#include "llvm/Support/CallSite.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/PromoteMemToReg.h"
#include "llvm/Transforms/Utils/SSAUpdater.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");
-STATISTIC(NumStackTempsIntroduced, "Number of stack temporaries introduced");
-
-static void PromoteAlloca(AllocaInst *AI);
+STATISTIC(NumResumesLowered, "Number of resume calls lowered");
namespace {
class DwarfEHPrepare : public FunctionPass {
const TargetMachine *TM;
const TargetLowering *TLI;
- bool CompileFast;
-
- // 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;
- // Dominator info is used when turning stack temporaries into registers.
- DominatorTree *DT;
-
- // The function we are running on.
- Function *F;
-
- // The landing pads for this function.
- typedef SmallPtrSet<BasicBlock*, 8> BBSet;
- BBSet LandingPads;
-
- // Stack temporary used to hold eh.exception values.
- AllocaInst *ExceptionValueVar;
-
- bool NormalizeLandingPads();
- bool LowerUnwinds();
- bool MoveExceptionValueCalls();
- bool FinishStackTemporaries();
- bool PromoteStackTemporaries();
-
- Instruction *CreateExceptionValueCall(BasicBlock *BB);
- Instruction *CreateValueLoad(BasicBlock *BB);
-
- /// CreateReadOfExceptionValue - Return the result of the eh.exception
- /// intrinsic by calling the intrinsic if in a landing pad, or loading it
- /// from the exception value variable otherwise.
- Instruction *CreateReadOfExceptionValue(BasicBlock *BB) {
- return LandingPads.count(BB) ?
- CreateExceptionValueCall(BB) : CreateValueLoad(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();
-
- /// 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);
-
- /// PromoteStoreInst - Perform Mem2Reg on a StoreInst.
- bool PromoteStoreInst(StoreInst *SI) {
- AllocaInst *AI = dyn_cast<AllocaInst>(SI->getOperand(1));
- if (!AI || !isAllocaPromotable(AI)) return false;
-
- PromoteAlloca(AI);
- return true;
- }
-
- /// PromoteEHPtrStore - Promote the storing of an EH pointer into a
- /// register. This should get rid of the store and subsequent loads.
- bool PromoteEHPtrStore(IntrinsicInst *II) {
- if (!CompileFast) return false;
-
- bool Changed = false;
- StoreInst *SI;
-
- while (1) {
- SI = 0;
- for (Value::use_iterator
- I = II->use_begin(), E = II->use_end(); I != E; ++I) {
- SI = dyn_cast<StoreInst>(*I);
- if (SI) break;
- }
-
- if (SI && !PromoteStoreInst(SI))
- break;
-
- Changed = true;
- }
-
- return Changed;
- }
+ bool InsertUnwindResumeCalls(Function &Fn);
public:
static char ID; // Pass identification, replacement for typeid.
- DwarfEHPrepare(const TargetMachine *tm, bool fast) :
+ DwarfEHPrepare(const TargetMachine *tm) :
FunctionPass(ID), TM(tm), TLI(TM->getTargetLowering()),
- CompileFast(fast),
- ExceptionValueIntrinsic(0), SelectorIntrinsic(0),
- URoR(0), EHCatchAllValue(0), RewindFunction(0) {}
+ RewindFunction(0) {
+ initializeDominatorTreePass(*PassRegistry::getPassRegistry());
+ }
virtual bool runOnFunction(Function &Fn);
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addPreserved<DominatorTree>();
- }
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const { }
const char *getPassName() const {
return "Exception handling preparation";
}
-
};
} // end anonymous namespace
char DwarfEHPrepare::ID = 0;
-FunctionPass *llvm::createDwarfEHPass(const TargetMachine *tm, bool fast) {
- return new DwarfEHPrepare(tm, fast);
-}
-
-/// PromoteAlloca - This promotes an alloca to registers when we know that it
-/// only has non-volatile loads and stores to it.
-static void PromoteAlloca(AllocaInst *AI) {
- assert(isAllocaPromotable(AI));
-
- // First step: bucket up uses of the pointers by the block they occur in.
