//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "dwarfehprepare"
-#include "llvm/Function.h"
-#include "llvm/Instructions.h"
-#include "llvm/IntrinsicInst.h"
-#include "llvm/Module.h"
-#include "llvm/Pass.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/CodeGen/Passes.h"
-#include "llvm/MC/MCAsmInfo.h"
-#include "llvm/Support/CallSite.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/CFG.h"
+#include "llvm/Analysis/LibCallSemantics.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/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/SSAUpdater.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
-STATISTIC(NumLandingPadsSplit, "Number of landing pads split");
-STATISTIC(NumUnwindsLowered, "Number of unwind instructions lowered");
-STATISTIC(NumExceptionValuesMoved, "Number of eh.exception calls moved");
+#define DEBUG_TYPE "dwarfehprepare"
+
+STATISTIC(NumResumesLowered, "Number of resume calls lowered");
namespace {
class DwarfEHPrepare : public FunctionPass {
const TargetMachine *TM;
- const TargetLowering *TLI;
- // The eh.exception intrinsic.
- Function *ExceptionValueIntrinsic;
-
- // The eh.selector intrinsic.
- Function *SelectorIntrinsic;
-
- // _Unwind_Resume_or_Rethrow call.
- Constant *URoR;
-
- // The EH language-specific catch-all type.
- GlobalVariable *EHCatchAllValue;
-
- // _Unwind_Resume or the target equivalent.
+ // RewindFunction - _Unwind_Resume or the target equivalent.
Constant *RewindFunction;
- // We both use and preserve dominator info.
DominatorTree *DT;
+ const TargetLowering *TLI;
- // The function we are running on.
- Function *F;
-
- // The landing pads for this function.
- typedef SmallPtrSet<BasicBlock*, 8> BBSet;
- BBSet LandingPads;
-
- bool NormalizeLandingPads();
- bool LowerUnwinds();
- bool MoveExceptionValueCalls();
-
- Instruction *CreateExceptionValueCall(BasicBlock *BB);
-
- /// CleanupSelectors - Any remaining eh.selector intrinsic calls which still
- /// use the "llvm.eh.catch.all.value" call need to convert to using its
- /// initializer instead.
- bool CleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels);
-
- bool HasCatchAllInSelector(IntrinsicInst *);
-
- /// FindAllCleanupSelectors - Find all eh.selector calls that are clean-ups.
- void FindAllCleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels,
- SmallPtrSet<IntrinsicInst*, 32> &CatchAllSels);
-
- /// FindAllURoRInvokes - Find all URoR invokes in the function.
- void FindAllURoRInvokes(SmallPtrSet<InvokeInst*, 32> &URoRInvokes);
-
- /// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow"
- /// calls. The "unwind" part of these invokes jump to a landing pad within
- /// the current function. This is a candidate to merge the selector
- /// associated with the URoR invoke with the one from the URoR's landing
- /// pad.
- bool HandleURoRInvokes();
+ bool InsertUnwindResumeCalls(Function &Fn);
+ Value *GetExceptionObject(ResumeInst *RI);
+ size_t
+ pruneUnreachableResumes(Function &Fn,
+ SmallVectorImpl<ResumeInst *> &Resumes,
+ SmallVectorImpl<LandingPadInst *> &CleanupLPads);
- /// FindSelectorAndURoR - Find the eh.selector call and URoR call associated
- /// with the eh.exception call. This recursively looks past instructions
- /// which don't change the EH pointer value, like casts or PHI nodes.
- bool FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke,
- SmallPtrSet<IntrinsicInst*, 8> &SelCalls);
-
public:
static char ID; // Pass identification, replacement for typeid.
- DwarfEHPrepare(const TargetMachine *tm) :
- FunctionPass(ID), TM(tm), TLI(TM->getTargetLowering()),
- ExceptionValueIntrinsic(0), SelectorIntrinsic(0),
- URoR(0), EHCatchAllValue(0), RewindFunction(0) {}
- virtual bool runOnFunction(Function &Fn);
+ // 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(const TargetMachine *TM)
+ : FunctionPass(ID), TM(TM), RewindFunction(nullptr), DT(nullptr),
+ TLI(nullptr) {}
- // getAnalysisUsage - We need the dominator tree for handling URoR.
