#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/TinyPtrVector.h"
+#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/LibCallSemantics.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/CodeGen/WinEHFuncInfo.h"
BasicBlock *EndBB);
void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB);
+ void insertPHIStores(PHINode *OriginalPHI, AllocaInst *SpillSlot);
+ void
+ insertPHIStore(BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot,
+ SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist);
+ AllocaInst *insertPHILoads(PHINode *PN, Function &F);
+ void replaceUseWithLoad(Value *V, Use &U, AllocaInst *&SpillSlot,
+ DenseMap<BasicBlock *, Value *> &Loads, Function &F);
+ void demoteNonlocalUses(Value *V, std::set<BasicBlock *> &ColorsForBB,
+ Function &F);
+ bool prepareExplicitEH(Function &F);
+ void numberFunclet(BasicBlock *InitialBB, BasicBlock *FuncletBB);
Triple TheTriple;
// outlined but before the outlined code is pruned from the parent function.
DenseMap<const BasicBlock *, BasicBlock *> LPadTargetBlocks;
- // Map from outlined handler to call to llvm.frameaddress(1). Only used for
+ // Map from outlined handler to call to parent local address. Only used for
// 32-bit EH.
DenseMap<Function *, Value *> HandlerToParentFP;
AllocaInst *SEHExceptionCodeSlot = nullptr;
+
+ std::map<BasicBlock *, std::set<BasicBlock *>> BlockColors;
+ std::map<BasicBlock *, std::set<BasicBlock *>> FuncletBlocks;
};
class WinEHFrameVariableMaterializer : public ValueMaterializer {
}
bool WinEHPrepare::runOnFunction(Function &Fn) {
+ if (!Fn.hasPersonalityFn())
+ return false;
+
// No need to prepare outlined handlers.
if (Fn.hasFnAttribute("wineh-parent"))
return false;
+ // Classify the personality to see what kind of preparation we need.
+ Personality = classifyEHPersonality(Fn.getPersonalityFn());
+
+ // Do nothing if this is not an MSVC personality.
+ if (!isMSVCEHPersonality(Personality))
+ return false;
+
SmallVector<LandingPadInst *, 4> LPads;
SmallVector<ResumeInst *, 4> Resumes;
+ bool ForExplicitEH = false;
for (BasicBlock &BB : Fn) {
- if (auto *LP = BB.getLandingPadInst())
+ if (auto *LP = BB.getLandingPadInst()) {
LPads.push_back(LP);
+ } else if (BB.getFirstNonPHI()->isEHPad()) {
+ ForExplicitEH = true;
+ break;
+ }
if (auto *Resume = dyn_cast<ResumeInst>(BB.getTerminator()))
Resumes.push_back(Resume);
}
+ if (ForExplicitEH)
+ return prepareExplicitEH(Fn);
+
// No need to prepare functions that lack landing pads.
if (LPads.empty())
return false;
- // Classify the personality to see what kind of preparation we need.
- Personality = classifyEHPersonality(Fn.getPersonalityFn());
-
- // Do nothing if this is not an MSVC personality.
- if (!isMSVCEHPersonality(Personality))
- return false;
-
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
LibInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
BasicBlock *NextBB;
Constant *Selector;
if (isSelectorDispatch(BB, CatchHandler, Selector, NextBB)) {
- // Split the edge if there is a phi node. Returning from EH to a phi node
- // is just as impossible as having a phi after an indirectbr.
- if (isa<PHINode>(CatchHandler->begin())) {
+ // Split the edge if there are multiple predecessors. This creates a place
+ // where we can insert EH recovery code.
+ if (!CatchHandler->getSinglePredecessor()) {
DEBUG(dbgs() << "splitting EH return edge from " << BB->getName()
<< " to " << CatchHandler->getName() << '\n');
BBI = CatchHandler = SplitCriticalEdge(
// identifyEHBlocks() should have been called before this function.
assert(!NormalBlocks.empty());
+ // Try to avoid demoting EH pointer and selector values. They get in the way
+ // of our pattern matching.
+ SmallPtrSet<Instruction *, 10> EHVals;
+ for (BasicBlock &BB : F) {
+ LandingPadInst *LP = BB.getLandingPadInst();
+ if (!LP)
+ continue;
+ EHVals.insert(LP);
+ for (User *U : LP->users()) {
+ auto *EI = dyn_cast<ExtractValueInst>(U);
+ if (!EI)
+ continue;
+ EHVals.insert(EI);
+ for (User *U2 : EI->users()) {
+ if (auto *PN = dyn_cast<PHINode>(U2))
+ EHVals.insert(PN);
+ }
+ }
+ }
+
SetVector<Argument *> ArgsToDemote;
SetVector<Instruction *> InstrsToDemote;
for (BasicBlock &BB : F) {
continue;
}
+ // Don't demote EH values.
auto *OpI = cast<Instruction>(Op);
+ if (EHVals.count(OpI))
+ continue;
+
BasicBlock *OpBB = OpI->getParent();
// If a value is produced and consumed in the same BB, we don't need to
// demote it.
