--- /dev/null
+//===- RewriteStatepointsForGC.cpp - Make GC relocations explicit ---------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Rewrite an existing set of gc.statepoints such that they make potential
+// relocations performed by the garbage collector explicit in the IR.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Pass.h"
+#include "llvm/Analysis/CFG.h"
+#include "llvm/ADT/SetOperations.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/InstIterator.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Statepoint.h"
+#include "llvm/IR/Value.h"
+#include "llvm/IR/Verifier.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/PromoteMemToReg.h"
+
+#define DEBUG_TYPE "rewrite-statepoints-for-gc"
+
+using namespace llvm;
+
+// Print tracing output
+static cl::opt<bool> TraceLSP("trace-rewrite-statepoints", cl::Hidden,
+ cl::init(false));
+
+// Print the liveset found at the insert location
+static cl::opt<bool> PrintLiveSet("spp-print-liveset", cl::Hidden,
+ cl::init(false));
+static cl::opt<bool> PrintLiveSetSize("spp-print-liveset-size",
+ cl::Hidden, cl::init(false));
+// Print out the base pointers for debugging
+static cl::opt<bool> PrintBasePointers("spp-print-base-pointers",
+ cl::Hidden, cl::init(false));
+
+struct RewriteStatepointsForGC : public FunctionPass {
+ static char ID; // Pass identification, replacement for typeid
+
+ RewriteStatepointsForGC() : FunctionPass(ID) {
+ initializeRewriteStatepointsForGCPass(*PassRegistry::getPassRegistry());
+ }
+ bool runOnFunction(Function &F) override;
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ // We add and rewrite a bunch of instructions, but don't really do much
+ // else. We could in theory preserve a lot more analyses here.
+ AU.addRequired<DominatorTreeWrapperPass>();
+ }
+};
+
+char RewriteStatepointsForGC::ID = 0;
+
+FunctionPass *llvm::createRewriteStatepointsForGCPass() {
+ return new RewriteStatepointsForGC();
+}
+
+INITIALIZE_PASS_BEGIN(RewriteStatepointsForGC, "rewrite-statepoints-for-gc",
+ "Make relocations explicit at statepoints", false, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_END(RewriteStatepointsForGC, "rewrite-statepoints-for-gc",
+ "Make relocations explicit at statepoints", false, false)
+
+namespace {
+// The type of the internal cache used inside the findBasePointers family
+// of functions. From the callers perspective, this is an opaque type and
+// should not be inspected.
+//
+// In the actual implementation this caches two relations:
+// - The base relation itself (i.e. this pointer is based on that one)
+// - The base defining value relation (i.e. before base_phi insertion)
+// Generally, after the execution of a full findBasePointer call, only the
+// base relation will remain. Internally, we add a mixture of the two
+// types, then update all the second type to the first type
+typedef std::map<Value *, Value *> DefiningValueMapTy;
+}
+
+namespace {
+struct PartiallyConstructedSafepointRecord {
+ /// The set of values known to be live accross this safepoint
+ std::set<llvm::Value *> liveset;
+
+ /// Mapping from live pointers to a base-defining-value
+ std::map<llvm::Value *, llvm::Value *> base_pairs;
+
+ /// Any new values which were added to the IR during base pointer analysis
+ /// for this safepoint
+ std::set<llvm::Value *> newInsertedDefs;
+
+ /// The bounds of the inserted code for the safepoint
+ std::pair<Instruction *, Instruction *> safepoint;
+
+ // Instruction to which exceptional gc relocates are attached
+ // Makes it easier to iterate through them during relocationViaAlloca.
+ Instruction *exceptional_relocates_token;
+
+ /// The result of the safepointing call (or nullptr)
+ Value *result;
+};
+}
+
+// TODO: Once we can get to the GCStrategy, this becomes
+// Optional<bool> isGCManagedPointer(const Value *V) const override {
+
+static bool isGCPointerType(const Type *T) {
+ if (const PointerType *PT = dyn_cast<PointerType>(T))
+ // For the sake of this example GC, we arbitrarily pick addrspace(1) as our
+ // GC managed heap. We know that a pointer into this heap needs to be
+ // updated and that no other pointer does.
+ return (1 == PT->getAddressSpace());
+ return false;
+}
+
+/// Return true if the Value is a gc reference type which is potentially used
+/// after the instruction 'loc'. This is only used with the edge reachability
+/// liveness code. Note: It is assumed the V dominates loc.
+static bool isLiveGCReferenceAt(Value &V, Instruction *loc, DominatorTree &DT,
+ LoopInfo *LI) {
+ if (!isGCPointerType(V.getType()))
+ return false;
+
+ if (V.use_empty())
+ return false;
+
+ // Given assumption that V dominates loc, this may be live
+ return true;
+}
+static bool isAggWhichContainsGCPtrType(Type *Ty) {
+ if (VectorType *VT = dyn_cast<VectorType>(Ty))
+ return isGCPointerType(VT->getScalarType());
+ else if (ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
+ return isGCPointerType(AT->getElementType()) ||
+ isAggWhichContainsGCPtrType(AT->getElementType());
+ } else if (StructType *ST = dyn_cast<StructType>(Ty)) {
+ bool UnsupportedType = false;
+ for (Type *SubType : ST->subtypes())
+ UnsupportedType |= isGCPointerType(SubType) || isAggWhichContainsGCPtrType(SubType);
+ return UnsupportedType;
+ } else
+ return false;
+}
+
+// Conservatively identifies any definitions which might be live at the
+// given instruction. The analysis is performed immediately before the
+// given instruction. Values defined by that instruction are not considered
+// live. Values used by that instruction are considered live.
+//
+// preconditions: valid IR graph, term is either a terminator instruction or
+// a call instruction, pred is the basic block of term, DT, LI are valid
+//
+// side effects: none, does not mutate IR
+//
+// postconditions: populates liveValues as discussed above
+static void findLiveGCValuesAtInst(Instruction *term, BasicBlock *pred,
+ DominatorTree &DT, LoopInfo *LI,
+ std::set<llvm::Value *> &liveValues) {
+ liveValues.clear();
+
+ assert(isa<CallInst>(term) || isa<InvokeInst>(term) || term->isTerminator());
+
+ Function *F = pred->getParent();
+
+ auto is_live_gc_reference =
+ [&](Value &V) { return isLiveGCReferenceAt(V, term, DT, LI); };
+
+ // Are there any gc pointer arguments live over this point? This needs to be
+ // special cased since arguments aren't defined in basic blocks.
+ for (Argument &arg : F->args()) {
+ assert(!isAggWhichContainsGCPtrType(arg.getType()) &&
+ "support for FCA unimplemented");
+
+ if (is_live_gc_reference(arg)) {
+ liveValues.insert(&arg);
+ }
+ }
+
+ // Walk through all dominating blocks - the ones which can contain
+ // definitions used in this block - and check to see if any of the values
+ // they define are used in locations potentially reachable from the
+ // interesting instruction.
+ BasicBlock *BBI = pred;
+ while (true) {
+ if (TraceLSP) {
+ errs() << "[LSP] Looking at dominating block " << pred->getName() << "\n";
+ }
+ assert(DT.dominates(BBI, pred));
+ assert(isPotentiallyReachable(BBI, pred, &DT) &&
+ "dominated block must be reachable");
+
+ // Walk through the instructions in dominating blocks and keep any
+ // that have a use potentially reachable from the block we're
+ // considering putting the safepoint in
+ for (Instruction &inst : *BBI) {
+ if (TraceLSP) {
+ errs() << "[LSP] Looking at instruction ";
+ inst.dump();
+ }
+
+ if (pred == BBI && (&inst) == term) {
+ if (TraceLSP) {
+ errs() << "[LSP] stopped because we encountered the safepoint "
+ "instruction.\n";
+ }
+
+ // If we're in the block which defines the interesting instruction,
+ // we don't want to include any values as live which are defined
+ // _after_ the interesting line or as part of the line itself
+ // i.e. "term" is the call instruction for a call safepoint, the
+ // results of the call should not be considered live in that stackmap
+ break;
+ }
+
+ assert(!isAggWhichContainsGCPtrType(inst.getType()) &&
+ "support for FCA unimplemented");
+
+ if (is_live_gc_reference(inst)) {
+ if (TraceLSP) {
+ errs() << "[LSP] found live value for this safepoint ";
+ inst.dump();
+ term->dump();
+ }
+ liveValues.insert(&inst);
+ }
+ }
+ if (!DT.getNode(BBI)->getIDom()) {
+ assert(BBI == &F->getEntryBlock() &&
+ "failed to find a dominator for something other than "
+ "the entry block");
+ break;
+ }
+ BBI = DT.getNode(BBI)->getIDom()->getBlock();
+ }
+}
+
+static bool order_by_name(llvm::Value *a, llvm::Value *b) {
+ if (a->hasName() && b->hasName()) {
+ return -1 == a->getName().compare(b->getName());
+ } else if (a->hasName() && !b->hasName()) {
+ return true;
+ } else if (!a->hasName() && b->hasName()) {
+ return false;
+ } else {
+ // Better than nothing, but not stable
+ return a < b;
+ }
+}
+
+/// Find the initial live set. Note that due to base pointer
+/// insertion, the live set may be incomplete.