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<DominatorTree>();
- AU.addPreserved<DominatorTree>();
+ bool runOnFunction(Function &Fn) override;
+
+ bool doFinalization(Module &M) override {
+ RewindFunction = nullptr;
+ return false;
}
- const char *getPassName() const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+ const char *getPassName() const override {
return "Exception handling preparation";
}
-
};
} // end anonymous namespace
char DwarfEHPrepare::ID = 0;
-
-FunctionPass *llvm::createDwarfEHPass(const TargetMachine *tm) {
- return new DwarfEHPrepare(tm);
-}
-
-/// HasCatchAllInSelector - Return true if the intrinsic instruction has a
-/// catch-all.
-bool DwarfEHPrepare::HasCatchAllInSelector(IntrinsicInst *II) {
- if (!EHCatchAllValue) return false;
-
- unsigned ArgIdx = II->getNumArgOperands() - 1;
- GlobalVariable *GV = dyn_cast<GlobalVariable>(II->getArgOperand(ArgIdx));
- return GV == EHCatchAllValue;
+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)
+
+FunctionPass *llvm::createDwarfEHPass(const TargetMachine *TM) {
+ return new DwarfEHPrepare(TM);
}
-/// FindAllCleanupSelectors - Find all eh.selector calls that are clean-ups.
-void DwarfEHPrepare::
-FindAllCleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels,
- SmallPtrSet<IntrinsicInst*, 32> &CatchAllSels) {
- for (Value::use_iterator
- I = SelectorIntrinsic->use_begin(),
- E = SelectorIntrinsic->use_end(); I != E; ++I) {
- IntrinsicInst *II = cast<IntrinsicInst>(*I);
-
- if (II->getParent()->getParent() != F)
- continue;
-
- if (!HasCatchAllInSelector(II))
- Sels.insert(II);
- else
- CatchAllSels.insert(II);
- }
-}
-
-/// FindAllURoRInvokes - Find all URoR invokes in the function.
-void DwarfEHPrepare::
-FindAllURoRInvokes(SmallPtrSet<InvokeInst*, 32> &URoRInvokes) {
- for (Value::use_iterator
- I = URoR->use_begin(),
- E = URoR->use_end(); I != E; ++I) {
- if (InvokeInst *II = dyn_cast<InvokeInst>(*I))
- URoRInvokes.insert(II);
- }
+void DwarfEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<TargetTransformInfoWrapperPass>();
+ AU.addRequired<DominatorTreeWrapperPass>();
}
-/// CleanupSelectors - Any remaining eh.selector intrinsic calls which still use
-/// the "llvm.eh.catch.all.value" call need to convert to using its
-/// initializer instead.
-bool DwarfEHPrepare::CleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels) {
- if (!EHCatchAllValue) return false;
-
- if (!SelectorIntrinsic) {
- SelectorIntrinsic =
- Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_selector);
- if (!SelectorIntrinsic) return false;
- }
-
- bool Changed = false;
- for (SmallPtrSet<IntrinsicInst*, 32>::iterator
- I = Sels.begin(), E = Sels.end(); I != E; ++I) {
- IntrinsicInst *Sel = *I;
-
- // Index of the "llvm.eh.catch.all.value" variable.
- unsigned OpIdx = Sel->getNumArgOperands() - 1;
- GlobalVariable *GV = dyn_cast<GlobalVariable>(Sel->getArgOperand(OpIdx));
- if (GV != EHCatchAllValue) continue;
- Sel->setArgOperand(OpIdx, EHCatchAllValue->getInitializer());
- Changed = true;
- }
-
- return Changed;
-}
-
-/// FindSelectorAndURoR - Find the eh.selector call associated with the
-/// eh.exception call. And indicate if there is a URoR "invoke" associated with
-/// the eh.exception call. This recursively looks past instructions which don't
-/// change the EH pointer value, like casts or PHI nodes.