LPad->replaceAllUsesWith(UndefValue::get(LPad->getType()));
// Rewrite uses of the exception pointer to loads of an alloca.
- for (Instruction *E : SEHCodeUses) {
+ while (!SEHCodeUses.empty()) {
+ Instruction *E = SEHCodeUses.pop_back_val();
SmallVector<Use *, 4> Uses;
for (Use &U : E->uses())
Uses.push_back(&U);
auto *I = cast<Instruction>(U->getUser());
if (isa<ResumeInst>(I))
continue;
- LoadInst *LI;
if (auto *Phi = dyn_cast<PHINode>(I))
- LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false,
- Phi->getIncomingBlock(*U)->getTerminator());
+ SEHCodeUses.push_back(Phi);
else
- LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I);
- U->set(LI);
+ U->set(new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I));
}
E->replaceAllUsesWith(UndefValue::get(E->getType()));
E->eraseFromParent();
VMap[Extract] = SelectorValue;
}
-static bool isFrameAddressCall(const Value *V) {
- return match(const_cast<Value *>(V),
- m_Intrinsic<Intrinsic::frameaddress>(m_SpecificInt(0)));
+static bool isLocalAddressCall(const Value *V) {
+ return match(const_cast<Value *>(V), m_Intrinsic<Intrinsic::localaddress>());
}
CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction(
if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
return handleTypeIdFor(VMap, Inst, NewBB);
- // When outlining llvm.frameaddress(i32 0), remap that to the second argument,
+ // When outlining llvm.localaddress(), remap that to the second argument,
// which is the FP of the parent.
- if (isFrameAddressCall(Inst)) {
+ if (isLocalAddressCall(Inst)) {
VMap[Inst] = ParentFP;
return CloningDirector::SkipInstruction;
}
// Under some circumstances optimized IR will flow unconditionally into a
// handler block without checking the selector. This can only happen if
// the landing pad has a catch-all handler and the handler for the
- // preceeding catch clause is identical to the catch-call handler
+ // preceding catch clause is identical to the catch-call handler
// (typically an empty catch). In this case, the handler must be shared
// by all remaining clauses.
if (isa<ConstantPointerNull>(
static CallSite matchOutlinedFinallyCall(BasicBlock *BB,
Instruction *MaybeCall) {
// Look for finally blocks that Clang has already outlined for us.
- // %fp = call i8* @llvm.frameaddress(i32 0)
+ // %fp = call i8* @llvm.localaddress()
// call void @"fin$parent"(iN 1, i8* %fp)
- if (isFrameAddressCall(MaybeCall) && MaybeCall != BB->getTerminator())
+ if (isLocalAddressCall(MaybeCall) && MaybeCall != BB->getTerminator())
MaybeCall = MaybeCall->getNextNode();
CallSite FinallyCall(MaybeCall);
if (!FinallyCall || FinallyCall.arg_size() != 2)
return CallSite();
if (!match(FinallyCall.getArgument(0), m_SpecificInt(1)))
return CallSite();
- if (!isFrameAddressCall(FinallyCall.getArgument(1)))
+ if (!isLocalAddressCall(FinallyCall.getArgument(1)))
return CallSite();
return FinallyCall;
}
};
}
-void WinEHNumbering::createUnwindMapEntry(int ToState, ActionHandler *AH) {
+static int addUnwindMapEntry(WinEHFuncInfo &FuncInfo, int ToState,
+ const Value *V) {
WinEHUnwindMapEntry UME;
UME.ToState = ToState;
- if (auto *CH = dyn_cast_or_null<CleanupHandler>(AH))
- UME.Cleanup = cast<Function>(CH->getHandlerBlockOrFunc());
- else
- UME.Cleanup = nullptr;
+ UME.Cleanup = V;
FuncInfo.UnwindMap.push_back(UME);
+ return FuncInfo.getLastStateNumber();
+}
+
+static void addTryBlockMapEntry(WinEHFuncInfo &FuncInfo, int TryLow,
+ int TryHigh, int CatchHigh,
+ ArrayRef<const CatchPadInst *> Handlers) {
+ WinEHTryBlockMapEntry TBME;
+ TBME.TryLow = TryLow;
+ TBME.TryHigh = TryHigh;
+ TBME.CatchHigh = CatchHigh;
+ assert(TBME.TryLow <= TBME.TryHigh);
+ for (const CatchPadInst *CPI : Handlers) {
+ WinEHHandlerType HT;
+ Constant *TypeInfo = cast<Constant>(CPI->getArgOperand(0));
+ if (TypeInfo->isNullValue()) {
+ HT.Adjectives = 0x40;
+ HT.TypeDescriptor = nullptr;
+ } else {
+ auto *GV = cast<GlobalVariable>(TypeInfo->stripPointerCasts());
+ // Selectors are always pointers to GlobalVariables with 'struct' type.