+static void
+analyzeParsePointLiveness(DominatorTree &DT, const CallSite &CS,
+ PartiallyConstructedSafepointRecord &result) {
+ Instruction *inst = CS.getInstruction();
+
+ BasicBlock *BB = inst->getParent();
+ std::set<Value *> liveset;
+ findLiveGCValuesAtInst(inst, BB, DT, nullptr, liveset);
+
+ if (PrintLiveSet) {
+ // Note: This output is used by several of the test cases
+ // The order of elemtns in a set is not stable, put them in a vec and sort
+ // by name
+ std::vector<Value *> temp;
+ temp.insert(temp.end(), liveset.begin(), liveset.end());
+ std::sort(temp.begin(), temp.end(), order_by_name);
+ errs() << "Live Variables:\n";
+ for (Value *V : temp) {
+ errs() << " " << V->getName(); // no newline
+ V->dump();
+ }
+ }
+ if (PrintLiveSetSize) {
+ errs() << "Safepoint For: " << CS.getCalledValue()->getName() << "\n";
+ errs() << "Number live values: " << liveset.size() << "\n";
+ }
+ result.liveset = liveset;
+}
+
+/// True iff this value is the null pointer constant (of any pointer type)
+static bool isNullConstant(Value *V) {
+ return isa<Constant>(V) && isa<PointerType>(V->getType()) &&
+ cast<Constant>(V)->isNullValue();
+}
+
+/// Helper function for findBasePointer - Will return a value which either a)
+/// defines the base pointer for the input or b) blocks the simple search
+/// (i.e. a PHI or Select of two derived pointers)
+static Value *findBaseDefiningValue(Value *I) {
+ assert(I->getType()->isPointerTy() &&
+ "Illegal to ask for the base pointer of a non-pointer type");
+
+ // There are instructions which can never return gc pointer values. Sanity
+ // check
+ // that this is actually true.
+ assert(!isa<InsertElementInst>(I) && !isa<ExtractElementInst>(I) &&
+ !isa<ShuffleVectorInst>(I) && "Vector types are not gc pointers");
+ assert((!isa<Instruction>(I) || isa<InvokeInst>(I) ||
+ !cast<Instruction>(I)->isTerminator()) &&
+ "With the exception of invoke terminators don't define values");
+ assert(!isa<StoreInst>(I) && !isa<FenceInst>(I) &&
+ "Can't be definitions to start with");
+ assert(!isa<ICmpInst>(I) && !isa<FCmpInst>(I) &&
+ "Comparisons don't give ops");
+ // There's a bunch of instructions which just don't make sense to apply to
+ // a pointer. The only valid reason for this would be pointer bit
+ // twiddling which we're just not going to support.
+ assert((!isa<Instruction>(I) || !cast<Instruction>(I)->isBinaryOp()) &&
+ "Binary ops on pointer values are meaningless. Unless your "
+ "bit-twiddling which we don't support");
+
+ if (Argument *Arg = dyn_cast<Argument>(I)) {
+ // An incoming argument to the function is a base pointer
+ // We should have never reached here if this argument isn't an gc value
+ assert(Arg->getType()->isPointerTy() &&
+ "Base for pointer must be another pointer");
+ return Arg;
+ }
+
+ if (GlobalVariable *global = dyn_cast<GlobalVariable>(I)) {
+ // base case
+ assert(global->getType()->isPointerTy() &&
+ "Base for pointer must be another pointer");
+ return global;
+ }
+
+ // inlining could possibly introduce phi node that contains
+ // undef if callee has multiple returns
+ if (UndefValue *undef = dyn_cast<UndefValue>(I)) {
+ assert(undef->getType()->isPointerTy() &&
+ "Base for pointer must be another pointer");
+ return undef; // utterly meaningless, but useful for dealing with
+ // partially optimized code.
+ }
+
+ // Due to inheritance, this must be _after_ the global variable and undef
+ // checks
+ if (Constant *con = dyn_cast<Constant>(I)) {
+ assert(!isa<GlobalVariable>(I) && !isa<UndefValue>(I) &&
+ "order of checks wrong!");
+ // Note: Finding a constant base for something marked for relocation
+ // doesn't really make sense. The most likely case is either a) some
+ // screwed up the address space usage or b) your validating against
+ // compiled C++ code w/o the proper separation. The only real exception
+ // is a null pointer. You could have generic code written to index of
+ // off a potentially null value and have proven it null. We also use
+ // null pointers in dead paths of relocation phis (which we might later
+ // want to find a base pointer for).
+ assert(con->getType()->isPointerTy() &&
+ "Base for pointer must be another pointer");
+ assert(con->isNullValue() && "null is the only case which makes sense");
+ return con;
+ }
+
+ if (CastInst *CI = dyn_cast<CastInst>(I)) {
+ Value *def = CI->stripPointerCasts();
+ assert(def->getType()->isPointerTy() &&
+ "Base for pointer must be another pointer");
+ if (isa<CastInst>(def)) {
+ // If we find a cast instruction here, it means we've found a cast
+ // which is not simply a pointer cast (i.e. an inttoptr). We don't
+ // know how to handle int->ptr conversion.
+ llvm_unreachable("Can not find the base pointers for an inttoptr cast");
+ }
+ assert(!isa<CastInst>(def) && "shouldn't find another cast here");
+ return findBaseDefiningValue(def);
+ }
+
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ if (LI->getType()->isPointerTy()) {
+ Value *Op = LI->getOperand(0);
+ // Has to be a pointer to an gc object, or possibly an array of such?
+ assert(Op->getType()->isPointerTy());
+ return LI; // The value loaded is an gc base itself
+ }
+ }
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
+ Value *Op = GEP->getOperand(0);
+ if (Op->getType()->isPointerTy()) {
+ return findBaseDefiningValue(Op); // The base of this GEP is the base
+ }
+ }
+
+ if (AllocaInst *alloc = dyn_cast<AllocaInst>(I)) {
+ // An alloca represents a conceptual stack slot. It's the slot itself
+ // that the GC needs to know about, not the value in the slot.
+ assert(alloc->getType()->isPointerTy() &&
+ "Base for pointer must be another pointer");
+ return alloc;
+ }
+
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
+ switch (II->getIntrinsicID()) {
+ default:
+ // fall through to general call handling
+ break;
+ case Intrinsic::experimental_gc_statepoint:
+ case Intrinsic::experimental_gc_result_float:
+ case Intrinsic::experimental_gc_result_int:
+ llvm_unreachable("these don't produce pointers");
+ case Intrinsic::experimental_gc_result_ptr:
+ // This is just a special case of the CallInst check below to handle a
+ // statepoint with deopt args which hasn't been rewritten for GC yet.
+ // TODO: Assert that the statepoint isn't rewritten yet.
+ return II;
+ case Intrinsic::experimental_gc_relocate: {
+ // Rerunning safepoint insertion after safepoints are already
+ // inserted is not supported. It could probably be made to work,
+ // but why are you doing this? There's no good reason.
+ llvm_unreachable("repeat safepoint insertion is not supported");
+ }
+ case Intrinsic::gcroot:
+ // Currently, this mechanism hasn't been extended to work with gcroot.
+ // There's no reason it couldn't be, but I haven't thought about the
+ // implications much.
+ llvm_unreachable(
+ "interaction with the gcroot mechanism is not supported");
+ }
+ }
+ // We assume that functions in the source language only return base
+ // pointers. This should probably be generalized via attributes to support
+ // both source language and internal functions.
+ if (CallInst *call = dyn_cast<CallInst>(I)) {
+ assert(call->getType()->isPointerTy() &&
+ "Base for pointer must be another pointer");
+ return call;
+ }
+ if (InvokeInst *invoke = dyn_cast<InvokeInst>(I)) {
+ assert(invoke->getType()->isPointerTy() &&
+ "Base for pointer must be another pointer");
+ return invoke;
+ }
+
+ // I have absolutely no idea how to implement this part yet. It's not
+ // neccessarily hard, I just haven't really looked at it yet.
+ assert(!isa<LandingPadInst>(I) && "Landing Pad is unimplemented");
+
+ if (AtomicCmpXchgInst *cas = dyn_cast<AtomicCmpXchgInst>(I)) {
+ // A CAS is effectively a atomic store and load combined under a
+ // predicate. From the perspective of base pointers, we just treat it
+ // like a load. We loaded a pointer from a address in memory, that value
+ // had better be a valid base pointer.
+ return cas->getPointerOperand();
+ }
+ if (AtomicRMWInst *atomic = dyn_cast<AtomicRMWInst>(I)) {
+ assert(AtomicRMWInst::Xchg == atomic->getOperation() &&
+ "All others are binary ops which don't apply to base pointers");
+ // semantically, a load, store pair. Treat it the same as a standard load
+ return atomic->getPointerOperand();
+ }
+
+ // The aggregate ops. Aggregates can either be in the heap or on the
+ // stack, but in either case, this is simply a field load. As a result,
+ // this is a defining definition of the base just like a load is.
+ if (ExtractValueInst *ev = dyn_cast<ExtractValueInst>(I)) {
+ return ev;
+ }
+
+ // We should never see an insert vector since that would require we be
+ // tracing back a struct value not a pointer value.
+ assert(!isa<InsertValueInst>(I) &&
+ "Base pointer for a struct is meaningless");
+
+ // The last two cases here don't return a base pointer. Instead, they
+ // return a value which dynamically selects from amoung several base
+ // derived pointers (each with it's own base potentially). It's the job of
+ // the caller to resolve these.
+ if (SelectInst *select = dyn_cast<SelectInst>(I)) {
+ return select;
+ }
+ if (PHINode *phi = dyn_cast<PHINode>(I)) {
+ return phi;
+ }
+
+ errs() << "unknown type: " << *I << "\n";
+ llvm_unreachable("unknown type");
+ return nullptr;
+}
+
+/// Returns the base defining value for this value.