-bool
-DwarfEHPrepare::FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke,
- SmallPtrSet<IntrinsicInst*, 8> &SelCalls) {
- SmallPtrSet<PHINode*, 32> SeenPHIs;
- bool Changed = false;
-
- for (Value::use_iterator
- I = Inst->use_begin(), E = Inst->use_end(); I != E; ++I) {
- Instruction *II = dyn_cast<Instruction>(*I);
- if (!II || II->getParent()->getParent() != F) continue;
-
- if (IntrinsicInst *Sel = dyn_cast<IntrinsicInst>(II)) {
- if (Sel->getIntrinsicID() == Intrinsic::eh_selector)
- SelCalls.insert(Sel);
- } else if (InvokeInst *Invoke = dyn_cast<InvokeInst>(II)) {
- if (Invoke->getCalledFunction() == URoR)
- URoRInvoke = true;
- } else if (CastInst *CI = dyn_cast<CastInst>(II)) {
- Changed |= FindSelectorAndURoR(CI, URoRInvoke, SelCalls);
- } else if (PHINode *PN = dyn_cast<PHINode>(II)) {
- if (SeenPHIs.insert(PN))
- // Don't process a PHI node more than once.
- Changed |= FindSelectorAndURoR(PN, URoRInvoke, SelCalls);
+/// 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.
+Value *DwarfEHPrepare::GetExceptionObject(ResumeInst *RI) {
+ Value *V = RI->getOperand(0);
+ Value *ExnObj = nullptr;
+ InsertValueInst *SelIVI = dyn_cast<InsertValueInst>(V);
+ LoadInst *SelLoad = nullptr;
+ InsertValueInst *ExcIVI = nullptr;
+ bool EraseIVIs = false;
+
+ if (SelIVI) {
+ if (SelIVI->getNumIndices() == 1 && *SelIVI->idx_begin() == 1) {
+ ExcIVI = dyn_cast<InsertValueInst>(SelIVI->getOperand(0));
+ if (ExcIVI && isa<UndefValue>(ExcIVI->getOperand(0)) &&
+ ExcIVI->getNumIndices() == 1 && *ExcIVI->idx_begin() == 0) {
+ ExnObj = ExcIVI->getOperand(1);
+ SelLoad = dyn_cast<LoadInst>(SelIVI->getOperand(1));
+ EraseIVIs = true;
+ }
}
}
- return Changed;
-}
+ if (!ExnObj)
+ ExnObj = ExtractValueInst::Create(RI->getOperand(0), 0, "exn.obj", RI);
-/// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" calls. The
-/// "unwind" part of these invokes jump to a landing pad within the current
-/// function. This is a candidate to merge the selector associated with the URoR
-/// invoke with the one from the URoR's landing pad.
-bool DwarfEHPrepare::HandleURoRInvokes() {
- if (!EHCatchAllValue) {
- EHCatchAllValue =
- F->getParent()->getNamedGlobal("llvm.eh.catch.all.value");
- if (!EHCatchAllValue) return false;
- }
-
- if (!SelectorIntrinsic) {
- SelectorIntrinsic =
- Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_selector);
- if (!SelectorIntrinsic) return false;
- }
-
- SmallPtrSet<IntrinsicInst*, 32> Sels;
- SmallPtrSet<IntrinsicInst*, 32> CatchAllSels;
- FindAllCleanupSelectors(Sels, CatchAllSels);
+ RI->eraseFromParent();
- if (!URoR) {
- URoR = F->getParent()->getFunction("_Unwind_Resume_or_Rethrow");
- if (!URoR) return CleanupSelectors(CatchAllSels);
+ if (EraseIVIs) {
+ if (SelIVI->use_empty())
+ SelIVI->eraseFromParent();
+ if (ExcIVI->use_empty())
+ ExcIVI->eraseFromParent();
+ if (SelLoad && SelLoad->use_empty())
+ SelLoad->eraseFromParent();
}
- SmallPtrSet<InvokeInst*, 32> URoRInvokes;
- FindAllURoRInvokes(URoRInvokes);
-
- SmallPtrSet<IntrinsicInst*, 32> SelsToConvert;
+ return ExnObj;
+}
- for (SmallPtrSet<IntrinsicInst*, 32>::iterator
- SI = Sels.begin(), SE = Sels.end(); SI != SE; ++SI) {
- const BasicBlock *SelBB = (*SI)->getParent();
- for (SmallPtrSet<InvokeInst*, 32>::iterator
- UI = URoRInvokes.begin(), UE = URoRInvokes.end(); UI != UE; ++UI) {
- const BasicBlock *URoRBB = (*UI)->getParent();
- if (DT->dominates(SelBB, URoRBB)) {
- SelsToConvert.insert(*SI);
+/// 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;
}
- bool Changed = false;
-
- if (Sels.size() != SelsToConvert.size()) {
- // If we haven't been able to convert all of the clean-up selectors, then
- // loop through the slow way to see if they still need to be converted.
