7f34aca083
There is already an API in BasicBlock that checks and returns the musttail call if it precedes the return instruction. Use it instead of manually checking in each place. Differential Revision: https://reviews.llvm.org/D90693
99 lines
3.1 KiB
C++
99 lines
3.1 KiB
C++
//===- EscapeEnumerator.cpp -----------------------------------------------===//
|
|
//
|
|
// 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
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// Defines a helper class that enumerates all possible exits from a function,
|
|
// including exception handling.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Transforms/Utils/EscapeEnumerator.h"
|
|
#include "llvm/ADT/Triple.h"
|
|
#include "llvm/Analysis/EHPersonalities.h"
|
|
#include "llvm/IR/Module.h"
|
|
#include "llvm/Transforms/Utils/Local.h"
|
|
|
|
using namespace llvm;
|
|
|
|
static FunctionCallee getDefaultPersonalityFn(Module *M) {
|
|
LLVMContext &C = M->getContext();
|
|
Triple T(M->getTargetTriple());
|
|
EHPersonality Pers = getDefaultEHPersonality(T);
|
|
return M->getOrInsertFunction(getEHPersonalityName(Pers),
|
|
FunctionType::get(Type::getInt32Ty(C), true));
|
|
}
|
|
|
|
IRBuilder<> *EscapeEnumerator::Next() {
|
|
if (Done)
|
|
return nullptr;
|
|
|
|
// Find all 'return', 'resume', and 'unwind' instructions.
|
|
while (StateBB != StateE) {
|
|
BasicBlock *CurBB = &*StateBB++;
|
|
|
|
// Branches and invokes do not escape, only unwind, resume, and return
|
|
// do.
|
|
Instruction *TI = CurBB->getTerminator();
|
|
if (!isa<ReturnInst>(TI) && !isa<ResumeInst>(TI))
|
|
continue;
|
|
|
|
if (CallInst *CI = CurBB->getTerminatingMustTailCall())
|
|
TI = CI;
|
|
Builder.SetInsertPoint(TI);
|
|
return &Builder;
|
|
}
|
|
|
|
Done = true;
|
|
|
|
if (!HandleExceptions)
|
|
return nullptr;
|
|
|
|
if (F.doesNotThrow())
|
|
return nullptr;
|
|
|
|
// Find all 'call' instructions that may throw.
|
|
// We cannot tranform calls with musttail tag.
|
|
SmallVector<Instruction *, 16> Calls;
|
|
for (BasicBlock &BB : F)
|
|
for (Instruction &II : BB)
|
|
if (CallInst *CI = dyn_cast<CallInst>(&II))
|
|
if (!CI->doesNotThrow() && !CI->isMustTailCall())
|
|
Calls.push_back(CI);
|
|
|
|
if (Calls.empty())
|
|
return nullptr;
|
|
|
|
// Create a cleanup block.
|
|
LLVMContext &C = F.getContext();
|
|
BasicBlock *CleanupBB = BasicBlock::Create(C, CleanupBBName, &F);
|
|
Type *ExnTy = StructType::get(Type::getInt8PtrTy(C), Type::getInt32Ty(C));
|
|
if (!F.hasPersonalityFn()) {
|
|
FunctionCallee PersFn = getDefaultPersonalityFn(F.getParent());
|
|
F.setPersonalityFn(cast<Constant>(PersFn.getCallee()));
|
|
}
|
|
|
|
if (isScopedEHPersonality(classifyEHPersonality(F.getPersonalityFn()))) {
|
|
report_fatal_error("Scoped EH not supported");
|
|
}
|
|
|
|
LandingPadInst *LPad =
|
|
LandingPadInst::Create(ExnTy, 1, "cleanup.lpad", CleanupBB);
|
|
LPad->setCleanup(true);
|
|
ResumeInst *RI = ResumeInst::Create(LPad, CleanupBB);
|
|
|
|
// Transform the 'call' instructions into 'invoke's branching to the
|
|
// cleanup block. Go in reverse order to make prettier BB names.
|
|
SmallVector<Value *, 16> Args;
|
|
for (unsigned I = Calls.size(); I != 0;) {
|
|
CallInst *CI = cast<CallInst>(Calls[--I]);
|
|
changeToInvokeAndSplitBasicBlock(CI, CleanupBB);
|
|
}
|
|
|
|
Builder.SetInsertPoint(RI);
|
|
return &Builder;
|
|
}
|