label %loop_begin, label %loop_exit
+; The 'loop_b' unswitched loop.
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_b
+;
+; CHECK: loop_b:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit.split
+;
+; CHECK: loop_exit.split:
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %loop_b ]
+; CHECK-NEXT: br label %loop_exit
+
+loop_exit:
+ %ab.phi = phi i32 [ %a, %loop_begin ], [ %b, %loop_b ]
+ ret i32 %ab.phi
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[AB_PHI:.*]] = phi i32 [ %[[B_LCSSA]], %loop_exit.split ], [ %[[A_LCSSA]], %loop_exit.split.us ]
+; CHECK-NEXT: ret i32 %[[AB_PHI]]
+}
+
+; Test a non-trivial unswitch of an exiting edge to an exit block with other
+; in-loop predecessors. This is the same as @test3a but with the reversed order
+; of successors so that the exiting edge is *not* the cloned edge.
+define i32 @test3b(i1* %ptr, i1 %cond1, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test3b(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond1, label %entry.split.us, label %entry.split
+
+loop_begin:
+ %v = load i1, i1* %ptr
+ %a = load i32, i32* %a.ptr
+ br i1 %cond1, label %loop_b, label %loop_exit
+; The 'loop_b' unswitched loop.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_b.us
+;
+; CHECK: loop_b.us:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin.us, label %loop_exit.split.us
+;
+; CHECK: loop_exit.split.us:
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %loop_b.us ]
+; CHECK-NEXT: br label %loop_exit
+
+loop_b:
+ %b = load i32, i32* %b.ptr
+ br i1 %v, label %loop_begin, label %loop_exit
+; The 'loop_b' unswitched loop.
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_exit.split
+;
+; CHECK: loop_exit.split:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A]], %loop_begin ]
+; CHECK-NEXT: br label %loop_exit
+
+loop_exit:
+ %ab.phi = phi i32 [ %b, %loop_b ], [ %a, %loop_begin ]
+ ret i32 %ab.phi
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[AB_PHI:.*]] = phi i32 [ %[[A_LCSSA]], %loop_exit.split ], [ %[[B_LCSSA]], %loop_exit.split.us ]
+; CHECK-NEXT: ret i32 %[[AB_PHI]]
+}
+
+; Test a non-trivial unswitch of an exiting edge to an exit block with no other
+; in-loop predecessors.
+define void @test4a(i1* %ptr, i1 %cond1, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test4a(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond1, label %entry.split.us, label %entry.split
+
+loop_begin:
+ %v = load i1, i1* %ptr
+ %a = load i32, i32* %a.ptr
+ br i1 %cond1, label %loop_exit1, label %loop_b
+; The 'loop_exit' clone.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_exit1.split.us
+;
+; CHECK: loop_exit1.split.us:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A]], %loop_begin.us ]
+; CHECK-NEXT: br label %loop_exit1
+
+loop_b:
+ %b = load i32, i32* %b.ptr
+ br i1 %v, label %loop_begin, label %loop_exit2
+; The 'loop_b' unswitched loop.
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_b
+;
+; CHECK: loop_b:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit2
+
+loop_exit1:
+ %a.phi = phi i32 [ %a, %loop_begin ]
+ call void @sink1(i32 %a.phi)
+ ret void
+; CHECK: loop_exit1:
+; CHECK-NEXT: %[[A_PHI:.*]] = phi i32 [ %[[A_LCSSA]], %loop_exit1.split.us ]
+; CHECK-NEXT: call void @sink1(i32 %[[A_PHI]])
+; CHECK-NEXT: ret void
+
+loop_exit2:
+ %b.phi = phi i32 [ %b, %loop_b ]
+ call void @sink2(i32 %b.phi)
+ ret void
+; CHECK: loop_exit2:
+; CHECK-NEXT: %[[B_PHI:.*]] = phi i32 [ %[[B]], %loop_b ]
+; CHECK-NEXT: call void @sink2(i32 %[[B_PHI]])
+; CHECK-NEXT: ret void
+}
+
+; Test a non-trivial unswitch of an exiting edge to an exit block with no other
+; in-loop predecessors. This is the same as @test4a but with the edges reversed
+; so that the exiting edge is *not* the cloned edge.
+define void @test4b(i1* %ptr, i1 %cond1, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test4b(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond1, label %entry.split.us, label %entry.split
+
+loop_begin:
+ %v = load i1, i1* %ptr
+ %a = load i32, i32* %a.ptr
+ br i1 %cond1, label %loop_b, label %loop_exit1
+; The 'loop_b' clone.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_b.us
+;
+; CHECK: loop_b.us:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin.us, label %loop_exit2.split.us
+;
+; CHECK: loop_exit2.split.us:
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %loop_b.us ]
+; CHECK-NEXT: br label %loop_exit2
+
+loop_b:
+ %b = load i32, i32* %b.ptr
+ br i1 %v, label %loop_begin, label %loop_exit2
+; The 'loop_exit' unswitched path.
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_exit1
+
+loop_exit1:
+ %a.phi = phi i32 [ %a, %loop_begin ]
+ call void @sink1(i32 %a.phi)
+ ret void
+; CHECK: loop_exit1:
+; CHECK-NEXT: %[[A_PHI:.*]] = phi i32 [ %[[A]], %loop_begin ]
+; CHECK-NEXT: call void @sink1(i32 %[[A_PHI]])
+; CHECK-NEXT: ret void
+
+loop_exit2:
+ %b.phi = phi i32 [ %b, %loop_b ]
+ call void @sink2(i32 %b.phi)
+ ret void
+; CHECK: loop_exit2:
+; CHECK-NEXT: %[[B_PHI:.*]] = phi i32 [ %[[B_LCSSA]], %loop_exit2.split.us ]
+; CHECK-NEXT: call void @sink2(i32 %[[B_PHI]])
+; CHECK-NEXT: ret void
+}
+
+; Test a non-trivial unswitch of an exiting edge to an exit block with no other
+; in-loop predecessors. This is the same as @test4a but with a common merge
+; block after the independent loop exits. This requires a different structural
+; update to the dominator tree.
+define void @test4c(i1* %ptr, i1 %cond1, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test4c(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond1, label %entry.split.us, label %entry.split
+
+loop_begin:
+ %v = load i1, i1* %ptr
+ %a = load i32, i32* %a.ptr
+ br i1 %cond1, label %loop_exit1, label %loop_b
+; The 'loop_exit' clone.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_exit1.split.us
+;
+; CHECK: loop_exit1.split.us:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A]], %loop_begin.us ]
+; CHECK-NEXT: br label %loop_exit1
+
+loop_b:
+ %b = load i32, i32* %b.ptr
+ br i1 %v, label %loop_begin, label %loop_exit2
+; The 'loop_b' unswitched loop.
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_b
+;
+; CHECK: loop_b:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit2
+
+loop_exit1:
+ %a.phi = phi i32 [ %a, %loop_begin ]
+ call void @sink1(i32 %a.phi)
+ br label %exit
+; CHECK: loop_exit1:
+; CHECK-NEXT: %[[A_PHI:.*]] = phi i32 [ %[[A_LCSSA]], %loop_exit1.split.us ]
+; CHECK-NEXT: call void @sink1(i32 %[[A_PHI]])
+; CHECK-NEXT: br label %exit
+
+loop_exit2:
+ %b.phi = phi i32 [ %b, %loop_b ]
+ call void @sink2(i32 %b.phi)
+ br label %exit
+; CHECK: loop_exit2:
+; CHECK-NEXT: %[[B_PHI:.*]] = phi i32 [ %[[B]], %loop_b ]
+; CHECK-NEXT: call void @sink2(i32 %[[B_PHI]])
+; CHECK-NEXT: br label %exit
+
+exit:
+ ret void
+; CHECK: exit:
+; CHECK-NEXT: ret void
+}
+
+; Test that we can unswitch a condition out of multiple layers of a loop nest.
+define i32 @test5(i1* %ptr, i1 %cond1, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test5(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond1, label %loop_begin.split.us, label %entry.split
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: br label %loop_begin.split
+
+loop_begin:
+ br label %inner_loop_begin
+
+inner_loop_begin:
+ %v = load i1, i1* %ptr
+ %a = load i32, i32* %a.ptr
+ br i1 %cond1, label %loop_exit, label %inner_loop_b
+; The 'loop_exit' clone.
+;
+; CHECK: loop_begin.split.us:
+; CHECK-NEXT: br label %inner_loop_begin.us
+;
+; CHECK: inner_loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_exit.loopexit.split.us
+;
+; CHECK: loop_exit.loopexit.split.us:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A]], %inner_loop_begin.us ]
+; CHECK-NEXT: br label %loop_exit
+
+inner_loop_b:
+ %b = load i32, i32* %b.ptr
+ br i1 %v, label %inner_loop_begin, label %loop_latch
+; The 'inner_loop_b' unswitched loop.