- // This is important because we have to handle multiple defs/uses in a block
- // ourselves: SSAUpdater is purely for cross-block references.
- // FIXME: Want a TinyVector<Instruction*> since there is usually 0/1 element.
- DenseMap<BasicBlock*, std::vector<Instruction*> > UsesByBlock;
- for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
- UI != E; ++UI) {
- Instruction *User = cast<Instruction>(*UI);
- UsesByBlock[User->getParent()].push_back(User);
- }
-
- SSAUpdater SSA;
-
- // It wants to know some value of the same type as what we'll be inserting.
- Value *SomeValue;
- if (isa<LoadInst>(*AI->use_begin()))
- SomeValue = *AI->use_begin();
- else
- SomeValue = cast<StoreInst>(*AI->use_begin())->getOperand(0);
- SSA.Initialize(SomeValue);
-
- // Okay, now we can iterate over all the blocks in the loop with uses,
- // processing them. Keep track of which loads are loading a live-in value.
- SmallVector<LoadInst*, 32> LiveInLoads;
-
- for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
- UI != E; ++UI) {
- Instruction *User = cast<Instruction>(*UI);
- std::vector<Instruction*> &BlockUses = UsesByBlock[User->getParent()];
-
- // If this block has already been processed, ignore this repeat use.
- if (BlockUses.empty()) continue;
-
- // Okay, this is the first use in the block. If this block just has a
- // single user in it, we can rewrite it trivially.
- if (BlockUses.size() == 1) {
- // If it is a store, it is a trivial def of the value in the block.
- if (isa<StoreInst>(User)) {
- SSA.AddAvailableValue(User->getParent(),
- cast<StoreInst>(User)->getOperand(0));
- } else {
- // Otherwise it is a load, queue it to rewrite as a live-in load.
- LiveInLoads.push_back(cast<LoadInst>(User));
- }
- BlockUses.clear();
- continue;
- }
-
- // Otherwise, check to see if this block is all loads. If so, we can queue
- // them all as live in loads.
- bool HasStore = false;
- for (unsigned i = 0, e = BlockUses.size(); i != e; ++i) {
- if (isa<StoreInst>(BlockUses[i])) {
- HasStore = true;
- break;
- }
- }
-
- if (!HasStore) {
- for (unsigned i = 0, e = BlockUses.size(); i != e; ++i)
- LiveInLoads.push_back(cast<LoadInst>(BlockUses[i]));
- BlockUses.clear();
- continue;
- }
-
- // Otherwise, we have mixed loads and stores (or just a bunch of stores).
- // Since SSAUpdater is purely for cross-block values, we need to determine
- // the order of these instructions in the block. If the first use in the
- // block is a load, then it uses the live in value. The last store defines
- // the live out value. We handle this by doing a linear scan of the block.
- BasicBlock *BB = User->getParent();
- Value *StoredValue = 0;
- for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
- if (LoadInst *L = dyn_cast<LoadInst>(II)) {
- // If this is a load to an unrelated pointer, ignore it.
- if (L->getOperand(0) != AI) continue;
-
- // If we haven't seen a store yet, this is a live in use, otherwise
- // use the stored value.
- if (StoredValue)
- L->replaceAllUsesWith(StoredValue);
- else
- LiveInLoads.push_back(L);
- continue;
- }
-
- if (StoreInst *S = dyn_cast<StoreInst>(II)) {
- // If this is a store to an unrelated pointer, ignore it.
- if (S->getOperand(1) != AI) continue;
-
- // Remember that this is the active value in the block.
- StoredValue = S->getOperand(0);
- }
- }
-
- // The last stored value that happened is the live-out for the block.
- assert(StoredValue && "Already checked that there is a store in block");
- SSA.AddAvailableValue(BB, StoredValue);
- BlockUses.clear();
- }
-
- // Okay, now we rewrite all loads that use live-in values in the loop,
- // inserting PHI nodes as necessary.
