[SimplifyCFG] Port SplitBlockAndInsertIfThen() to DomTreeUpdater

This is not nice, but it's the best transient solution possible,
and is better than just duplicating the whole function.

The problem is, this function is widely used,
and it is not at all obvious that all the users
could be painlessly switched to operate on DomTreeUpdater,
and somehow i don't feel like porting all those users first.

This function is one of last three that not operate on DomTreeUpdater.

diff --git a/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h b/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h
index a75e49d..b75fe1f 100644 (file)
--- a/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h
+++ b/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h
@@ -356,10 +356,39 @@ ReturnInst *FoldReturnIntoUncondBranch(ReturnInst *RI, BasicBlock *BB,
 /// Returns the NewBasicBlock's terminator.
 ///
 /// Updates DT and LI if given.
+///
+/// FIXME: deprecated, switch to the DomTreeUpdater-based one.
+Instruction *SplitBlockAndInsertIfThen(Value *Cond, Instruction *SplitBefore,
+                                       bool Unreachable, MDNode *BranchWeights,
+                                       DominatorTree *DT,
+                                       LoopInfo *LI = nullptr,
+                                       BasicBlock *ThenBlock = nullptr);
+
+/// Split the containing block at the specified instruction - everything before
+/// SplitBefore stays in the old basic block, and the rest of the instructions
+/// in the BB are moved to a new block. The two blocks are connected by a
+/// conditional branch (with value of Cmp being the condition).
+/// Before:
+///   Head
+///   SplitBefore
+///   Tail
+/// After:
+///   Head
+///   if (Cond)
+///     ThenBlock
+///   SplitBefore
+///   Tail
+///
+/// If \p ThenBlock is not specified, a new block will be created for it.
+/// If \p Unreachable is true, the newly created block will end with
+/// UnreachableInst, otherwise it branches to Tail.
+/// Returns the NewBasicBlock's terminator.
+///
+/// Updates DT and LI if given.
 Instruction *SplitBlockAndInsertIfThen(Value *Cond, Instruction *SplitBefore,
                                        bool Unreachable,
                                        MDNode *BranchWeights = nullptr,
-                                       DominatorTree *DT = nullptr,
+                                       DomTreeUpdater *DTU = nullptr,
                                        LoopInfo *LI = nullptr,
                                        BasicBlock *ThenBlock = nullptr);
 

diff --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
index 79a2aa3..fedd9bf 100644 (file)
--- a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -773,7 +773,8 @@ void HWAddressSanitizer::instrumentMemAccessInline(Value *Ptr, bool IsWrite,
   Value *PtrLowBitsOOB = IRB.CreateICmpUGE(PtrLowBits, MemTag);
   SplitBlockAndInsertIfThen(PtrLowBitsOOB, CheckTerm, false,
                             MDBuilder(*C).createBranchWeights(1, 100000),
-                            nullptr, nullptr, CheckFailTerm->getParent());
+                            (DomTreeUpdater *)nullptr, nullptr,
+                            CheckFailTerm->getParent());
 
   IRB.SetInsertPoint(CheckTerm);
   Value *InlineTagAddr = IRB.CreateOr(AddrLong, 15);
@@ -782,7 +783,8 @@ void HWAddressSanitizer::instrumentMemAccessInline(Value *Ptr, bool IsWrite,
   Value *InlineTagMismatch = IRB.CreateICmpNE(PtrTag, InlineTag);
   SplitBlockAndInsertIfThen(InlineTagMismatch, CheckTerm, false,
                             MDBuilder(*C).createBranchWeights(1, 100000),
-                            nullptr, nullptr, CheckFailTerm->getParent());
+                            (DomTreeUpdater *)nullptr, nullptr,
+                            CheckFailTerm->getParent());
 
   IRB.SetInsertPoint(CheckFailTerm);
   InlineAsm *Asm;

diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index 91ce485..257a143 100644 (file)
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -1065,14 +1065,24 @@ ReturnInst *llvm::FoldReturnIntoUncondBranch(ReturnInst *RI, BasicBlock *BB,
   return cast<ReturnInst>(NewRet);
 }
 