+Value *findBaseDefiningValueCached(Value *I, DefiningValueMapTy &cache) {
+ if (cache.find(I) == cache.end()) {
+ cache[I] = findBaseDefiningValue(I);
+ }
+ assert(cache.find(I) != cache.end());
+
+ if (TraceLSP) {
+ errs() << "fBDV-cached: " << I->getName() << " -> " << cache[I]->getName()
+ << "\n";
+ }
+ return cache[I];
+}
+
+/// Return a base pointer for this value if known. Otherwise, return it's
+/// base defining value.
+static Value *findBaseOrBDV(Value *I, DefiningValueMapTy &cache) {
+ Value *def = findBaseDefiningValueCached(I, cache);
+ if (cache.count(def)) {
+ // Either a base-of relation, or a self reference. Caller must check.
+ return cache[def];
+ }
+ // Only a BDV available
+ return def;
+}
+
+/// Given the result of a call to findBaseDefiningValue, or findBaseOrBDV,
+/// is it known to be a base pointer? Or do we need to continue searching.
+static bool isKnownBaseResult(Value *v) {
+ if (!isa<PHINode>(v) && !isa<SelectInst>(v)) {
+ // no recursion possible
+ return true;
+ }
+ if (cast<Instruction>(v)->getMetadata("is_base_value")) {
+ // This is a previously inserted base phi or select. We know
+ // that this is a base value.
+ return true;
+ }
+
+ // We need to keep searching
+ return false;
+}
+
+// TODO: find a better name for this
+namespace {
+class PhiState {
+public:
+ enum Status { Unknown, Base, Conflict };
+
+ PhiState(Status s, Value *b = nullptr) : status(s), base(b) {
+ assert(status != Base || b);
+ }
+ PhiState(Value *b) : status(Base), base(b) {}
+ PhiState() : status(Unknown), base(nullptr) {}
+ PhiState(const PhiState &other) : status(other.status), base(other.base) {
+ assert(status != Base || base);
+ }
+
+ Status getStatus() const { return status; }
+ Value *getBase() const { return base; }
+
+ bool isBase() const { return getStatus() == Base; }
+ bool isUnknown() const { return getStatus() == Unknown; }
+ bool isConflict() const { return getStatus() == Conflict; }
+
+ bool operator==(const PhiState &other) const {
+ return base == other.base && status == other.status;
+ }
+
+ bool operator!=(const PhiState &other) const { return !(*this == other); }
+
+ void dump() {
+ errs() << status << " (" << base << " - "
+ << (base ? base->getName() : "nullptr") << "): ";
+ }
+
+private:
+ Status status;
+ Value *base; // non null only if status == base
+};
+
+// Values of type PhiState form a lattice, and this is a helper
+// class that implementes the meet operation. The meat of the meet
+// operation is implemented in MeetPhiStates::pureMeet
+class MeetPhiStates {
+public:
+ // phiStates is a mapping from PHINodes and SelectInst's to PhiStates.
+ explicit MeetPhiStates(const std::map<Value *, PhiState> &phiStates)
+ : phiStates(phiStates) {}
+
+ // Destructively meet the current result with the base V. V can
+ // either be a merge instruction (SelectInst / PHINode), in which
+ // case its status is looked up in the phiStates map; or a regular
+ // SSA value, in which case it is assumed to be a base.
+ void meetWith(Value *V) {
+ PhiState otherState = getStateForBDV(V);
+ assert((MeetPhiStates::pureMeet(otherState, currentResult) ==
+ MeetPhiStates::pureMeet(currentResult, otherState)) &&
+ "math is wrong: meet does not commute!");
+ currentResult = MeetPhiStates::pureMeet(otherState, currentResult);
+ }
+
+ PhiState getResult() const { return currentResult; }
+
+private:
+ const std::map<Value *, PhiState> &phiStates;
+ PhiState currentResult;
+
+ /// Return a phi state for a base defining value. We'll generate a new
+ /// base state for known bases and expect to find a cached state otherwise
+ PhiState getStateForBDV(Value *baseValue) {
+ if (isKnownBaseResult(baseValue)) {
+ return PhiState(baseValue);
+ } else {
+ return lookupFromMap(baseValue);
+ }
+ }
+
+ PhiState lookupFromMap(Value *V) {
+ auto I = phiStates.find(V);
+ assert(I != phiStates.end() && "lookup failed!");
+ return I->second;
+ }
+
+ static PhiState pureMeet(const PhiState &stateA, const PhiState &stateB) {
+ switch (stateA.getStatus()) {
+ case PhiState::Unknown:
+ return stateB;
+
+ case PhiState::Base:
+ assert(stateA.getBase() && "can't be null");
+ if (stateB.isUnknown()) {
+ return stateA;
+ } else if (stateB.isBase()) {
+ if (stateA.getBase() == stateB.getBase()) {
+ assert(stateA == stateB && "equality broken!");
+ return stateA;
+ }
+ return PhiState(PhiState::Conflict);
+ } else {
+ assert(stateB.isConflict() && "only three states!");
+ return PhiState(PhiState::Conflict);
+ }
+
+ case PhiState::Conflict:
+ return stateA;
+ }
+ assert(false && "only three states!");
+ }
+};
+}
+/// For a given value or instruction, figure out what base ptr it's derived
+/// from. For gc objects, this is simply itself. On success, returns a value
+/// which is the base pointer. (This is reliable and can be used for
+/// relocation.) On failure, returns nullptr.
+static Value *findBasePointer(Value *I, DefiningValueMapTy &cache,
+ std::set<llvm::Value *> &newInsertedDefs) {
+ Value *def = findBaseOrBDV(I, cache);
+
+ if (isKnownBaseResult(def)) {
+ return def;
+ }
+
+ // Here's the rough algorithm:
+ // - For every SSA value, construct a mapping to either an actual base
+ // pointer or a PHI which obscures the base pointer.
+ // - Construct a mapping from PHI to unknown TOP state. Use an
+ // optimistic algorithm to propagate base pointer information. Lattice
+ // looks like:
+ // UNKNOWN
+ // b1 b2 b3 b4
+ // CONFLICT
+ // When algorithm terminates, all PHIs will either have a single concrete
+ // base or be in a conflict state.
+ // - For every conflict, insert a dummy PHI node without arguments. Add
+ // these to the base[Instruction] = BasePtr mapping. For every
+ // non-conflict, add the actual base.
+ // - For every conflict, add arguments for the base[a] of each input
+ // arguments.
+ //
+ // Note: A simpler form of this would be to add the conflict form of all
+ // PHIs without running the optimistic algorithm. This would be
+ // analougous to pessimistic data flow and would likely lead to an
+ // overall worse solution.
+
+ std::map<Value *, PhiState> states;
+ states[def] = PhiState();
+ // Recursively fill in all phis & selects reachable from the initial one
+ // for which we don't already know a definite base value for
+ // PERF: Yes, this is as horribly inefficient as it looks.
+ bool done = false;
+ while (!done) {
+ done = true;
+ for (auto Pair : states) {
+ Value *v = Pair.first;
+ assert(!isKnownBaseResult(v) && "why did it get added?");
+ if (PHINode *phi = dyn_cast<PHINode>(v)) {
+ unsigned NumPHIValues = phi->getNumIncomingValues();
+ assert(NumPHIValues > 0 && "zero input phis are illegal");
+ for (unsigned i = 0; i != NumPHIValues; ++i) {
+ Value *InVal = phi->getIncomingValue(i);
+ Value *local = findBaseOrBDV(InVal, cache);
+ if (!isKnownBaseResult(local) && states.find(local) == states.end()) {
+ states[local] = PhiState();
+ done = false;
+ }
+ }
+ } else if (SelectInst *sel = dyn_cast<SelectInst>(v)) {
+ Value *local = findBaseOrBDV(sel->getTrueValue(), cache);
+ if (!isKnownBaseResult(local) && states.find(local) == states.end()) {
+ states[local] = PhiState();
+ done = false;
+ }
+ local = findBaseOrBDV(sel->getFalseValue(), cache);
+ if (!isKnownBaseResult(local) && states.find(local) == states.end()) {
+ states[local] = PhiState();
+ done = false;
+ }
+ }
+ }
+ }
+
+ if (TraceLSP) {
+ errs() << "States after initialization:\n";
+ for (auto Pair : states) {
+ Instruction *v = cast<Instruction>(Pair.first);
+ PhiState state = Pair.second;
+ state.dump();
+ v->dump();
+ }
+ }
+
+ // TODO: come back and revisit the state transitions around inputs which
+ // have reached conflict state. The current version seems too conservative.