+;
+; CHECK: loop_begin.split:
+; CHECK-NEXT: br label %inner_loop_begin
+;
+; CHECK: inner_loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_b
+;
+; CHECK: inner_loop_b:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_begin, label %loop_latch
+
+loop_latch:
+ %b.phi = phi i32 [ %b, %inner_loop_b ]
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %loop_begin, label %loop_exit
+; CHECK: loop_latch:
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %inner_loop_b ]
+; CHECK-NEXT: %[[V2:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V2]], label %loop_begin, label %loop_exit.loopexit1
+
+loop_exit:
+ %ab.phi = phi i32 [ %a, %inner_loop_begin ], [ %b.phi, %loop_latch ]
+ ret i32 %ab.phi
+; CHECK: loop_exit.loopexit:
+; CHECK-NEXT: %[[A_PHI:.*]] = phi i32 [ %[[A_LCSSA]], %loop_exit.loopexit.split.us ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit.loopexit1:
+; CHECK-NEXT: %[[B_PHI:.*]] = phi i32 [ %[[B_LCSSA]], %loop_latch ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[AB_PHI:.*]] = phi i32 [ %[[A_PHI]], %loop_exit.loopexit ], [ %[[B_PHI]], %loop_exit.loopexit1 ]
+; CHECK-NEXT: ret i32 %[[AB_PHI]]
+}
+
+; Test that we can unswitch a condition where we end up only cloning some of
+; the nested loops and needing to delete some of the nested loops.
+define i32 @test6(i1* %ptr, i1 %cond1, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test6(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond1, label %entry.split.us, label %entry.split
+
+loop_begin:
+ %v = load i1, i1* %ptr
+ br i1 %cond1, label %loop_a, label %loop_b
+
+loop_a:
+ br label %loop_a_inner
+
+loop_a_inner:
+ %va = load i1, i1* %ptr
+ %a = load i32, i32* %a.ptr
+ br i1 %va, label %loop_a_inner, label %loop_a_inner_exit
+
+loop_a_inner_exit:
+ %a.lcssa = phi i32 [ %a, %loop_a_inner ]
+ br label %latch
+; The 'loop_a' cloned loop.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br label %loop_a.us
+;
+; CHECK: loop_a.us:
+; CHECK-NEXT: br label %loop_a_inner.us
+;
+; CHECK: loop_a_inner.us
+; CHECK-NEXT: %[[VA:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br i1 %[[VA]], label %loop_a_inner.us, label %loop_a_inner_exit.us
+;
+; CHECK: loop_a_inner_exit.us:
+; CHECK-NEXT: %[[A_INNER_LCSSA:.*]] = phi i32 [ %[[A]], %loop_a_inner.us ]
+; CHECK-NEXT: br label %latch.us
+;
+; CHECK: latch.us:
+; CHECK-NEXT: %[[A_PHI:.*]] = phi i32 [ %[[A_INNER_LCSSA]], %loop_a_inner_exit.us ]
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin.us, label %loop_exit.split.us
+;
+; CHECK: loop_exit.split.us:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A_PHI]], %latch.us ]
+; CHECK-NEXT: br label %loop_exit
+
+loop_b:
+ br label %loop_b_inner
+
+loop_b_inner:
+ %vb = load i1, i1* %ptr
+ %b = load i32, i32* %b.ptr
+ br i1 %vb, label %loop_b_inner, label %loop_b_inner_exit
+
+loop_b_inner_exit:
+ %b.lcssa = phi i32 [ %b, %loop_b_inner ]
+ br label %latch
+
+latch:
+ %ab.phi = phi i32 [ %a.lcssa, %loop_a_inner_exit ], [ %b.lcssa, %loop_b_inner_exit ]
+ br i1 %v, label %loop_begin, label %loop_exit
+; The 'loop_b' unswitched loop.
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br label %loop_b
+;
+; CHECK: loop_b:
+; CHECK-NEXT: br label %loop_b_inner
+;
+; CHECK: loop_b_inner
+; CHECK-NEXT: %[[VB:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br i1 %[[VB]], label %loop_b_inner, label %loop_b_inner_exit
+;
+; CHECK: loop_b_inner_exit:
+; CHECK-NEXT: %[[B_INNER_LCSSA:.*]] = phi i32 [ %[[B]], %loop_b_inner ]
+; CHECK-NEXT: br label %latch
+;
+; CHECK: latch:
+; CHECK-NEXT: %[[B_PHI:.*]] = phi i32 [ %[[B_INNER_LCSSA]], %loop_b_inner_exit ]
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit.split
+;
+; CHECK: loop_exit.split:
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B_PHI]], %latch ]
+; CHECK-NEXT: br label %loop_exit
+
+loop_exit:
+ %ab.lcssa = phi i32 [ %ab.phi, %latch ]
+ ret i32 %ab.lcssa
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[AB_PHI:.*]] = phi i32 [ %[[B_LCSSA]], %loop_exit.split ], [ %[[A_LCSSA]], %loop_exit.split.us ]
+; CHECK-NEXT: ret i32 %[[AB_PHI]]
+}
+
+; Test that when unswitching a deeply nested loop condition in a way that
+; produces a non-loop clone that can reach multiple exit blocks which are part
+; of different outer loops we correctly divide the cloned loop blocks between
+; the outer loops based on reachability.
+define i32 @test7a(i1* %ptr, i1* %cond.ptr, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test7a(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+
+loop_begin:
+ %a = load i32, i32* %a.ptr
+ br label %inner_loop_begin
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_begin
+
+inner_loop_begin:
+ %a.phi = phi i32 [ %a, %loop_begin ], [ %a2, %inner_inner_loop_exit ]
+ %cond = load i1, i1* %cond.ptr
+ %b = load i32, i32* %b.ptr
+ br label %inner_inner_loop_begin
+; CHECK: inner_loop_begin:
+; CHECK-NEXT: %[[A_INNER_PHI:.*]] = phi i32 [ %[[A]], %loop_begin ], [ %[[A2:.*]], %inner_inner_loop_exit ]
+; CHECK-NEXT: %[[COND:.*]] = load i1, i1* %cond.ptr
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br i1 %[[COND]], label %inner_loop_begin.split.us, label %inner_loop_begin.split
+
+inner_inner_loop_begin:
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %inner_inner_loop_a, label %inner_inner_loop_b
+
+inner_inner_loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %loop_exit, label %inner_inner_loop_c
+
+inner_inner_loop_b:
+ %v3 = load i1, i1* %ptr
+ br i1 %v3, label %inner_inner_loop_exit, label %inner_inner_loop_c
+
+inner_inner_loop_c:
+ %v4 = load i1, i1* %ptr
+ br i1 %v4, label %inner_loop_exit, label %inner_inner_loop_d
+
+inner_inner_loop_d:
+ br i1 %cond, label %inner_loop_exit, label %inner_inner_loop_begin
+; The cloned copy that always exits with the adjustments required to fix up
+; loop exits.
+;
+; CHECK: inner_loop_begin.split.us:
+; CHECK-NEXT: br label %inner_inner_loop_begin.us
+;
+; CHECK: inner_inner_loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_a.us, label %inner_inner_loop_b.us
+;
+; CHECK: inner_inner_loop_b.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_exit.split.us, label %inner_inner_loop_c.us.loopexit
+;
+; CHECK: inner_inner_loop_a.us:
+; CHECK-NEXT: %[[A_NEW_LCSSA:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_inner_loop_begin.us ]
+; CHECK-NEXT: %[[B_NEW_LCSSA:.*]] = phi i32 [ %[[B]], %inner_inner_loop_begin.us ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit.split.us, label %inner_inner_loop_c.us
+;
+; CHECK: inner_inner_loop_c.us.loopexit:
+; CHECK-NEXT: br label %inner_inner_loop_c.us
+;
+; CHECK: inner_inner_loop_c.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_exit.loopexit.split.us, label %inner_inner_loop_d.us
+;
+; CHECK: inner_inner_loop_d.us:
+; CHECK-NEXT: br label %inner_loop_exit.loopexit.split
+;
+; CHECK: inner_inner_loop_exit.split.us:
+; CHECK-NEXT: br label %inner_inner_loop_exit
+;
+; CHECK: loop_exit.split.us:
+; CHECK-NEXT: %[[A_LCSSA_US:.*]] = phi i32 [ %[[A_NEW_LCSSA]], %inner_inner_loop_a.us ]
+; CHECK-NEXT: %[[B_LCSSA_US:.*]] = phi i32 [ %[[B_NEW_LCSSA]], %inner_inner_loop_a.us ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: inner_loop_exit.loopexit.split.us:
+; CHECK-NEXT: br label %inner_loop_exit.loopexit
+;
+; The original copy that continues to loop.