-Instruction *llvm::SplitBlockAndInsertIfThen(Value *Cond,
-                                             Instruction *SplitBefore,
-                                             bool Unreachable,
-                                             MDNode *BranchWeights,
-                                             DominatorTree *DT, LoopInfo *LI,
-                                             BasicBlock *ThenBlock) {
+static Instruction *
+SplitBlockAndInsertIfThenImpl(Value *Cond, Instruction *SplitBefore,
+                              bool Unreachable, MDNode *BranchWeights,
+                              DomTreeUpdater *DTU, DominatorTree *DT,
+                              LoopInfo *LI, BasicBlock *ThenBlock) {
+  SmallVector<DominatorTree::UpdateType, 8> Updates;
   BasicBlock *Head = SplitBefore->getParent();
   BasicBlock *Tail = Head->splitBasicBlock(SplitBefore->getIterator());
+  if (DTU) {
+    SmallSetVector<BasicBlock *, 8> UniqueSuccessorsOfHead(succ_begin(Tail),
+                                                           succ_end(Tail));
+    Updates.push_back({DominatorTree::Insert, Head, Tail});
+    Updates.reserve(Updates.size() + 2 * UniqueSuccessorsOfHead.size());
+    for (BasicBlock *UniqueSuccessorOfHead : UniqueSuccessorsOfHead) {
+      Updates.push_back({DominatorTree::Insert, Tail, UniqueSuccessorOfHead});
+      Updates.push_back({DominatorTree::Delete, Head, UniqueSuccessorOfHead});
+    }
+  }
   Instruction *HeadOldTerm = Head->getTerminator();
   LLVMContext &C = Head->getContext();
   Instruction *CheckTerm;
@@ -1081,17 +1091,24 @@ Instruction *llvm::SplitBlockAndInsertIfThen(Value *Cond,
     ThenBlock = BasicBlock::Create(C, "", Head->getParent(), Tail);
     if (Unreachable)
       CheckTerm = new UnreachableInst(C, ThenBlock);
-    else
+    else {
       CheckTerm = BranchInst::Create(Tail, ThenBlock);
+      if (DTU)
+        Updates.push_back({DominatorTree::Insert, ThenBlock, Tail});
+    }
     CheckTerm->setDebugLoc(SplitBefore->getDebugLoc());
   } else
     CheckTerm = ThenBlock->getTerminator();
   BranchInst *HeadNewTerm =
-    BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/Tail, Cond);
+      BranchInst::Create(/*ifTrue*/ ThenBlock, /*ifFalse*/ Tail, Cond);
+  if (DTU)
+    Updates.push_back({DominatorTree::Insert, Head, ThenBlock});
   HeadNewTerm->setMetadata(LLVMContext::MD_prof, BranchWeights);
   ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
 
-  if (DT) {
+  if (DTU)
+    DTU->applyUpdates(Updates);
+  else if (DT) {
     if (DomTreeNode *OldNode = DT->getNode(Head)) {
       std::vector<DomTreeNode *> Children(OldNode->begin(), OldNode->end());
 
@@ -1117,6 +1134,27 @@ Instruction *llvm::SplitBlockAndInsertIfThen(Value *Cond,
   return CheckTerm;
 }
 
+Instruction *llvm::SplitBlockAndInsertIfThen(Value *Cond,
+                                             Instruction *SplitBefore,
+                                             bool Unreachable,
+                                             MDNode *BranchWeights,
+                                             DominatorTree *DT, LoopInfo *LI,
+                                             BasicBlock *ThenBlock) {
+  return SplitBlockAndInsertIfThenImpl(Cond, SplitBefore, Unreachable,
+                                       BranchWeights,
+                                       /*DTU=*/nullptr, DT, LI, ThenBlock);
+}
+Instruction *llvm::SplitBlockAndInsertIfThen(Value *Cond,
+                                             Instruction *SplitBefore,
+                                             bool Unreachable,
+                                             MDNode *BranchWeights,
+                                             DomTreeUpdater *DTU, LoopInfo *LI,
+                                             BasicBlock *ThenBlock) {
+  return SplitBlockAndInsertIfThenImpl(Cond, SplitBefore, Unreachable,
+                                       BranchWeights, DTU, /*DT=*/nullptr, LI,
+                                       ThenBlock);
+}
+
 void llvm::SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
                                          Instruction **ThenTerm,
                                          Instruction **ElseTerm,

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 3271564..a534643 100644 (file)
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -3421,9 +3421,9 @@ static bool mergeConditionalStoreToAddress(
     QPred = QB.CreateNot(QPred);
   Value *CombinedPred = QB.CreateOr(PPred, QPred);
 
-  auto *T = SplitBlockAndInsertIfThen(
-      CombinedPred, &*QB.GetInsertPoint(), /*Unreachable=*/false,
-      /*BranchWeights=*/nullptr, DTU ? &DTU->getDomTree() : nullptr);
+  auto *T = SplitBlockAndInsertIfThen(CombinedPred, &*QB.GetInsertPoint(),
+                                      /*Unreachable=*/false,
+                                      /*BranchWeights=*/nullptr, DTU);
   QB.SetInsertPoint(T);
   StoreInst *SI = cast<StoreInst>(QB.CreateStore(QPHI, Address));
   AAMDNodes AAMD;