+
+ bool progress = true;
+ size_t oldSize = 0;
+ while (progress) {
+ oldSize = states.size();
+ progress = false;
+ for (auto Pair : states) {
+ MeetPhiStates calculateMeet(states);
+ Value *v = Pair.first;
+ assert(!isKnownBaseResult(v) && "why did it get added?");
+ assert(isa<SelectInst>(v) || isa<PHINode>(v));
+ if (SelectInst *select = dyn_cast<SelectInst>(v)) {
+ calculateMeet.meetWith(findBaseOrBDV(select->getTrueValue(), cache));
+ calculateMeet.meetWith(findBaseOrBDV(select->getFalseValue(), cache));
+ } else if (PHINode *phi = dyn_cast<PHINode>(v)) {
+ for (unsigned i = 0; i < phi->getNumIncomingValues(); i++) {
+ calculateMeet.meetWith(
+ findBaseOrBDV(phi->getIncomingValue(i), cache));
+ }
+ } else {
+ llvm_unreachable("no such state expected");
+ }
+
+ PhiState oldState = states[v];
+ PhiState newState = calculateMeet.getResult();
+ if (oldState != newState) {
+ progress = true;
+ states[v] = newState;
+ }
+ }
+
+ assert(oldSize <= states.size());
+ assert(oldSize == states.size() || progress);
+ }
+
+ if (TraceLSP) {
+ errs() << "States after meet iteration:\n";
+ for (auto Pair : states) {
+ Instruction *v = cast<Instruction>(Pair.first);
+ PhiState state = Pair.second;
+ state.dump();
+ v->dump();
+ }
+ }
+
+ // Insert Phis for all conflicts
+ for (auto Pair : states) {
+ Instruction *v = cast<Instruction>(Pair.first);
+ PhiState state = Pair.second;
+ assert(!isKnownBaseResult(v) && "why did it get added?");
+ assert(!state.isUnknown() && "Optimistic algorithm didn't complete!");
+ if (state.isConflict()) {
+ if (isa<PHINode>(v)) {
+ int num_preds =
+ std::distance(pred_begin(v->getParent()), pred_end(v->getParent()));
+ assert(num_preds > 0 && "how did we reach here");
+ PHINode *phi = PHINode::Create(v->getType(), num_preds, "base_phi", v);
+ newInsertedDefs.insert(phi);
+ // Add metadata marking this as a base value
+ auto *const_1 = ConstantInt::get(
+ Type::getInt32Ty(
+ v->getParent()->getParent()->getParent()->getContext()),
+ 1);
+ auto MDConst = ConstantAsMetadata::get(const_1);
+ MDNode *md = MDNode::get(
+ v->getParent()->getParent()->getParent()->getContext(), MDConst);
+ phi->setMetadata("is_base_value", md);
+ states[v] = PhiState(PhiState::Conflict, phi);
+ } else if (SelectInst *sel = dyn_cast<SelectInst>(v)) {
+ // The undef will be replaced later
+ UndefValue *undef = UndefValue::get(sel->getType());
+ SelectInst *basesel = SelectInst::Create(sel->getCondition(), undef,
+ undef, "base_select", sel);
+ newInsertedDefs.insert(basesel);
+ // Add metadata marking this as a base value
+ auto *const_1 = ConstantInt::get(
+ Type::getInt32Ty(
+ v->getParent()->getParent()->getParent()->getContext()),
+ 1);
+ auto MDConst = ConstantAsMetadata::get(const_1);
+ MDNode *md = MDNode::get(
+ v->getParent()->getParent()->getParent()->getContext(), MDConst);
+ basesel->setMetadata("is_base_value", md);
+ states[v] = PhiState(PhiState::Conflict, basesel);
+ } else {
+ assert(false);
+ }
+ }
+ }
+
+ // Fixup all the inputs of the new PHIs
+ for (auto Pair : states) {
+ Instruction *v = cast<Instruction>(Pair.first);
+ PhiState state = Pair.second;
+
+ assert(!isKnownBaseResult(v) && "why did it get added?");
+ assert(!state.isUnknown() && "Optimistic algorithm didn't complete!");
+ if (state.isConflict()) {
+ if (PHINode *basephi = dyn_cast<PHINode>(state.getBase())) {
+ PHINode *phi = cast<PHINode>(v);
+ unsigned NumPHIValues = phi->getNumIncomingValues();
+ for (unsigned i = 0; i < NumPHIValues; i++) {
+ Value *InVal = phi->getIncomingValue(i);
+ BasicBlock *InBB = phi->getIncomingBlock(i);
+
+ // If we've already seen InBB, add the same incoming value
+ // we added for it earlier. The IR verifier requires phi
+ // nodes with multiple entries from the same basic block
+ // to have the same incoming value for each of those
+ // entries. If we don't do this check here and basephi
+ // has a different type than base, we'll end up adding two
+ // bitcasts (and hence two distinct values) as incoming
+ // values for the same basic block.
+
+ int blockIndex = basephi->getBasicBlockIndex(InBB);
+ if (blockIndex != -1) {
+ Value *oldBase = basephi->getIncomingValue(blockIndex);
+ basephi->addIncoming(oldBase, InBB);
+#ifndef NDEBUG
+ Value *base = findBaseOrBDV(InVal, cache);
+ if (!isKnownBaseResult(base)) {
+ // Either conflict or base.
+ assert(states.count(base));
+ base = states[base].getBase();
+ assert(base != nullptr && "unknown PhiState!");
+ assert(newInsertedDefs.count(base) &&
+ "should have already added this in a prev. iteration!");
+ }
+
+ // In essense this assert states: the only way two
+ // values incoming from the same basic block may be
+ // different is by being different bitcasts of the same
+ // value. A cleanup that remains TODO is changing
+ // findBaseOrBDV to return an llvm::Value of the correct
+ // type (and still remain pure). This will remove the
+ // need to add bitcasts.
+ assert(base->stripPointerCasts() == oldBase->stripPointerCasts() &&
+ "sanity -- findBaseOrBDV should be pure!");
+#endif
+ continue;
+ }
+
+ // Find either the defining value for the PHI or the normal base for
+ // a non-phi node
+ Value *base = findBaseOrBDV(InVal, cache);
+ if (!isKnownBaseResult(base)) {
+ // Either conflict or base.
+ assert(states.count(base));
+ base = states[base].getBase();
+ assert(base != nullptr && "unknown PhiState!");
+ }
+ assert(base && "can't be null");
+ // Must use original input BB since base may not be Instruction
+ // The cast is needed since base traversal may strip away bitcasts
+ if (base->getType() != basephi->getType()) {
+ base = new BitCastInst(base, basephi->getType(), "cast",
+ InBB->getTerminator());
+ newInsertedDefs.insert(base);
+ }
+ basephi->addIncoming(base, InBB);
+ }
+ assert(basephi->getNumIncomingValues() == NumPHIValues);
+ } else if (SelectInst *basesel = dyn_cast<SelectInst>(state.getBase())) {
+ SelectInst *sel = cast<SelectInst>(v);
+ // Operand 1 & 2 are true, false path respectively. TODO: refactor to
+ // something more safe and less hacky.
+ for (int i = 1; i <= 2; i++) {
+ Value *InVal = sel->getOperand(i);
+ // Find either the defining value for the PHI or the normal base for
+ // a non-phi node
+ Value *base = findBaseOrBDV(InVal, cache);
+ if (!isKnownBaseResult(base)) {
+ // Either conflict or base.
+ assert(states.count(base));
+ base = states[base].getBase();
+ assert(base != nullptr && "unknown PhiState!");
+ }
+ assert(base && "can't be null");
+ // Must use original input BB since base may not be Instruction
+ // The cast is needed since base traversal may strip away bitcasts
+ if (base->getType() != basesel->getType()) {
+ base = new BitCastInst(base, basesel->getType(), "cast", basesel);
+ newInsertedDefs.insert(base);
+ }
+ basesel->setOperand(i, base);
+ }
+ } else {
+ assert(false && "unexpected type");
+ }
+ }
+ }
+
+ // Cache all of our results so we can cheaply reuse them
+ // NOTE: This is actually two caches: one of the base defining value
+ // relation and one of the base pointer relation! FIXME
+ for (auto item : states) {
+ Value *v = item.first;
+ Value *base = item.second.getBase();
+ assert(v && base);
+ assert(!isKnownBaseResult(v) && "why did it get added?");
+
+ if (TraceLSP) {
+ std::string fromstr =
+ cache.count(v) ? (cache[v]->hasName() ? cache[v]->getName() : "")
+ : "none";
+ errs() << "Updating base value cache"
+ << " for: " << (v->hasName() ? v->getName() : "")
+ << " from: " << fromstr
+ << " to: " << (base->hasName() ? base->getName() : "") << "\n";
+ }
+
+ assert(isKnownBaseResult(base) &&
+ "must be something we 'know' is a base pointer");
+ if (cache.count(v)) {
+ // Once we transition from the BDV relation being store in the cache to
+ // the base relation being stored, it must be stable
+ assert((!isKnownBaseResult(cache[v]) || cache[v] == base) &&
+ "base relation should be stable");
+ }
+ cache[v] = base;
+ }
+ assert(cache.find(def) != cache.end());
+ return cache[def];
+}
+
+// For a set of live pointers (base and/or derived), identify the base
+// pointer of the object which they are derived from. This routine will
+// mutate the IR graph as needed to make the 'base' pointer live at the
+// definition site of 'derived'. This ensures that any use of 'derived' can
+// also use 'base'. This may involve the insertion of a number of
+// additional PHI nodes.
+//
+// preconditions: live is a set of pointer type Values
+//
+// side effects: may insert PHI nodes into the existing CFG, will preserve
+// CFG, will not remove or mutate any existing nodes
+//
+// post condition: base_pairs contains one (derived, base) pair for every
+// pointer in live. Note that derived can be equal to base if the original
+// pointer was a base pointer.
+static void findBasePointers(const std::set<llvm::Value *> &live,
+ std::map<llvm::Value *, llvm::Value *> &base_pairs,
+ DominatorTree *DT, DefiningValueMapTy &DVCache,
+ std::set<llvm::Value *> &newInsertedDefs) {
+ for (Value *ptr : live) {
+ Value *base = findBasePointer(ptr, DVCache, newInsertedDefs);
+ assert(base && "failed to find base pointer");
+ base_pairs[ptr] = base;
+ assert((!isa<Instruction>(base) || !isa<Instruction>(ptr) ||
+ DT->dominates(cast<Instruction>(base)->getParent(),
+ cast<Instruction>(ptr)->getParent())) &&
+ "The base we found better dominate the derived pointer");
+
+ if (isNullConstant(base))
+ // If you see this trip and like to live really dangerously, the code
+ // should be correct, just with idioms the verifier can't handle. You
+ // can try disabling the verifier at your own substaintial risk.
