AllowStatepointWithNoDeoptInfo("rs4gc-allow-statepoint-with-no-deopt-info",
cl::Hidden, cl::init(true));
+/// Should we split vectors of pointers into their individual elements? This
+/// is known to be buggy, but the alternate implementation isn't yet ready.
+/// This is purely to provide a debugging and dianostic hook until the vector
+/// split is replaced with vector relocations.
+static cl::opt<bool> UseVectorSplit("rs4gc-split-vector-values", cl::Hidden,
+ cl::init(true));
+
namespace {
struct RewriteStatepointsForGC : public ModulePass {
static char ID; // Pass identification, replacement for typeid
/// particular element in 'I'.
static BaseDefiningValueResult
findBaseDefiningValueOfVector(Value *I) {
- assert(I->getType()->isVectorTy() &&
- cast<VectorType>(I->getType())->getElementType()->isPointerTy() &&
- "Illegal to ask for the base pointer of a non-pointer type");
-
// Each case parallels findBaseDefiningValue below, see that code for
// detailed motivation.
/// (i.e. a PHI or Select of two derived pointers), or c) involves a change
/// from pointer to vector type or back.
static BaseDefiningValueResult findBaseDefiningValue(Value *I) {
+ assert(I->getType()->isPtrOrPtrVectorTy() &&
+ "Illegal to ask for the base pointer of a non-pointer type");
+
if (I->getType()->isVectorTy())
return findBaseDefiningValueOfVector(I);
-
- assert(I->getType()->isPointerTy() &&
- "Illegal to ask for the base pointer of a non-pointer type");
if (isa<Argument>(I))
// An incoming argument to the function is a base pointer
assert(Index < LiveVec.size() && "Bug in std::find?");
return Index;
};
-
- // All gc_relocate are set to i8 addrspace(1)* type. We originally generated
- // unique declarations for each pointer type, but this proved problematic
- // because the intrinsic mangling code is incomplete and fragile. Since
- // we're moving towards a single unified pointer type anyways, we can just
- // cast everything to an i8* of the right address space. A bitcast is added
- // later to convert gc_relocate to the actual value's type.
Module *M = StatepointToken->getModule();
- auto AS = cast<PointerType>(LiveVariables[0]->getType())->getAddressSpace();
- Type *Types[] = {Type::getInt8PtrTy(M->getContext(), AS)};
- Value *GCRelocateDecl =
- Intrinsic::getDeclaration(M, Intrinsic::experimental_gc_relocate, Types);
+
+ // All gc_relocate are generated as i8 addrspace(1)* (or a vector type whose
+ // element type is i8 addrspace(1)*). We originally generated unique
+ // declarations for each pointer type, but this proved problematic because
+ // the intrinsic mangling code is incomplete and fragile. Since we're moving
+ // towards a single unified pointer type anyways, we can just cast everything
+ // to an i8* of the right address space. A bitcast is added later to convert
+ // gc_relocate to the actual value's type.
+ auto getGCRelocateDecl = [&] (Type *Ty) {
+ assert(isHandledGCPointerType(Ty));
+ auto AS = Ty->getScalarType()->getPointerAddressSpace();
+ Type *NewTy = Type::getInt8PtrTy(M->getContext(), AS);
+ if (auto *VT = dyn_cast<VectorType>(Ty))
+ NewTy = VectorType::get(NewTy, VT->getNumElements());
+ return Intrinsic::getDeclaration(M, Intrinsic::experimental_gc_relocate,
+ {NewTy});
+ };
+
+ // Lazily populated map from input types to the canonicalized form mentioned
+ // in the comment above. This should probably be cached somewhere more
+ // broadly.
+ DenseMap<Type*, Value*> TypeToDeclMap;
for (unsigned i = 0; i < LiveVariables.size(); i++) {
// Generate the gc.relocate call and save the result
Builder.getInt32(LiveStart + FindIndex(LiveVariables, BasePtrs[i]));
Value *LiveIdx = Builder.getInt32(LiveStart + i);
+ Type *Ty = LiveVariables[i]->getType();
+ if (!TypeToDeclMap.count(Ty))
+ TypeToDeclMap[Ty] = getGCRelocateDecl(Ty);
+ Value *GCRelocateDecl = TypeToDeclMap[Ty];
+
// only specify a debug name if we can give a useful one
CallInst *Reloc = Builder.CreateCall(
GCRelocateDecl, {StatepointToken, BaseIdx, LiveIdx},
// Do a limited scalarization of any live at safepoint vector values which
// contain pointers. This enables this pass to run after vectorization at
- // the cost of some possible performance loss. TODO: it would be nice to
- // natively support vectors all the way through the backend so we don't need
- // to scalarize here.
- for (size_t i = 0; i < Records.size(); i++) {
- PartiallyConstructedSafepointRecord &Info = Records[i];
- Instruction *Statepoint = ToUpdate[i].getInstruction();
- splitVectorValues(cast<Instruction>(Statepoint), Info.LiveSet,
- Info.PointerToBase, DT);
- }
+ // the cost of some possible performance loss. Note: This is known to not
+ // handle updating of the side tables correctly which can lead to relocation
+ // bugs when the same vector is live at multiple statepoints. We're in the
+ // process of implementing the alternate lowering - relocating the
+ // vector-of-pointers as first class item and updating the backend to
+ // understand that - but that's not yet complete.
+ if (UseVectorSplit)
+ for (size_t i = 0; i < Records.size(); i++) {
+ PartiallyConstructedSafepointRecord &Info = Records[i];
+ Instruction *Statepoint = ToUpdate[i].getInstruction();
+ splitVectorValues(cast<Instruction>(Statepoint), Info.LiveSet,
+ Info.PointerToBase, DT);
+ }
// In order to reduce live set of statepoint we might choose to rematerialize
// some values instead of relocating them. This is purely an optimization and
#ifndef NDEBUG
// sanity check
for (auto *Ptr : Live)
- assert(isGCPointerType(Ptr->getType()) && "must be a gc pointer type");
+ assert(isHandledGCPointerType(Ptr->getType()) &&
+ "must be a gc pointer type");
#endif
relocationViaAlloca(F, DT, Live, Records);
static bool shouldRewriteStatepointsIn(Function &F) {
// TODO: This should check the GCStrategy
if (F.hasGC()) {
- const char *FunctionGCName = F.getGC();
+ const auto &FunctionGCName = F.getGC();
const StringRef StatepointExampleName("statepoint-example");
const StringRef CoreCLRName("coreclr");
return (StatepointExampleName == FunctionGCName) ||
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