+ // The struct has two fields, adjectives and a type descriptor.
+ auto *CS = cast<ConstantStruct>(GV->getInitializer());
+ HT.Adjectives =
+ cast<ConstantInt>(CS->getAggregateElement(0U))->getZExtValue();
+ HT.TypeDescriptor =
+ cast<GlobalVariable>(CS->getAggregateElement(1)->stripPointerCasts());
+ }
+ HT.Handler = CPI->getParent();
+ // FIXME: Pass CPI->getArgOperand(1).
+ HT.CatchObjRecoverIdx = -1;
+ TBME.HandlerArray.push_back(HT);
+ }
+ FuncInfo.TryBlockMap.push_back(TBME);
+}
+
+void WinEHNumbering::createUnwindMapEntry(int ToState, ActionHandler *AH) {
+ Value *V = nullptr;
+ if (auto *CH = dyn_cast_or_null<CleanupHandler>(AH))
+ V = cast<Function>(CH->getHandlerBlockOrFunc());
+ addUnwindMapEntry(FuncInfo, ToState, V);
}
void WinEHNumbering::createTryBlockMapEntry(int TryLow, int TryHigh,
continue;
processCallSite(ActionList, II);
ActionList.clear();
- FuncInfo.LandingPadStateMap[LPI] = currentEHNumber();
+ FuncInfo.EHPadStateMap[LPI] = currentEHNumber();
DEBUG(dbgs() << "Assigning state " << currentEHNumber()
<< " to landing pad at " << LPI->getParent()->getName()
<< '\n');
}
}
+static const BasicBlock *getSingleCatchPadPredecessor(const BasicBlock &BB) {
+ for (const BasicBlock *PredBlock : predecessors(&BB))
+ if (isa<CatchPadInst>(PredBlock->getFirstNonPHI()))
+ return PredBlock;
+ return nullptr;
+}
+
+// Given BB which ends in an unwind edge, return the EHPad that this BB belongs
+// to. If the unwind edge came from an invoke, return null.
+static const BasicBlock *getEHPadFromPredecessor(const BasicBlock *BB) {
+ const TerminatorInst *TI = BB->getTerminator();
+ if (isa<InvokeInst>(TI))
+ return nullptr;
+ if (isa<CatchPadInst>(TI) || isa<CatchEndPadInst>(TI) ||
+ isa<TerminatePadInst>(TI))
+ return BB;
+ return cast<CleanupPadInst>(cast<CleanupReturnInst>(TI)->getReturnValue())
+ ->getParent();
+}
+
+static void calculateExplicitStateNumbers(WinEHFuncInfo &FuncInfo,
+ const BasicBlock &BB,
+ int ParentState) {
+ assert(BB.isEHPad());
+ const Instruction *FirstNonPHI = BB.getFirstNonPHI();
+ // All catchpad instructions will be handled when we process their
+ // respective catchendpad instruction.
+ if (isa<CatchPadInst>(FirstNonPHI))
+ return;
+
+ if (isa<CatchEndPadInst>(FirstNonPHI)) {
+ const BasicBlock *TryPad = &BB;
+ const BasicBlock *LastTryPad = nullptr;
+ SmallVector<const CatchPadInst *, 2> Handlers;
+ do {
+ LastTryPad = TryPad;
+ TryPad = getSingleCatchPadPredecessor(*TryPad);
+ if (TryPad)
+ Handlers.push_back(cast<CatchPadInst>(TryPad->getFirstNonPHI()));
+ } while (TryPad);
+ // We've pushed these back into reverse source order. Reverse them to get
+ // the list back into source order.