+;
+; CHECK: inner_loop_begin.split:
+; CHECK-NEXT: br label %inner_inner_loop_begin
+;
+; CHECK: inner_inner_loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_a, label %inner_inner_loop_b
+;
+; CHECK: inner_inner_loop_a:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit.split, label %inner_inner_loop_c
+;
+; CHECK: inner_inner_loop_b:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_exit.split, label %inner_inner_loop_c
+;
+; CHECK: inner_inner_loop_c:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_exit.loopexit.split, label %inner_inner_loop_d
+;
+; CHECK: inner_inner_loop_d:
+; CHECK-NEXT: br label %inner_inner_loop_begin
+;
+; CHECK: inner_inner_loop_exit.split:
+; CHECK-NEXT: br label %inner_inner_loop_exit
+
+inner_inner_loop_exit:
+ %a2 = load i32, i32* %a.ptr
+ %v5 = load i1, i1* %ptr
+ br i1 %v5, label %inner_loop_exit, label %inner_loop_begin
+; CHECK: inner_inner_loop_exit:
+; CHECK-NEXT: %[[A2]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_exit.loopexit1, label %inner_loop_begin
+
+inner_loop_exit:
+ br label %loop_begin
+; CHECK: inner_loop_exit.loopexit.split:
+; CHECK-NEXT: br label %inner_loop_exit.loopexit
+;
+; CHECK: inner_loop_exit.loopexit:
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit.loopexit1:
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit:
+; CHECK-NEXT: br label %loop_begin
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a.phi, %inner_inner_loop_a ]
+ %b.lcssa = phi i32 [ %b, %inner_inner_loop_a ]
+ %result = add i32 %a.lcssa, %b.lcssa
+ ret i32 %result
+; CHECK: loop_exit.split:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_inner_loop_a ]
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %inner_inner_loop_a ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_PHI:.*]] = phi i32 [ %[[A_LCSSA]], %loop_exit.split ], [ %[[A_LCSSA_US]], %loop_exit.split.us ]
+; CHECK-NEXT: %[[B_PHI:.*]] = phi i32 [ %[[B_LCSSA]], %loop_exit.split ], [ %[[B_LCSSA_US]], %loop_exit.split.us ]
+; CHECK-NEXT: %[[RESULT:.*]] = add i32 %[[A_PHI]], %[[B_PHI]]
+; CHECK-NEXT: ret i32 %[[RESULT]]
+}
+
+; Same pattern as @test7a but here the original loop becomes a non-loop that
+; can reach multiple exit blocks which are part of different outer loops.
+define i32 @test7b(i1* %ptr, i1* %cond.ptr, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test7b(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+
+loop_begin:
+ %a = load i32, i32* %a.ptr
+ br label %inner_loop_begin
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_begin
+
+inner_loop_begin:
+ %a.phi = phi i32 [ %a, %loop_begin ], [ %a2, %inner_inner_loop_exit ]
+ %cond = load i1, i1* %cond.ptr
+ %b = load i32, i32* %b.ptr
+ br label %inner_inner_loop_begin
+; CHECK: inner_loop_begin:
+; CHECK-NEXT: %[[A_INNER_PHI:.*]] = phi i32 [ %[[A]], %loop_begin ], [ %[[A2:.*]], %inner_inner_loop_exit ]
+; CHECK-NEXT: %[[COND:.*]] = load i1, i1* %cond.ptr
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br i1 %[[COND]], label %inner_loop_begin.split.us, label %inner_loop_begin.split
+
+inner_inner_loop_begin:
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %inner_inner_loop_a, label %inner_inner_loop_b
+
+inner_inner_loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %loop_exit, label %inner_inner_loop_c
+
+inner_inner_loop_b:
+ %v3 = load i1, i1* %ptr
+ br i1 %v3, label %inner_inner_loop_exit, label %inner_inner_loop_c
+
+inner_inner_loop_c:
+ %v4 = load i1, i1* %ptr
+ br i1 %v4, label %inner_loop_exit, label %inner_inner_loop_d
+
+inner_inner_loop_d:
+ br i1 %cond, label %inner_inner_loop_begin, label %inner_loop_exit
+; The cloned copy that continues looping.
+;
+; CHECK: inner_loop_begin.split.us:
+; CHECK-NEXT: br label %inner_inner_loop_begin.us
+;
+; CHECK: inner_inner_loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_a.us, label %inner_inner_loop_b.us
+;
+; CHECK: inner_inner_loop_b.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_exit.split.us, label %inner_inner_loop_c.us
+;
+; CHECK: inner_inner_loop_a.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit.split.us, label %inner_inner_loop_c.us
+;
+; CHECK: inner_inner_loop_c.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_exit.loopexit.split.us, label %inner_inner_loop_d.us
+;
+; CHECK: inner_inner_loop_d.us:
+; CHECK-NEXT: br label %inner_inner_loop_begin.us
+;
+; CHECK: inner_inner_loop_exit.split.us:
+; CHECK-NEXT: br label %inner_inner_loop_exit
+;
+; CHECK: loop_exit.split.us:
+; CHECK-NEXT: %[[A_LCSSA_US:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_inner_loop_a.us ]
+; CHECK-NEXT: %[[B_LCSSA_US:.*]] = phi i32 [ %[[B]], %inner_inner_loop_a.us ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: inner_loop_exit.loopexit.split.us:
+; CHECK-NEXT: br label %inner_loop_exit.loopexit
+;
+; The original copy that now always exits and needs adjustments for exit
+; blocks.
+;
+; CHECK: inner_loop_begin.split:
+; CHECK-NEXT: br label %inner_inner_loop_begin
+;
+; CHECK: inner_inner_loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_a, label %inner_inner_loop_b
+;
+; CHECK: inner_inner_loop_a:
+; CHECK-NEXT: %[[A_NEW_LCSSA:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_inner_loop_begin ]
+; CHECK-NEXT: %[[B_NEW_LCSSA:.*]] = phi i32 [ %[[B]], %inner_inner_loop_begin ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit.split, label %inner_inner_loop_c
+;
+; CHECK: inner_inner_loop_b:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_exit.split, label %inner_inner_loop_c.loopexit
+;
+; CHECK: inner_inner_loop_c.loopexit:
+; CHECK-NEXT: br label %inner_inner_loop_c
+;
+; CHECK: inner_inner_loop_c:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_exit.loopexit.split, label %inner_inner_loop_d
+;
+; CHECK: inner_inner_loop_d:
+; CHECK-NEXT: br label %inner_loop_exit.loopexit.split
+;
+; CHECK: inner_inner_loop_exit.split:
+; CHECK-NEXT: br label %inner_inner_loop_exit
+
+inner_inner_loop_exit:
+ %a2 = load i32, i32* %a.ptr
+ %v5 = load i1, i1* %ptr
+ br i1 %v5, label %inner_loop_exit, label %inner_loop_begin
+; CHECK: inner_inner_loop_exit:
+; CHECK-NEXT: %[[A2]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_exit.loopexit1, label %inner_loop_begin
+
+inner_loop_exit:
+ br label %loop_begin
+; CHECK: inner_loop_exit.loopexit.split:
+; CHECK-NEXT: br label %inner_loop_exit.loopexit
+;
+; CHECK: inner_loop_exit.loopexit:
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit.loopexit1:
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit:
+; CHECK-NEXT: br label %loop_begin
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a.phi, %inner_inner_loop_a ]
+ %b.lcssa = phi i32 [ %b, %inner_inner_loop_a ]
+ %result = add i32 %a.lcssa, %b.lcssa
+ ret i32 %result
+; CHECK: loop_exit.split:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A_NEW_LCSSA]], %inner_inner_loop_a ]
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B_NEW_LCSSA]], %inner_inner_loop_a ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_PHI:.*]] = phi i32 [ %[[A_LCSSA]], %loop_exit.split ], [ %[[A_LCSSA_US]], %loop_exit.split.us ]
+; CHECK-NEXT: %[[B_PHI:.*]] = phi i32 [ %[[B_LCSSA]], %loop_exit.split ], [ %[[B_LCSSA_US]], %loop_exit.split.us ]
+; CHECK-NEXT: %[[RESULT:.*]] = add i32 %[[A_PHI]], %[[B_PHI]]
+; CHECK-NEXT: ret i32 %[[RESULT]]
+}
+
+; Test that when the exit block set of an inner loop changes to start at a less
+; high level of the loop nest we correctly hoist the loop up the nest.
+define i32 @test8a(i1* %ptr, i1* %cond.ptr, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test8a(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+
+loop_begin:
+ %a = load i32, i32* %a.ptr
+ br label %inner_loop_begin
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_begin
+
+inner_loop_begin:
+ %a.phi = phi i32 [ %a, %loop_begin ], [ %a2, %inner_inner_loop_exit ]
+ %cond = load i1, i1* %cond.ptr
+ %b = load i32, i32* %b.ptr
+ br label %inner_inner_loop_begin
+; CHECK: inner_loop_begin:
+; CHECK-NEXT: %[[A_INNER_PHI:.*]] = phi i32 [ %[[A]], %loop_begin ], [ %[[A2:.*]], %inner_inner_loop_exit ]
+; CHECK-NEXT: %[[COND:.*]] = load i1, i1* %cond.ptr
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br i1 %[[COND]], label %inner_loop_begin.split.us, label %inner_loop_begin.split
+
+inner_inner_loop_begin:
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %inner_inner_loop_a, label %inner_inner_loop_b
+
+inner_inner_loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %inner_inner_loop_latch, label %inner_loop_exit
+
+inner_inner_loop_b:
+ br i1 %cond, label %inner_inner_loop_latch, label %inner_inner_loop_exit
+
+inner_inner_loop_latch:
+ br label %inner_inner_loop_begin
+; The cloned region is now an exit from the inner loop.
