//===----------------------------------------------------------------------===//
//
// This pass lowers LLVM IR exception handling into something closer to what the
-// backend wants. It snifs the personality function to see which kind of
-// preparation is necessary. If the personality function uses the Itanium LSDA,
-// this pass delegates to the DWARF EH preparation pass.
+// backend wants for functions using a personality function from a runtime
+// provided by MSVC. Functions with other personality functions are left alone
+// and may be prepared by other passes. In particular, all supported MSVC
+// personality functions require cleanup code to be outlined, and the C++
+// personality requires catch handler code to be outlined.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/Passes.h"
#include "llvm/ADT/MapVector.h"
-#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/Triple.h"
#include "llvm/ADT/TinyPtrVector.h"
#include "llvm/Analysis/LibCallSemantics.h"
+#include "llvm/CodeGen/WinEHFuncInfo.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/PromoteMemToReg.h"
#include <memory>
using namespace llvm;
// frame allocation structure.
typedef MapVector<Value *, TinyPtrVector<AllocaInst *>> FrameVarInfoMap;
-typedef SmallSet<BasicBlock *, 4> VisitedBlockSet;
+// TinyPtrVector cannot hold nullptr, so we need our own sentinel that isn't
+// quite null.
+AllocaInst *getCatchObjectSentinel() {
+ return static_cast<AllocaInst *>(nullptr) + 1;
+}
-enum ActionType { Catch, Cleanup };
+typedef SmallSet<BasicBlock *, 4> VisitedBlockSet;
class LandingPadActions;
-class ActionHandler;
-class CatchHandler;
-class CleanupHandler;
class LandingPadMap;
typedef DenseMap<const BasicBlock *, CatchHandler *> CatchHandlerMapTy;
public:
static char ID; // Pass identification, replacement for typeid.
WinEHPrepare(const TargetMachine *TM = nullptr)
- : FunctionPass(ID) {}
+ : FunctionPass(ID) {
+ if (TM)
+ TheTriple = Triple(TM->getTargetTriple());
+ }
bool runOnFunction(Function &Fn) override;
}
private:
- bool prepareCPPEHHandlers(Function &F,
- SmallVectorImpl<LandingPadInst *> &LPads);
+ bool prepareExceptionHandlers(Function &F,
+ SmallVectorImpl<LandingPadInst *> &LPads);
+ void promoteLandingPadValues(LandingPadInst *LPad);
+ void demoteValuesLiveAcrossHandlers(Function &F,
+ SmallVectorImpl<LandingPadInst *> &LPads);
+ void findSEHEHReturnPoints(Function &F,
+ SetVector<BasicBlock *> &EHReturnBlocks);
+ void findCXXEHReturnPoints(Function &F,
+ SetVector<BasicBlock *> &EHReturnBlocks);
+ void getPossibleReturnTargets(Function *ParentF, Function *HandlerF,
+ SetVector<BasicBlock*> &Targets);
+ void completeNestedLandingPad(Function *ParentFn,
+ LandingPadInst *OutlinedLPad,
+ const LandingPadInst *OriginalLPad,
+ FrameVarInfoMap &VarInfo);
+ Function *createHandlerFunc(Type *RetTy, const Twine &Name, Module *M,
+ Value *&ParentFP);
bool outlineHandler(ActionHandler *Action, Function *SrcFn,
LandingPadInst *LPad, BasicBlock *StartBB,
FrameVarInfoMap &VarInfo);
+ void addStubInvokeToHandlerIfNeeded(Function *Handler, Value *PersonalityFn);
void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions);
CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB,
VisitedBlockSet &VisitedBlocks);
- CleanupHandler *findCleanupHandler(BasicBlock *StartBB, BasicBlock *EndBB);
+ void findCleanupHandlers(LandingPadActions &Actions, BasicBlock *StartBB,
+ BasicBlock *EndBB);
+
+ void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB);
+ Triple TheTriple;
+
+ // All fields are reset by runOnFunction.
+ DominatorTree *DT = nullptr;
+ EHPersonality Personality = EHPersonality::Unknown;
CatchHandlerMapTy CatchHandlerMap;
CleanupHandlerMapTy CleanupHandlerMap;
- DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps;
+ DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps;
+
+ // This maps landing pad instructions found in outlined handlers to
+ // the landing pad instruction in the parent function from which they
+ // were cloned. The cloned/nested landing pad is used as the key
+ // because the landing pad may be cloned into multiple handlers.
+ // This map will be used to add the llvm.eh.actions call to the nested
+ // landing pads after all handlers have been outlined.
+ DenseMap<LandingPadInst *, const LandingPadInst *> NestedLPtoOriginalLP;
+
+ // This maps blocks in the parent function which are destinations of
+ // catch handlers to cloned blocks in (other) outlined handlers. This
+ // handles the case where a nested landing pads has a catch handler that
+ // returns to a handler function rather than the parent function.
+ // The original block is used as the key here because there should only
+ // ever be one handler function from which the cloned block is not pruned.
+ // The original block will be pruned from the parent function after all
+ // handlers have been outlined. This map will be used to adjust the
+ // return instructions of handlers which return to the block that was
+ // outlined into a handler. This is done after all handlers have been
+ // 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
+ // 32-bit EH.
+ DenseMap<Function *, Value *> HandlerToParentFP;
+
+ AllocaInst *SEHExceptionCodeSlot = nullptr;
};
class WinEHFrameVariableMaterializer : public ValueMaterializer {
public:
- WinEHFrameVariableMaterializer(Function *OutlinedFn,
+ WinEHFrameVariableMaterializer(Function *OutlinedFn, Value *ParentFP,
FrameVarInfoMap &FrameVarInfo);
- ~WinEHFrameVariableMaterializer() {}
+ ~WinEHFrameVariableMaterializer() override {}
+
+ Value *materializeValueFor(Value *V) override;
- virtual Value *materializeValueFor(Value *V) override;
+ void escapeCatchObject(Value *V);
private:
FrameVarInfoMap &FrameVarInfo;
bool isInitialized() { return OriginLPad != nullptr; }
- bool mapIfEHPtrLoad(const LoadInst *Load) {
- return mapIfEHLoad(Load, EHPtrStores, EHPtrStoreAddrs);
- }
- bool mapIfSelectorLoad(const LoadInst *Load) {
- return mapIfEHLoad(Load, SelectorStores, SelectorStoreAddrs);
- }
-
+ bool isOriginLandingPadBlock(const BasicBlock *BB) const;
bool isLandingPadSpecificInst(const Instruction *Inst) const;
- void remapSelector(ValueToValueMapTy &VMap, Value *MappedValue) const;
+ void remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
+ Value *SelectorValue) const;
private:
- bool mapIfEHLoad(const LoadInst *Load,
- SmallVectorImpl<const StoreInst *> &Stores,
- SmallVectorImpl<const Value *> &StoreAddrs);
-
const LandingPadInst *OriginLPad;
// We will normally only see one of each of these instructions, but
// if more than one occurs for some reason we can handle that.
TinyPtrVector<const ExtractValueInst *> ExtractedEHPtrs;
TinyPtrVector<const ExtractValueInst *> ExtractedSelectors;
-
- // In optimized code, there will typically be at most one instance of
- // each of the following, but in unoptimized IR it is not uncommon
- // for the values to be stored, loaded and then stored again. In that
- // case we will create a second entry for each store and store address.
- SmallVector<const StoreInst *, 2> EHPtrStores;
- SmallVector<const StoreInst *, 2> SelectorStores;
- SmallVector<const Value *, 2> EHPtrStoreAddrs;
- SmallVector<const Value *, 2> SelectorStoreAddrs;
};
class WinEHCloningDirectorBase : public CloningDirector {
public:
- WinEHCloningDirectorBase(Function *HandlerFn,
- FrameVarInfoMap &VarInfo,
- LandingPadMap &LPadMap)
- : Materializer(HandlerFn, VarInfo),
+ WinEHCloningDirectorBase(Function *HandlerFn, Value *ParentFP,
+ FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
+ : Materializer(HandlerFn, ParentFP, VarInfo),
SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())),
Int8PtrType(Type::getInt8PtrTy(HandlerFn->getContext())),
- LPadMap(LPadMap) {}
+ LPadMap(LPadMap), ParentFP(ParentFP) {}
CloningAction handleInstruction(ValueToValueMapTy &VMap,
const Instruction *Inst,
virtual CloningAction handleResume(ValueToValueMapTy &VMap,
const ResumeInst *Resume,
BasicBlock *NewBB) = 0;
+ virtual CloningAction handleCompare(ValueToValueMapTy &VMap,
+ const CmpInst *Compare,
+ BasicBlock *NewBB) = 0;
+ virtual CloningAction handleLandingPad(ValueToValueMapTy &VMap,
+ const LandingPadInst *LPad,
+ BasicBlock *NewBB) = 0;
ValueMaterializer *getValueMaterializer() override { return &Materializer; }
Type *SelectorIDType;
Type *Int8PtrType;
LandingPadMap &LPadMap;
+
+ /// The value representing the parent frame pointer.
+ Value *ParentFP;
};
class WinEHCatchDirector : public WinEHCloningDirectorBase {
public:
- WinEHCatchDirector(Function *CatchFn, Value *Selector,
- FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
- : WinEHCloningDirectorBase(CatchFn, VarInfo, LPadMap),
+ WinEHCatchDirector(
+ Function *CatchFn, Value *ParentFP, Value *Selector,
+ FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap,
+ DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads)
+ : WinEHCloningDirectorBase(CatchFn, ParentFP, VarInfo, LPadMap),
CurrentSelector(Selector->stripPointerCasts()),
- ExceptionObjectVar(nullptr) {}
+ ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads) {}
CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
const Instruction *Inst,
BasicBlock *NewBB) override;
CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
BasicBlock *NewBB) override;
+ CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare,
+ BasicBlock *NewBB) override;
+ CloningAction handleLandingPad(ValueToValueMapTy &VMap,
+ const LandingPadInst *LPad,
+ BasicBlock *NewBB) override;
- const Value *getExceptionVar() { return ExceptionObjectVar; }
+ Value *getExceptionVar() { return ExceptionObjectVar; }
TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; }
private:
Value *CurrentSelector;
- const Value *ExceptionObjectVar;
+ Value *ExceptionObjectVar;
TinyPtrVector<BasicBlock *> ReturnTargets;
+
+ // This will be a reference to the field of the same name in the WinEHPrepare
+ // object which instantiates this WinEHCatchDirector object.
+ DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPtoOriginalLP;
};
class WinEHCleanupDirector : public WinEHCloningDirectorBase {
public:
- WinEHCleanupDirector(Function *CleanupFn,
+ WinEHCleanupDirector(Function *CleanupFn, Value *ParentFP,
FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
- : WinEHCloningDirectorBase(CleanupFn, VarInfo, LPadMap) {}
+ : WinEHCloningDirectorBase(CleanupFn, ParentFP, VarInfo,
+ LPadMap) {}
CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
const Instruction *Inst,
BasicBlock *NewBB) override;
CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
BasicBlock *NewBB) override;
-};
-
-class ActionHandler {
-public:
- ActionHandler(BasicBlock *BB, ActionType Type)
- : StartBB(BB), Type(Type), OutlinedFn(nullptr) {}
-
- ActionType getType() const { return Type; }
- BasicBlock *getStartBlock() const { return StartBB; }
-
- bool hasBeenOutlined() { return OutlinedFn != nullptr; }
-
- void setOutlinedFunction(Function *F) { OutlinedFn = F; }
- Function *getOutlinedFunction() { return OutlinedFn; }
-
-private:
- BasicBlock *StartBB;
- ActionType Type;
- Function *OutlinedFn;
-};
-
-class CatchHandler : public ActionHandler {
-public:
- CatchHandler(BasicBlock *BB, Constant *Selector, BasicBlock *NextBB)
- : ActionHandler(BB, ActionType::Catch), Selector(Selector),
- NextBB(NextBB), ExceptionObjectVar(nullptr) {}
-
- // Method for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const ActionHandler *H) {
- return H->getType() == ActionType::Catch;
- }
-
- Constant *getSelector() const { return Selector; }
- BasicBlock *getNextBB() const { return NextBB; }
-
- const Value *getExceptionVar() { return ExceptionObjectVar; }
- TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; }
-
- void setExceptionVar(const Value *Val) { ExceptionObjectVar = Val; }
- void setReturnTargets(TinyPtrVector<BasicBlock *> &Targets) {
- ReturnTargets = Targets;
- }
-
-private:
- Constant *Selector;
- BasicBlock *NextBB;
- const Value *ExceptionObjectVar;
- TinyPtrVector<BasicBlock *> ReturnTargets;
-};
-
-class CleanupHandler : public ActionHandler {
-public:
- CleanupHandler(BasicBlock *BB) : ActionHandler(BB, ActionType::Cleanup) {}
-
- // Method for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const ActionHandler *H) {
- return H->getType() == ActionType::Cleanup;
- }
+ CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare,
+ BasicBlock *NewBB) override;
+ CloningAction handleLandingPad(ValueToValueMapTy &VMap,
+ const LandingPadInst *LPad,
+ BasicBlock *NewBB) override;
};
class LandingPadActions {
bool includesCleanup() const { return HasCleanupHandlers; }
+ SmallVectorImpl<ActionHandler *> &actions() { return Actions; }
SmallVectorImpl<ActionHandler *>::iterator begin() { return Actions.begin(); }
SmallVectorImpl<ActionHandler *>::iterator end() { return Actions.end(); }
}
bool WinEHPrepare::runOnFunction(Function &Fn) {
+ // No need to prepare outlined handlers.
+ if (Fn.hasFnAttribute("wineh-parent"))
+ return false;
+
SmallVector<LandingPadInst *, 4> LPads;
SmallVector<ResumeInst *, 4> Resumes;
for (BasicBlock &BB : Fn) {
return false;
// Classify the personality to see what kind of preparation we need.
- EHPersonality Pers = classifyEHPersonality(LPads.back()->getPersonalityFn());
+ Personality = classifyEHPersonality(LPads.back()->getPersonalityFn());
// Do nothing if this is not an MSVC personality.
- if (!isMSVCEHPersonality(Pers))
+ if (!isMSVCEHPersonality(Personality))
return false;
- // FIXME: This only returns true if the C++ EH handlers were outlined.
- // When that code is complete, it should always return whatever
- // prepareCPPEHHandlers returns.
- if (Pers == EHPersonality::MSVC_CXX && prepareCPPEHHandlers(Fn, LPads))
- return true;
+ DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
- // FIXME: SEH Cleanups are unimplemented. Replace them with unreachable.
- if (Resumes.empty())
- return false;
+ // If there were any landing pads, prepareExceptionHandlers will make changes.
+ prepareExceptionHandlers(Fn, LPads);
+ return true;
+}
+
+bool WinEHPrepare::doFinalization(Module &M) { return false; }
+
+void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<DominatorTreeWrapperPass>();
+}
+
+static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
+ Constant *&Selector, BasicBlock *&NextBB);
+
+// Finds blocks reachable from the starting set Worklist. Does not follow unwind
+// edges or blocks listed in StopPoints.
+static void findReachableBlocks(SmallPtrSetImpl<BasicBlock *> &ReachableBBs,
+ SetVector<BasicBlock *> &Worklist,
+ const SetVector<BasicBlock *> *StopPoints) {
+ while (!Worklist.empty()) {
+ BasicBlock *BB = Worklist.pop_back_val();
+
+ // Don't cross blocks that we should stop at.
+ if (StopPoints && StopPoints->count(BB))
+ continue;
+
+ if (!ReachableBBs.insert(BB).second)
+ continue; // Already visited.
+
+ // Don't follow unwind edges of invokes.
+ if (auto *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
+ Worklist.insert(II->getNormalDest());
+ continue;
+ }
- for (ResumeInst *Resume : Resumes) {
- IRBuilder<>(Resume).CreateUnreachable();
- Resume->eraseFromParent();
+ // Otherwise, follow all successors.
+ Worklist.insert(succ_begin(BB), succ_end(BB));
}
+}
- return true;
+// Attempt to find an instruction where a block can be split before
+// a call to llvm.eh.begincatch and its operands. If the block
+// begins with the begincatch call or one of its adjacent operands
+// the block will not be split.
+static Instruction *findBeginCatchSplitPoint(BasicBlock *BB,
+ IntrinsicInst *II) {
+ // If the begincatch call is already the first instruction in the block,
+ // don't split.
+ Instruction *FirstNonPHI = BB->getFirstNonPHI();
+ if (II == FirstNonPHI)
+ return nullptr;
+
+ // If either operand is in the same basic block as the instruction and
+ // isn't used by another instruction before the begincatch call, include it
+ // in the split block.
+ auto *Op0 = dyn_cast<Instruction>(II->getOperand(0));
+ auto *Op1 = dyn_cast<Instruction>(II->getOperand(1));
+
+ Instruction *I = II->getPrevNode();
+ Instruction *LastI = II;
+
+ while (I == Op0 || I == Op1) {
+ // If the block begins with one of the operands and there are no other
+ // instructions between the operand and the begincatch call, don't split.
+ if (I == FirstNonPHI)
+ return nullptr;
+
+ LastI = I;
+ I = I->getPrevNode();
+ }
+
+ // If there is at least one instruction in the block before the begincatch
+ // call and its operands, split the block at either the begincatch or
+ // its operand.
+ return LastI;
}
-bool WinEHPrepare::doFinalization(Module &M) {
- return false;
+/// Find all points where exceptional control rejoins normal control flow via
+/// llvm.eh.endcatch. Add them to the normal bb reachability worklist.
+void WinEHPrepare::findCXXEHReturnPoints(
+ Function &F, SetVector<BasicBlock *> &EHReturnBlocks) {
+ for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
+ BasicBlock *BB = BBI;
+ for (Instruction &I : *BB) {
+ if (match(&I, m_Intrinsic<Intrinsic::eh_begincatch>())) {
+ Instruction *SplitPt =
+ findBeginCatchSplitPoint(BB, cast<IntrinsicInst>(&I));
+ if (SplitPt) {
+ // Split the block before the llvm.eh.begincatch call to allow
+ // cleanup and catch code to be distinguished later.
+ // Do not update BBI because we still need to process the
+ // portion of the block that we are splitting off.
+ SplitBlock(BB, SplitPt, DT);
+ break;
+ }
+ }
+ if (match(&I, m_Intrinsic<Intrinsic::eh_endcatch>())) {
+ // Split the block after the call to llvm.eh.endcatch if there is
+ // anything other than an unconditional branch, or if the successor
+ // starts with a phi.
+ auto *Br = dyn_cast<BranchInst>(I.getNextNode());
+ if (!Br || !Br->isUnconditional() ||
+ isa<PHINode>(Br->getSuccessor(0)->begin())) {
+ DEBUG(dbgs() << "splitting block " << BB->getName()
+ << " with llvm.eh.endcatch\n");
+ BBI = SplitBlock(BB, I.getNextNode(), DT);
+ }
+ // The next BB is normal control flow.
+ EHReturnBlocks.insert(BB->getTerminator()->getSuccessor(0));
+ break;
+ }
+ }
+ }
}
-void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {}
+static bool isCatchAllLandingPad(const BasicBlock *BB) {
+ const LandingPadInst *LP = BB->getLandingPadInst();
+ if (!LP)
+ return false;
+ unsigned N = LP->getNumClauses();
+ return (N > 0 && LP->isCatch(N - 1) &&
+ isa<ConstantPointerNull>(LP->getClause(N - 1)));
+}
+
+/// Find all points where exceptions control rejoins normal control flow via
+/// selector dispatch.
+void WinEHPrepare::findSEHEHReturnPoints(
+ Function &F, SetVector<BasicBlock *> &EHReturnBlocks) {
+ for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
+ BasicBlock *BB = BBI;
+ // If the landingpad is a catch-all, treat the whole lpad as if it is
+ // reachable from normal control flow.
+ // FIXME: This is imprecise. We need a better way of identifying where a
+ // catch-all starts and cleanups stop. As far as LLVM is concerned, there
+ // is no difference.
+ if (isCatchAllLandingPad(BB)) {
+ EHReturnBlocks.insert(BB);
+ continue;
+ }
+
+ BasicBlock *CatchHandler;
+ 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())) {
+ DEBUG(dbgs() << "splitting EH return edge from " << BB->getName()
+ << " to " << CatchHandler->getName() << '\n');
+ BBI = CatchHandler = SplitCriticalEdge(
+ BB, std::find(succ_begin(BB), succ_end(BB), CatchHandler));
+ }
+ EHReturnBlocks.insert(CatchHandler);
+ }
+ }
+}
-bool WinEHPrepare::prepareCPPEHHandlers(
+/// Ensure that all values live into and out of exception handlers are stored
+/// in memory.
+/// FIXME: This falls down when values are defined in one handler and live into
+/// another handler. For example, a cleanup defines a value used only by a
+/// catch handler.
+void WinEHPrepare::demoteValuesLiveAcrossHandlers(
Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
+ DEBUG(dbgs() << "Demoting values live across exception handlers in function "
+ << F.getName() << '\n');
+
+ // Build a set of all non-exceptional blocks and exceptional blocks.
+ // - Non-exceptional blocks are blocks reachable from the entry block while
+ // not following invoke unwind edges.
+ // - Exceptional blocks are blocks reachable from landingpads. Analysis does
+ // not follow llvm.eh.endcatch blocks, which mark a transition from
+ // exceptional to normal control.