- if (!ExceptionValueIntrinsic) {
- ExceptionValueIntrinsic =
- Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_exception);
- if (!ExceptionValueIntrinsic)
- return CleanupSelectors(CatchAllSels);
- }
-
- for (Value::use_iterator
- I = ExceptionValueIntrinsic->use_begin(),
- E = ExceptionValueIntrinsic->use_end(); I != E; ++I) {
- IntrinsicInst *EHPtr = dyn_cast<IntrinsicInst>(*I);
- if (!EHPtr || EHPtr->getParent()->getParent() != F) continue;
-
- bool URoRInvoke = false;
- SmallPtrSet<IntrinsicInst*, 8> SelCalls;
- Changed |= FindSelectorAndURoR(EHPtr, URoRInvoke, SelCalls);
-
- if (URoRInvoke) {
- // This EH pointer is being used by an invoke of an URoR instruction and
- // an eh.selector intrinsic call. If the eh.selector is a 'clean-up', we
- // need to convert it to a 'catch-all'.
- for (SmallPtrSet<IntrinsicInst*, 8>::iterator
- SI = SelCalls.begin(), SE = SelCalls.end(); SI != SE; ++SI)
- if (!HasCatchAllInSelector(*SI))
- SelsToConvert.insert(*SI);
- }
+ // 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);
}
}
-
- if (!SelsToConvert.empty()) {
- // Convert all clean-up eh.selectors, which are associated with "invokes" of
- // URoR calls, into catch-all eh.selectors.
- Changed = true;
-
- for (SmallPtrSet<IntrinsicInst*, 8>::iterator
- SI = SelsToConvert.begin(), SE = SelsToConvert.end();
- SI != SE; ++SI) {
- IntrinsicInst *II = *SI;
-
- // Use the exception object pointer and the personality function
- // from the original selector.
- CallSite CS(II);
- IntrinsicInst::op_iterator I = CS.arg_begin();
- IntrinsicInst::op_iterator E = CS.arg_end();
- IntrinsicInst::op_iterator B = prior(E);
-
- // Exclude last argument if it is an integer.
- if (isa<ConstantInt>(B)) E = B;
-
- // Add exception object pointer (front).
- // Add personality function (next).
- // Add in any filter IDs (rest).
- SmallVector<Value*, 8> Args(I, E);
-
- Args.push_back(EHCatchAllValue->getInitializer()); // Catch-all indicator.
-
- CallInst *NewSelector =
- CallInst::Create(SelectorIntrinsic, Args.begin(), Args.end(),
- "eh.sel.catch.all", II);
-
- NewSelector->setTailCall(II->isTailCall());
- NewSelector->setAttributes(II->getAttributes());
- NewSelector->setCallingConv(II->getCallingConv());
-
- II->replaceAllUsesWith(NewSelector);
- II->eraseFromParent();
- }
- }
-
- Changed |= CleanupSelectors(CatchAllSels);
- return Changed;
+ Resumes.resize(ResumesLeft);
+ return ResumesLeft;
}
-/// NormalizeLandingPads - Normalize and discover landing pads, noting them
-/// in the LandingPads set. A landing pad is normal if the only CFG edges
-/// that end at it are unwind edges from invoke instructions. If we inlined
-/// through an invoke we could have a normal branch from the previous
-/// unwind block through to the landing pad for the original invoke.
-/// Abnormal landing pads are fixed up by redirecting all unwind edges to
-/// a new basic block which falls through to the original.
-bool DwarfEHPrepare::NormalizeLandingPads() {
- bool Changed = false;
-
- const MCAsmInfo *MAI = TM->getMCAsmInfo();
- bool usingSjLjEH = MAI->getExceptionHandlingType() == ExceptionHandling::SjLj;
-
- for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
- TerminatorInst *TI = I->getTerminator();
- if (!isa<InvokeInst>(TI))
- continue;
- BasicBlock *LPad = TI->getSuccessor(1);
- // Skip landing pads that have already been normalized.
- if (LandingPads.count(LPad))
- continue;
-
- // Check that only invoke unwind edges end at the landing pad.
- bool OnlyUnwoundTo = true;
- bool SwitchOK = usingSjLjEH;
- for (pred_iterator PI = pred_begin(LPad), PE = pred_end(LPad);
- PI != PE; ++PI) {
- TerminatorInst *PT = (*PI)->getTerminator();
- // The SjLj dispatch block uses a switch instruction. This is effectively
- // an unwind edge, so we can disregard it here. There will only ever
- // be one dispatch, however, so if there are multiple switches, one
- // of them truly is a normal edge, not an unwind edge.