+;
+; CHECK: inner_loop_begin.split.us:
+; CHECK-NEXT: %[[A_INNER_INNER_LCSSA:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_loop_begin ]
+; CHECK-NEXT: br label %inner_inner_loop_begin.us
+;
+; CHECK: inner_inner_loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_a.us, label %inner_inner_loop_b.us
+;
+; CHECK: inner_inner_loop_b.us:
+; CHECK-NEXT: br label %inner_inner_loop_latch.us
+;
+; CHECK: inner_inner_loop_a.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_latch.us, label %inner_loop_exit.loopexit.split.us
+;
+; CHECK: inner_inner_loop_latch.us:
+; CHECK-NEXT: br label %inner_inner_loop_begin.us
+;
+; CHECK: inner_loop_exit.loopexit.split.us:
+; CHECK-NEXT: %[[A_INNER_LCSSA_US:.*]] = phi i32 [ %[[A_INNER_INNER_LCSSA]], %inner_inner_loop_a.us ]
+; CHECK-NEXT: br label %inner_loop_exit.loopexit
+;
+; The original region exits the loop earlier.
+;
+; CHECK: inner_loop_begin.split:
+; CHECK-NEXT: br label %inner_inner_loop_begin
+;
+; CHECK: inner_inner_loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_a, label %inner_inner_loop_b
+;
+; CHECK: inner_inner_loop_a:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_latch, label %inner_loop_exit.loopexit.split
+;
+; CHECK: inner_inner_loop_b:
+; CHECK-NEXT: br label %inner_inner_loop_exit
+;
+; CHECK: inner_inner_loop_latch:
+; CHECK-NEXT: br label %inner_inner_loop_begin
+
+inner_inner_loop_exit:
+ %a2 = load i32, i32* %a.ptr
+ %v4 = load i1, i1* %ptr
+ br i1 %v4, label %inner_loop_exit, label %inner_loop_begin
+; CHECK: inner_inner_loop_exit:
+; CHECK-NEXT: %[[A2]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_exit.loopexit1, label %inner_loop_begin
+
+inner_loop_exit:
+ %v5 = load i1, i1* %ptr
+ br i1 %v5, label %loop_exit, label %loop_begin
+; CHECK: inner_loop_exit.loopexit.split:
+; CHECK-NEXT: %[[A_INNER_LCSSA:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_inner_loop_a ]
+; CHECK-NEXT: br label %inner_loop_exit.loopexit
+;
+; CHECK: inner_loop_exit.loopexit:
+; CHECK-NEXT: %[[A_INNER_US_PHI:.*]] = phi i32 [ %[[A_INNER_LCSSA]], %inner_loop_exit.loopexit.split ], [ %[[A_INNER_LCSSA_US]], %inner_loop_exit.loopexit.split.us ]
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit.loopexit1:
+; CHECK-NEXT: %[[A_INNER_LCSSA2:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_inner_loop_exit ]
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit:
+; CHECK-NEXT: %[[A_INNER_PHI:.*]] = phi i32 [ %[[A_INNER_LCSSA2]], %inner_loop_exit.loopexit1 ], [ %[[A_INNER_US_PHI]], %inner_loop_exit.loopexit ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit, label %loop_begin
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a.phi, %inner_loop_exit ]
+ ret i32 %a.lcssa
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_loop_exit ]
+; CHECK-NEXT: ret i32 %[[A_LCSSA]]
+}
+
+; Same pattern as @test8a but where the original loop looses an exit block and
+; needs to be hoisted up the nest.
+define i32 @test8b(i1* %ptr, i1* %cond.ptr, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test8b(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+
+loop_begin:
+ %a = load i32, i32* %a.ptr
+ br label %inner_loop_begin
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_begin
+
+inner_loop_begin:
+ %a.phi = phi i32 [ %a, %loop_begin ], [ %a2, %inner_inner_loop_exit ]
+ %cond = load i1, i1* %cond.ptr
+ %b = load i32, i32* %b.ptr
+ br label %inner_inner_loop_begin
+; CHECK: inner_loop_begin:
+; CHECK-NEXT: %[[A_INNER_PHI:.*]] = phi i32 [ %[[A]], %loop_begin ], [ %[[A2:.*]], %inner_inner_loop_exit ]
+; CHECK-NEXT: %[[COND:.*]] = load i1, i1* %cond.ptr
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br i1 %[[COND]], label %inner_loop_begin.split.us, label %inner_loop_begin.split
+
+inner_inner_loop_begin:
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %inner_inner_loop_a, label %inner_inner_loop_b
+
+inner_inner_loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %inner_inner_loop_latch, label %inner_loop_exit
+
+inner_inner_loop_b:
+ br i1 %cond, label %inner_inner_loop_exit, label %inner_inner_loop_latch
+
+inner_inner_loop_latch:
+ br label %inner_inner_loop_begin
+; The cloned region is similar to before but with one earlier exit.
+;
+; CHECK: inner_loop_begin.split.us:
+; CHECK-NEXT: br label %inner_inner_loop_begin.us
+;
+; CHECK: inner_inner_loop_begin.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_a.us, label %inner_inner_loop_b.us
+;
+; CHECK: inner_inner_loop_b.us:
+; CHECK-NEXT: br label %inner_inner_loop_exit.split.us
+;
+; CHECK: inner_inner_loop_a.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_latch.us, label %inner_loop_exit.loopexit.split.us
+;
+; CHECK: inner_inner_loop_latch.us:
+; CHECK-NEXT: br label %inner_inner_loop_begin.us
+;
+; CHECK: inner_inner_loop_exit.split.us:
+; CHECK-NEXT: br label %inner_inner_loop_exit
+;
+; CHECK: inner_loop_exit.loopexit.split.us:
+; CHECK-NEXT: %[[A_INNER_LCSSA_US:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_inner_loop_a.us ]
+; CHECK-NEXT: br label %inner_loop_exit.loopexit
+;
+; The original region is now an exit in the preheader.
+;
+; CHECK: inner_loop_begin.split:
+; CHECK-NEXT: %[[A_INNER_INNER_LCSSA:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_loop_begin ]
+; CHECK-NEXT: br label %inner_inner_loop_begin
+;
+; CHECK: inner_inner_loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_a, label %inner_inner_loop_b
+;
+; CHECK: inner_inner_loop_a:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_latch, label %inner_loop_exit.loopexit.split
+;
+; CHECK: inner_inner_loop_b:
+; CHECK-NEXT: br label %inner_inner_loop_latch
+;
+; CHECK: inner_inner_loop_latch:
+; CHECK-NEXT: br label %inner_inner_loop_begin
+
+inner_inner_loop_exit:
+ %a2 = load i32, i32* %a.ptr
+ %v4 = load i1, i1* %ptr
+ br i1 %v4, label %inner_loop_exit, label %inner_loop_begin
+; CHECK: inner_inner_loop_exit:
+; CHECK-NEXT: %[[A2]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_exit.loopexit1, label %inner_loop_begin
+
+inner_loop_exit:
+ %v5 = load i1, i1* %ptr
+ br i1 %v5, label %loop_exit, label %loop_begin
+; CHECK: inner_loop_exit.loopexit.split:
+; CHECK-NEXT: %[[A_INNER_LCSSA:.*]] = phi i32 [ %[[A_INNER_INNER_LCSSA]], %inner_inner_loop_a ]
+; CHECK-NEXT: br label %inner_loop_exit.loopexit
+;
+; CHECK: inner_loop_exit.loopexit:
+; CHECK-NEXT: %[[A_INNER_US_PHI:.*]] = phi i32 [ %[[A_INNER_LCSSA]], %inner_loop_exit.loopexit.split ], [ %[[A_INNER_LCSSA_US]], %inner_loop_exit.loopexit.split.us ]
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit.loopexit1:
+; CHECK-NEXT: %[[A_INNER_LCSSA2:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_inner_loop_exit ]
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit:
+; CHECK-NEXT: %[[A_INNER_PHI:.*]] = phi i32 [ %[[A_INNER_LCSSA2]], %inner_loop_exit.loopexit1 ], [ %[[A_INNER_US_PHI]], %inner_loop_exit.loopexit ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit, label %loop_begin
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a.phi, %inner_loop_exit ]
+ ret i32 %a.lcssa
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_loop_exit ]
+; CHECK-NEXT: ret i32 %[[A_LCSSA]]
+}
+
+; Test for when unswitching produces a clone of an inner loop but
+; the clone no longer has an exiting edge *at all* and loops infinitely.