- for (unsigned i = 0, e = LiveInLoads.size(); i != e; ++i) {
- LoadInst *ALoad = LiveInLoads[i];
- ALoad->replaceAllUsesWith(SSA.GetValueInMiddleOfBlock(ALoad->getParent()));
- }
-
- // Now that everything is rewritten, delete the old instructions from the body
- // of the loop. They should all be dead now.
- for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
- UI != E; ++UI)
- cast<Instruction>(*UI)->eraseFromParent();
-}
-
-
-
-/// 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;
-}
-
-/// 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);
- }
-}
-
-/// 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;
-
- restart:
- 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 (StoreInst *SI = dyn_cast<StoreInst>(II)) {
- if (!PromoteStoreInst(SI)) continue;
- Changed = true;
- SeenPHIs.clear();
- goto restart; // Uses may have changed, restart loop.
- } 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);
- }
- }
-
- return Changed;
-}
-
-/// 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);
-
- if (!DT)
- // We require DominatorTree information.
- return CleanupSelectors(CatchAllSels);
-
- if (!URoR) {
- URoR = F->getParent()->getFunction("_Unwind_Resume_or_Rethrow");
- if (!URoR) return CleanupSelectors(CatchAllSels);
- }
-
- SmallPtrSet<InvokeInst*, 32> URoRInvokes;
- FindAllURoRInvokes(URoRInvokes);
-
- SmallPtrSet<IntrinsicInst*, 32> SelsToConvert;
-
- 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);
- break;
- }
- }
- }
-
- 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;
-
- Changed |= PromoteEHPtrStore(EHPtr);
-
- 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 (!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;
-}
-
-/// 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 if it is around.
- if (DT)
- 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;
- }
-
- return Changed;
+FunctionPass *llvm::createDwarfEHPass(const TargetMachine *tm) {
+ return new DwarfEHPrepare(tm);
}
-/// 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) {
+/// InsertUnwindResumeCalls - Convert the ResumeInsts that are still present
+/// into calls to the appropriate _Unwind_Resume function.
+bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) {
+ bool UsesNewEH = false;
+ SmallVector<ResumeInst*, 16> Resumes;
+ for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
TerminatorInst *TI = I->getTerminator();
- if (isa<UnwindInst>(TI))
- UnwindInsts.push_back(TI);
+ if (ResumeInst *RI = dyn_cast<ResumeInst>(TI))
+ Resumes.push_back(RI);
+ else if (InvokeInst *II = dyn_cast<InvokeInst>(TI))
+ UsesNewEH = II->getUnwindDest()->isLandingPad();
}
- if (UnwindInsts.empty()) return false;
+ if (Resumes.empty())
+ return UsesNewEH;
// 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));
+ LLVMContext &Ctx = Resumes[0]->getContext();
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;
+ // Create the basic block where the _Unwind_Resume call will live.
+ LLVMContext &Ctx = Fn.getContext();
+ BasicBlock *UnwindBB = BasicBlock::Create(Ctx, "unwind_resume", &Fn);
+ PHINode *PN = PHINode::Create(Type::getInt8PtrTy(Ctx), Resumes.size(),
+ "exn.obj", UnwindBB);
- for (SmallVectorImpl<TerminatorInst*>::iterator
- I = UnwindInsts.begin(), E = UnwindInsts.end(); I != E; ++I) {
- TerminatorInst *TI = *I;
-
- // 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,
- CreateReadOfExceptionValue(TI->getParent()),
- "", TI);
- 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;
+ // Extract the exception object from the ResumeInst and add it to the PHI node
+ // that feeds the _Unwind_Resume call.
+ for (SmallVectorImpl<ResumeInst*>::iterator
+ I = Resumes.begin(), E = Resumes.end(); I != E; ++I) {
+ ResumeInst *RI = *I;
+ BranchInst::Create(UnwindBB, RI->getParent());
+ ExtractValueInst *ExnObj = ExtractValueInst::Create(RI->getOperand(0),
+ 0, "exn.obj", RI);
+ PN->addIncoming(ExnObj, RI->getParent());
+ RI->eraseFromParent();
+ ++NumResumesLowered;
}
- return Changed;
-}
-
-/// MoveExceptionValueCalls - Ensure that eh.exception is only ever called from
-/// landing pads by replacing calls outside of landing pads with loads from a
-/// stack temporary. 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;
+ // Call the function.