- if (SwitchOK && isa<SwitchInst>(PT)) {
- SwitchOK = false;
- continue;
- }
- if (!isa<InvokeInst>(PT) || LPad == PT->getSuccessor(0)) {
- OnlyUnwoundTo = false;
- break;
- }
- }
-
- if (OnlyUnwoundTo) {
- // Only unwind edges lead to the landing pad. Remember the landing pad.
- LandingPads.insert(LPad);
- continue;
- }
-
- // At least one normal edge ends at the landing pad. Redirect the unwind
- // edges to a new basic block which falls through into this one.
-
- // Create the new basic block.
- BasicBlock *NewBB = BasicBlock::Create(F->getContext(),
- LPad->getName() + "_unwind_edge");
-
- // Insert it into the function right before the original landing pad.
- LPad->getParent()->getBasicBlockList().insert(LPad, NewBB);
-
- // Redirect unwind edges from the original landing pad to NewBB.
- for (pred_iterator PI = pred_begin(LPad), PE = pred_end(LPad); PI != PE; ) {
- TerminatorInst *PT = (*PI++)->getTerminator();
- if (isa<InvokeInst>(PT) && PT->getSuccessor(1) == LPad)
- // Unwind to the new block.
- PT->setSuccessor(1, NewBB);
- }
-
- // If there are any PHI nodes in LPad, we need to update them so that they
- // merge incoming values from NewBB instead.
- for (BasicBlock::iterator II = LPad->begin(); isa<PHINode>(II); ++II) {
- PHINode *PN = cast<PHINode>(II);
- pred_iterator PB = pred_begin(NewBB), PE = pred_end(NewBB);
-
- // Check to see if all of the values coming in via unwind edges are the
- // same. If so, we don't need to create a new PHI node.
- Value *InVal = PN->getIncomingValueForBlock(*PB);
- for (pred_iterator PI = PB; PI != PE; ++PI) {
- if (PI != PB && InVal != PN->getIncomingValueForBlock(*PI)) {
- InVal = 0;
- break;
- }
- }
-
- if (InVal == 0) {
- // Different unwind edges have different values. Create a new PHI node
- // in NewBB.
- PHINode *NewPN = PHINode::Create(PN->getType(), PN->getName()+".unwind",
- NewBB);
- // Add an entry for each unwind edge, using the value from the old PHI.
- for (pred_iterator PI = PB; PI != PE; ++PI)
- NewPN->addIncoming(PN->getIncomingValueForBlock(*PI), *PI);
-
- // Now use this new PHI as the common incoming value for NewBB in PN.
- InVal = NewPN;
- }
-
- // Revector exactly one entry in the PHI node to come from NewBB
- // and delete all other entries that come from unwind edges. If
- // there are both normal and unwind edges from the same predecessor,
- // this leaves an entry for the normal edge.
- for (pred_iterator PI = PB; PI != PE; ++PI)
- PN->removeIncomingValue(*PI);
- PN->addIncoming(InVal, NewBB);
- }
-
- // Add a fallthrough from NewBB to the original landing pad.
- BranchInst::Create(LPad, NewBB);
-
- // Now update DominatorTree analysis information.
- DT->splitBlock(NewBB);
-
- // Remember the newly constructed landing pad. The original landing pad
- // LPad is no longer a landing pad now that all unwind edges have been
- // revectored to NewBB.
- LandingPads.insert(NewBB);
- ++NumLandingPadsSplit;
- Changed = true;
+/// 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);
}
- return Changed;
-}
+ if (Resumes.empty())
+ return false;
-/// LowerUnwinds - Turn unwind instructions into calls to _Unwind_Resume,
-/// rethrowing any previously caught exception. This will crash horribly
-/// at runtime if there is no such exception: using unwind to throw a new
-/// exception is currently not supported.
-bool DwarfEHPrepare::LowerUnwinds() {
- SmallVector<TerminatorInst*, 16> UnwindInsts;
-
- for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
- TerminatorInst *TI = I->getTerminator();
- if (isa<UnwindInst>(TI))
- UnwindInsts.push_back(TI);
- }
+ // Check the personality, don't do anything if it's for MSVC.