+ std::reverse(Handlers.begin(), Handlers.end());
+ int TryLow = addUnwindMapEntry(FuncInfo, ParentState, nullptr);
+ FuncInfo.EHPadStateMap[Handlers.front()] = TryLow;
+ for (const BasicBlock *PredBlock : predecessors(LastTryPad))
+ if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
+ calculateExplicitStateNumbers(FuncInfo, *PredBlock, TryLow);
+ int CatchLow = addUnwindMapEntry(FuncInfo, ParentState, nullptr);
+ FuncInfo.EHPadStateMap[FirstNonPHI] = CatchLow;
+ int TryHigh = CatchLow - 1;
+ for (const BasicBlock *PredBlock : predecessors(&BB))
+ if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
+ calculateExplicitStateNumbers(FuncInfo, *PredBlock, CatchLow);
+ int CatchHigh = FuncInfo.getLastStateNumber();
+ addTryBlockMapEntry(FuncInfo, TryLow, TryHigh, CatchHigh, Handlers);
+ DEBUG(dbgs() << "TryLow[" << LastTryPad->getName() << "]: " << TryLow
+ << '\n');
+ DEBUG(dbgs() << "TryHigh[" << LastTryPad->getName() << "]: " << TryHigh
+ << '\n');
+ DEBUG(dbgs() << "CatchHigh[" << LastTryPad->getName() << "]: " << CatchHigh
+ << '\n');
+ } else if (isa<CleanupPadInst>(FirstNonPHI)) {
+ int CleanupState = addUnwindMapEntry(FuncInfo, ParentState, &BB);
+ FuncInfo.EHPadStateMap[FirstNonPHI] = CleanupState;
+ DEBUG(dbgs() << "Assigning state #" << CleanupState << " to BB "
+ << BB.getName() << '\n');
+ for (const BasicBlock *PredBlock : predecessors(&BB))
+ if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
+ calculateExplicitStateNumbers(FuncInfo, *PredBlock, CleanupState);
+ } else if (isa<TerminatePadInst>(FirstNonPHI)) {
+ report_fatal_error("Not yet implemented!");
+ } else {
+ llvm_unreachable("unexpected EH Pad!");
+ }
+}
+
void llvm::calculateWinCXXEHStateNumbers(const Function *ParentFn,
WinEHFuncInfo &FuncInfo) {
// Return if it's already been done.
- if (!FuncInfo.LandingPadStateMap.empty())
+ if (!FuncInfo.EHPadStateMap.empty())
+ return;
+
+ bool IsExplicit = false;
+ for (const BasicBlock &BB : *ParentFn) {
+ if (!BB.isEHPad())
+ continue;
+ // Check if the EH Pad has no exceptional successors (i.e. it unwinds to
+ // caller). Cleanups are a little bit of a special case because their
+ // control flow cannot be determined by looking at the pad but instead by
+ // the pad's users.
+ bool HasNoSuccessors = false;
+ const Instruction *FirstNonPHI = BB.getFirstNonPHI();
+ if (FirstNonPHI->mayThrow()) {
+ HasNoSuccessors = true;
+ } else if (auto *CPI = dyn_cast<CleanupPadInst>(FirstNonPHI)) {
+ HasNoSuccessors =
+ CPI->use_empty() ||
+ cast<CleanupReturnInst>(CPI->user_back())->unwindsToCaller();
+ }
+
+ if (!HasNoSuccessors)
+ continue;
+ calculateExplicitStateNumbers(FuncInfo, BB, -1);
+ IsExplicit = true;
+ }
+
+ if (IsExplicit)
return;
WinEHNumbering Num(FuncInfo);
while (!Num.HandlerStack.empty())
Num.processCallSite(None, ImmutableCallSite());
}
+
+void WinEHPrepare::numberFunclet(BasicBlock *InitialBB, BasicBlock *FuncletBB) {
+ Instruction *FirstNonPHI = FuncletBB->getFirstNonPHI();
+ bool IsCatch = isa<CatchPadInst>(FirstNonPHI);
+ bool IsCleanup = isa<CleanupPadInst>(FirstNonPHI);
+
+ // Initialize the worklist with the funclet's entry point.
+ std::vector<BasicBlock *> Worklist;
+ Worklist.push_back(InitialBB);
+
+ while (!Worklist.empty()) {
+ BasicBlock *BB = Worklist.back();
+ Worklist.pop_back();
+
+ // There can be only one "pad" basic block in the funclet: the initial one.
+ if (BB != FuncletBB && BB->isEHPad())
+ continue;
+
+ // Add 'FuncletBB' as a possible color for 'BB'.
+ if (BlockColors[BB].insert(FuncletBB).second == false) {
+ // Skip basic blocks which we have already visited.
+ continue;
+ }
+
+ FuncletBlocks[FuncletBB].insert(BB);
+
+ Instruction *Terminator = BB->getTerminator();
+ // The catchret's successors cannot be part of the funclet.
+ if (IsCatch && isa<CatchReturnInst>(Terminator))
+ continue;
+ // The cleanupret's successors cannot be part of the funclet.
+ if (IsCleanup && isa<CleanupReturnInst>(Terminator))
+ continue;
+
+ Worklist.insert(Worklist.end(), succ_begin(BB), succ_end(BB));
+ }
+}
+
+bool WinEHPrepare::prepareExplicitEH(Function &F) {
+ // Remove unreachable blocks. It is not valuable to assign them a color and
+ // their existence can trick us into thinking values are alive when they are
+ // not.