+ CallInst *CI = CallInst::Create(RewindFunction, PN, "", UnwindBB);
+ CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
- bool Changed = false;
-
- for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
- for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E;)
- if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(II++))
- if (CI->getIntrinsicID() == Intrinsic::eh_exception) {
- if (!CI->use_empty()) {
- Value *ExceptionValue = CreateReadOfExceptionValue(BB);
- if (CI == ExceptionValue) {
- // The call was at the start of a landing pad - leave it alone.
- assert(LandingPads.count(BB) &&
- "Created eh.exception call outside landing pad!");
- continue;
- }
- CI->replaceAllUsesWith(ExceptionValue);
- }
- CI->eraseFromParent();
- ++NumExceptionValuesMoved;
- Changed = true;
- }
- }
-
- return Changed;
-}
-
-/// FinishStackTemporaries - If we introduced a stack variable to hold the
-/// exception value then initialize it in each landing pad.
-bool DwarfEHPrepare::FinishStackTemporaries() {
- if (!ExceptionValueVar)
- // Nothing to do.
- return false;
-
- bool Changed = false;
-
- // Make sure that there is a store of the exception value at the start of
- // each landing pad.
- for (BBSet::iterator LI = LandingPads.begin(), LE = LandingPads.end();
- LI != LE; ++LI) {
- Instruction *ExceptionValue = CreateReadOfExceptionValue(*LI);
- Instruction *Store = new StoreInst(ExceptionValue, ExceptionValueVar);
- Store->insertAfter(ExceptionValue);
- Changed = true;
- }
-
- return Changed;
-}
-
-/// PromoteStackTemporaries - Turn any stack temporaries we introduced into
-/// registers if possible.
-bool DwarfEHPrepare::PromoteStackTemporaries() {
- // Turn the exception temporary into registers and phi nodes if possible.
- if (ExceptionValueVar && isAllocaPromotable(ExceptionValueVar)) {
- PromoteAlloca(ExceptionValueVar);
- return true;
- }
- return false;
-}
-
-/// 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);
-}
-
-/// CreateValueLoad - Insert a load of the exception value stack variable
-/// (creating it if necessary) at the start of the basic block (unless
-/// there already is a load, in which case the existing load is returned).
-Instruction *DwarfEHPrepare::CreateValueLoad(BasicBlock *BB) {
- Instruction *Start = BB->getFirstNonPHIOrDbg();
- // Is this a load of the exception temporary?
- if (ExceptionValueVar)
- if (LoadInst* LI = dyn_cast<LoadInst>(Start))
- if (LI->getPointerOperand() == ExceptionValueVar)
- // Reuse the existing load.
- return Start;
-
- // Create the temporary if we didn't already.
- if (!ExceptionValueVar) {
- ExceptionValueVar = new AllocaInst(PointerType::getUnqual(
- Type::getInt8Ty(BB->getContext())), "eh.value", F->begin()->begin());
- ++NumStackTempsIntroduced;
- }
-
- // Load the value.
- return new LoadInst(ExceptionValueVar, "eh.value.load", Start);
+ // We never expect _Unwind_Resume to return.
+ new UnreachableInst(Ctx, UnwindBB);
+ return true;
}
bool DwarfEHPrepare::runOnFunction(Function &Fn) {
- bool Changed = false;
-
- // Initialize internal state.
- DT = getAnalysisIfAvailable<DominatorTree>();
- ExceptionValueVar = 0;
- 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();
-
- // Initialize any stack temporaries we introduced.
- Changed |= FinishStackTemporaries();
-
- // Turn any stack temporaries into registers.
- if (!CompileFast)
- Changed |= PromoteStackTemporaries();
-
- Changed |= HandleURoRInvokes();
-
- LandingPads.clear();
-
+ bool Changed = InsertUnwindResumeCalls(Fn);
return Changed;
}