+; Because it doesn't ever exit to the outer loop it is no longer an inner loop
+; but needs to be hoisted up the nest to be a top-level loop.
+define i32 @test9a(i1* %ptr, i1* %cond.ptr, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test9a(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+
+loop_begin:
+ %b = load i32, i32* %b.ptr
+ %cond = load i1, i1* %cond.ptr
+ br label %inner_loop_begin
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: %[[COND:.*]] = load i1, i1* %cond.ptr
+; CHECK-NEXT: br i1 %[[COND]], label %loop_begin.split.us, label %loop_begin.split
+
+inner_loop_begin:
+ %a = load i32, i32* %a.ptr
+ br i1 %cond, label %inner_loop_latch, label %inner_loop_exit
+
+inner_loop_latch:
+ call void @sink1(i32 %b)
+ br label %inner_loop_begin
+; The cloned inner loop ends up as an infinite loop and thus being a top-level
+; loop with the preheader as an exit block of the outer loop.
+;
+; CHECK: loop_begin.split.us
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %loop_begin ]
+; CHECK-NEXT: br label %inner_loop_begin.us
+;
+; CHECK: inner_loop_begin.us:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_latch.us
+;
+; CHECK: inner_loop_latch.us:
+; CHECK-NEXT: call void @sink1(i32 %[[B_LCSSA]])
+; CHECK-NEXT: br label %inner_loop_begin.us
+;
+; The original loop becomes boring non-loop code.
+;
+; CHECK: loop_begin.split
+; CHECK-NEXT: br label %inner_loop_begin
+;
+; CHECK: inner_loop_begin:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_exit
+
+inner_loop_exit:
+ %a.inner_lcssa = phi i32 [ %a, %inner_loop_begin ]
+ %v = load i1, i1* %ptr
+ br i1 %v, label %loop_begin, label %loop_exit
+; CHECK: inner_loop_exit:
+; CHECK-NEXT: %[[A_INNER_LCSSA:.*]] = phi i32 [ %[[A]], %inner_loop_begin ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a.inner_lcssa, %inner_loop_exit ]
+ ret i32 %a.lcssa
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A_INNER_LCSSA]], %inner_loop_exit ]
+; CHECK-NEXT: ret i32 %[[A_LCSSA]]
+}
+
+; The same core pattern as @test9a, but instead of the cloned loop becoming an
+; infinite loop, the original loop has its only exit unswitched and the
+; original loop becomes infinite and must be hoisted out of the loop nest.
+define i32 @test9b(i1* %ptr, i1* %cond.ptr, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test9b(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+
+loop_begin:
+ %b = load i32, i32* %b.ptr
+ %cond = load i1, i1* %cond.ptr
+ br label %inner_loop_begin
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: %[[COND:.*]] = load i1, i1* %cond.ptr
+; CHECK-NEXT: br i1 %[[COND]], label %loop_begin.split.us, label %loop_begin.split
+
+inner_loop_begin:
+ %a = load i32, i32* %a.ptr
+ br i1 %cond, label %inner_loop_exit, label %inner_loop_latch
+
+inner_loop_latch:
+ call void @sink1(i32 %b)
+ br label %inner_loop_begin
+; The cloned inner loop becomes a boring non-loop.
+;
+; CHECK: loop_begin.split.us
+; CHECK-NEXT: br label %inner_loop_begin.us
+;
+; CHECK: inner_loop_begin.us:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_exit.split.us
+;
+; CHECK: inner_loop_exit.split.us
+; CHECK-NEXT: %[[A_INNER_LCSSA_US:.*]] = phi i32 [ %[[A]], %inner_loop_begin.us ]
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; The original loop becomes an infinite loop and thus a top-level loop with the
+; preheader as an exit block for the outer loop.
+;
+; CHECK: loop_begin.split
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %loop_begin ]
+; CHECK-NEXT: br label %inner_loop_begin
+;
+; CHECK: inner_loop_begin:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_latch
+;
+; CHECK: inner_loop_latch:
+; CHECK-NEXT: call void @sink1(i32 %[[B_LCSSA]])
+; CHECK-NEXT: br label %inner_loop_begin
+
+inner_loop_exit:
+ %a.inner_lcssa = phi i32 [ %a, %inner_loop_begin ]
+ %v = load i1, i1* %ptr
+ br i1 %v, label %loop_begin, label %loop_exit
+; CHECK: inner_loop_exit:
+; CHECK-NEXT: %[[A_INNER_LCSSA:.*]] = phi i32 [ %[[A_INNER_LCSSA_US]], %inner_loop_exit.split.us ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a.inner_lcssa, %inner_loop_exit ]
+ ret i32 %a.lcssa
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A_INNER_LCSSA]], %inner_loop_exit ]
+; CHECK-NEXT: ret i32 %[[A_LCSSA]]
+}
+
+; Test that requires re-forming dedicated exits for the cloned loop.
+define i32 @test10a(i1* %ptr, i1 %cond, i32* %a.ptr) {
+; CHECK-LABEL: @test10a(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond, label %entry.split.us, label %entry.split
+
+loop_begin:
+ %a = load i32, i32* %a.ptr
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %loop_a, label %loop_b
+
+loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %loop_exit, label %loop_begin
+
+loop_b:
+ br i1 %cond, label %loop_exit, label %loop_begin
+; The cloned loop with one edge as a direct exit.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_a.us, label %loop_b.us
+;
+; CHECK: loop_b.us:
+; CHECK-NEXT: %[[A_LCSSA_B:.*]] = phi i32 [ %[[A]], %loop_begin.us ]
+; CHECK-NEXT: br label %loop_exit.split.us
+;
+; CHECK: loop_a.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit.split.us.loopexit, label %loop_begin.backedge.us
+;
+; CHECK: loop_begin.backedge.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_exit.split.us.loopexit:
+; CHECK-NEXT: %[[A_LCSSA_A:.*]] = phi i32 [ %[[A]], %loop_a.us ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit.split.us:
+; CHECK-NEXT: %[[A_PHI_US:.*]] = phi i32 [ %[[A_LCSSA_B]], %loop_b.us ], [ %[[A_LCSSA_A]], %loop_exit.split.us.loopexit ]
+; CHECK-NEXT: br label %loop_exit
+
+; The original loop without one 'loop_exit' edge.
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_a, label %loop_b
+;
+; CHECK: loop_a:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit.split, label %loop_begin.backedge
+;
+; CHECK: loop_begin.backedge:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_b:
+; CHECK-NEXT: br label %loop_begin.backedge
+;
+; CHECK: loop_exit.split:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A]], %loop_a ]
+; CHECK-NEXT: br label %loop_exit
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a, %loop_a ], [ %a, %loop_b ]
+ ret i32 %a.lcssa
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_PHI:.*]] = phi i32 [ %[[A_LCSSA]], %loop_exit.split ], [ %[[A_PHI_US]], %loop_exit.split.us ]
+; CHECK-NEXT: ret i32 %[[AB_PHI]]
+}
+
+; Test that requires re-forming dedicated exits for the original loop.
+define i32 @test10b(i1* %ptr, i1 %cond, i32* %a.ptr) {
+; CHECK-LABEL: @test10b(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond, label %entry.split.us, label %entry.split
+
+loop_begin:
+ %a = load i32, i32* %a.ptr
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %loop_a, label %loop_b
+
+loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %loop_begin, label %loop_exit
+
+loop_b:
+ br i1 %cond, label %loop_begin, label %loop_exit
+; The cloned loop without one of the exits.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_a.us, label %loop_b.us
+;
+; CHECK: loop_b.us:
+; CHECK-NEXT: br label %loop_begin.backedge.us
+;
+; CHECK: loop_a.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin.backedge.us, label %loop_exit.split.us
+;
+; CHECK: loop_begin.backedge.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_exit.split.us:
+; CHECK-NEXT: %[[A_LCSSA_US:.*]] = phi i32 [ %[[A]], %loop_a.us ]
+; CHECK-NEXT: br label %loop_exit
+
+; The original loop without one 'loop_exit' edge.
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_a, label %loop_b
+;
+; CHECK: loop_a:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin.backedge, label %loop_exit.split.loopexit
+;
+; CHECK: loop_begin.backedge:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_b:
+; CHECK-NEXT: %[[A_LCSSA_B:.*]] = phi i32 [ %[[A]], %loop_begin ]
+; CHECK-NEXT: br label %loop_exit.split
+;
+; CHECK: loop_exit.split.loopexit:
+; CHECK-NEXT: %[[A_LCSSA_A:.*]] = phi i32 [ %[[A]], %loop_a ]
+; CHECK-NEXT: br label %loop_exit.split
+;
+; CHECK: loop_exit.split:
+; CHECK-NEXT: %[[A_PHI_SPLIT:.*]] = phi i32 [ %[[A_LCSSA_B]], %loop_b ], [ %[[A_LCSSA_A]], %loop_exit.split.loopexit ]
+; CHECK-NEXT: br label %loop_exit
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a, %loop_a ], [ %a, %loop_b ]
+ ret i32 %a.lcssa
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_PHI:.*]] = phi i32 [ %[[A_PHI_SPLIT]], %loop_exit.split ], [ %[[A_LCSSA_US]], %loop_exit.split.us ]
+; CHECK-NEXT: ret i32 %[[AB_PHI]]
+}
+
+; Check that if a cloned inner loop after unswitching doesn't loop and directly
+; exits even an outer loop, we don't add the cloned preheader to the outer
+; loop and do add the needed LCSSA phi nodes for the new exit block from the
+; outer loop.