+ SmallPtrSet<BasicBlock *, 4> NormalBlocks;
+ SmallPtrSet<BasicBlock *, 4> EHBlocks;
+ SetVector<BasicBlock *> EHReturnBlocks;
+ SetVector<BasicBlock *> Worklist;
+
+ if (Personality == EHPersonality::MSVC_CXX)
+ findCXXEHReturnPoints(F, EHReturnBlocks);
+ else
+ findSEHEHReturnPoints(F, EHReturnBlocks);
+
+ DEBUG({
+ dbgs() << "identified the following blocks as EH return points:\n";
+ for (BasicBlock *BB : EHReturnBlocks)
+ dbgs() << " " << BB->getName() << '\n';
+ });
+
+// Join points should not have phis at this point, unless they are a
+// landingpad, in which case we will demote their phis later.
+#ifndef NDEBUG
+ for (BasicBlock *BB : EHReturnBlocks)
+ assert((BB->isLandingPad() || !isa<PHINode>(BB->begin())) &&
+ "non-lpad EH return block has phi");
+#endif
+
+ // Normal blocks are the blocks reachable from the entry block and all EH
+ // return points.
+ Worklist = EHReturnBlocks;
+ Worklist.insert(&F.getEntryBlock());
+ findReachableBlocks(NormalBlocks, Worklist, nullptr);
+ DEBUG({
+ dbgs() << "marked the following blocks as normal:\n";
+ for (BasicBlock *BB : NormalBlocks)
+ dbgs() << " " << BB->getName() << '\n';
+ });
+
+ // Exceptional blocks are the blocks reachable from landingpads that don't
+ // cross EH return points.
+ Worklist.clear();
+ for (auto *LPI : LPads)
+ Worklist.insert(LPI->getParent());
+ findReachableBlocks(EHBlocks, Worklist, &EHReturnBlocks);
+ DEBUG({
+ dbgs() << "marked the following blocks as exceptional:\n";
+ for (BasicBlock *BB : EHBlocks)
+ dbgs() << " " << BB->getName() << '\n';
+ });
+
+ SetVector<Argument *> ArgsToDemote;
+ SetVector<Instruction *> InstrsToDemote;
+ for (BasicBlock &BB : F) {
+ bool IsNormalBB = NormalBlocks.count(&BB);
+ bool IsEHBB = EHBlocks.count(&BB);
+ if (!IsNormalBB && !IsEHBB)
+ continue; // Blocks that are neither normal nor EH are unreachable.
+ for (Instruction &I : BB) {
+ for (Value *Op : I.operands()) {
+ // Don't demote static allocas, constants, and labels.
+ if (isa<Constant>(Op) || isa<BasicBlock>(Op) || isa<InlineAsm>(Op))
+ continue;
+ auto *AI = dyn_cast<AllocaInst>(Op);
+ if (AI && AI->isStaticAlloca())
+ continue;
+
+ if (auto *Arg = dyn_cast<Argument>(Op)) {
+ if (IsEHBB) {
+ DEBUG(dbgs() << "Demoting argument " << *Arg
+ << " used by EH instr: " << I << "\n");
+ ArgsToDemote.insert(Arg);
+ }
+ continue;
+ }
+
+ auto *OpI = cast<Instruction>(Op);
+ BasicBlock *OpBB = OpI->getParent();
+ // If a value is produced and consumed in the same BB, we don't need to
+ // demote it.
+ if (OpBB == &BB)
+ continue;
+ bool IsOpNormalBB = NormalBlocks.count(OpBB);
+ bool IsOpEHBB = EHBlocks.count(OpBB);
+ if (IsNormalBB != IsOpNormalBB || IsEHBB != IsOpEHBB) {
+ DEBUG({
+ dbgs() << "Demoting instruction live in-out from EH:\n";
+ dbgs() << "Instr: " << *OpI << '\n';
+ dbgs() << "User: " << I << '\n';
+ });
+ InstrsToDemote.insert(OpI);
+ }
+ }
+ }
+ }
+
+ // Demote values live into and out of handlers.
+ // FIXME: This demotion is inefficient. We should insert spills at the point
+ // of definition, insert one reload in each handler that uses the value, and
+ // insert reloads in the BB used to rejoin normal control flow.
+ Instruction *AllocaInsertPt = F.getEntryBlock().getFirstInsertionPt();
+ for (Instruction *I : InstrsToDemote)
+ DemoteRegToStack(*I, false, AllocaInsertPt);
+
+ // Demote arguments separately, and only for uses in EH blocks.
+ for (Argument *Arg : ArgsToDemote) {
+ auto *Slot = new AllocaInst(Arg->getType(), nullptr,
+ Arg->getName() + ".reg2mem", AllocaInsertPt);
+ SmallVector<User *, 4> Users(Arg->user_begin(), Arg->user_end());
+ for (User *U : Users) {
+ auto *I = dyn_cast<Instruction>(U);
+ if (I && EHBlocks.count(I->getParent())) {
+ auto *Reload = new LoadInst(Slot, Arg->getName() + ".reload", false, I);
+ U->replaceUsesOfWith(Arg, Reload);
+ }
+ }
+ new StoreInst(Arg, Slot, AllocaInsertPt);
+ }
+
+ // Demote landingpad phis, as the landingpad will be removed from the machine
+ // CFG.
+ for (LandingPadInst *LPI : LPads) {
+ BasicBlock *BB = LPI->getParent();
+ while (auto *Phi = dyn_cast<PHINode>(BB->begin()))
+ DemotePHIToStack(Phi, AllocaInsertPt);
+ }
+
+ DEBUG(dbgs() << "Demoted " << InstrsToDemote.size() << " instructions and "
+ << ArgsToDemote.size() << " arguments for WinEHPrepare\n\n");
+}
+
+bool WinEHPrepare::prepareExceptionHandlers(
+ Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
+ // Don't run on functions that are already prepared.
+ for (LandingPadInst *LPad : LPads) {
+ BasicBlock *LPadBB = LPad->getParent();
+ for (Instruction &Inst : *LPadBB)
+ if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>()))
+ return false;
+ }
+
+ demoteValuesLiveAcrossHandlers(F, LPads);
+
// These containers are used to re-map frame variables that are used in
// outlined catch and cleanup handlers. They will be populated as the
// handlers are outlined.
Module *M = F.getParent();
LLVMContext &Context = M->getContext();
- // FIXME: Make this an intrinsic.
// Create a new function to receive the handler contents.
PointerType *Int8PtrType = Type::getInt8PtrTy(Context);
Type *Int32Type = Type::getInt32Ty(Context);
- FunctionType *ActionTy = FunctionType::get(Int8PtrType, true);
- Value *ActionIntrin = M->getOrInsertFunction("llvm.eh.actions", ActionTy);
+ Function *ActionIntrin = Intrinsic::getDeclaration(M, Intrinsic::eh_actions);
+
+ if (isAsynchronousEHPersonality(Personality)) {
+ // FIXME: Switch the ehptr type to i32 and then switch this.
+ SEHExceptionCodeSlot =
+ new AllocaInst(Int8PtrType, nullptr, "seh_exception_code",
+ F.getEntryBlock().getFirstInsertionPt());
+ }
+
+ // This container stores the llvm.eh.recover and IndirectBr instructions
+ // that make up the body of each landing pad after it has been outlined.
+ // We need to defer the population of the target list for the indirectbr
+ // until all landing pads have been outlined so that we can handle the
+ // case of blocks in the target that are reached only from nested
+ // landing pads.
+ SmallVector<std::pair<CallInst*, IndirectBrInst *>, 4> LPadImpls;
for (LandingPadInst *LPad : LPads) {
// Look for evidence that this landingpad has already been processed.
bool LPadHasActionList = false;
BasicBlock *LPadBB = LPad->getParent();
- for (Instruction &Inst : LPadBB->getInstList()) {
- // FIXME: Make this an intrinsic.
- if (auto *Call = dyn_cast<CallInst>(&Inst)) {
- if (Call->getCalledFunction()->getName() == "llvm.eh.actions") {
- LPadHasActionList = true;
- break;
- }
- }
- // FIXME: This is here to help with the development of nested landing pad
- // outlining. It should be removed when that is finished.
- if (isa<UnreachableInst>(Inst)) {
+ for (Instruction &Inst : *LPadBB) {
+ if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>())) {
LPadHasActionList = true;
break;
}
if (LPadHasActionList)
continue;
+ // If either of the values in the aggregate returned by the landing pad is
+ // extracted and stored to memory, promote the stored value to a register.
+ promoteLandingPadValues(LPad);
+
LandingPadActions Actions;
mapLandingPadBlocks(LPad, Actions);
+ HandlersOutlined |= !Actions.actions().empty();
for (ActionHandler *Action : Actions) {
- if (Action->hasBeenOutlined())
+ if (Action->hasBeenProcessed())
continue;
BasicBlock *StartBB = Action->getStartBlock();
- if (outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo)) {
- HandlersOutlined = true;
+
+ // SEH doesn't do any outlining for catches. Instead, pass the handler
+ // basic block addr to llvm.eh.actions and list the block as a return
+ // target.
+ if (isAsynchronousEHPersonality(Personality)) {
+ if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
+ processSEHCatchHandler(CatchAction, StartBB);
+ continue;
+ }
}
- } // End for each Action
- // FIXME: We need a guard against partially outlined functions.
- if (!HandlersOutlined)
- continue;
+ outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo);
+ }
- // Replace the landing pad with a new llvm.eh.action based landing pad.
- BasicBlock *NewLPadBB = BasicBlock::Create(Context, "lpad", &F, LPadBB);
- assert(!isa<PHINode>(LPadBB->begin()));
- Instruction *NewLPad = LPad->clone();
- NewLPadBB->getInstList().push_back(NewLPad);
- while (!pred_empty(LPadBB)) {
- auto *pred = *pred_begin(LPadBB);
- InvokeInst *Invoke = cast<InvokeInst>(pred->getTerminator());
- Invoke->setUnwindDest(NewLPadBB);
+ // Split the block after the landingpad instruction so that it is just a
+ // call to llvm.eh.actions followed by indirectbr.
+ assert(!isa<PHINode>(LPadBB->begin()) && "lpad phi not removed");
+ SplitBlock(LPadBB, LPad->getNextNode(), DT);
+ // Erase the branch inserted by the split so we can insert indirectbr.
+ LPadBB->getTerminator()->eraseFromParent();
+
+ // Replace all extracted values with undef and ultimately replace the
+ // landingpad with undef.
+ SmallVector<Instruction *, 4> SEHCodeUses;
+ SmallVector<Instruction *, 4> EHUndefs;
+ for (User *U : LPad->users()) {
+ auto *E = dyn_cast<ExtractValueInst>(U);
+ if (!E)
+ continue;
+ assert(E->getNumIndices() == 1 &&
+ "Unexpected operation: extracting both landing pad values");
+ unsigned Idx = *E->idx_begin();
+ assert((Idx == 0 || Idx == 1) && "unexpected index");
+ if (Idx == 0 && isAsynchronousEHPersonality(Personality))
+ SEHCodeUses.push_back(E);
+ else
+ EHUndefs.push_back(E);
+ }
+ for (Instruction *E : EHUndefs) {
+ E->replaceAllUsesWith(UndefValue::get(E->getType()));
+ E->eraseFromParent();
+ }
+ LPad->replaceAllUsesWith(UndefValue::get(LPad->getType()));
+
+ // Rewrite uses of the exception pointer to loads of an alloca.