+ EHPersonality Pers = classifyEHPersonality(Fn.getPersonalityFn());
+ if (isMSVCEHPersonality(Pers))
+ return false;
+
+ LLVMContext &Ctx = Fn.getContext();
- if (UnwindInsts.empty()) return false;
+ 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.
if (!RewindFunction) {
- LLVMContext &Ctx = UnwindInsts[0]->getContext();
- std::vector<const Type*>
- Params(1, Type::getInt8PtrTy(Ctx));
FunctionType *FTy = FunctionType::get(Type::getVoidTy(Ctx),
- Params, false);
+ Type::getInt8PtrTy(Ctx), false);
const char *RewindName = TLI->getLibcallName(RTLIB::UNWIND_RESUME);
- RewindFunction = F->getParent()->getOrInsertFunction(RewindName, FTy);
+ RewindFunction = Fn.getParent()->getOrInsertFunction(RewindName, FTy);
}
- bool Changed = false;
-
- for (SmallVectorImpl<TerminatorInst*>::iterator
- I = UnwindInsts.begin(), E = UnwindInsts.end(); I != E; ++I) {
- TerminatorInst *TI = *I;
+ // Create the basic block where the _Unwind_Resume call will live.
+ if (ResumesLeft == 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 = RI->getParent();
+ Value *ExnObj = GetExceptionObject(RI);
- // Replace the unwind instruction with a call to _Unwind_Resume (or the
- // appropriate target equivalent) followed by an UnreachableInst.
-
- // Create the call...
- CallInst *CI = CallInst::Create(RewindFunction,
- CreateExceptionValueCall(TI->getParent()),
- "", TI);
+ // Call the _Unwind_Resume function.
+ CallInst *CI = CallInst::Create(RewindFunction, ExnObj, "", UnwindBB);
CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
- // ...followed by an UnreachableInst.
- new UnreachableInst(TI->getContext(), TI);
- // Nuke the unwind instruction.
- TI->eraseFromParent();
- ++NumUnwindsLowered;
- Changed = true;
+ // We never expect _Unwind_Resume to return.
+ new UnreachableInst(Ctx, UnwindBB);
+ return true;
}
- return Changed;
-}
+ BasicBlock *UnwindBB = BasicBlock::Create(Ctx, "unwind_resume", &Fn);
+ PHINode *PN = PHINode::Create(Type::getInt8PtrTy(Ctx), ResumesLeft,
+ "exn.obj", UnwindBB);
-/// MoveExceptionValueCalls - Ensure that eh.exception is only ever called from
-/// landing pads by replacing calls outside of landing pads with direct use of
-/// a register holding the appropriate value; this requires adding calls inside
-/// all landing pads to initialize the register. Also, move eh.exception calls
-/// inside landing pads to the start of the landing pad (optional, but may make
-/// things simpler for later passes).
-bool DwarfEHPrepare::MoveExceptionValueCalls() {
- // If the eh.exception intrinsic is not declared in the module then there is
- // nothing to do. Speed up compilation by checking for this common case.
- if (!ExceptionValueIntrinsic &&
- !F->getParent()->getFunction(Intrinsic::getName(Intrinsic::eh_exception)))
- return false;
-
- bool Changed = false;
-
- // Move calls to eh.exception that are inside a landing pad to the start of
- // the landing pad.
- for (BBSet::const_iterator LI = LandingPads.begin(), LE = LandingPads.end();
- LI != LE; ++LI) {
- BasicBlock *LP = *LI;
- for (BasicBlock::iterator II = LP->getFirstNonPHIOrDbg(), IE = LP->end();
- II != IE;)
- if (EHExceptionInst *EI = dyn_cast<EHExceptionInst>(II++)) {
- // Found a call to eh.exception.
- if (!EI->use_empty()) {
- // If there is already a call to eh.exception at the start of the
- // landing pad, then get hold of it; otherwise create such a call.
- Value *CallAtStart = CreateExceptionValueCall(LP);
-
- // If the call was at the start of a landing pad then leave it alone.
- if (EI == CallAtStart)
- continue;
- EI->replaceAllUsesWith(CallAtStart);
- }
- EI->eraseFromParent();
- ++NumExceptionValuesMoved;
- Changed = true;
- }
- }
+ // Extract the exception object from the ResumeInst and add it to the PHI node
+ // that feeds the _Unwind_Resume call.
