blob: 3ae76ffd5ecab4e590571948eb61072c7f4af05e [file] [log] [blame]
//===- StripGCRelocates.cpp - Remove gc.relocates inserted by RewriteStatePoints===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See 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 intrinsics would still be
// present.
#include "llvm/Transforms/Utils/StripGCRelocates.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Statepoint.h"
using namespace llvm;
static bool stripGCRelocates(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 (isa<GCStatepointInst>(GCR->getOperand(0)))
// 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->getIterator());
// 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.
return !GCRelocates.empty();
PreservedAnalyses StripGCRelocates::run(Function &F,
FunctionAnalysisManager &AM) {
if (!stripGCRelocates(F))
return PreservedAnalyses::all();
// Removing gc.relocate preserves the CFG, but most other analysis probably
// need to re-run.
PreservedAnalyses PA;
return PA;