+ for (Instruction *E : SEHCodeUses) {
+ SmallVector<Use *, 4> Uses;
+ for (Use &U : E->uses())
+ Uses.push_back(&U);
+ for (Use *U : Uses) {
+ 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));
+ else
+ LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I);
+ U->set(LI);
+ }
+ E->replaceAllUsesWith(UndefValue::get(E->getType()));
+ E->eraseFromParent();
}
// Add a call to describe the actions for this landing pad.
std::vector<Value *> ActionArgs;
- ActionArgs.push_back(NewLPad);
for (ActionHandler *Action : Actions) {
+ // Action codes from docs are: 0 cleanup, 1 catch.
if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
- ActionArgs.push_back(ConstantInt::get(Int32Type, 0));
+ ActionArgs.push_back(ConstantInt::get(Int32Type, 1));
ActionArgs.push_back(CatchAction->getSelector());
+ // Find the frame escape index of the exception object alloca in the
+ // parent.
+ int FrameEscapeIdx = -1;
Value *EHObj = const_cast<Value *>(CatchAction->getExceptionVar());
- if (EHObj)
- ActionArgs.push_back(EHObj);
- else
- ActionArgs.push_back(ConstantPointerNull::get(Int8PtrType));
+ if (EHObj && !isa<ConstantPointerNull>(EHObj)) {
+ auto I = FrameVarInfo.find(EHObj);
+ assert(I != FrameVarInfo.end() &&
+ "failed to map llvm.eh.begincatch var");
+ FrameEscapeIdx = std::distance(FrameVarInfo.begin(), I);
+ }
+ ActionArgs.push_back(ConstantInt::get(Int32Type, FrameEscapeIdx));
} else {
- ActionArgs.push_back(ConstantInt::get(Int32Type, 1));
+ ActionArgs.push_back(ConstantInt::get(Int32Type, 0));
}
- Constant *HandlerPtr =
- ConstantExpr::getBitCast(Action->getOutlinedFunction(), Int8PtrType);
- ActionArgs.push_back(HandlerPtr);
+ ActionArgs.push_back(Action->getHandlerBlockOrFunc());
}
CallInst *Recover =
- CallInst::Create(ActionIntrin, ActionArgs, "recover", NewLPadBB);
-
- // Add an indirect branch listing possible successors of the catch handlers.
- IndirectBrInst *Branch = IndirectBrInst::Create(Recover, 0, NewLPadBB);
- for (ActionHandler *Action : Actions) {
- if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
- for (auto *Target : CatchAction->getReturnTargets()) {
- Branch->addDestination(Target);
+ CallInst::Create(ActionIntrin, ActionArgs, "recover", LPadBB);
+
+ if (isAsynchronousEHPersonality(Personality)) {
+ // SEH can create the target list directly, since catch handlers
+ // are not outlined.
+ SetVector<BasicBlock *> ReturnTargets;
+ for (ActionHandler *Action : Actions) {
+ if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
+ const auto &CatchTargets = CatchAction->getReturnTargets();
+ ReturnTargets.insert(CatchTargets.begin(), CatchTargets.end());
}
}
+ IndirectBrInst *Branch =
+ IndirectBrInst::Create(Recover, ReturnTargets.size(), LPadBB);
+ for (BasicBlock *Target : ReturnTargets)
+ Branch->addDestination(Target);
+ } else {
+ // C++ EH must defer populating the targets to handle the case of
+ // targets that are reached indirectly through nested landing pads.
+ IndirectBrInst *Branch =
+ IndirectBrInst::Create(Recover, 0, LPadBB);
+
+ LPadImpls.push_back(std::make_pair(Recover, Branch));
}
} // End for each landingpad
if (!HandlersOutlined)
return false;
+ // Replace any nested landing pad stubs with the correct action handler.
+ // This must be done before we remove unreachable blocks because it
+ // cleans up references to outlined blocks that will be deleted.
+ for (auto &LPadPair : NestedLPtoOriginalLP)
+ completeNestedLandingPad(&F, LPadPair.first, LPadPair.second, FrameVarInfo);
+ NestedLPtoOriginalLP.clear();
+
+ // Populate the indirectbr instructions' target lists if we deferred
+ // doing so above.
+ SetVector<BasicBlock*> CheckedTargets;
+ SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
+ for (auto &LPadImplPair : LPadImpls) {
+ IntrinsicInst *Recover = cast<IntrinsicInst>(LPadImplPair.first);
+ IndirectBrInst *Branch = LPadImplPair.second;
+
+ // Get a list of handlers called by
+ parseEHActions(Recover, ActionList);
+
+ // Add an indirect branch listing possible successors of the catch handlers.
+ SetVector<BasicBlock *> ReturnTargets;
+ for (const auto &Action : ActionList) {
+ if (auto *CA = dyn_cast<CatchHandler>(Action.get())) {
+ Function *Handler = cast<Function>(CA->getHandlerBlockOrFunc());
+ getPossibleReturnTargets(&F, Handler, ReturnTargets);
+ }
+ }
+ ActionList.clear();
+ for (BasicBlock *Target : ReturnTargets) {
+ Branch->addDestination(Target);
+ // The target may be a block that we excepted to get pruned.
+ // If it is, it may contain a call to llvm.eh.endcatch.
+ if (CheckedTargets.insert(Target)) {
+ // Earlier preparations guarantee that all calls to llvm.eh.endcatch
+ // will be followed by an unconditional branch.
+ auto *Br = dyn_cast<BranchInst>(Target->getTerminator());
+ if (Br && Br->isUnconditional() &&
+ Br != Target->getFirstNonPHIOrDbgOrLifetime()) {
+ Instruction *Prev = Br->getPrevNode();
+ if (match(cast<Value>(Prev), m_Intrinsic<Intrinsic::eh_endcatch>()))
+ Prev->eraseFromParent();
+ }
+ }
+ }
+ }
+ LPadImpls.clear();
+
+ F.addFnAttr("wineh-parent", F.getName());
+
// Delete any blocks that were only used by handlers that were outlined above.
removeUnreachableBlocks(F);
Intrinsic::getDeclaration(M, Intrinsic::frameescape);
Function *RecoverFrameFn =
Intrinsic::getDeclaration(M, Intrinsic::framerecover);
+ SmallVector<Value *, 8> AllocasToEscape;
+
+ // Scan the entry block for an existing call to llvm.frameescape. We need to
+ // keep escaping those objects.
+ for (Instruction &I : F.front()) {
+ auto *II = dyn_cast<IntrinsicInst>(&I);
+ if (II && II->getIntrinsicID() == Intrinsic::frameescape) {
+ auto Args = II->arg_operands();
+ AllocasToEscape.append(Args.begin(), Args.end());
+ II->eraseFromParent();
+ break;
+ }
+ }
// Finally, replace all of the temporary allocas for frame variables used in
// the outlined handlers with calls to llvm.framerecover.
- BasicBlock::iterator II = Entry->getFirstInsertionPt();
- Instruction *AllocaInsertPt = II;
- SmallVector<Value *, 8> AllocasToEscape;
for (auto &VarInfoEntry : FrameVarInfo) {
Value *ParentVal = VarInfoEntry.first;
TinyPtrVector<AllocaInst *> &Allocas = VarInfoEntry.second;
+ AllocaInst *ParentAlloca = cast<AllocaInst>(ParentVal);
- // If the mapped value isn't already an alloca, we need to spill it if it
- // is a computed value or copy it if it is an argument.
- AllocaInst *ParentAlloca = dyn_cast<AllocaInst>(ParentVal);
- if (!ParentAlloca) {
- if (auto *Arg = dyn_cast<Argument>(ParentVal)) {
- // Lower this argument to a copy and then demote that to the stack.
- // We can't just use the argument location because the handler needs
- // it to be in the frame allocation block.
- // Use 'select i8 true, %arg, undef' to simulate a 'no-op' instruction.
- Value *TrueValue = ConstantInt::getTrue(Context);
- Value *UndefValue = UndefValue::get(Arg->getType());
- Instruction *SI =
- SelectInst::Create(TrueValue, Arg, UndefValue,
- Arg->getName() + ".tmp", AllocaInsertPt);
- Arg->replaceAllUsesWith(SI);
- // Reset the select operand, because it was clobbered by the RAUW above.
- SI->setOperand(1, Arg);
- ParentAlloca = DemoteRegToStack(*SI, true, SI);
- } else if (auto *PN = dyn_cast<PHINode>(ParentVal)) {
- ParentAlloca = DemotePHIToStack(PN, AllocaInsertPt);
- } else {
- Instruction *ParentInst = cast<Instruction>(ParentVal);
- // FIXME: This is a work-around to temporarily handle the case where an
- // instruction that is only used in handlers is not sunk.
- // Without uses, DemoteRegToStack would just eliminate the value.
- // This will fail if ParentInst is an invoke.
- if (ParentInst->getNumUses() == 0) {
- BasicBlock::iterator InsertPt = ParentInst;
- ++InsertPt;
- ParentAlloca =
- new AllocaInst(ParentInst->getType(), nullptr,
- ParentInst->getName() + ".reg2mem", InsertPt);
- new StoreInst(ParentInst, ParentAlloca, InsertPt);
- } else {
- ParentAlloca = DemoteRegToStack(*ParentInst, true, ParentInst);
- }
- }
- }
-
- // If the parent alloca is no longer used and only one of the handlers used
- // it, erase the parent and leave the copy in the outlined handler.
- if (ParentAlloca->getNumUses() == 0 && Allocas.size() == 1) {
- ParentAlloca->eraseFromParent();
- continue;
- }
+ // FIXME: We should try to sink unescaped allocas from the parent frame into
+ // the child frame. If the alloca is escaped, we have to use the lifetime
+ // markers to ensure that the alloca is only live within the child frame.
// Add this alloca to the list of things to escape.
AllocasToEscape.push_back(ParentAlloca);
// Next replace all outlined allocas that are mapped to it.
for (AllocaInst *TempAlloca : Allocas) {
+ if (TempAlloca == getCatchObjectSentinel())
+ continue; // Skip catch parameter sentinels.
Function *HandlerFn = TempAlloca->getParent()->getParent();
- // FIXME: Sink this GEP into the blocks where it is used.
+ llvm::Value *FP = HandlerToParentFP[HandlerFn];
+ assert(FP);
+
+ // FIXME: Sink this framerecover into the blocks where it is used.