+ llvm_unreachable("the relocation code needs adjustment to handle the"
+ "relocation of a null pointer constant without causing"
+ "false positives in the safepoint ir verifier.");
+ }
+}
+
+/// Find the required based pointers (and adjust the live set) for the given
+/// parse point.
+static void findBasePointers(DominatorTree &DT, DefiningValueMapTy &DVCache,
+ const CallSite &CS,
+ PartiallyConstructedSafepointRecord &result) {
+ std::map<llvm::Value *, llvm::Value *> base_pairs;
+ std::set<llvm::Value *> newInsertedDefs;
+ findBasePointers(result.liveset, base_pairs, &DT, DVCache, newInsertedDefs);
+
+ if (PrintBasePointers) {
+ errs() << "Base Pairs (w/o Relocation):\n";
+ for (auto Pair : base_pairs) {
+ errs() << " derived %" << Pair.first->getName() << " base %"
+ << Pair.second->getName() << "\n";
+ }
+ }
+
+ result.base_pairs = base_pairs;
+ result.newInsertedDefs = newInsertedDefs;
+}
+
+/// Check for liveness of items in the insert defs and add them to the live
+/// and base pointer sets
+static void fixupLiveness(DominatorTree &DT, const CallSite &CS,
+ const std::set<Value *> &allInsertedDefs,
+ PartiallyConstructedSafepointRecord &result) {
+ Instruction *inst = CS.getInstruction();
+
+ std::set<llvm::Value *> liveset = result.liveset;
+ std::map<llvm::Value *, llvm::Value *> base_pairs = result.base_pairs;
+
+ auto is_live_gc_reference =
+ [&](Value &V) { return isLiveGCReferenceAt(V, inst, DT, nullptr); };
+
+ // For each new definition, check to see if a) the definition dominates the
+ // instruction we're interested in, and b) one of the uses of that definition
+ // is edge-reachable from the instruction we're interested in. This is the
+ // same definition of liveness we used in the intial liveness analysis
+ for (Value *newDef : allInsertedDefs) {
+ if (liveset.count(newDef)) {
+ // already live, no action needed
+ continue;
+ }
+
+ // PERF: Use DT to check instruction domination might not be good for
+ // compilation time, and we could change to optimal solution if this
+ // turn to be a issue
+ if (!DT.dominates(cast<Instruction>(newDef), inst)) {
+ // can't possibly be live at inst
+ continue;
+ }
+
+ if (is_live_gc_reference(*newDef)) {
+ // Add the live new defs into liveset and base_pairs
+ liveset.insert(newDef);
+ base_pairs[newDef] = newDef;
+ }
+ }
+
+ result.liveset = liveset;
+ result.base_pairs = base_pairs;
+}
+
+static void fixupLiveReferences(
+ Function &F, DominatorTree &DT, Pass *P,
+ const std::set<llvm::Value *> &allInsertedDefs,
+ std::vector<CallSite> &toUpdate,
+ std::vector<struct PartiallyConstructedSafepointRecord> &records) {
+ for (size_t i = 0; i < records.size(); i++) {
+ struct PartiallyConstructedSafepointRecord &info = records[i];
+ CallSite &CS = toUpdate[i];
+ fixupLiveness(DT, CS, allInsertedDefs, info);
+ }
+}
+
+// Normalize basic block to make it ready to be target of invoke statepoint.
+// It means spliting it to have single predecessor. Return newly created BB
+// ready to be successor of invoke statepoint.
+static BasicBlock *normalizeBBForInvokeSafepoint(BasicBlock *BB,
+ BasicBlock *InvokeParent,
+ Pass *P) {
+ BasicBlock *ret = BB;
+
+ if (!BB->getUniquePredecessor()) {
+ ret = SplitBlockPredecessors(BB, InvokeParent, "");
+ }
+
+ // Another requirement for such basic blocks is to not have any phi nodes.
+ // Since we just ensured that new BB will have single predecessor,
+ // all phi nodes in it will have one value. Here it would be naturall place
+ // to
+ // remove them all. But we can not do this because we are risking to remove
+ // one of the values stored in liveset of another statepoint. We will do it
+ // later after placing all safepoints.
+
+ return ret;
+}
+
+static void
+VerifySafepointBounds(const std::pair<Instruction *, Instruction *> &bounds) {
+ assert(bounds.first->getParent() && bounds.second->getParent() &&
+ "both must belong to basic blocks");
+ if (bounds.first->getParent() == bounds.second->getParent()) {
+ // This is a call safepoint
+ // TODO: scan the range to find the statepoint
+ // TODO: check that the following instruction is not a gc_relocate or
+ // gc_result
+ } else {
+ // This is an invoke safepoint
+ InvokeInst *invoke = dyn_cast<InvokeInst>(bounds.first);
+ assert(invoke && "only continues over invokes!");
+ assert(invoke->getNormalDest() == bounds.second->getParent() &&
+ "safepoint should continue into normal exit block");
+ }
+}
+
+static int find_index(const SmallVectorImpl<Value *> &livevec, Value *val) {
+ auto itr = std::find(livevec.begin(), livevec.end(), val);
+ assert(livevec.end() != itr);
+ size_t index = std::distance(livevec.begin(), itr);
+ assert(index < livevec.size());
+ return index;
+}
+
+// Create new attribute set containing only attributes which can be transfered
+// from original call to the safepoint.
+static AttributeSet legalizeCallAttributes(AttributeSet AS) {
+ AttributeSet ret;
+
+ for (unsigned Slot = 0; Slot < AS.getNumSlots(); Slot++) {
+ unsigned index = AS.getSlotIndex(Slot);
+
+ if (index == AttributeSet::ReturnIndex ||
+ index == AttributeSet::FunctionIndex) {
+
+ for (auto it = AS.begin(Slot), it_end = AS.end(Slot); it != it_end;
+ ++it) {
+ Attribute attr = *it;
+
+ // Do not allow certain attributes - just skip them
+ // Safepoint can not be read only or read none.
+ if (attr.hasAttribute(Attribute::ReadNone) ||
+ attr.hasAttribute(Attribute::ReadOnly))
+ continue;
+
+ ret = ret.addAttributes(
+ AS.getContext(), index,
+ AttributeSet::get(AS.getContext(), index, AttrBuilder(attr)));
+ }
+ }
+
+ // Just skip parameter attributes for now
+ }
+
+ return ret;
+}
+
+/// Helper function to place all gc relocates necessary for the given
+/// statepoint.
+/// Inputs:
+/// liveVariables - list of variables to be relocated.
+/// liveStart - index of the first live variable.
+/// basePtrs - base pointers.
+/// statepointToken - statepoint instruction to which relocates should be
+/// bound.
+/// Builder - Llvm IR builder to be used to construct new calls.
+/// Returns array with newly created relocates.
+static std::vector<llvm::Instruction *>
+CreateGCRelocates(const SmallVectorImpl<llvm::Value *> &liveVariables,
+ const int liveStart,
+ const SmallVectorImpl<llvm::Value *> &basePtrs,
+ Instruction *statepointToken, IRBuilder<> Builder) {
+
+ std::vector<llvm::Instruction *> newDefs;
+
+ Module *M = statepointToken->getParent()->getParent()->getParent();
+
+ for (unsigned i = 0; i < liveVariables.size(); i++) {
+ // We generate a (potentially) unique declaration for every pointer type
+ // combination. This results is some blow up the function declarations in
+ // the IR, but removes the need for argument bitcasts which shrinks the IR
+ // greatly and makes it much more readable.
+ std::vector<Type *> types; // one per 'any' type
+ types.push_back(liveVariables[i]->getType()); // result type
+ Value *gc_relocate_decl = Intrinsic::getDeclaration(
+ M, Intrinsic::experimental_gc_relocate, types);
+
+ // Generate the gc.relocate call and save the result
+ Value *baseIdx =
+ ConstantInt::get(Type::getInt32Ty(M->getContext()),
+ liveStart + find_index(liveVariables, basePtrs[i]));
+ Value *liveIdx = ConstantInt::get(
+ Type::getInt32Ty(M->getContext()),
+ liveStart + find_index(liveVariables, liveVariables[i]));
+
+ // only specify a debug name if we can give a useful one
+ Value *reloc = Builder.CreateCall3(
+ gc_relocate_decl, statepointToken, baseIdx, liveIdx,
+ liveVariables[i]->hasName() ? liveVariables[i]->getName() + ".relocated"
+ : "");
+ // Trick CodeGen into thinking there are lots of free registers at this
+ // fake call.
+ cast<CallInst>(reloc)->setCallingConv(CallingConv::Cold);
+
+ newDefs.push_back(cast<Instruction>(reloc));
+ }
+ assert(newDefs.size() == liveVariables.size() &&
+ "missing or extra redefinition at safepoint");
+
+ return newDefs;
+}
+
+static void
+makeStatepointExplicitImpl(const CallSite &CS, /* to replace */
+ const SmallVectorImpl<llvm::Value *> &basePtrs,
+ const SmallVectorImpl<llvm::Value *> &liveVariables,
+ Pass *P,
+ PartiallyConstructedSafepointRecord &result) {
+ assert(basePtrs.size() == liveVariables.size());
+ assert(isStatepoint(CS) &&
+ "This method expects to be rewriting a statepoint");
+
+ BasicBlock *BB = CS.getInstruction()->getParent();
+ assert(BB);
+ Function *F = BB->getParent();
+ assert(F && "must be set");
+ Module *M = F->getParent();
+ assert(M && "must be set");
+
+ // We're not changing the function signature of the statepoint since the gc
+ // arguments go into the var args section.