+ removeUnreachableBlocks(F);
+
+ BasicBlock *EntryBlock = &F.getEntryBlock();
+
+ // Number everything starting from the entry block.
+ numberFunclet(EntryBlock, EntryBlock);
+
+ for (BasicBlock &BB : F) {
+ // Remove single entry PHIs to simplify preparation.
+ if (auto *PN = dyn_cast<PHINode>(BB.begin()))
+ if (PN->getNumIncomingValues() == 1)
+ FoldSingleEntryPHINodes(&BB);
+
+ // EH pad instructions are always the first non-PHI nodes in a block if they
+ // are at all present.
+ Instruction *I = BB.getFirstNonPHI();
+ if (I->isEHPad())
+ numberFunclet(&BB, &BB);
+
+ // It is possible for a normal basic block to only be reachable via an
+ // exceptional basic block. The successor of a catchret is the only case
+ // where this is possible.
+ if (auto *CRI = dyn_cast<CatchReturnInst>(BB.getTerminator()))
+ numberFunclet(CRI->getSuccessor(), EntryBlock);
+ }
+
+ // Strip PHI nodes off of EH pads.
+ SmallVector<PHINode *, 16> PHINodes;
+ for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
+ BasicBlock *BB = FI++;
+ if (!BB->isEHPad())
+ continue;
+ for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
+ Instruction *I = BI++;
+ auto *PN = dyn_cast<PHINode>(I);
+ // Stop at the first non-PHI.
+ if (!PN)
+ break;
+
+ AllocaInst *SpillSlot = insertPHILoads(PN, F);
+ if (SpillSlot)
+ insertPHIStores(PN, SpillSlot);
+
+ PHINodes.push_back(PN);
+ }
+ }
+
+ for (auto *PN : PHINodes) {
+ // There may be lingering uses on other EH PHIs being removed
+ PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
+ PN->eraseFromParent();
+ }
+
+ // Turn all inter-funclet uses of a Value into loads and stores.
+ for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
+ BasicBlock *BB = FI++;
+ std::set<BasicBlock *> &ColorsForBB = BlockColors[BB];
+ for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
+ Instruction *I = BI++;
+ // Funclets are permitted to use static allocas.
+ if (auto *AI = dyn_cast<AllocaInst>(I))
+ if (AI->isStaticAlloca())
+ continue;
+
+ demoteNonlocalUses(I, ColorsForBB, F);
+ }
+ }
+ // Also demote function parameters used in funclets.
+ std::set<BasicBlock *> &ColorsForEntry = BlockColors[&F.getEntryBlock()];
+ for (Argument &Arg : F.args())
+ demoteNonlocalUses(&Arg, ColorsForEntry, F);
+
+ // We need to clone all blocks which belong to multiple funclets. Values are
+ // remapped throughout the funclet to propogate both the new instructions
+ // *and* the new basic blocks themselves.
+ for (auto &Funclet : FuncletBlocks) {
+ BasicBlock *FuncletPadBB = Funclet.first;
+ std::set<BasicBlock *> &BlocksInFunclet = Funclet.second;
+
+ std::map<BasicBlock *, BasicBlock *> Orig2Clone;
+ ValueToValueMapTy VMap;
+ for (BasicBlock *BB : BlocksInFunclet) {
+ std::set<BasicBlock *> &ColorsForBB = BlockColors[BB];
+ // We don't need to do anything if the block is monochromatic.
+ size_t NumColorsForBB = ColorsForBB.size();
+ if (NumColorsForBB == 1)
+ continue;
+
+ assert(!isa<PHINode>(BB->front()) &&
+ "Polychromatic PHI nodes should have been demoted!");
+
+ // Create a new basic block and copy instructions into it!
+ BasicBlock *CBB = CloneBasicBlock(
+ BB, VMap, Twine(".for.", FuncletPadBB->getName()), &F);
+
+ // Add basic block mapping.
+ VMap[BB] = CBB;
+
+ // Record delta operations that we need to perform to our color mappings.
+ Orig2Clone[BB] = CBB;
+ }
+
+ // Update our color mappings to reflect that one block has lost a color and
+ // another has gained a color.
+ for (auto &BBMapping : Orig2Clone) {
+ BasicBlock *OldBlock = BBMapping.first;
+ BasicBlock *NewBlock = BBMapping.second;
+
+ BlocksInFunclet.insert(NewBlock);
+ BlockColors[NewBlock].insert(FuncletPadBB);
+
+ BlocksInFunclet.erase(OldBlock);
+ BlockColors[OldBlock].erase(FuncletPadBB);
+ }
+
+ // Loop over all of the instructions in the function, fixing up operand
+ // references as we go. This uses VMap to do all the hard work.