+define i32 @test11a(i1* %ptr, i1* %cond.ptr, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test11a(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+
+loop_begin:
+ %b = load i32, i32* %b.ptr
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %loop_latch, label %inner_loop_ph
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_latch, label %inner_loop_ph
+
+inner_loop_ph:
+ %cond = load i1, i1* %cond.ptr
+ br label %inner_loop_begin
+; CHECK: inner_loop_ph:
+; CHECK-NEXT: %[[COND:.*]] = load i1, i1* %cond.ptr
+; CHECK-NEXT: br i1 %[[COND]], label %inner_loop_ph.split.us, label %inner_loop_ph.split
+
+inner_loop_begin:
+ call void @sink1(i32 %b)
+ %a = load i32, i32* %a.ptr
+ br i1 %cond, label %loop_exit, label %inner_loop_a
+
+inner_loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %inner_loop_exit, label %inner_loop_begin
+; The cloned path doesn't actually loop and is an exit from the outer loop as
+; well.
+;
+; CHECK: inner_loop_ph.split.us:
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %inner_loop_ph ]
+; CHECK-NEXT: br label %inner_loop_begin.us
+;
+; CHECK: inner_loop_begin.us:
+; CHECK-NEXT: call void @sink1(i32 %[[B_LCSSA]])
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_exit.loopexit.split.us
+;
+; CHECK: loop_exit.loopexit.split.us:
+; CHECK-NEXT: %[[A_INNER_LCSSA_US:.*]] = phi i32 [ %[[A]], %inner_loop_begin.us ]
+; CHECK-NEXT: br label %loop_exit.loopexit
+;
+; The original remains a loop losing the exit edge.
+;
+; CHECK: inner_loop_ph.split:
+; CHECK-NEXT: br label %inner_loop_begin
+;
+; CHECK: inner_loop_begin:
+; CHECK-NEXT: call void @sink1(i32 %[[B]])
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_a
+;
+; CHECK: inner_loop_a:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_exit, label %inner_loop_begin
+
+inner_loop_exit:
+ %a.inner_lcssa = phi i32 [ %a, %inner_loop_a ]
+ %v3 = load i1, i1* %ptr
+ br i1 %v3, label %loop_latch, label %loop_exit
+; CHECK: inner_loop_exit:
+; CHECK-NEXT: %[[A_INNER_LCSSA:.*]] = phi i32 [ %[[A]], %inner_loop_a ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_latch, label %loop_exit.loopexit1
+
+loop_latch:
+ br label %loop_begin
+; CHECK: loop_latch:
+; CHECK-NEXT: br label %loop_begin
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a, %inner_loop_begin ], [ %a.inner_lcssa, %inner_loop_exit ]
+ ret i32 %a.lcssa
+; CHECK: loop_exit.loopexit:
+; CHECK-NEXT: %[[A_LCSSA_US:.*]] = phi i32 [ %[[A_INNER_LCSSA_US]], %loop_exit.loopexit.split.us ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit.loopexit1:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A_INNER_LCSSA]], %inner_loop_exit ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_PHI:.*]] = phi i32 [ %[[A_LCSSA_US]], %loop_exit.loopexit ], [ %[[A_LCSSA]], %loop_exit.loopexit1 ]
+; CHECK-NEXT: ret i32 %[[A_PHI]]
+}
+
+; Check that if the original inner loop after unswitching doesn't loop and
+; directly exits even an outer loop, we remove the original preheader from the
+; outer loop and add needed LCSSA phi nodes for the new exit block from the
+; outer loop.
+define i32 @test11b(i1* %ptr, i1* %cond.ptr, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test11b(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+
+loop_begin:
+ %b = load i32, i32* %b.ptr
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %loop_latch, label %inner_loop_ph
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_latch, label %inner_loop_ph
+
+inner_loop_ph:
+ %cond = load i1, i1* %cond.ptr
+ br label %inner_loop_begin
+; CHECK: inner_loop_ph:
+; CHECK-NEXT: %[[COND:.*]] = load i1, i1* %cond.ptr
+; CHECK-NEXT: br i1 %[[COND]], label %inner_loop_ph.split.us, label %inner_loop_ph.split
+
+inner_loop_begin:
+ call void @sink1(i32 %b)
+ %a = load i32, i32* %a.ptr
+ br i1 %cond, label %inner_loop_a, label %loop_exit
+
+inner_loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %inner_loop_exit, label %inner_loop_begin
+; The cloned path continues to loop without the exit out of the entire nest.
+;
+; CHECK: inner_loop_ph.split.us:
+; CHECK-NEXT: br label %inner_loop_begin.us
+;
+; CHECK: inner_loop_begin.us:
+; CHECK-NEXT: call void @sink1(i32 %[[B]])
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_a.us
+;
+; CHECK: inner_loop_a.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_exit.split.us, label %inner_loop_begin.us
+;
+; CHECK: inner_loop_exit.split.us:
+; CHECK-NEXT: %[[A_INNER_LCSSA_US:.*]] = phi i32 [ %[[A]], %inner_loop_a.us ]
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; The original remains a loop losing the exit edge.
+;
+; CHECK: inner_loop_ph.split:
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %inner_loop_ph ]
+; CHECK-NEXT: br label %inner_loop_begin
+;
+; CHECK: inner_loop_begin:
+; CHECK-NEXT: call void @sink1(i32 %[[B_LCSSA]])
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %loop_exit.loopexit
+
+inner_loop_exit:
+ %a.inner_lcssa = phi i32 [ %a, %inner_loop_a ]
+ %v3 = load i1, i1* %ptr
+ br i1 %v3, label %loop_latch, label %loop_exit
+; CHECK: inner_loop_exit:
+; CHECK-NEXT: %[[A_INNER_PHI:.*]] = phi i32 [ %[[A_INNER_LCSSA_US]], %inner_loop_exit.split.us ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_latch, label %loop_exit.loopexit1
+
+loop_latch:
+ br label %loop_begin
+; CHECK: loop_latch:
+; CHECK-NEXT: br label %loop_begin
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a, %inner_loop_begin ], [ %a.inner_lcssa, %inner_loop_exit ]
+ ret i32 %a.lcssa
+; CHECK: loop_exit.loopexit:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A]], %inner_loop_begin ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit.loopexit1:
+; CHECK-NEXT: %[[A_LCSSA_US:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_loop_exit ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_PHI:.*]] = phi i32 [ %[[A_LCSSA]], %loop_exit.loopexit ], [ %[[A_LCSSA_US]], %loop_exit.loopexit1 ]
+; CHECK-NEXT: ret i32 %[[A_PHI]]
+}
+
+; Like test11a, but checking that when the whole thing is wrapped in yet
+; another loop, we correctly attribute the cloned preheader to that outermost
+; loop rather than only handling the case where the preheader is not in any loop
+; at all.
+define i32 @test12a(i1* %ptr, i1* %cond.ptr, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test12a(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+
+loop_begin:
+ br label %inner_loop_begin
+; CHECK: loop_begin:
+; CHECK-NEXT: br label %inner_loop_begin
+
+inner_loop_begin:
+ %b = load i32, i32* %b.ptr
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %inner_loop_latch, label %inner_inner_loop_ph
+; CHECK: inner_loop_begin:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_latch, label %inner_inner_loop_ph
+
+inner_inner_loop_ph:
+ %cond = load i1, i1* %cond.ptr
+ br label %inner_inner_loop_begin
+; CHECK: inner_inner_loop_ph:
+; CHECK-NEXT: %[[COND:.*]] = load i1, i1* %cond.ptr
+; CHECK-NEXT: br i1 %[[COND]], label %inner_inner_loop_ph.split.us, label %inner_inner_loop_ph.split
+
+inner_inner_loop_begin:
+ call void @sink1(i32 %b)
+ %a = load i32, i32* %a.ptr
+ br i1 %cond, label %inner_loop_exit, label %inner_inner_loop_a
+
+inner_inner_loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %inner_inner_loop_exit, label %inner_inner_loop_begin
+; The cloned path doesn't actually loop and is an exit from the outer loop as
+; well.