+ Function *gc_statepoint_decl = CS.getCalledFunction();
+
+ // Then go ahead and use the builder do actually do the inserts. We insert
+ // immediately before the previous instruction under the assumption that all
+ // arguments will be available here. We can't insert afterwards since we may
+ // be replacing a terminator.
+ Instruction *insertBefore = CS.getInstruction();
+ IRBuilder<> Builder(insertBefore);
+ // Copy all of the arguments from the original statepoint - this includes the
+ // target, call args, and deopt args
+ std::vector<llvm::Value *> args;
+ args.insert(args.end(), CS.arg_begin(), CS.arg_end());
+ // TODO: Clear the 'needs rewrite' flag
+
+ // add all the pointers to be relocated (gc arguments)
+ // Capture the start of the live variable list for use in the gc_relocates
+ const int live_start = args.size();
+ args.insert(args.end(), liveVariables.begin(), liveVariables.end());
+
+ // Create the statepoint given all the arguments
+ Instruction *token = nullptr;
+ AttributeSet return_attributes;
+ if (CS.isCall()) {
+ CallInst *toReplace = cast<CallInst>(CS.getInstruction());
+ CallInst *call =
+ Builder.CreateCall(gc_statepoint_decl, args, "safepoint_token");
+ call->setTailCall(toReplace->isTailCall());
+ call->setCallingConv(toReplace->getCallingConv());
+
+ // Currently we will fail on parameter attributes and on certain
+ // function attributes.
+ AttributeSet new_attrs = legalizeCallAttributes(toReplace->getAttributes());
+ // In case if we can handle this set of sttributes - set up function attrs
+ // directly on statepoint and return attrs later for gc_result intrinsic.
+ call->setAttributes(new_attrs.getFnAttributes());
+ return_attributes = new_attrs.getRetAttributes();
+
+ token = call;
+
+ // Put the following gc_result and gc_relocate calls immediately after the
+ // the old call (which we're about to delete)
+ BasicBlock::iterator next(toReplace);
+ assert(BB->end() != next && "not a terminator, must have next");
+ next++;
+ Instruction *IP = &*(next);
+ Builder.SetInsertPoint(IP);
+ Builder.SetCurrentDebugLocation(IP->getDebugLoc());
+
+ } else if (CS.isInvoke()) {
+ InvokeInst *toReplace = cast<InvokeInst>(CS.getInstruction());
+
+ // Insert the new invoke into the old block. We'll remove the old one in a
+ // moment at which point this will become the new terminator for the
+ // original block.
+ InvokeInst *invoke = InvokeInst::Create(
+ gc_statepoint_decl, toReplace->getNormalDest(),
+ toReplace->getUnwindDest(), args, "", toReplace->getParent());
+ invoke->setCallingConv(toReplace->getCallingConv());
+
+ // Currently we will fail on parameter attributes and on certain
+ // function attributes.
+ AttributeSet new_attrs = legalizeCallAttributes(toReplace->getAttributes());
+ // In case if we can handle this set of sttributes - set up function attrs
+ // directly on statepoint and return attrs later for gc_result intrinsic.
+ invoke->setAttributes(new_attrs.getFnAttributes());
+ return_attributes = new_attrs.getRetAttributes();
+
+ token = invoke;
+
+ // Generate gc relocates in exceptional path
+ BasicBlock *unwindBlock = normalizeBBForInvokeSafepoint(
+ toReplace->getUnwindDest(), invoke->getParent(), P);
+
+ Instruction *IP = &*(unwindBlock->getFirstInsertionPt());
+ Builder.SetInsertPoint(IP);
+ Builder.SetCurrentDebugLocation(toReplace->getDebugLoc());
+
+ // Extract second element from landingpad return value. We will attach
+ // exceptional gc relocates to it.
+ const unsigned idx = 1;
+ Instruction *exceptional_token =
+ cast<Instruction>(Builder.CreateExtractValue(
+ unwindBlock->getLandingPadInst(), idx, "relocate_token"));
+ result.exceptional_relocates_token = exceptional_token;
+
+ // Just throw away return value. We will use the one we got for normal
+ // block.
+ (void)CreateGCRelocates(liveVariables, live_start, basePtrs,
+ exceptional_token, Builder);
+
+ // Generate gc relocates and returns for normal block
+ BasicBlock *normalDest = normalizeBBForInvokeSafepoint(
+ toReplace->getNormalDest(), invoke->getParent(), P);
+
+ IP = &*(normalDest->getFirstInsertionPt());
+ Builder.SetInsertPoint(IP);
+
+ // gc relocates will be generated later as if it were regular call
+ // statepoint
+ } else {
+ llvm_unreachable("unexpect type of CallSite");
+ }
+ assert(token);
+
+ // Take the name of the original value call if it had one.
+ token->takeName(CS.getInstruction());
+
+ // The GCResult is already inserted, we just need to find it
+ Instruction *gc_result = nullptr;
+ /* scope */ {
+ Instruction *toReplace = CS.getInstruction();
+ assert((toReplace->hasNUses(0) || toReplace->hasNUses(1)) &&
+ "only valid use before rewrite is gc.result");
+ if (toReplace->hasOneUse()) {
+ Instruction *GCResult = cast<Instruction>(*toReplace->user_begin());
+ assert(isGCResult(GCResult));
+ gc_result = GCResult;
+ }
+ }
+
+ // Update the gc.result of the original statepoint (if any) to use the newly
+ // inserted statepoint. This is safe to do here since the token can't be
+ // considered a live reference.
+ CS.getInstruction()->replaceAllUsesWith(token);
+
+ // Second, create a gc.relocate for every live variable
+ std::vector<llvm::Instruction *> newDefs =
+ CreateGCRelocates(liveVariables, live_start, basePtrs, token, Builder);
+
+ // Need to pass through the last part of the safepoint block so that we
+ // don't accidentally update uses in a following gc.relocate which is
+ // still conceptually part of the same safepoint. Gah.
+ Instruction *last = nullptr;
+ if (!newDefs.empty()) {
+ last = newDefs.back();
+ } else if (gc_result) {
+ last = gc_result;
+ } else {
+ last = token;
+ }
+ assert(last && "can't be null");
+ const auto bounds = std::make_pair(token, last);
+
+ // Sanity check our results - this is slightly non-trivial due to invokes
+ VerifySafepointBounds(bounds);
+
+ result.safepoint = bounds;
+}
+
+namespace {
+struct name_ordering {
+ Value *base;
+ Value *derived;
+ bool operator()(name_ordering const &a, name_ordering const &b) {
+ return -1 == a.derived->getName().compare(b.derived->getName());
+ }
+};
+}
+static void stablize_order(SmallVectorImpl<Value *> &basevec,
+ SmallVectorImpl<Value *> &livevec) {
+ assert(basevec.size() == livevec.size());
+
+ std::vector<name_ordering> temp;
+ for (size_t i = 0; i < basevec.size(); i++) {
+ name_ordering v;
+ v.base = basevec[i];
+ v.derived = livevec[i];
+ temp.push_back(v);
+ }
+ std::sort(temp.begin(), temp.end(), name_ordering());
+ for (size_t i = 0; i < basevec.size(); i++) {
+ basevec[i] = temp[i].base;
+ livevec[i] = temp[i].derived;
+ }
+}
+
+// Replace an existing gc.statepoint with a new one and a set of gc.relocates
+// which make the relocations happening at this safepoint explicit.
+//
+// WARNING: Does not do any fixup to adjust users of the original live
+// values. That's the callers responsibility.
+static void
+makeStatepointExplicit(DominatorTree &DT, const CallSite &CS, Pass *P,
+ PartiallyConstructedSafepointRecord &result) {
+ std::set<llvm::Value *> liveset = result.liveset;
+ std::map<llvm::Value *, llvm::Value *> base_pairs = result.base_pairs;
+
+ // Convert to vector for efficient cross referencing.
+ SmallVector<Value *, 64> basevec, livevec;
+ livevec.reserve(liveset.size());
+ basevec.reserve(liveset.size());
+ for (Value *L : liveset) {
+ livevec.push_back(L);
+
+ assert(base_pairs.find(L) != base_pairs.end());
+ Value *base = base_pairs[L];
+ basevec.push_back(base);
+ }
+ assert(livevec.size() == basevec.size());
+
+ // To make the output IR slightly more stable (for use in diffs), ensure a
+ // fixed order of the values in the safepoint (by sorting the value name).
+ // The order is otherwise meaningless.
+ stablize_order(basevec, livevec);
+
+ // Do the actual rewriting and delete the old statepoint
+ makeStatepointExplicitImpl(CS, basevec, livevec, P, result);
+ CS.getInstruction()->eraseFromParent();
+}
+
+// Helper function for the relocationViaAlloca.
+// It receives iterator to the statepoint gc relocates and emits store to the
+// assigned
+// location (via allocaMap) for the each one of them.
+// Add visited values into the visitedLiveValues set we will later use them
+// for sanity check.
