1 //===- EscapeEnumerator.cpp -----------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Defines a helper class that enumerates all possible exits from a function,
11 // including exception handling.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Transforms/Utils/EscapeEnumerator.h"
16 #include "llvm/Analysis/EHPersonalities.h"
17 #include "llvm/IR/CallSite.h"
18 #include "llvm/IR/Module.h"
19 #include "llvm/Transforms/Utils/Local.h"
22 static Constant *getDefaultPersonalityFn(Module *M) {
23 LLVMContext &C = M->getContext();
24 Triple T(M->getTargetTriple());
25 EHPersonality Pers = getDefaultEHPersonality(T);
26 return M->getOrInsertFunction(getEHPersonalityName(Pers),
27 FunctionType::get(Type::getInt32Ty(C), true));
30 IRBuilder<> *EscapeEnumerator::Next() {
34 // Find all 'return', 'resume', and 'unwind' instructions.
35 while (StateBB != StateE) {
36 BasicBlock *CurBB = &*StateBB++;
38 // Branches and invokes do not escape, only unwind, resume, and return
40 TerminatorInst *TI = CurBB->getTerminator();
41 if (!isa<ReturnInst>(TI) && !isa<ResumeInst>(TI))
44 Builder.SetInsertPoint(TI);
50 if (!HandleExceptions)
56 // Find all 'call' instructions that may throw.
57 SmallVector<Instruction *, 16> Calls;
58 for (BasicBlock &BB : F)
59 for (Instruction &II : BB)
60 if (CallInst *CI = dyn_cast<CallInst>(&II))
61 if (!CI->doesNotThrow())
67 // Create a cleanup block.
68 LLVMContext &C = F.getContext();
69 BasicBlock *CleanupBB = BasicBlock::Create(C, CleanupBBName, &F);
70 Type *ExnTy = StructType::get(Type::getInt8PtrTy(C), Type::getInt32Ty(C));
71 if (!F.hasPersonalityFn()) {
72 Constant *PersFn = getDefaultPersonalityFn(F.getParent());
73 F.setPersonalityFn(PersFn);
76 if (isFuncletEHPersonality(classifyEHPersonality(F.getPersonalityFn()))) {
77 report_fatal_error("Funclet EH not supported");
80 LandingPadInst *LPad =
81 LandingPadInst::Create(ExnTy, 1, "cleanup.lpad", CleanupBB);
82 LPad->setCleanup(true);
83 ResumeInst *RI = ResumeInst::Create(LPad, CleanupBB);
85 // Transform the 'call' instructions into 'invoke's branching to the
86 // cleanup block. Go in reverse order to make prettier BB names.
87 SmallVector<Value *, 16> Args;
88 for (unsigned I = Calls.size(); I != 0;) {
89 CallInst *CI = cast<CallInst>(Calls[--I]);
90 changeToInvokeAndSplitBasicBlock(CI, CleanupBB);
93 Builder.SetInsertPoint(RI);