Builder.SetInsertPoint(TempAlloca);
Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc());
Value *RecoverArgs[] = {
- Builder.CreateBitCast(&F, Int8PtrType, ""),
- &(HandlerFn->getArgumentList().back()),
+ Builder.CreateBitCast(&F, Int8PtrType, ""), FP,
llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)};
- Value *RecoveredAlloca = Builder.CreateCall(RecoverFrameFn, RecoverArgs);
+ Instruction *RecoveredAlloca =
+ Builder.CreateCall(RecoverFrameFn, RecoverArgs);
+
// Add a pointer bitcast if the alloca wasn't an i8.
if (RecoveredAlloca->getType() != TempAlloca->getType()) {
RecoveredAlloca->setName(Twine(TempAlloca->getName()) + ".i8");
- RecoveredAlloca =
- Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType());
+ RecoveredAlloca = cast<Instruction>(
+ Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType()));
}
TempAlloca->replaceAllUsesWith(RecoveredAlloca);
TempAlloca->removeFromParent();
Builder.SetInsertPoint(&F.getEntryBlock().back());
Builder.CreateCall(FrameEscapeFn, AllocasToEscape);
+ if (SEHExceptionCodeSlot) {
+ if (SEHExceptionCodeSlot->hasNUses(0))
+ SEHExceptionCodeSlot->eraseFromParent();
+ else if (isAllocaPromotable(SEHExceptionCodeSlot))
+ PromoteMemToReg(SEHExceptionCodeSlot, *DT);
+ }
+
// Clean up the handler action maps we created for this function
DeleteContainerSeconds(CatchHandlerMap);
CatchHandlerMap.clear();
DeleteContainerSeconds(CleanupHandlerMap);
CleanupHandlerMap.clear();
+ HandlerToParentFP.clear();
+ DT = nullptr;
+ SEHExceptionCodeSlot = nullptr;
return HandlersOutlined;
}
+void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) {
+ // If the return values of the landing pad instruction are extracted and
+ // stored to memory, we want to promote the store locations to reg values.
+ SmallVector<AllocaInst *, 2> EHAllocas;
+
+ // The landingpad instruction returns an aggregate value. Typically, its
+ // value will be passed to a pair of extract value instructions and the
+ // results of those extracts are often passed to store instructions.
+ // In unoptimized code the stored value will often be loaded and then stored
+ // again.
+ for (auto *U : LPad->users()) {
+ ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
+ if (!Extract)
+ continue;
+
+ for (auto *EU : Extract->users()) {
+ if (auto *Store = dyn_cast<StoreInst>(EU)) {
+ auto *AV = cast<AllocaInst>(Store->getPointerOperand());
+ EHAllocas.push_back(AV);
+ }
+ }
+ }
+
+ // We can't do this without a dominator tree.
+ assert(DT);
+
+ if (!EHAllocas.empty()) {
+ PromoteMemToReg(EHAllocas, *DT);
+ EHAllocas.clear();
+ }
+
+ // After promotion, some extracts may be trivially dead. Remove them.
+ SmallVector<Value *, 4> Users(LPad->user_begin(), LPad->user_end());
+ for (auto *U : Users)
+ RecursivelyDeleteTriviallyDeadInstructions(U);
+}
+
+void WinEHPrepare::getPossibleReturnTargets(Function *ParentF,
+ Function *HandlerF,
+ SetVector<BasicBlock*> &Targets) {
+ for (BasicBlock &BB : *HandlerF) {
+ // If the handler contains landing pads, check for any
+ // handlers that may return directly to a block in the
+ // parent function.
+ if (auto *LPI = BB.getLandingPadInst()) {
+ IntrinsicInst *Recover = cast<IntrinsicInst>(LPI->getNextNode());
+ SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
+ parseEHActions(Recover, ActionList);
+ for (const auto &Action : ActionList) {
+ if (auto *CH = dyn_cast<CatchHandler>(Action.get())) {
+ Function *NestedF = cast<Function>(CH->getHandlerBlockOrFunc());
+ getPossibleReturnTargets(ParentF, NestedF, Targets);
+ }
+ }
+ }
+
+ auto *Ret = dyn_cast<ReturnInst>(BB.getTerminator());
+ if (!Ret)
+ continue;
+
+ // Handler functions must always return a block address.
+ BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue());
+
+ // If this is the handler for a nested landing pad, the
+ // return address may have been remapped to a block in the
+ // parent handler. We're not interested in those.
+ if (BA->getFunction() != ParentF)
+ continue;
+
+ Targets.insert(BA->getBasicBlock());
+ }
+}
+
+void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
+ LandingPadInst *OutlinedLPad,
+ const LandingPadInst *OriginalLPad,
+ FrameVarInfoMap &FrameVarInfo) {
+ // Get the nested block and erase the unreachable instruction that was
+ // temporarily inserted as its terminator.
+ LLVMContext &Context = ParentFn->getContext();
+ BasicBlock *OutlinedBB = OutlinedLPad->getParent();
+ assert(isa<UnreachableInst>(OutlinedBB->getTerminator()));
+ OutlinedBB->getTerminator()->eraseFromParent();
+ // That should leave OutlinedLPad as the last instruction in its block.
+ assert(&OutlinedBB->back() == OutlinedLPad);
+
+ // The original landing pad will have already had its action intrinsic
+ // built by the outlining loop. We need to clone that into the outlined
+ // location. It may also be necessary to add references to the exception
+ // variables to the outlined handler in which this landing pad is nested
+ // and remap return instructions in the nested handlers that should return
+ // to an address in the outlined handler.
+ Function *OutlinedHandlerFn = OutlinedBB->getParent();
+ BasicBlock::const_iterator II = OriginalLPad;
+ ++II;
+ // The instruction after the landing pad should now be a call to eh.actions.
+ const Instruction *Recover = II;
+ assert(match(Recover, m_Intrinsic<Intrinsic::eh_actions>()));
+ IntrinsicInst *EHActions = cast<IntrinsicInst>(Recover->clone());
+
+ // Remap the exception variables into the outlined function.
+ SmallVector<BlockAddress *, 4> ActionTargets;
+ SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
+ parseEHActions(EHActions, ActionList);
+ for (const auto &Action : ActionList) {
+ auto *Catch = dyn_cast<CatchHandler>(Action.get());
+ if (!Catch)
+ continue;
+ // The dyn_cast to function here selects C++ catch handlers and skips
+ // SEH catch handlers.
+ auto *Handler = dyn_cast<Function>(Catch->getHandlerBlockOrFunc());
+ if (!Handler)
+ continue;
+ // Visit all the return instructions, looking for places that return
+ // to a location within OutlinedHandlerFn.
+ for (BasicBlock &NestedHandlerBB : *Handler) {
+ auto *Ret = dyn_cast<ReturnInst>(NestedHandlerBB.getTerminator());
+ if (!Ret)
+ continue;
+
+ // Handler functions must always return a block address.
+ BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue());
+ // The original target will have been in the main parent function,
+ // but if it is the address of a block that has been outlined, it
+ // should be a block that was outlined into OutlinedHandlerFn.
+ assert(BA->getFunction() == ParentFn);
+
+ // Ignore targets that aren't part of OutlinedHandlerFn.
+ if (!LPadTargetBlocks.count(BA->getBasicBlock()))
+ continue;
+
+ // If the return value is the address ofF a block that we
+ // previously outlined into the parent handler function, replace
+ // the return instruction and add the mapped target to the list
+ // of possible return addresses.
+ BasicBlock *MappedBB = LPadTargetBlocks[BA->getBasicBlock()];
+ assert(MappedBB->getParent() == OutlinedHandlerFn);
+ BlockAddress *NewBA = BlockAddress::get(OutlinedHandlerFn, MappedBB);
+ Ret->eraseFromParent();
+ ReturnInst::Create(Context, NewBA, &NestedHandlerBB);
+ ActionTargets.push_back(NewBA);
+ }
+ }
+ ActionList.clear();
+ OutlinedBB->getInstList().push_back(EHActions);
+
+ // Insert an indirect branch into the outlined landing pad BB.
+ IndirectBrInst *IBr = IndirectBrInst::Create(EHActions, 0, OutlinedBB);
+ // Add the previously collected action targets.
+ for (auto *Target : ActionTargets)
+ IBr->addDestination(Target->getBasicBlock());
+}
+
// This function examines a block to determine whether the block ends with a
// conditional branch to a catch handler based on a selector comparison.
// This function is used both by the WinEHPrepare::findSelectorComparison() and
return false;
}
+static bool isCatchBlock(BasicBlock *BB) {
+ for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
+ II != IE; ++II) {
+ if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_begincatch>()))
+ return true;
+ }
+ return false;
+}
+
+static BasicBlock *createStubLandingPad(Function *Handler,
+ Value *PersonalityFn) {
+ // FIXME: Finish this!
+ LLVMContext &Context = Handler->getContext();
+ BasicBlock *StubBB = BasicBlock::Create(Context, "stub");
+ Handler->getBasicBlockList().push_back(StubBB);
+ IRBuilder<> Builder(StubBB);
+ LandingPadInst *LPad = Builder.CreateLandingPad(
+ llvm::StructType::get(Type::getInt8PtrTy(Context),
+ Type::getInt32Ty(Context), nullptr),
+ PersonalityFn, 0);
+ // Insert a call to llvm.eh.actions so that we don't try to outline this lpad.
+ Function *ActionIntrin =
+ Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::eh_actions);
+ Builder.CreateCall(ActionIntrin, {}, "recover");
+ LPad->setCleanup(true);
+ Builder.CreateUnreachable();
+ return StubBB;
+}
+
+// Cycles through the blocks in an outlined handler function looking for an
+// invoke instruction and inserts an invoke of llvm.donothing with an empty
+// landing pad if none is found. The code that generates the .xdata tables for
+// the handler needs at least one landing pad to identify the parent function's
+// personality.
+void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler,
+ Value *PersonalityFn) {
+ ReturnInst *Ret = nullptr;
+ UnreachableInst *Unreached = nullptr;
+ for (BasicBlock &BB : *Handler) {
+ TerminatorInst *Terminator = BB.getTerminator();
+ // If we find an invoke, there is nothing to be done.
+ auto *II = dyn_cast<InvokeInst>(Terminator);
+ if (II)
+ return;
+ // If we've already recorded a return instruction, keep looking for invokes.
+ if (!Ret)
+ Ret = dyn_cast<ReturnInst>(Terminator);
+ // If we haven't recorded an unreachable instruction, try this terminator.
+ if (!Unreached)
+ Unreached = dyn_cast<UnreachableInst>(Terminator);
+ }
+
+ // If we got this far, the handler contains no invokes. We should have seen
+ // at least one return or unreachable instruction. We'll insert an invoke of
+ // llvm.donothing ahead of that instruction.
+ assert(Ret || Unreached);
+ TerminatorInst *Term;
+ if (Ret)
+ Term = Ret;
+ else
+ Term = Unreached;
+ BasicBlock *OldRetBB = Term->getParent();
+ BasicBlock *NewRetBB = SplitBlock(OldRetBB, Term, DT);
+ // SplitBlock adds an unconditional branch instruction at the end of the
+ // parent block. We want to replace that with an invoke call, so we can
+ // erase it now.