+static void
+insertRelocationStores(iterator_range<Value::user_iterator> gcRelocs,
+ DenseMap<Value *, Value *> &allocaMap,
+ DenseSet<Value *> &visitedLiveValues) {
+
+ for (User *U : gcRelocs) {
+ if (!isa<IntrinsicInst>(U))
+ continue;
+
+ IntrinsicInst *relocatedValue = cast<IntrinsicInst>(U);
+
+ // We only care about relocates
+ if (relocatedValue->getIntrinsicID() !=
+ Intrinsic::experimental_gc_relocate) {
+ continue;
+ }
+
+ GCRelocateOperands relocateOperands(relocatedValue);
+ Value *originalValue = const_cast<Value *>(relocateOperands.derivedPtr());
+ assert(allocaMap.count(originalValue));
+ Value *alloca = allocaMap[originalValue];
+
+ // Emit store into the related alloca
+ StoreInst *store = new StoreInst(relocatedValue, alloca);
+ store->insertAfter(relocatedValue);
+
+#ifndef NDEBUG
+ visitedLiveValues.insert(originalValue);
+#endif
+ }
+}
+
+/// do all the relocation update via allocas and mem2reg
+static void relocationViaAlloca(
+ Function &F, DominatorTree &DT, const std::vector<Value *> &live,
+ const std::vector<struct PartiallyConstructedSafepointRecord> &records) {
+#ifndef NDEBUG
+ int initialAllocaNum = 0;
+
+ // record initial number of allocas
+ for (inst_iterator itr = inst_begin(F), end = inst_end(F); itr != end;
+ itr++) {
+ if (isa<AllocaInst>(*itr))
+ initialAllocaNum++;
+ }
+#endif
+
+ // TODO-PERF: change data structures, reserve
+ DenseMap<Value *, Value *> allocaMap;
+ SmallVector<AllocaInst *, 200> PromotableAllocas;
+ PromotableAllocas.reserve(live.size());
+
+ // emit alloca for each live gc pointer
+ for (unsigned i = 0; i < live.size(); i++) {
+ Value *liveValue = live[i];
+ AllocaInst *alloca = new AllocaInst(liveValue->getType(), "",
+ F.getEntryBlock().getFirstNonPHI());
+ allocaMap[liveValue] = alloca;
+ PromotableAllocas.push_back(alloca);
+ }
+
+ // The next two loops are part of the same conceptual operation. We need to
+ // insert a store to the alloca after the original def and at each
+ // redefinition. We need to insert a load before each use. These are split
+ // into distinct loops for performance reasons.
+
+ // update gc pointer after each statepoint
+ // either store a relocated value or null (if no relocated value found for
+ // this gc pointer and it is not a gc_result)
+ // this must happen before we update the statepoint with load of alloca
+ // otherwise we lose the link between statepoint and old def
+ for (size_t i = 0; i < records.size(); i++) {
+ const struct PartiallyConstructedSafepointRecord &info = records[i];
+ Value *statepoint = info.safepoint.first;
+
+ // This will be used for consistency check
+ DenseSet<Value *> visitedLiveValues;
+
+ // Insert stores for normal statepoint gc relocates
+ insertRelocationStores(statepoint->users(), allocaMap, visitedLiveValues);
+
+ // In case if it was invoke statepoint
+ // we will insert stores for exceptional path gc relocates.
+ if (isa<InvokeInst>(statepoint)) {
+ insertRelocationStores(info.exceptional_relocates_token->users(),
+ allocaMap, visitedLiveValues);
+ }
+
+#ifndef NDEBUG
+ // For consistency check store null's into allocas for values that are not
+ // relocated
+ // by this statepoint.
+ for (auto Pair : allocaMap) {
+ Value *def = Pair.first;
+ Value *alloca = Pair.second;
+
+ // This value was relocated
+ if (visitedLiveValues.count(def)) {
+ continue;
+ }
+ // Result should not be relocated
+ if (def == info.result) {
+ continue;
+ }
+
+ Constant *CPN =
+ ConstantPointerNull::get(cast<PointerType>(def->getType()));
+ StoreInst *store = new StoreInst(CPN, alloca);
+ store->insertBefore(info.safepoint.second);
+ }
+#endif
+ }
+ // update use with load allocas and add store for gc_relocated
+ for (auto Pair : allocaMap) {
+ Value *def = Pair.first;
+ Value *alloca = Pair.second;
+
+ // we pre-record the uses of allocas so that we dont have to worry about
+ // later update
+ // that change the user information.
+ SmallVector<Instruction *, 20> uses;
+ // PERF: trade a linear scan for repeated reallocation
+ uses.reserve(std::distance(def->user_begin(), def->user_end()));
+ for (User *U : def->users()) {
+ if (!isa<ConstantExpr>(U)) {
+ // If the def has a ConstantExpr use, then the def is either a
+ // ConstantExpr use itself or null. In either case
+ // (recursively in the first, directly in the second), the oop
+ // it is ultimately dependent on is null and this particular
+ // use does not need to be fixed up.
+ uses.push_back(cast<Instruction>(U));
+ }
+ }
+
+ std::sort(uses.begin(), uses.end());
+ auto last = std::unique(uses.begin(), uses.end());
+ uses.erase(last, uses.end());
+
+ for (Instruction *use : uses) {
+ if (isa<PHINode>(use)) {
+ PHINode *phi = cast<PHINode>(use);
+ for (unsigned i = 0; i < phi->getNumIncomingValues(); i++) {
+ if (def == phi->getIncomingValue(i)) {
+ LoadInst *load = new LoadInst(
+ alloca, "", phi->getIncomingBlock(i)->getTerminator());
+ phi->setIncomingValue(i, load);
+ }
+ }
+ } else {
+ LoadInst *load = new LoadInst(alloca, "", use);
+ use->replaceUsesOfWith(def, load);
+ }
+ }
+
+ // emit store for the initial gc value
+ // store must be inserted after load, otherwise store will be in alloca's
+ // use list and an extra load will be inserted before it
+ StoreInst *store = new StoreInst(def, alloca);
+ if (isa<Instruction>(def)) {
+ store->insertAfter(cast<Instruction>(def));
+ } else {
+ assert((isa<Argument>(def) || isa<GlobalVariable>(def) ||
+ (isa<Constant>(def) && cast<Constant>(def)->isNullValue())) &&
+ "Must be argument or global");
+ store->insertAfter(cast<Instruction>(alloca));
+ }
+ }
+
+ assert(PromotableAllocas.size() == live.size() &&
+ "we must have the same allocas with lives");
+ if (!PromotableAllocas.empty()) {
+ // apply mem2reg to promote alloca to SSA
+ PromoteMemToReg(PromotableAllocas, DT);
+ }
+
+#ifndef NDEBUG
+ for (inst_iterator itr = inst_begin(F), end = inst_end(F); itr != end;
+ itr++) {
+ if (isa<AllocaInst>(*itr))
+ initialAllocaNum--;
+ }
+ assert(initialAllocaNum == 0 && "We must not introduce any extra allocas");
+#endif
+}
+
+/// Implement a unique function which doesn't require we sort the input
+/// vector. Doing so has the effect of changing the output of a couple of
+/// tests in ways which make them less useful in testing fused safepoints.
+template <typename T> static void unique_unsorted(std::vector<T> &vec) {
+ DenseSet<T> seen;
+ std::vector<T> tmp;
+ vec.reserve(vec.size());
+ std::swap(tmp, vec);
+ for (auto V : tmp) {
+ if (seen.insert(V).second) {
+ vec.push_back(V);
+ }
+ }
+}
+
+static Function *getUseHolder(Module &M) {
+ FunctionType *ftype =
+ FunctionType::get(Type::getVoidTy(M.getContext()), true);
+ Function *Func = cast<Function>(M.getOrInsertFunction("__tmp_use", ftype));
+ return Func;
+}
+
+/// Insert holders so that each Value is obviously live through the entire
+/// liftetime of the call.
+static void insertUseHolderAfter(CallSite &CS, const ArrayRef<Value *> Values,
+ std::vector<CallInst *> &holders) {
+ Module *M = CS.getInstruction()->getParent()->getParent()->getParent();
+ Function *Func = getUseHolder(*M);
+ if (CS.isCall()) {
+ // For call safepoints insert dummy calls right after safepoint
+ BasicBlock::iterator next(CS.getInstruction());
+ next++;
+ CallInst *base_holder = CallInst::Create(Func, Values, "", next);
+ holders.push_back(base_holder);
+ } else if (CS.isInvoke()) {
+ // For invoke safepooints insert dummy calls both in normal and
+ // exceptional destination blocks
+ InvokeInst *invoke = cast<InvokeInst>(CS.getInstruction());
+ CallInst *normal_holder = CallInst::Create(
+ Func, Values, "", invoke->getNormalDest()->getFirstInsertionPt());
+ CallInst *unwind_holder = CallInst::Create(
+ Func, Values, "", invoke->getUnwindDest()->getFirstInsertionPt());
+ holders.push_back(normal_holder);
+ holders.push_back(unwind_holder);
+ } else {
+ assert(false && "Unsupported");
+ }
+}
+
+static void findLiveReferences(
+ Function &F, DominatorTree &DT, Pass *P, std::vector<CallSite> &toUpdate,
+ std::vector<struct PartiallyConstructedSafepointRecord> &records) {
+ for (size_t i = 0; i < records.size(); i++) {
+ struct PartiallyConstructedSafepointRecord &info = records[i];
+ CallSite &CS = toUpdate[i];
+ analyzeParsePointLiveness(DT, CS, info);
+ }
+}
+
+static void addBasesAsLiveValues(std::set<Value *> &liveset,
+ std::map<Value *, Value *> &base_pairs) {
+ // Identify any base pointers which are used in this safepoint, but not
+ // themselves relocated. We need to relocate them so that later inserted
+ // safepoints can get the properly relocated base register.
+ DenseSet<Value *> missing;
+ for (Value *L : liveset) {
+ assert(base_pairs.find(L) != base_pairs.end());
+ Value *base = base_pairs[L];
+ assert(base);
+ if (liveset.find(base) == liveset.end()) {
+ assert(base_pairs.find(base) == base_pairs.end());
+ // uniqued by set insert
+ missing.insert(base);
+ }
+ }
+
+ // Note that we want these at the end of the list, otherwise
+ // register placement gets screwed up once we lower to STATEPOINT
+ // instructions. This is an utter hack, but there doesn't seem to be a
+ // better one.