+ for (BasicBlock *BB : BlocksInFunclet)
+ // Loop over all instructions, fixing each one as we find it...
+ for (Instruction &I : *BB)
+ RemapInstruction(&I, VMap, RF_IgnoreMissingEntries);
+ }
+
+ // Remove implausible terminators and replace them with UnreachableInst.
+ for (auto &Funclet : FuncletBlocks) {
+ BasicBlock *FuncletPadBB = Funclet.first;
+ std::set<BasicBlock *> &BlocksInFunclet = Funclet.second;
+ Instruction *FirstNonPHI = FuncletPadBB->getFirstNonPHI();
+ auto *CatchPad = dyn_cast<CatchPadInst>(FirstNonPHI);
+ auto *CleanupPad = dyn_cast<CleanupPadInst>(FirstNonPHI);
+
+ for (BasicBlock *BB : BlocksInFunclet) {
+ TerminatorInst *TI = BB->getTerminator();
+ // CatchPadInst and CleanupPadInst can't transfer control to a ReturnInst.
+ bool IsUnreachableRet = isa<ReturnInst>(TI) && (CatchPad || CleanupPad);
+ // The token consumed by a CatchReturnInst must match the funclet token.
+ bool IsUnreachableCatchret = false;
+ if (auto *CRI = dyn_cast<CatchReturnInst>(TI))
+ IsUnreachableCatchret = CRI->getReturnValue() != CatchPad;
+ // The token consumed by a CleanupPadInst must match the funclet token.
+ bool IsUnreachableCleanupret = false;
+ if (auto *CRI = dyn_cast<CleanupReturnInst>(TI))
+ IsUnreachableCleanupret = CRI->getReturnValue() != CleanupPad;
+ if (IsUnreachableRet || IsUnreachableCatchret || IsUnreachableCleanupret) {
+ new UnreachableInst(BB->getContext(), TI);
+ TI->eraseFromParent();
+ }
+ }
+ }
+
+ // Clean-up some of the mess we made by removing useles PHI nodes, trivial
+ // branches, etc.
+ for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
+ BasicBlock *BB = FI++;
+ SimplifyInstructionsInBlock(BB);
+ ConstantFoldTerminator(BB, /*DeleteDeadConditions=*/true);
+ MergeBlockIntoPredecessor(BB);
+ }
+
+ // We might have some unreachable blocks after cleaning up some impossible
+ // control flow.
+ removeUnreachableBlocks(F);
+
+ // Recolor the CFG to verify that all is well.
+ for (BasicBlock &BB : F) {
+ size_t NumColors = BlockColors[&BB].size();
+ assert(NumColors == 1 && "Expected monochromatic BB!");
+ if (NumColors == 0)
+ report_fatal_error("Uncolored BB!");
+ if (NumColors > 1)
+ report_fatal_error("Multicolor BB!");
+ bool EHPadHasPHI = BB.isEHPad() && isa<PHINode>(BB.begin());
+ assert(!EHPadHasPHI && "EH Pad still has a PHI!");
+ if (EHPadHasPHI)
+ report_fatal_error("EH Pad still has a PHI!");
+ }
+
+ BlockColors.clear();
+ FuncletBlocks.clear();
+
+ return true;
+}
+
+// TODO: Share loads when one use dominates another, or when a catchpad exit
+// dominates uses (needs dominators).
+AllocaInst *WinEHPrepare::insertPHILoads(PHINode *PN, Function &F) {
+ BasicBlock *PHIBlock = PN->getParent();
+ AllocaInst *SpillSlot = nullptr;
+
+ if (isa<CleanupPadInst>(PHIBlock->getFirstNonPHI())) {
+ // Insert a load in place of the PHI and replace all uses.
+ SpillSlot = new AllocaInst(PN->getType(), nullptr,
+ Twine(PN->getName(), ".wineh.spillslot"),
+ F.getEntryBlock().begin());
+ Value *V = new LoadInst(SpillSlot, Twine(PN->getName(), ".wineh.reload"),
+ PHIBlock->getFirstInsertionPt());
+ PN->replaceAllUsesWith(V);
+ return SpillSlot;
+ }
+
+ DenseMap<BasicBlock *, Value *> Loads;
+ for (Value::use_iterator UI = PN->use_begin(), UE = PN->use_end();
+ UI != UE;) {
+ Use &U = *UI++;
+ auto *UsingInst = cast<Instruction>(U.getUser());
+ BasicBlock *UsingBB = UsingInst->getParent();
+ if (UsingBB->isEHPad()) {
+ // Use is on an EH pad phi. Leave it alone; we'll insert loads and
+ // stores for it separately.