+ OldRetBB->getTerminator()->eraseFromParent();
+ BasicBlock *StubLandingPad = createStubLandingPad(Handler, PersonalityFn);
+ Function *F =
+ Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::donothing);
+ InvokeInst::Create(F, NewRetBB, StubLandingPad, None, "", OldRetBB);
+}
+
+// FIXME: Consider sinking this into lib/Target/X86 somehow. TargetLowering
+// usually doesn't build LLVM IR, so that's probably the wrong place.
+Function *WinEHPrepare::createHandlerFunc(Type *RetTy, const Twine &Name,
+ Module *M, Value *&ParentFP) {
+ // x64 uses a two-argument prototype where the parent FP is the second
+ // argument. x86 uses no arguments, just the incoming EBP value.
+ LLVMContext &Context = M->getContext();
+ FunctionType *FnType;
+ if (TheTriple.getArch() == Triple::x86_64) {
+ Type *Int8PtrType = Type::getInt8PtrTy(Context);
+ Type *ArgTys[2] = {Int8PtrType, Int8PtrType};
+ FnType = FunctionType::get(RetTy, ArgTys, false);
+ } else {
+ FnType = FunctionType::get(RetTy, None, false);
+ }
+
+ Function *Handler =
+ Function::Create(FnType, GlobalVariable::InternalLinkage, Name, M);
+ BasicBlock *Entry = BasicBlock::Create(Context, "entry");
+ Handler->getBasicBlockList().push_front(Entry);
+ if (TheTriple.getArch() == Triple::x86_64) {
+ ParentFP = &(Handler->getArgumentList().back());
+ } else {
+ assert(M);
+ Function *FrameAddressFn =
+ Intrinsic::getDeclaration(M, Intrinsic::frameaddress);
+ Value *Args[1] = {ConstantInt::get(Type::getInt32Ty(Context), 1)};
+ ParentFP = CallInst::Create(FrameAddressFn, Args, "parent_fp",
+ &Handler->getEntryBlock());
+ }
+ return Handler;
+}
+
bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
LandingPadInst *LPad, BasicBlock *StartBB,
FrameVarInfoMap &VarInfo) {
Module *M = SrcFn->getParent();
LLVMContext &Context = M->getContext();
+ Type *Int8PtrType = Type::getInt8PtrTy(Context);
// Create a new function to receive the handler contents.
- Type *Int8PtrType = Type::getInt8PtrTy(Context);
- std::vector<Type *> ArgTys;
- ArgTys.push_back(Int8PtrType);
- ArgTys.push_back(Int8PtrType);
+ Value *ParentFP;
Function *Handler;
if (Action->getType() == Catch) {
- FunctionType *FnType = FunctionType::get(Int8PtrType, ArgTys, false);
- Handler = Function::Create(FnType, GlobalVariable::InternalLinkage,
- SrcFn->getName() + ".catch", M);
+ Handler = createHandlerFunc(Int8PtrType, SrcFn->getName() + ".catch", M,
+ ParentFP);
} else {
- FunctionType *FnType =
- FunctionType::get(Type::getVoidTy(Context), ArgTys, false);
- Handler = Function::Create(FnType, GlobalVariable::InternalLinkage,
- SrcFn->getName() + ".cleanup", M);
+ Handler = createHandlerFunc(Type::getVoidTy(Context),
+ SrcFn->getName() + ".cleanup", M, ParentFP);
}
+ HandlerToParentFP[Handler] = ParentFP;
+ Handler->addFnAttr("wineh-parent", SrcFn->getName());
+ BasicBlock *Entry = &Handler->getEntryBlock();
// Generate a standard prolog to setup the frame recovery structure.
IRBuilder<> Builder(Context);
- BasicBlock *Entry = BasicBlock::Create(Context, "entry");
- Handler->getBasicBlockList().push_front(Entry);
Builder.SetInsertPoint(Entry);
Builder.SetCurrentDebugLocation(LPad->getDebugLoc());
LandingPadMap &LPadMap = LPadMaps[LPad];
if (!LPadMap.isInitialized())
LPadMap.mapLandingPad(LPad);
- if (Action->getType() == Catch) {
- Constant *SelectorType = cast<CatchHandler>(Action)->getSelector();
- Director.reset(
- new WinEHCatchDirector(Handler, SelectorType, VarInfo, LPadMap));
- LPadMap.remapSelector(VMap, ConstantInt::get( Type::getInt32Ty(Context), 1));
+ if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
+ Constant *Sel = CatchAction->getSelector();
+ Director.reset(new WinEHCatchDirector(Handler, ParentFP, Sel,
+ VarInfo, LPadMap,
+ NestedLPtoOriginalLP));
+ LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
+ ConstantInt::get(Type::getInt32Ty(Context), 1));
} else {
- Director.reset(new WinEHCleanupDirector(Handler, VarInfo, LPadMap));
+ Director.reset(
+ new WinEHCleanupDirector(Handler, ParentFP, VarInfo, LPadMap));
+ LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
+ UndefValue::get(Type::getInt32Ty(Context)));
}
SmallVector<ReturnInst *, 8> Returns;
ClonedCodeInfo OutlinedFunctionInfo;
+ // If the start block contains PHI nodes, we need to map them.
+ BasicBlock::iterator II = StartBB->begin();
+ while (auto *PN = dyn_cast<PHINode>(II)) {
+ bool Mapped = false;
+ // Look for PHI values that we have already mapped (such as the selector).
+ for (Value *Val : PN->incoming_values()) {
+ if (VMap.count(Val)) {
+ VMap[PN] = VMap[Val];
+ Mapped = true;
+ }
+ }
+ // If we didn't find a match for this value, map it as an undef.
+ if (!Mapped) {
+ VMap[PN] = UndefValue::get(PN->getType());
+ }
+ ++II;
+ }
+
+ // The landing pad value may be used by PHI nodes. It will ultimately be
+ // eliminated, but we need it in the map for intermediate handling.
+ VMap[LPad] = UndefValue::get(LPad->getType());
+
// Skip over PHIs and, if applicable, landingpad instructions.
- BasicBlock::iterator II = StartBB->getFirstInsertionPt();
+ II = StartBB->getFirstInsertionPt();
CloneAndPruneIntoFromInst(Handler, SrcFn, II, VMap,
/*ModuleLevelChanges=*/false, Returns, "",
&OutlinedFunctionInfo, Director.get());
- // Move all the instructions in the first cloned block into our entry block.
- BasicBlock *FirstClonedBB = std::next(Function::iterator(Entry));
- Entry->getInstList().splice(Entry->end(), FirstClonedBB->getInstList());
- FirstClonedBB->eraseFromParent();
+ // Move all the instructions in the cloned "entry" block into our entry block.
+ // Depending on how the parent function was laid out, the block that will
+ // correspond to the outlined entry block may not be the first block in the
+ // list. We can recognize it, however, as the cloned block which has no
+ // predecessors. Any other block wouldn't have been cloned if it didn't
+ // have a predecessor which was also cloned.
+ Function::iterator ClonedIt = std::next(Function::iterator(Entry));
+ while (!pred_empty(ClonedIt))
+ ++ClonedIt;
+ BasicBlock *ClonedEntryBB = ClonedIt;
+ assert(ClonedEntryBB);
+ Entry->getInstList().splice(Entry->end(), ClonedEntryBB->getInstList());
+ ClonedEntryBB->eraseFromParent();
+
+ // Make sure we can identify the handler's personality later.
+ addStubInvokeToHandlerIfNeeded(Handler, LPad->getPersonalityFn());
if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
WinEHCatchDirector *CatchDirector =
reinterpret_cast<WinEHCatchDirector *>(Director.get());
CatchAction->setExceptionVar(CatchDirector->getExceptionVar());
CatchAction->setReturnTargets(CatchDirector->getReturnTargets());
- }
- Action->setOutlinedFunction(Handler);
+ // Look for blocks that are not part of the landing pad that we just
+ // outlined but terminate with a call to llvm.eh.endcatch and a
+ // branch to a block that is in the handler we just outlined.
+ // These blocks will be part of a nested landing pad that intends to
+ // return to an address in this handler. This case is best handled
+ // after both landing pads have been outlined, so for now we'll just
+ // save the association of the blocks in LPadTargetBlocks. The
+ // return instructions which are created from these branches will be
+ // replaced after all landing pads have been outlined.
+ for (const auto MapEntry : VMap) {
+ // VMap maps all values and blocks that were just cloned, but dead
+ // blocks which were pruned will map to nullptr.
+ if (!isa<BasicBlock>(MapEntry.first) || MapEntry.second == nullptr)
+ continue;
+ const BasicBlock *MappedBB = cast<BasicBlock>(MapEntry.first);
+ for (auto *Pred : predecessors(const_cast<BasicBlock *>(MappedBB))) {
+ auto *Branch = dyn_cast<BranchInst>(Pred->getTerminator());
+ if (!Branch || !Branch->isUnconditional() || Pred->size() <= 1)
+ continue;
+ BasicBlock::iterator II = const_cast<BranchInst *>(Branch);
+ --II;
+ if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_endcatch>())) {
+ // This would indicate that a nested landing pad wants to return
+ // to a block that is outlined into two different handlers.
+ assert(!LPadTargetBlocks.count(MappedBB));
+ LPadTargetBlocks[MappedBB] = cast<BasicBlock>(MapEntry.second);
+ }
+ }
+ }
+ } // End if (CatchAction)
+
+ Action->setHandlerBlockOrFunc(Handler);
return true;
}
+/// This BB must end in a selector dispatch. All we need to do is pass the
+/// handler block to llvm.eh.actions and list it as a possible indirectbr
+/// target.
+void WinEHPrepare::processSEHCatchHandler(CatchHandler *CatchAction,
+ BasicBlock *StartBB) {
+ BasicBlock *HandlerBB;
+ BasicBlock *NextBB;
+ Constant *Selector;
+ bool Res = isSelectorDispatch(StartBB, HandlerBB, Selector, NextBB);
+ if (Res) {
+ // If this was EH dispatch, this must be a conditional branch to the handler
+ // block.
+ // FIXME: Handle instructions in the dispatch block. Currently we drop them,
+ // leading to crashes if some optimization hoists stuff here.
+ assert(CatchAction->getSelector() && HandlerBB &&
+ "expected catch EH dispatch");
+ } else {
+ // This must be a catch-all. Split the block after the landingpad.
