//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/Passes.h"
-#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/CFG.h"
-#include "llvm/Analysis/TargetTransformInfo.h"
-#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetSubtargetInfo.h"
-#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
#define DEBUG_TYPE "dwarfehprepare"
// RewindFunction - _Unwind_Resume or the target equivalent.
Constant *RewindFunction;
- DominatorTree *DT;
- const TargetLowering *TLI;
-
bool InsertUnwindResumeCalls(Function &Fn);
Value *GetExceptionObject(ResumeInst *RI);
- size_t
- pruneUnreachableResumes(Function &Fn,
- SmallVectorImpl<ResumeInst *> &Resumes,
- SmallVectorImpl<LandingPadInst *> &CleanupLPads);
public:
static char ID; // Pass identification, replacement for typeid.
// INITIALIZE_TM_PASS requires a default constructor, but it isn't used in
// practice.
- DwarfEHPrepare()
- : FunctionPass(ID), TM(nullptr), RewindFunction(nullptr), DT(nullptr),
- TLI(nullptr) {}
+ DwarfEHPrepare() : FunctionPass(ID), TM(nullptr), RewindFunction(nullptr) {}
DwarfEHPrepare(const TargetMachine *TM)
- : FunctionPass(ID), TM(TM), RewindFunction(nullptr), DT(nullptr),
- TLI(nullptr) {}
+ : FunctionPass(ID), TM(TM), RewindFunction(nullptr) {}
bool runOnFunction(Function &Fn) override;
return false;
}
- void getAnalysisUsage(AnalysisUsage &AU) const override;
-
const char *getPassName() const override {
return "Exception handling preparation";
}
} // end anonymous namespace
char DwarfEHPrepare::ID = 0;
-INITIALIZE_TM_PASS_BEGIN(DwarfEHPrepare, "dwarfehprepare",
- "Prepare DWARF exceptions", false, false)
-INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
-INITIALIZE_TM_PASS_END(DwarfEHPrepare, "dwarfehprepare",
- "Prepare DWARF exceptions", false, false)
+INITIALIZE_TM_PASS(DwarfEHPrepare, "dwarfehprepare", "Prepare DWARF exceptions",
+ false, false)
FunctionPass *llvm::createDwarfEHPass(const TargetMachine *TM) {
return new DwarfEHPrepare(TM);
}
-void DwarfEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<TargetTransformInfoWrapperPass>();
- AU.addRequired<DominatorTreeWrapperPass>();
-}
-
/// GetExceptionObject - Return the exception object from the value passed into
/// the 'resume' instruction (typically an aggregate). Clean up any dead
/// instructions, including the 'resume' instruction.
return ExnObj;
}
-/// Replace resumes that are not reachable from a cleanup landing pad with
-/// unreachable and then simplify those blocks.
-size_t DwarfEHPrepare::pruneUnreachableResumes(
- Function &Fn, SmallVectorImpl<ResumeInst *> &Resumes,
- SmallVectorImpl<LandingPadInst *> &CleanupLPads) {
- BitVector ResumeReachable(Resumes.size());
- size_t ResumeIndex = 0;
- for (auto *RI : Resumes) {
- for (auto *LP : CleanupLPads) {
- if (isPotentiallyReachable(LP, RI, DT)) {
- ResumeReachable.set(ResumeIndex);
- break;
- }
- }
- ++ResumeIndex;
- }
-
- // If everything is reachable, there is no change.
- if (ResumeReachable.all())
- return Resumes.size();
-
- const TargetTransformInfo &TTI =
- getAnalysis<TargetTransformInfoWrapperPass>().getTTI(Fn);
- LLVMContext &Ctx = Fn.getContext();
-
- // Otherwise, insert unreachable instructions and call simplifycfg.
- size_t ResumesLeft = 0;
- for (size_t I = 0, E = Resumes.size(); I < E; ++I) {
- ResumeInst *RI = Resumes[I];
- if (ResumeReachable[I]) {
- Resumes[ResumesLeft++] = RI;
- } else {
- BasicBlock *BB = RI->getParent();
- new UnreachableInst(Ctx, RI);
- RI->eraseFromParent();
- SimplifyCFG(BB, TTI, 1, TLI->getDataLayout());
- }
- }
- Resumes.resize(ResumesLeft);
- return ResumesLeft;
-}
-
/// InsertUnwindResumeCalls - Convert the ResumeInsts that are still present
/// into calls to the appropriate _Unwind_Resume function.
bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) {
SmallVector<ResumeInst*, 16> Resumes;
- SmallVector<LandingPadInst*, 16> CleanupLPads;
for (BasicBlock &BB : Fn) {
if (auto *RI = dyn_cast<ResumeInst>(BB.getTerminator()))
Resumes.push_back(RI);
- if (auto *LP = BB.getLandingPadInst())
- if (LP->isCleanup())
- CleanupLPads.push_back(LP);
}
if (Resumes.empty())
return false;
- LLVMContext &Ctx = Fn.getContext();
-
- size_t ResumesLeft = pruneUnreachableResumes(Fn, Resumes, CleanupLPads);
- if (ResumesLeft == 0)
- return true; // We pruned them all.
-
// Find the rewind function if we didn't already.
+ const TargetLowering *TLI = TM->getSubtargetImpl(Fn)->getTargetLowering();
+ LLVMContext &Ctx = Fn.getContext();
if (!RewindFunction) {
FunctionType *FTy = FunctionType::get(Type::getVoidTy(Ctx),
Type::getInt8PtrTy(Ctx), false);
}
// Create the basic block where the _Unwind_Resume call will live.
- if (ResumesLeft == 1) {
+ unsigned ResumesSize = Resumes.size();
+
+ if (ResumesSize == 1) {
// Instead of creating a new BB and PHI node, just append the call to
// _Unwind_Resume to the end of the single resume block.
ResumeInst *RI = Resumes.front();
}
BasicBlock *UnwindBB = BasicBlock::Create(Ctx, "unwind_resume", &Fn);
- PHINode *PN = PHINode::Create(Type::getInt8PtrTy(Ctx), ResumesLeft,
+ PHINode *PN = PHINode::Create(Type::getInt8PtrTy(Ctx), ResumesSize,
"exn.obj", UnwindBB);
// Extract the exception object from the ResumeInst and add it to the PHI node
bool DwarfEHPrepare::runOnFunction(Function &Fn) {
assert(TM && "DWARF EH preparation requires a target machine");
- DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
- TLI = TM->getSubtargetImpl(Fn)->getTargetLowering();
bool Changed = InsertUnwindResumeCalls(Fn);
- DT = nullptr;
- TLI = nullptr;
return Changed;
}
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