+;
+; CHECK: inner_inner_loop_ph.split.us:
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %inner_inner_loop_ph ]
+; CHECK-NEXT: br label %inner_inner_loop_begin.us
+;
+; CHECK: inner_inner_loop_begin.us:
+; CHECK-NEXT: call void @sink1(i32 %[[B_LCSSA]])
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_exit.loopexit.split.us
+;
+; CHECK: inner_loop_exit.loopexit.split.us:
+; CHECK-NEXT: %[[A_INNER_INNER_LCSSA_US:.*]] = phi i32 [ %[[A]], %inner_inner_loop_begin.us ]
+; CHECK-NEXT: br label %inner_loop_exit.loopexit
+;
+; The original remains a loop losing the exit edge.
+;
+; CHECK: inner_inner_loop_ph.split:
+; CHECK-NEXT: br label %inner_inner_loop_begin
+;
+; CHECK: inner_inner_loop_begin:
+; CHECK-NEXT: call void @sink1(i32 %[[B]])
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_inner_loop_a
+;
+; CHECK: inner_inner_loop_a:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_exit, label %inner_inner_loop_begin
+
+inner_inner_loop_exit:
+ %a.inner_inner_lcssa = phi i32 [ %a, %inner_inner_loop_a ]
+ %v3 = load i1, i1* %ptr
+ br i1 %v3, label %inner_loop_latch, label %inner_loop_exit
+; CHECK: inner_inner_loop_exit:
+; CHECK-NEXT: %[[A_INNER_INNER_LCSSA:.*]] = phi i32 [ %[[A]], %inner_inner_loop_a ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_latch, label %inner_loop_exit.loopexit1
+
+inner_loop_latch:
+ br label %inner_loop_begin
+; CHECK: inner_loop_latch:
+; CHECK-NEXT: br label %inner_loop_begin
+
+inner_loop_exit:
+ %a.inner_lcssa = phi i32 [ %a, %inner_inner_loop_begin ], [ %a.inner_inner_lcssa, %inner_inner_loop_exit ]
+ %v4 = load i1, i1* %ptr
+ br i1 %v4, label %loop_begin, label %loop_exit
+; CHECK: inner_loop_exit.loopexit:
+; CHECK-NEXT: %[[A_INNER_LCSSA_US:.*]] = phi i32 [ %[[A_INNER_INNER_LCSSA_US]], %inner_loop_exit.loopexit.split.us ]
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit.loopexit1:
+; CHECK-NEXT: %[[A_INNER_LCSSA:.*]] = phi i32 [ %[[A_INNER_INNER_LCSSA]], %inner_inner_loop_exit ]
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit:
+; CHECK-NEXT: %[[A_INNER_PHI:.*]] = phi i32 [ %[[A_INNER_LCSSA_US]], %inner_loop_exit.loopexit ], [ %[[A_INNER_LCSSA]], %inner_loop_exit.loopexit1 ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a.inner_lcssa, %inner_loop_exit ]
+ ret i32 %a.lcssa
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_loop_exit ]
+; CHECK-NEXT: ret i32 %[[A_LCSSA]]
+}
+
+; Like test11b, but checking that when the whole thing is wrapped in yet
+; another loop, we correctly sink the preheader to the outermost loop rather
+; than only handling the case where the preheader is completely removed from
+; a loop.
+define i32 @test12b(i1* %ptr, i1* %cond.ptr, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test12b(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+
+loop_begin:
+ br label %inner_loop_begin
+; CHECK: loop_begin:
+; CHECK-NEXT: br label %inner_loop_begin
+
+inner_loop_begin:
+ %b = load i32, i32* %b.ptr
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %inner_loop_latch, label %inner_inner_loop_ph
+; CHECK: inner_loop_begin:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_latch, label %inner_inner_loop_ph
+
+inner_inner_loop_ph:
+ %cond = load i1, i1* %cond.ptr
+ br label %inner_inner_loop_begin
+; CHECK: inner_inner_loop_ph:
+; CHECK-NEXT: %[[COND:.*]] = load i1, i1* %cond.ptr
+; CHECK-NEXT: br i1 %[[COND]], label %inner_inner_loop_ph.split.us, label %inner_inner_loop_ph.split
+
+inner_inner_loop_begin:
+ call void @sink1(i32 %b)
+ %a = load i32, i32* %a.ptr
+ br i1 %cond, label %inner_inner_loop_a, label %inner_loop_exit
+
+inner_inner_loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %inner_inner_loop_exit, label %inner_inner_loop_begin
+; The cloned path continues to loop without the exit out of the entire nest.
+;
+; CHECK: inner_inner_loop_ph.split.us:
+; CHECK-NEXT: br label %inner_inner_loop_begin.us
+;
+; CHECK: inner_inner_loop_begin.us:
+; CHECK-NEXT: call void @sink1(i32 %[[B]])
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_inner_loop_a.us
+;
+; CHECK: inner_inner_loop_a.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_inner_loop_exit.split.us, label %inner_inner_loop_begin.us
+;
+; CHECK: inner_inner_loop_exit.split.us:
+; CHECK-NEXT: %[[A_INNER_INNER_LCSSA_US:.*]] = phi i32 [ %[[A]], %inner_inner_loop_a.us ]
+; CHECK-NEXT: br label %inner_inner_loop_exit
+;
+; The original remains a loop losing the exit edge.
+;
+; CHECK: inner_inner_loop_ph.split:
+; CHECK-NEXT: %[[B_LCSSA:.*]] = phi i32 [ %[[B]], %inner_inner_loop_ph ]
+; CHECK-NEXT: br label %inner_inner_loop_begin
+;
+; CHECK: inner_inner_loop_begin:
+; CHECK-NEXT: call void @sink1(i32 %[[B_LCSSA]])
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: br label %inner_loop_exit.loopexit
+
+inner_inner_loop_exit:
+ %a.inner_inner_lcssa = phi i32 [ %a, %inner_inner_loop_a ]
+ %v3 = load i1, i1* %ptr
+ br i1 %v3, label %inner_loop_latch, label %inner_loop_exit
+; CHECK: inner_inner_loop_exit:
+; CHECK-NEXT: %[[A_INNER_INNER_PHI:.*]] = phi i32 [ %[[A_INNER_INNER_LCSSA_US]], %inner_inner_loop_exit.split.us ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %inner_loop_latch, label %inner_loop_exit.loopexit1
+
+inner_loop_latch:
+ br label %inner_loop_begin
+; CHECK: inner_loop_latch:
+; CHECK-NEXT: br label %inner_loop_begin
+
+inner_loop_exit:
+ %a.inner_lcssa = phi i32 [ %a, %inner_inner_loop_begin ], [ %a.inner_inner_lcssa, %inner_inner_loop_exit ]
+ %v4 = load i1, i1* %ptr
+ br i1 %v4, label %loop_begin, label %loop_exit
+; CHECK: inner_loop_exit.loopexit:
+; CHECK-NEXT: %[[A_INNER_LCSSA:.*]] = phi i32 [ %[[A]], %inner_inner_loop_begin ]
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit.loopexit1:
+; CHECK-NEXT: %[[A_INNER_LCSSA_US:.*]] = phi i32 [ %[[A_INNER_INNER_PHI]], %inner_inner_loop_exit ]
+; CHECK-NEXT: br label %inner_loop_exit
+;
+; CHECK: inner_loop_exit:
+; CHECK-NEXT: %[[A_INNER_PHI:.*]] = phi i32 [ %[[A_INNER_LCSSA]], %inner_loop_exit.loopexit ], [ %[[A_INNER_LCSSA_US]], %inner_loop_exit.loopexit1 ]
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_begin, label %loop_exit
+
+loop_exit:
+ %a.lcssa = phi i32 [ %a.inner_lcssa, %inner_loop_exit ]
+ ret i32 %a.lcssa
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A_INNER_PHI]], %inner_loop_exit ]
+; CHECK-NEXT: ret i32 %[[A_LCSSA]]
+}
+
+; Test where the cloned loop has an inner loop that has to be traversed to form
+; the cloned loop, and where this inner loop has multiple blocks, and where the
+; exiting block that connects the inner loop to the cloned loop is not the header
+; block. This ensures that we correctly handle interesting corner cases of
+; traversing back to the header when establishing the cloned loop.