+ assert(isa<PHINode>(UsingInst));
+ continue;
+ }
+ replaceUseWithLoad(PN, U, SpillSlot, Loads, F);
+ }
+ return SpillSlot;
+}
+
+// TODO: improve store placement. Inserting at def is probably good, but need
+// to be careful not to introduce interfering stores (needs liveness analysis).
+// TODO: identify related phi nodes that can share spill slots, and share them
+// (also needs liveness).
+void WinEHPrepare::insertPHIStores(PHINode *OriginalPHI,
+ AllocaInst *SpillSlot) {
+ // Use a worklist of (Block, Value) pairs -- the given Value needs to be
+ // stored to the spill slot by the end of the given Block.
+ SmallVector<std::pair<BasicBlock *, Value *>, 4> Worklist;
+
+ Worklist.push_back({OriginalPHI->getParent(), OriginalPHI});
+
+ while (!Worklist.empty()) {
+ BasicBlock *EHBlock;
+ Value *InVal;
+ std::tie(EHBlock, InVal) = Worklist.pop_back_val();
+
+ PHINode *PN = dyn_cast<PHINode>(InVal);
+ if (PN && PN->getParent() == EHBlock) {
+ // The value is defined by another PHI we need to remove, with no room to
+ // insert a store after the PHI, so each predecessor needs to store its
+ // incoming value.
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i < e; ++i) {
+ Value *PredVal = PN->getIncomingValue(i);
+
+ // Undef can safely be skipped.
+ if (isa<UndefValue>(PredVal))
+ continue;
+
+ insertPHIStore(PN->getIncomingBlock(i), PredVal, SpillSlot, Worklist);
+ }
+ } else {
+ // We need to store InVal, which dominates EHBlock, but can't put a store
+ // in EHBlock, so need to put stores in each predecessor.
+ for (BasicBlock *PredBlock : predecessors(EHBlock)) {
+ insertPHIStore(PredBlock, InVal, SpillSlot, Worklist);
+ }
+ }
+ }
+}
+
+void WinEHPrepare::insertPHIStore(
+ BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot,
+ SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist) {
+
+ if (PredBlock->isEHPad() &&
+ !isa<CleanupPadInst>(PredBlock->getFirstNonPHI())) {
+ // Pred is unsplittable, so we need to queue it on the worklist.
+ Worklist.push_back({PredBlock, PredVal});
+ return;
+ }
+
+ // Otherwise, insert the store at the end of the basic block.
+ new StoreInst(PredVal, SpillSlot, PredBlock->getTerminator());
+}
+
+// TODO: Share loads for same-funclet uses (requires dominators if funclets
+// aren't properly nested).
+void WinEHPrepare::demoteNonlocalUses(Value *V,
+ std::set<BasicBlock *> &ColorsForBB,
+ Function &F) {
+ // Tokens can only be used non-locally due to control flow involving
+ // unreachable edges. Don't try to demote the token usage, we'll simply
+ // delete the cloned user later.
+ if (isa<CatchPadInst>(V) || isa<CleanupPadInst>(V))
+ return;
+
+ DenseMap<BasicBlock *, Value *> Loads;
+ AllocaInst *SpillSlot = nullptr;
+ for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;) {
+ Use &U = *UI++;
+ auto *UsingInst = cast<Instruction>(U.getUser());
+ BasicBlock *UsingBB = UsingInst->getParent();
+
+ // Is the Use inside a block which is colored with a subset of the Def?
+ // If so, we don't need to escape the Def because we will clone
+ // ourselves our own private copy.
+ std::set<BasicBlock *> &ColorsForUsingBB = BlockColors[UsingBB];
+ if (std::includes(ColorsForBB.begin(), ColorsForBB.end(),
+ ColorsForUsingBB.begin(), ColorsForUsingBB.end()))
+ continue;
+
+ replaceUseWithLoad(V, U, SpillSlot, Loads, F);
+ }
+ if (SpillSlot) {
+ // Insert stores of the computed value into the stack slot.
+ // We have to be careful if I is an invoke instruction,
+ // because we can't insert the store AFTER the terminator instruction.
+ BasicBlock::iterator InsertPt;
+ if (isa<Argument>(V)) {
+ InsertPt = F.getEntryBlock().getTerminator();
+ } else if (isa<TerminatorInst>(V)) {
+ auto *II = cast<InvokeInst>(V);
+ // We cannot demote invoke instructions to the stack if their normal
+ // edge is critical. Therefore, split the critical edge and create a
+ // basic block into which the store can be inserted.
