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06fe9815da
This adds support for TSan C++ exception handling, where we need to add extra calls to __tsan_func_exit when a function is exitted via exception mechanisms. Otherwise the shadow stack gets corrupted (leaked). This patch moves and enhances the existing implementation of EscapeEnumerator that finds all possible function exit points, and adds extra EH cleanup blocks where needed. Differential Revision: https://reviews.llvm.org/D26177 llvm-svn: 286893
97 lines
2.9 KiB
C++
97 lines
2.9 KiB
C++
//===- EscapeEnumerator.cpp -----------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Defines a helper class that enumerates all possible exits from a function,
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// including exception handling.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Utils/EscapeEnumerator.h"
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#include "llvm/Analysis/EHPersonalities.h"
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#include "llvm/IR/CallSite.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Transforms/Utils/Local.h"
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using namespace llvm;
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static Constant *getDefaultPersonalityFn(Module *M) {
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LLVMContext &C = M->getContext();
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Triple T(M->getTargetTriple());
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EHPersonality Pers = getDefaultEHPersonality(T);
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return M->getOrInsertFunction(getEHPersonalityName(Pers),
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FunctionType::get(Type::getInt32Ty(C), true));
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}
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IRBuilder<> *EscapeEnumerator::Next() {
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if (Done)
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return nullptr;
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// Find all 'return', 'resume', and 'unwind' instructions.
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while (StateBB != StateE) {
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BasicBlock *CurBB = &*StateBB++;
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// Branches and invokes do not escape, only unwind, resume, and return
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// do.
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TerminatorInst *TI = CurBB->getTerminator();
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if (!isa<ReturnInst>(TI) && !isa<ResumeInst>(TI))
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continue;
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Builder.SetInsertPoint(TI);
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return &Builder;
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}
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Done = true;
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if (!HandleExceptions)
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return nullptr;
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if (F.doesNotThrow())
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return nullptr;
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// Find all 'call' instructions that may throw.
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SmallVector<Instruction *, 16> Calls;
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for (BasicBlock &BB : F)
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for (Instruction &II : BB)
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if (CallInst *CI = dyn_cast<CallInst>(&II))
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if (!CI->doesNotThrow())
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Calls.push_back(CI);
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if (Calls.empty())
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return nullptr;
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// Create a cleanup block.
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LLVMContext &C = F.getContext();
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BasicBlock *CleanupBB = BasicBlock::Create(C, CleanupBBName, &F);
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Type *ExnTy =
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StructType::get(Type::getInt8PtrTy(C), Type::getInt32Ty(C), nullptr);
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if (!F.hasPersonalityFn()) {
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Constant *PersFn = getDefaultPersonalityFn(F.getParent());
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F.setPersonalityFn(PersFn);
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}
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if (isFuncletEHPersonality(classifyEHPersonality(F.getPersonalityFn()))) {
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report_fatal_error("Funclet EH not supported");
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}
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LandingPadInst *LPad =
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LandingPadInst::Create(ExnTy, 1, "cleanup.lpad", CleanupBB);
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LPad->setCleanup(true);
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ResumeInst *RI = ResumeInst::Create(LPad, CleanupBB);
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// Transform the 'call' instructions into 'invoke's branching to the
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// cleanup block. Go in reverse order to make prettier BB names.
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SmallVector<Value *, 16> Args;
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for (unsigned I = Calls.size(); I != 0;) {
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CallInst *CI = cast<CallInst>(Calls[--I]);
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changeToInvokeAndSplitBasicBlock(CI, CleanupBB);
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}
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Builder.SetInsertPoint(RI);
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return &Builder;
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}
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