+ assert(CatchAction->getSelector()->isNullValue() && "expected catch-all");
+ HandlerBB = SplitBlock(StartBB, StartBB->getFirstInsertionPt(), DT);
+ }
+ IRBuilder<> Builder(HandlerBB->getFirstInsertionPt());
+ Function *EHCodeFn = Intrinsic::getDeclaration(
+ StartBB->getParent()->getParent(), Intrinsic::eh_exceptioncode);
+ Value *Code = Builder.CreateCall(EHCodeFn, {}, "sehcode");
+ Code = Builder.CreateIntToPtr(Code, SEHExceptionCodeSlot->getAllocatedType());
+ Builder.CreateStore(Code, SEHExceptionCodeSlot);
+ CatchAction->setHandlerBlockOrFunc(BlockAddress::get(HandlerBB));
+ TinyPtrVector<BasicBlock *> Targets(HandlerBB);
+ CatchAction->setReturnTargets(Targets);
+}
+
void LandingPadMap::mapLandingPad(const LandingPadInst *LPad) {
// Each instance of this class should only ever be used to map a single
// landing pad.
// The landingpad instruction returns an aggregate value. Typically, its
// value will be passed to a pair of extract value instructions and the
- // results of those extracts are often passed to store instructions.
- // In unoptimized code the stored value will often be loaded and then stored
- // again.
+ // results of those extracts will have been promoted to reg values before
+ // this routine is called.
for (auto *U : LPad->users()) {
const ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
if (!Extract)
assert((Idx == 0 || Idx == 1) &&
"Unexpected operation: extracting an unknown landing pad element");
if (Idx == 0) {
- // Element 0 doesn't directly corresponds to anything in the WinEH
- // scheme.
- // It will be stored to a memory location, then later loaded and finally
- // the loaded value will be used as the argument to an
- // llvm.eh.begincatch
- // call. We're tracking it here so that we can skip the store and load.
ExtractedEHPtrs.push_back(Extract);
} else if (Idx == 1) {
- // Element 1 corresponds to the filter selector. We'll map it to 1 for
- // matching purposes, but it will also probably be stored to memory and
- // reloaded, so we need to track the instuction so that we can map the
- // loaded value too.
ExtractedSelectors.push_back(Extract);
}
-
- // Look for stores of the extracted values.
- for (auto *EU : Extract->users()) {
- if (auto *Store = dyn_cast<StoreInst>(EU)) {
- if (Idx == 1) {
- SelectorStores.push_back(Store);
- SelectorStoreAddrs.push_back(Store->getPointerOperand());
- } else {
- EHPtrStores.push_back(Store);
- EHPtrStoreAddrs.push_back(Store->getPointerOperand());
- }
- }
- }
}
}
+bool LandingPadMap::isOriginLandingPadBlock(const BasicBlock *BB) const {
+ return BB->getLandingPadInst() == OriginLPad;
+}
+
bool LandingPadMap::isLandingPadSpecificInst(const Instruction *Inst) const {
if (Inst == OriginLPad)
return true;
if (Inst == Extract)
return true;
}
- for (auto *Store : EHPtrStores) {
- if (Inst == Store)
- return true;
- }
- for (auto *Store : SelectorStores) {
- if (Inst == Store)
- return true;
- }
-
return false;
}
-void LandingPadMap::remapSelector(ValueToValueMapTy &VMap,
- Value *MappedValue) const {
- // Remap all selector extract instructions to the specified value.
+void LandingPadMap::remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
+ Value *SelectorValue) const {
+ // Remap all landing pad extract instructions to the specified values.
+ for (auto *Extract : ExtractedEHPtrs)
+ VMap[Extract] = EHPtrValue;
for (auto *Extract : ExtractedSelectors)
- VMap[Extract] = MappedValue;
+ VMap[Extract] = SelectorValue;
}
-bool LandingPadMap::mapIfEHLoad(const LoadInst *Load,
- SmallVectorImpl<const StoreInst *> &Stores,
- SmallVectorImpl<const Value *> &StoreAddrs) {
- // This makes the assumption that a store we've previously seen dominates
- // this load instruction. That might seem like a rather huge assumption,
- // but given the way that landingpads are constructed its fairly safe.
- // FIXME: Add debug/assert code that verifies this.
- const Value *LoadAddr = Load->getPointerOperand();
- for (auto *StoreAddr : StoreAddrs) {
- if (LoadAddr == StoreAddr) {
- // Handle the common debug scenario where this loaded value is stored
- // to a different location.
- for (auto *U : Load->users()) {
- if (auto *Store = dyn_cast<StoreInst>(U)) {
- Stores.push_back(Store);
- StoreAddrs.push_back(Store->getPointerOperand());
- }
- }
- return true;
- }
- }
- return false;
+static bool isFrameAddressCall(const Value *V) {
+ return match(const_cast<Value *>(V),
+ m_Intrinsic<Intrinsic::frameaddress>(m_SpecificInt(0)));
}
CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction(
if (LPadMap.isLandingPadSpecificInst(Inst))
return CloningDirector::SkipInstruction;
- if (auto *Load = dyn_cast<LoadInst>(Inst)) {
- // Look for loads of (previously suppressed) landingpad values.
- // The EHPtr load can be mapped to an undef value as it should only be used
- // as an argument to llvm.eh.begincatch, but the selector value needs to be
- // mapped to a constant value of 1. This value will be used to simplify the
- // branching to always flow to the current handler.
- if (LPadMap.mapIfSelectorLoad(Load)) {
- VMap[Inst] = ConstantInt::get(SelectorIDType, 1);
- return CloningDirector::SkipInstruction;
- }
- if (LPadMap.mapIfEHPtrLoad(Load)) {
- VMap[Inst] = UndefValue::get(Int8PtrType);
- return CloningDirector::SkipInstruction;
- }
-
- // Any other loads just get cloned.
- return CloningDirector::CloneInstruction;
- }
-
// Nested landing pads will be cloned as stubs, with just the
// landingpad instruction and an unreachable instruction. When
// all landingpads have been outlined, we'll replace this with the
// llvm.eh.actions call and indirect branch created when the
// landing pad was outlined.
- if (auto *NestedLPad = dyn_cast<LandingPadInst>(Inst)) {
- Instruction *NewInst = NestedLPad->clone();
- if (NestedLPad->hasName())
- NewInst->setName(NestedLPad->getName());
- // FIXME: Store this mapping somewhere else also.
- VMap[NestedLPad] = NewInst;
- BasicBlock::InstListType &InstList = NewBB->getInstList();
- InstList.push_back(NewInst);
- InstList.push_back(new UnreachableInst(NewBB->getContext()));
- return CloningDirector::StopCloningBB;
+ if (auto *LPad = dyn_cast<LandingPadInst>(Inst)) {
+ return handleLandingPad(VMap, LPad, NewBB);
}
if (auto *Invoke = dyn_cast<InvokeInst>(Inst))
if (auto *Resume = dyn_cast<ResumeInst>(Inst))
return handleResume(VMap, Resume, NewBB);
+ if (auto *Cmp = dyn_cast<CmpInst>(Inst))
+ return handleCompare(VMap, Cmp, NewBB);
+
if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
return handleBeginCatch(VMap, Inst, NewBB);
if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
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,
+ // which is the FP of the parent.
+ if (isFrameAddressCall(Inst)) {
+ VMap[Inst] = ParentFP;
+ return CloningDirector::SkipInstruction;
+ }
+
// Continue with the default cloning behavior.
return CloningDirector::CloneInstruction;
}
+CloningDirector::CloningAction WinEHCatchDirector::handleLandingPad(
+ ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
+ Instruction *NewInst = LPad->clone();
+ if (LPad->hasName())
+ NewInst->setName(LPad->getName());
+ // Save this correlation for later processing.
+ NestedLPtoOriginalLP[cast<LandingPadInst>(NewInst)] = LPad;
+ VMap[LPad] = NewInst;
+ BasicBlock::InstListType &InstList = NewBB->getInstList();
+ InstList.push_back(NewInst);
+ InstList.push_back(new UnreachableInst(NewBB->getContext()));
+ return CloningDirector::StopCloningBB;
+}
+
CloningDirector::CloningAction WinEHCatchDirector::handleBeginCatch(
ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
// The argument to the call is some form of the first element of the
"llvm.eh.begincatch found while "
"outlining catch handler.");
ExceptionObjectVar = Inst->getOperand(1)->stripPointerCasts();
+ if (isa<ConstantPointerNull>(ExceptionObjectVar))
+ return CloningDirector::SkipInstruction;
+ assert(cast<AllocaInst>(ExceptionObjectVar)->isStaticAlloca() &&
+ "catch parameter is not static alloca");
+ Materializer.escapeCatchObject(ExceptionObjectVar);
return CloningDirector::SkipInstruction;
}
// The end catch call can occur in one of two places: either in a
// landingpad block that is part of the catch handlers exception mechanism,
- // or at the end of the catch block. If it occurs in a landing pad, we must
- // skip it and continue so that the landing pad gets cloned.
- // FIXME: This case isn't fully supported yet and shouldn't turn up in any
- // of the test cases until it is.
- if (IntrinCall->getParent()->isLandingPad())
+ // or at the end of the catch block. However, a catch-all handler may call
+ // end catch from the original landing pad. If the call occurs in a nested
+ // landing pad block, we must skip it and continue so that the landing pad
+ // gets cloned.
+ auto *ParentBB = IntrinCall->getParent();
+ if (ParentBB->isLandingPad() && !LPadMap.isOriginLandingPadBlock(ParentBB))
return CloningDirector::SkipInstruction;
- // If an end catch occurs anywhere else the next instruction should be an
- // unconditional branch instruction that we want to replace with a return
- // to the the address of the branch target.
- const BasicBlock *EndCatchBB = IntrinCall->getParent();
- const TerminatorInst *Terminator = EndCatchBB->getTerminator();
- const BranchInst *Branch = dyn_cast<BranchInst>(Terminator);
- assert(Branch && Branch->isUnconditional());
- assert(std::next(BasicBlock::const_iterator(IntrinCall)) ==
- BasicBlock::const_iterator(Branch));
-
- BasicBlock *ContinueLabel = Branch->getSuccessor(0);
- ReturnInst::Create(NewBB->getContext(), BlockAddress::get(ContinueLabel),
- NewBB);
- ReturnTargets.push_back(ContinueLabel);
+ // If an end catch occurs anywhere else we want to terminate the handler
+ // with a return to the code that follows the endcatch call. If the
+ // next instruction is not an unconditional branch, we need to split the
+ // block to provide a clear target for the return instruction.
+ BasicBlock *ContinueBB;
+ auto Next = std::next(BasicBlock::const_iterator(IntrinCall));
+ const BranchInst *Branch = dyn_cast<BranchInst>(Next);
+ if (!Branch || !Branch->isUnconditional()) {
+ // We're interrupting the cloning process at this location, so the
+ // const_cast we're doing here will not cause a problem.
+ ContinueBB = SplitBlock(const_cast<BasicBlock *>(ParentBB),
+ const_cast<Instruction *>(cast<Instruction>(Next)));
+ } else {
+ ContinueBB = Branch->getSuccessor(0);
+ }
+
+ ReturnInst::Create(NewBB->getContext(), BlockAddress::get(ContinueBB), NewBB);
+ ReturnTargets.push_back(ContinueBB);
// We just added a terminator to the cloned block.