+ if (!II->getNormalDest()->getSinglePredecessor()) {
+ unsigned SuccNum =
+ GetSuccessorNumber(II->getParent(), II->getNormalDest());
+ assert(isCriticalEdge(II, SuccNum) && "Expected a critical edge!");
+ BasicBlock *NewBlock = SplitCriticalEdge(II, SuccNum);
+ assert(NewBlock && "Unable to split critical edge.");
+ // Update the color mapping for the newly split edge.
+ std::set<BasicBlock *> &ColorsForUsingBB = BlockColors[II->getParent()];
+ BlockColors[NewBlock] = ColorsForUsingBB;
+ for (BasicBlock *FuncletPad : ColorsForUsingBB)
+ FuncletBlocks[FuncletPad].insert(NewBlock);
+ }
+ InsertPt = II->getNormalDest()->getFirstInsertionPt();
+ } else {
+ InsertPt = cast<Instruction>(V);
+ ++InsertPt;
+ // Don't insert before PHI nodes or EH pad instrs.
+ for (; isa<PHINode>(InsertPt) || InsertPt->isEHPad(); ++InsertPt)
+ ;
+ }
+ new StoreInst(V, SpillSlot, InsertPt);
+ }
+}
+
+void WinEHPrepare::replaceUseWithLoad(Value *V, Use &U, AllocaInst *&SpillSlot,
+ DenseMap<BasicBlock *, Value *> &Loads,
+ Function &F) {
+ // Lazilly create the spill slot.
+ if (!SpillSlot)
+ SpillSlot = new AllocaInst(V->getType(), nullptr,
+ Twine(V->getName(), ".wineh.spillslot"),
+ F.getEntryBlock().begin());
+
+ auto *UsingInst = cast<Instruction>(U.getUser());
+ if (auto *UsingPHI = dyn_cast<PHINode>(UsingInst)) {
+ // If this is a PHI node, we can't insert a load of the value before
+ // the use. Instead insert the load in the predecessor block
+ // corresponding to the incoming value.
+ //
+ // Note that if there are multiple edges from a basic block to this
+ // PHI node that we cannot have multiple loads. The problem is that
+ // the resulting PHI node will have multiple values (from each load)
+ // coming in from the same block, which is illegal SSA form.
+ // For this reason, we keep track of and reuse loads we insert.
+ BasicBlock *IncomingBlock = UsingPHI->getIncomingBlock(U);
+ if (auto *CatchRet =
+ dyn_cast<CatchReturnInst>(IncomingBlock->getTerminator())) {
+ // Putting a load above a catchret and use on the phi would still leave
+ // a cross-funclet def/use. We need to split the edge, change the
+ // catchret to target the new block, and put the load there.
+ BasicBlock *PHIBlock = UsingInst->getParent();
+ BasicBlock *NewBlock = SplitEdge(IncomingBlock, PHIBlock);
+ // SplitEdge gives us:
+ // IncomingBlock:
+ // ...
+ // br label %NewBlock
+ // NewBlock:
+ // catchret label %PHIBlock
+ // But we need:
+ // IncomingBlock:
+ // ...
+ // catchret label %NewBlock
+ // NewBlock:
+ // br label %PHIBlock
+ // So move the terminators to each others' blocks and swap their
+ // successors.
+ BranchInst *Goto = cast<BranchInst>(IncomingBlock->getTerminator());
+ Goto->removeFromParent();
+ CatchRet->removeFromParent();
+ IncomingBlock->getInstList().push_back(CatchRet);
+ NewBlock->getInstList().push_back(Goto);
+ Goto->setSuccessor(0, PHIBlock);
+ CatchRet->setSuccessor(NewBlock);
+ // Update the color mapping for the newly split edge.
+ std::set<BasicBlock *> &ColorsForPHIBlock = BlockColors[PHIBlock];
+ BlockColors[NewBlock] = ColorsForPHIBlock;
+ for (BasicBlock *FuncletPad : ColorsForPHIBlock)
+ FuncletBlocks[FuncletPad].insert(NewBlock);
+ // Treat the new block as incoming for load insertion.
+ IncomingBlock = NewBlock;
+ }
+ Value *&Load = Loads[IncomingBlock];
+ // Insert the load into the predecessor block
+ if (!Load)
+ Load = new LoadInst(SpillSlot, Twine(V->getName(), ".wineh.reload"),
+ /*Volatile=*/false, IncomingBlock->getTerminator());
+
+ U.set(Load);
+ } else {
+ // Reload right before the old use.
+ auto *Load = new LoadInst(SpillSlot, Twine(V->getName(), ".wineh.reload"),
+ /*Volatile=*/false, UsingInst);
+ U.set(Load);
+ }
+}
projects / oota-llvm.git / blobdiff