+ for (Value *base : missing) {
+ assert(base);
+ liveset.insert(base);
+ base_pairs[base] = base;
+ }
+ assert(liveset.size() == base_pairs.size());
+}
+
+static bool insertParsePoints(Function &F, DominatorTree &DT, Pass *P,
+ std::vector<CallSite> &toUpdate) {
+#ifndef NDEBUG
+ // sanity check the input
+ std::set<CallSite> uniqued;
+ uniqued.insert(toUpdate.begin(), toUpdate.end());
+ assert(uniqued.size() == toUpdate.size() && "no duplicates please!");
+
+ for (size_t i = 0; i < toUpdate.size(); i++) {
+ CallSite &CS = toUpdate[i];
+ assert(CS.getInstruction()->getParent()->getParent() == &F);
+ assert(isStatepoint(CS) && "expected to already be a deopt statepoint");
+ }
+#endif
+
+ // A list of dummy calls added to the IR to keep various values obviously
+ // live in the IR. We'll remove all of these when done.
+ std::vector<CallInst *> holders;
+
+ // Insert a dummy call with all of the arguments to the vm_state we'll need
+ // for the actual safepoint insertion. This ensures reference arguments in
+ // the deopt argument list are considered live through the safepoint (and
+ // thus makes sure they get relocated.)
+ for (size_t i = 0; i < toUpdate.size(); i++) {
+ CallSite &CS = toUpdate[i];
+ Statepoint StatepointCS(CS);
+
+ SmallVector<Value *, 64> DeoptValues;
+ for (Use &U : StatepointCS.vm_state_args()) {
+ Value *Arg = cast<Value>(&U);
+ if (isGCPointerType(Arg->getType()))
+ DeoptValues.push_back(Arg);
+ }
+ insertUseHolderAfter(CS, DeoptValues, holders);
+ }
+
+ std::vector<struct PartiallyConstructedSafepointRecord> records;
+ records.reserve(toUpdate.size());
+ for (size_t i = 0; i < toUpdate.size(); i++) {
+ struct PartiallyConstructedSafepointRecord info;
+ records.push_back(info);
+ }
+ assert(records.size() == toUpdate.size());
+
+ // A) Identify all gc pointers which are staticly live at the given call
+ // site.
+ findLiveReferences(F, DT, P, toUpdate, records);
+
+ // B) Find the base pointers for each live pointer
+ /* scope for caching */ {
+ // Cache the 'defining value' relation used in the computation and
+ // insertion of base phis and selects. This ensures that we don't insert
+ // large numbers of duplicate base_phis.
+ DefiningValueMapTy DVCache;
+
+ for (size_t i = 0; i < records.size(); i++) {
+ struct PartiallyConstructedSafepointRecord &info = records[i];
+ CallSite &CS = toUpdate[i];
+ findBasePointers(DT, DVCache, CS, info);
+ }
+ } // end of cache scope
+
+ // The base phi insertion logic (for any safepoint) may have inserted new
+ // instructions which are now live at some safepoint. The simplest such
+ // example is:
+ // loop:
+ // phi a <-- will be a new base_phi here
+ // safepoint 1 <-- that needs to be live here
+ // gep a + 1
+ // safepoint 2
+ // br loop
+ std::set<llvm::Value *> allInsertedDefs;
+ for (size_t i = 0; i < records.size(); i++) {
+ struct PartiallyConstructedSafepointRecord &info = records[i];
+ allInsertedDefs.insert(info.newInsertedDefs.begin(),
+ info.newInsertedDefs.end());
+ }
+
+ // We insert some dummy calls after each safepoint to definitely hold live
+ // the base pointers which were identified for that safepoint. We'll then
+ // ask liveness for _every_ base inserted to see what is now live. Then we
+ // remove the dummy calls.
+ holders.reserve(holders.size() + records.size());
+ for (size_t i = 0; i < records.size(); i++) {
+ struct PartiallyConstructedSafepointRecord &info = records[i];
+ CallSite &CS = toUpdate[i];
+
+ SmallVector<Value *, 128> Bases;
+ for (auto Pair : info.base_pairs) {
+ Bases.push_back(Pair.second);
+ }
+ insertUseHolderAfter(CS, Bases, holders);
+ }
+
+ // Add the bases explicitly to the live vector set. This may result in a few
+ // extra relocations, but the base has to be available whenever a pointer
+ // derived from it is used. Thus, we need it to be part of the statepoint's
+ // gc arguments list. TODO: Introduce an explicit notion (in the following
+ // code) of the GC argument list as seperate from the live Values at a
+ // given statepoint.
+ for (size_t i = 0; i < records.size(); i++) {
+ struct PartiallyConstructedSafepointRecord &info = records[i];
+ addBasesAsLiveValues(info.liveset, info.base_pairs);
+ }
+
+ // If we inserted any new values, we need to adjust our notion of what is
+ // live at a particular safepoint.
+ if (!allInsertedDefs.empty()) {
+ fixupLiveReferences(F, DT, P, allInsertedDefs, toUpdate, records);
+ }
+ if (PrintBasePointers) {
+ for (size_t i = 0; i < records.size(); i++) {
+ struct PartiallyConstructedSafepointRecord &info = records[i];
+ errs() << "Base Pairs: (w/Relocation)\n";
+ for (auto Pair : info.base_pairs) {
+ errs() << " derived %" << Pair.first->getName() << " base %"
+ << Pair.second->getName() << "\n";
+ }
+ }
+ }
+ for (size_t i = 0; i < holders.size(); i++) {
+ holders[i]->eraseFromParent();
+ holders[i] = nullptr;
+ }
+ holders.clear();
+
+ // Now run through and replace the existing statepoints with new ones with
+ // the live variables listed. We do not yet update uses of the values being
+ // relocated. We have references to live variables that need to
+ // survive to the last iteration of this loop. (By construction, the
+ // previous statepoint can not be a live variable, thus we can and remove
+ // the old statepoint calls as we go.)
+ for (size_t i = 0; i < records.size(); i++) {
+ struct PartiallyConstructedSafepointRecord &info = records[i];
+ CallSite &CS = toUpdate[i];
+ makeStatepointExplicit(DT, CS, P, info);
+ }
+ toUpdate.clear(); // prevent accident use of invalid CallSites
+
+ // In case if we inserted relocates in a different basic block than the
+ // original safepoint (this can happen for invokes). We need to be sure that
+ // original values were not used in any of the phi nodes at the
+ // beginning of basic block containing them. Because we know that all such
+ // blocks will have single predecessor we can safely assume that all phi
+ // nodes have single entry (because of normalizeBBForInvokeSafepoint).
+ // Just remove them all here.
+ for (size_t i = 0; i < records.size(); i++) {
+ Instruction *I = records[i].safepoint.first;
+
+ if (InvokeInst *invoke = dyn_cast<InvokeInst>(I)) {
+ FoldSingleEntryPHINodes(invoke->getNormalDest());
+ assert(!isa<PHINode>(invoke->getNormalDest()->begin()));
+
+ FoldSingleEntryPHINodes(invoke->getUnwindDest());
+ assert(!isa<PHINode>(invoke->getUnwindDest()->begin()));
+ }
+ }
+
+ // Do all the fixups of the original live variables to their relocated selves
+ std::vector<Value *> live;
+ for (size_t i = 0; i < records.size(); i++) {
+ struct PartiallyConstructedSafepointRecord &info = records[i];
+ // We can't simply save the live set from the original insertion. One of
+ // the live values might be the result of a call which needs a safepoint.
+ // That Value* no longer exists and we need to use the new gc_result.
+ // Thankfully, the liveset is embedded in the statepoint (and updated), so
+ // we just grab that.
+ Statepoint statepoint(info.safepoint.first);
+ live.insert(live.end(), statepoint.gc_args_begin(),
+ statepoint.gc_args_end());
+ }
+ unique_unsorted(live);
+
+ // sanity check
+ for (auto ptr : live) {
+ assert(isGCPointerType(ptr->getType()) && "must be a gc pointer type");
+ }
+
+ relocationViaAlloca(F, DT, live, records);
+ return !records.empty();
+}
+
+/// Returns true if this function should be rewritten by this pass. The main
+/// point of this function is as an extension point for custom logic.
+static bool shouldRewriteStatepointsIn(Function &F) {
+ // TODO: This should check the GCStrategy
+ return true;
+}
+
+bool RewriteStatepointsForGC::runOnFunction(Function &F) {
+ // Nothing to do for declarations.
+ if (F.isDeclaration() || F.empty())
+ return false;
+
+ // Policy choice says not to rewrite - the most common reason is that we're
+ // compiling code without a GCStrategy.
+ if (!shouldRewriteStatepointsIn(F))
+ return false;
+
+ // Gather all the statepoints which need rewritten.
+ std::vector<CallSite> ParsePointNeeded;
+ for (inst_iterator itr = inst_begin(F), end = inst_end(F); itr != end;
+ itr++) {
+ // TODO: only the ones with the flag set!
+ if (isStatepoint(*itr))
+ ParsePointNeeded.push_back(CallSite(&*itr));
+ }
+
+ // Return early if no work to do.
+ if (ParsePointNeeded.empty())
+ return false;
+
+ DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ return insertParsePoints(F, DT, this, ParsePointNeeded);
+}
projects / platform / upstream / llvm.git / commitdiff