| //===- StripGCRelocates.cpp - Remove gc.relocates inserted by RewriteStatePoints===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This is a little utility pass that removes the gc.relocates inserted by |
| // RewriteStatepointsForGC. Note that the generated IR is incorrect, |
| // but this is useful as a single pass in itself, for analysis of IR, without |
| // the GC.relocates. The statepoint and gc.result instrinsics would still be |
| // present. |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/IR/Function.h" |
| #include "llvm/IR/InstIterator.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/Statepoint.h" |
| #include "llvm/IR/Type.h" |
| #include "llvm/InitializePasses.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| using namespace llvm; |
| |
| namespace { |
| struct StripGCRelocates : public FunctionPass { |
| static char ID; // Pass identification, replacement for typeid |
| StripGCRelocates() : FunctionPass(ID) { |
| initializeStripGCRelocatesPass(*PassRegistry::getPassRegistry()); |
| } |
| |
| void getAnalysisUsage(AnalysisUsage &Info) const override {} |
| |
| bool runOnFunction(Function &F) override; |
| |
| }; |
| char StripGCRelocates::ID = 0; |
| } |
| |
| bool StripGCRelocates::runOnFunction(Function &F) { |
| // Nothing to do for declarations. |
| if (F.isDeclaration()) |
| return false; |
| SmallVector<GCRelocateInst *, 20> GCRelocates; |
| // TODO: We currently do not handle gc.relocates that are in landing pads, |
| // i.e. not bound to a single statepoint token. |
| for (Instruction &I : instructions(F)) { |
| if (auto *GCR = dyn_cast<GCRelocateInst>(&I)) |
| if (isStatepoint(GCR->getOperand(0))) |
| GCRelocates.push_back(GCR); |
| } |
| // All gc.relocates are bound to a single statepoint token. The order of |
| // visiting gc.relocates for deletion does not matter. |
| for (GCRelocateInst *GCRel : GCRelocates) { |
| Value *OrigPtr = GCRel->getDerivedPtr(); |
| Value *ReplaceGCRel = OrigPtr; |
| |
| // All gc_relocates are i8 addrspace(1)* typed, we need a bitcast from i8 |
| // addrspace(1)* to the type of the OrigPtr, if the are not the same. |
| if (GCRel->getType() != OrigPtr->getType()) |
| ReplaceGCRel = new BitCastInst(OrigPtr, GCRel->getType(), "cast", GCRel); |
| |
| // Replace all uses of gc.relocate and delete the gc.relocate |
| // There maybe unncessary bitcasts back to the OrigPtr type, an instcombine |
| // pass would clear this up. |
| GCRel->replaceAllUsesWith(ReplaceGCRel); |
| GCRel->eraseFromParent(); |
| } |
| return !GCRelocates.empty(); |
| } |
| |
| INITIALIZE_PASS(StripGCRelocates, "strip-gc-relocates", |
| "Strip gc.relocates inserted through RewriteStatepointsForGC", |
| true, false) |