+ for (ResumeInst *RI : Resumes) {
+ BasicBlock *Parent = RI->getParent();
+ BranchInst::Create(UnwindBB, Parent);
- // Look for calls to eh.exception that are not in a landing pad. If one is
- // found, then a register that holds the exception value will be created in
- // each landing pad, and the SSAUpdater will be used to compute the values
- // returned by eh.exception calls outside of landing pads.
- SSAUpdater SSA;
-
- // Remember where we found the eh.exception call, to avoid rescanning earlier
- // basic blocks which we already know contain no eh.exception calls.
- bool FoundCallOutsideLandingPad = false;
- Function::iterator BB = F->begin();
- for (Function::iterator BE = F->end(); BB != BE; ++BB) {
- // Skip over landing pads.
- if (LandingPads.count(BB))
- continue;
-
- for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
- II != IE; ++II)
- if (isa<EHExceptionInst>(II)) {
- SSA.Initialize(II->getType(), II->getName());
- FoundCallOutsideLandingPad = true;
- break;
- }
+ Value *ExnObj = GetExceptionObject(RI);
+ PN->addIncoming(ExnObj, Parent);
- if (FoundCallOutsideLandingPad)
- break;
+ ++NumResumesLowered;
}
- // If all calls to eh.exception are in landing pads then we are done.
- if (!FoundCallOutsideLandingPad)
- return Changed;
-
- // Add a call to eh.exception at the start of each landing pad, and tell the
- // SSAUpdater that this is the value produced by the landing pad.
- for (BBSet::iterator LI = LandingPads.begin(), LE = LandingPads.end();
- LI != LE; ++LI)
- SSA.AddAvailableValue(*LI, CreateExceptionValueCall(*LI));
-
- // Now turn all calls to eh.exception that are not in a landing pad into a use
- // of the appropriate register.
- for (Function::iterator BE = F->end(); BB != BE; ++BB) {
- // Skip over landing pads.
- if (LandingPads.count(BB))
- continue;
-
- for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
- II != IE;)
- if (EHExceptionInst *EI = dyn_cast<EHExceptionInst>(II++)) {
- // Found a call to eh.exception, replace it with the value from any
- // upstream landing pad(s).
- EI->replaceAllUsesWith(SSA.GetValueAtEndOfBlock(BB));
- EI->eraseFromParent();
- ++NumExceptionValuesMoved;
- }
- }
+ // Call the function.
+ CallInst *CI = CallInst::Create(RewindFunction, PN, "", UnwindBB);
+ CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
+ // We never expect _Unwind_Resume to return.
+ new UnreachableInst(Ctx, UnwindBB);
return true;
}
-/// CreateExceptionValueCall - Insert a call to the eh.exception intrinsic at
-/// the start of the basic block (unless there already is one, in which case
-/// the existing call is returned).
-Instruction *DwarfEHPrepare::CreateExceptionValueCall(BasicBlock *BB) {
- Instruction *Start = BB->getFirstNonPHIOrDbg();
- // Is this a call to eh.exception?
- if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(Start))
- if (CI->getIntrinsicID() == Intrinsic::eh_exception)
- // Reuse the existing call.
- return Start;
-
- // Find the eh.exception intrinsic if we didn't already.
- if (!ExceptionValueIntrinsic)
- ExceptionValueIntrinsic = Intrinsic::getDeclaration(F->getParent(),
- Intrinsic::eh_exception);
-
- // Create the call.
- return CallInst::Create(ExceptionValueIntrinsic, "eh.value.call", Start);
-}
-
bool DwarfEHPrepare::runOnFunction(Function &Fn) {
- bool Changed = false;
-
- // Initialize internal state.
- DT = &getAnalysis<DominatorTree>();
- F = &Fn;
-
- // Ensure that only unwind edges end at landing pads (a landing pad is a
- // basic block where an invoke unwind edge ends).
- Changed |= NormalizeLandingPads();
-
- // Turn unwind instructions into libcalls.
- Changed |= LowerUnwinds();
-
- // TODO: Move eh.selector calls to landing pads and combine them.
-
- // Move eh.exception calls to landing pads.
- Changed |= MoveExceptionValueCalls();
-
- Changed |= HandleURoRInvokes();
-
- LandingPads.clear();
-
+ 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;
}
projects / oota-llvm.git / blobdiff