+define i32 @test13a(i1* %ptr, i1 %cond, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test13a(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond, label %entry.split.us, label %entry.split
+
+loop_begin:
+ %a = load i32, i32* %a.ptr
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %loop_a, label %loop_b
+
+loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %loop_exit, label %loop_latch
+
+loop_b:
+ %b = load i32, i32* %b.ptr
+ br i1 %cond, label %loop_b_inner_ph, label %loop_exit
+
+loop_b_inner_ph:
+ br label %loop_b_inner_header
+
+loop_b_inner_header:
+ %v3 = load i1, i1* %ptr
+ br i1 %v3, label %loop_b_inner_latch, label %loop_b_inner_body
+
+loop_b_inner_body:
+ %v4 = load i1, i1* %ptr
+ br i1 %v4, label %loop_b_inner_latch, label %loop_b_inner_exit
+
+loop_b_inner_latch:
+ br label %loop_b_inner_header
+
+loop_b_inner_exit:
+ br label %loop_latch
+
+loop_latch:
+ br label %loop_begin
+; The cloned loop contains an inner loop within it.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_a.us, label %loop_b.us
+;
+; CHECK: loop_b.us:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br label %loop_b_inner_ph.us
+;
+; CHECK: loop_b_inner_ph.us:
+; CHECK-NEXT: br label %loop_b_inner_header.us
+;
+; CHECK: loop_b_inner_header.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_b_inner_latch.us, label %loop_b_inner_body.us
+;
+; CHECK: loop_b_inner_body.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_b_inner_latch.us, label %loop_b_inner_exit.us
+;
+; CHECK: loop_b_inner_exit.us:
+; CHECK-NEXT: br label %loop_latch.us
+;
+; CHECK: loop_b_inner_latch.us:
+; CHECK-NEXT: br label %loop_b_inner_header.us
+;
+; CHECK: loop_a.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit.split.us, label %loop_latch.us
+;
+; CHECK: loop_latch.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_exit.split.us:
+; CHECK-NEXT: %[[A_LCSSA_US:.*]] = phi i32 [ %[[A]], %loop_a.us ]
+; CHECK-NEXT: br label %loop_exit
+;
+; And the original loop no longer contains an inner loop.
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_a, label %loop_b
+;
+; CHECK: loop_a:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit.split.loopexit, label %loop_latch
+;
+; CHECK: loop_b:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br label %loop_exit.split
+;
+; CHECK: loop_latch:
+; CHECK-NEXT: br label %loop_begin
+
+loop_exit:
+ %lcssa = phi i32 [ %a, %loop_a ], [ %b, %loop_b ]
+ ret i32 %lcssa
+; CHECK: loop_exit.split.loopexit:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A]], %loop_a ]
+; CHECK-NEXT: br label %loop_exit.split
+;
+; CHECK: loop_exit.split:
+; CHECK-NEXT: %[[AB_PHI:.*]] = phi i32 [ %[[B]], %loop_b ], [ %[[A_LCSSA]], %loop_exit.split.loopexit ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[AB_PHI_US:.*]] = phi i32 [ %[[AB_PHI]], %loop_exit.split ], [ %[[A_LCSSA_US]], %loop_exit.split.us ]
+; CHECK-NEXT: ret i32 %[[AB_PHI_US]]
+}
+
+; Test where the original loop has an inner loop that has to be traversed to
+; rebuild the loop, and where this inner loop has multiple blocks, and where
+; the exiting block that connects the inner loop to the original loop is not
+; the header block. This ensures that we correctly handle interesting corner
+; cases of traversing back to the header when re-establishing the original loop
+; still exists after unswitching.
+define i32 @test13b(i1* %ptr, i1 %cond, i32* %a.ptr, i32* %b.ptr) {
+; CHECK-LABEL: @test13b(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond, label %entry.split.us, label %entry.split
+
+loop_begin:
+ %a = load i32, i32* %a.ptr
+ %v1 = load i1, i1* %ptr
+ br i1 %v1, label %loop_a, label %loop_b
+
+loop_a:
+ %v2 = load i1, i1* %ptr
+ br i1 %v2, label %loop_exit, label %loop_latch
+
+loop_b:
+ %b = load i32, i32* %b.ptr
+ br i1 %cond, label %loop_exit, label %loop_b_inner_ph
+
+loop_b_inner_ph:
+ br label %loop_b_inner_header
+
+loop_b_inner_header:
+ %v3 = load i1, i1* %ptr
+ br i1 %v3, label %loop_b_inner_latch, label %loop_b_inner_body
+
+loop_b_inner_body:
+ %v4 = load i1, i1* %ptr
+ br i1 %v4, label %loop_b_inner_latch, label %loop_b_inner_exit
+
+loop_b_inner_latch:
+ br label %loop_b_inner_header
+
+loop_b_inner_exit:
+ br label %loop_latch
+
+loop_latch:
+ br label %loop_begin
+; The cloned loop doesn't contain an inner loop.
+;
+; CHECK: entry.split.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_begin.us:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_a.us, label %loop_b.us
+;
+; CHECK: loop_b.us:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br label %loop_exit.split.us
+;
+; CHECK: loop_a.us:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit.split.us.loopexit, label %loop_latch.us
+;
+; CHECK: loop_latch.us:
+; CHECK-NEXT: br label %loop_begin.us
+;
+; CHECK: loop_exit.split.us.loopexit:
+; CHECK-NEXT: %[[A_LCSSA_US:.*]] = phi i32 [ %[[A]], %loop_a.us ]
+; CHECK-NEXT: br label %loop_exit.split.us
+;
+; CHECK: loop_exit.split.us:
+; CHECK-NEXT: %[[AB_PHI_US:.*]] = phi i32 [ %[[B]], %loop_b.us ], [ %[[A_LCSSA_US]], %loop_exit.split.us.loopexit ]
+; CHECK-NEXT: br label %loop_exit
+;
+; But the original loop contains an inner loop that must be traversed.;
+;
+; CHECK: entry.split:
+; CHECK-NEXT: br label %loop_begin
+;
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[A:.*]] = load i32, i32* %a.ptr
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_a, label %loop_b
+;
+; CHECK: loop_a:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_exit.split, label %loop_latch
+;
+; CHECK: loop_b:
+; CHECK-NEXT: %[[B:.*]] = load i32, i32* %b.ptr
+; CHECK-NEXT: br label %loop_b_inner_ph
+;
+; CHECK: loop_b_inner_ph:
+; CHECK-NEXT: br label %loop_b_inner_header
+;
+; CHECK: loop_b_inner_header:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_b_inner_latch, label %loop_b_inner_body
+;
+; CHECK: loop_b_inner_body:
+; CHECK-NEXT: %[[V:.*]] = load i1, i1* %ptr
+; CHECK-NEXT: br i1 %[[V]], label %loop_b_inner_latch, label %loop_b_inner_exit
+;
+; CHECK: loop_b_inner_latch:
+; CHECK-NEXT: br label %loop_b_inner_header
+;
+; CHECK: loop_b_inner_exit:
+; CHECK-NEXT: br label %loop_latch
+;
+; CHECK: loop_latch:
+; CHECK-NEXT: br label %loop_begin
+
+loop_exit:
+ %lcssa = phi i32 [ %a, %loop_a ], [ %b, %loop_b ]
+ ret i32 %lcssa
+; CHECK: loop_exit.split:
+; CHECK-NEXT: %[[A_LCSSA:.*]] = phi i32 [ %[[A]], %loop_a ]
+; CHECK-NEXT: br label %loop_exit
+;
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[AB_PHI:.*]] = phi i32 [ %[[A_LCSSA]], %loop_exit.split ], [ %[[AB_PHI_US]], %loop_exit.split.us ]
+; CHECK-NEXT: ret i32 %[[AB_PHI]]
+}
+
+define i32 @test20(i32* %var, i32 %cond1, i32 %cond2) {
+; CHECK-LABEL: @test20(
+entry:
+ br label %loop_begin
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %loop_begin
+
+loop_begin:
+ %var_val = load i32, i32* %var
+ switch i32 %cond2, label %loop_a [
+ i32 0, label %loop_b
+ i32 1, label %loop_b
+ i32 13, label %loop_c
+ i32 2, label %loop_b
+ i32 42, label %loop_exit
+ ]
+; CHECK: loop_begin:
+; CHECK-NEXT: %[[V:.*]] = load i32, i32* %var
+; CHECK-NEXT: switch i32 %cond2, label %loop_a [
+; CHECK-NEXT: i32 0, label %loop_b
+; CHECK-NEXT: i32 1, label %loop_b
+; CHECK-NEXT: i32 13, label %loop_c
+; CHECK-NEXT: i32 2, label %loop_b
+; CHECK-NEXT: i32 42, label %loop_exit
+; CHECK-NEXT: ]
+
+loop_a:
+ call void @a()
+ br label %loop_latch
+; CHECK: loop_a:
+; CHECK-NEXT: call void @a()
+; CHECK-NEXT: br label %loop_latch
+
+loop_b:
+ call void @b()
+ br label %loop_latch
+; CHECK: loop_b:
+; CHECK-NEXT: call void @b()
+; CHECK-NEXT: br label %loop_latch
+
+loop_c:
+ call void @c() noreturn nounwind
+ br label %loop_latch
+; CHECK: loop_c:
+; CHECK-NEXT: call void @c()
+; CHECK-NEXT: br label %loop_latch
+
+loop_latch:
+ br label %loop_begin
+; CHECK: loop_latch:
+; CHECK-NEXT: br label %loop_begin
+
+loop_exit:
+ %lcssa = phi i32 [ %var_val, %loop_begin ]
+ ret i32 %lcssa
+; CHECK: loop_exit:
+; CHECK-NEXT: %[[LCSSA:.*]] = phi i32 [ %[[V]], %loop_begin ]
+; CHECK-NEXT: ret i32 %[[LCSSA]]
+}