// Tell the caller to stop processing the current basic block so that
return CloningDirector::StopCloningBB;
}
+CloningDirector::CloningAction
+WinEHCatchDirector::handleCompare(ValueToValueMapTy &VMap,
+ const CmpInst *Compare, BasicBlock *NewBB) {
+ const IntrinsicInst *IntrinCall = nullptr;
+ if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
+ IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(0));
+ } else if (match(Compare->getOperand(1),
+ m_Intrinsic<Intrinsic::eh_typeid_for>())) {
+ IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(1));
+ }
+ if (IntrinCall) {
+ Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
+ // This causes a replacement that will collapse the landing pad CFG based
+ // on the filter function we intend to match.
+ if (Selector == CurrentSelector->stripPointerCasts()) {
+ VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
+ } else {
+ VMap[Compare] = ConstantInt::get(SelectorIDType, 0);
+ }
+ return CloningDirector::SkipInstruction;
+ }
+ return CloningDirector::CloneInstruction;
+}
+
+CloningDirector::CloningAction WinEHCleanupDirector::handleLandingPad(
+ ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
+ // The MS runtime will terminate the process if an exception occurs in a
+ // cleanup handler, so we shouldn't encounter landing pads in the actual
+ // cleanup code, but they may appear in catch blocks. Depending on where
+ // we started cloning we may see one, but it will get dropped during dead
+ // block pruning.
+ Instruction *NewInst = new UnreachableInst(NewBB->getContext());
+ VMap[LPad] = NewInst;
+ BasicBlock::InstListType &InstList = NewBB->getInstList();
+ InstList.push_back(NewInst);
+ return CloningDirector::StopCloningBB;
+}
+
CloningDirector::CloningAction WinEHCleanupDirector::handleBeginCatch(
ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
- // Catch blocks within cleanup handlers will always be unreachable.
- // We'll insert an unreachable instruction now, but it will be pruned
- // before the cloning process is complete.
- BasicBlock::InstListType &InstList = NewBB->getInstList();
- InstList.push_back(new UnreachableInst(NewBB->getContext()));
+ // Cleanup code may flow into catch blocks or the catch block may be part
+ // of a branch that will be optimized away. We'll insert a return
+ // instruction now, but it may be pruned before the cloning process is
+ // complete.
+ ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
return CloningDirector::StopCloningBB;
}
CloningDirector::CloningAction WinEHCleanupDirector::handleEndCatch(
ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
- // Catch blocks within cleanup handlers will always be unreachable.
- // We'll insert an unreachable instruction now, but it will be pruned
- // before the cloning process is complete.
- BasicBlock::InstListType &InstList = NewBB->getInstList();
- InstList.push_back(new UnreachableInst(NewBB->getContext()));
- return CloningDirector::StopCloningBB;
+ // Cleanup handlers nested within catch handlers may begin with a call to
+ // eh.endcatch. We can just ignore that instruction.
+ return CloningDirector::SkipInstruction;
}
CloningDirector::CloningAction WinEHCleanupDirector::handleTypeIdFor(
NewCall->setDebugLoc(Invoke->getDebugLoc());
VMap[Invoke] = NewCall;
+ // Remap the operands.
+ llvm::RemapInstruction(NewCall, VMap, RF_None, nullptr, &Materializer);
+
// Insert an unconditional branch to the normal destination.
BranchInst::Create(Invoke->getNormalDest(), NewBB);
// We just added a terminator to the cloned block.
// Tell the caller to stop processing the current basic block.
- return CloningDirector::StopCloningBB;
+ return CloningDirector::CloneSuccessors;
}
CloningDirector::CloningAction WinEHCleanupDirector::handleResume(
return CloningDirector::StopCloningBB;
}
+CloningDirector::CloningAction
+WinEHCleanupDirector::handleCompare(ValueToValueMapTy &VMap,
+ const CmpInst *Compare, BasicBlock *NewBB) {
+ if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>()) ||
+ match(Compare->getOperand(1), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
+ VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
+ return CloningDirector::SkipInstruction;
+ }
+ return CloningDirector::CloneInstruction;
+}
+
WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer(
- Function *OutlinedFn, FrameVarInfoMap &FrameVarInfo)
+ Function *OutlinedFn, Value *ParentFP, FrameVarInfoMap &FrameVarInfo)
: FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) {
- Builder.SetInsertPoint(&OutlinedFn->getEntryBlock());
+ BasicBlock *EntryBB = &OutlinedFn->getEntryBlock();
+
+ // New allocas should be inserted in the entry block, but after the parent FP
+ // is established if it is an instruction.
+ Instruction *InsertPoint = EntryBB->getFirstInsertionPt();
+ if (auto *FPInst = dyn_cast<Instruction>(ParentFP))
+ InsertPoint = FPInst->getNextNode();
+ Builder.SetInsertPoint(EntryBB, InsertPoint);
}
Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) {
- // If we're asked to materialize a value that is an instruction, we
- // temporarily create an alloca in the outlined function and add this
- // to the FrameVarInfo map. When all the outlining is complete, we'll
- // collect these into a structure, spilling non-alloca values in the
- // parent frame as necessary, and replace these temporary allocas with
- // GEPs referencing the frame allocation block.
-
- // If the value is an alloca, the mapping is direct.
+ // If we're asked to materialize a static alloca, we temporarily create an
+ // alloca in the outlined function and add this to the FrameVarInfo map. When
+ // all the outlining is complete, we'll replace these temporary allocas with
+ // calls to llvm.framerecover.
if (auto *AV = dyn_cast<AllocaInst>(V)) {
+ assert(AV->isStaticAlloca() &&
+ "cannot materialize un-demoted dynamic alloca");
AllocaInst *NewAlloca = dyn_cast<AllocaInst>(AV->clone());
Builder.Insert(NewAlloca, AV->getName());
FrameVarInfo[AV].push_back(NewAlloca);
return NewAlloca;
}
- // For other types of instructions or arguments, we need an alloca based on
- // the value's type and a load of the alloca. The alloca will be replaced
- // by a GEP, but the load will stay. In the parent function, the value will
- // be spilled to a location in the frame allocation block.
if (isa<Instruction>(V) || isa<Argument>(V)) {
- AllocaInst *NewAlloca =
- Builder.CreateAlloca(V->getType(), nullptr, "eh.temp.alloca");
- FrameVarInfo[V].push_back(NewAlloca);
- LoadInst *NewLoad = Builder.CreateLoad(NewAlloca, V->getName() + ".reload");
- return NewLoad;
+ Function *Parent = isa<Instruction>(V)
+ ? cast<Instruction>(V)->getParent()->getParent()
+ : cast<Argument>(V)->getParent();
+ errs()
+ << "Failed to demote instruction used in exception handler of function "
+ << GlobalValue::getRealLinkageName(Parent->getName()) << ":\n";
+ errs() << " " << *V << '\n';
+ report_fatal_error("WinEHPrepare failed to demote instruction");
}
// Don't materialize other values.
return nullptr;
}
+void WinEHFrameVariableMaterializer::escapeCatchObject(Value *V) {
+ // Catch parameter objects have to live in the parent frame. When we see a use
+ // of a catch parameter, add a sentinel to the multimap to indicate that it's
+ // used from another handler. This will prevent us from trying to sink the
+ // alloca into the handler and ensure that the catch parameter is present in
+ // the call to llvm.frameescape.
+ FrameVarInfo[V].push_back(getCatchObjectSentinel());
+}
+
// This function maps the catch and cleanup handlers that are reachable from the
// specified landing pad. The landing pad sequence will have this basic shape:
//
DEBUG(dbgs() << "Mapping landing pad: " << BB->getName() << "\n");
if (NumClauses == 0) {
- // This landing pad contains only cleanup code.
- CleanupHandler *Action = new CleanupHandler(BB);
- CleanupHandlerMap[BB] = Action;
- Actions.insertCleanupHandler(Action);
- DEBUG(dbgs() << " Assuming cleanup code in block " << BB->getName()
- << "\n");
- assert(LPad->isCleanup());
+ findCleanupHandlers(Actions, BB, nullptr);
return;
}
while (HandlersFound != NumClauses) {
BasicBlock *NextBB = nullptr;
+ // Skip over filter clauses.
+ if (LPad->isFilter(HandlersFound)) {
+ ++HandlersFound;
+ continue;
+ }
+
// See if the clause we're looking for is a catch-all.
// If so, the catch begins immediately.
- if (isa<ConstantPointerNull>(LPad->getClause(HandlersFound))) {
+ Constant *ExpectedSelector =
+ LPad->getClause(HandlersFound)->stripPointerCasts();
+ if (isa<ConstantPointerNull>(ExpectedSelector)) {
// The catch all must occur last.
assert(HandlersFound == NumClauses - 1);
- // See if there is any interesting code executed before the catch.
- if (auto *CleanupAction = findCleanupHandler(BB, BB)) {
- // Add a cleanup entry to the list
- Actions.insertCleanupHandler(CleanupAction);
- DEBUG(dbgs() << " Found cleanup code in block "
- << CleanupAction->getStartBlock()->getName() << "\n");
+ // There can be additional selector dispatches in the call chain that we
+ // need to ignore.
+ BasicBlock *CatchBlock = nullptr;
+ Constant *Selector;
+ while (BB && isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
+ DEBUG(dbgs() << " Found extra catch dispatch in block "
+ << CatchBlock->getName() << "\n");
+ BB = NextBB;
}
// Add the catch handler to the action list.
- CatchHandler *Action =
- new CatchHandler(BB, LPad->getClause(HandlersFound), nullptr);
- CatchHandlerMap[BB] = Action;
+ CatchHandler *Action = nullptr;
+ if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
+ // If the CatchHandlerMap already has an entry for this BB, re-use it.
+ Action = CatchHandlerMap[BB];
+ assert(Action->getSelector() == ExpectedSelector);
+ } else {
+ // We don't expect a selector dispatch, but there may be a call to
+ // llvm.eh.begincatch, which separates catch handling code from
+ // cleanup code in the same control flow. This call looks for the
+ // begincatch intrinsic.
+ Action = findCatchHandler(BB, NextBB, VisitedBlocks);
+ if (Action) {
+ // For C++ EH, check if there is any interesting cleanup code before
+ // we begin the catch. This is important because cleanups cannot
+ // rethrow exceptions but code called from catches can. For SEH, it
+ // isn't important if some finally code before a catch-all is executed
+ // out of line or after recovering from the exception.
+ if (Personality == EHPersonality::MSVC_CXX)
+ findCleanupHandlers(Actions, BB, BB);
+ } else {
+ // If an action was not found, it means that the control flows
+ // directly into the catch-all handler and there is no cleanup code.
+ // That's an expected situation and we must create a catch action.
+ // Since this is a catch-all handler, the selector won't actually
+ // appear in the code anywhere. ExpectedSelector here is the constant
+ // null ptr that we got from the landing pad instruction.
+ Action = new CatchHandler(BB, ExpectedSelector, nullptr);
+ CatchHandlerMap[BB] = Action;
+ }
+ }
Actions.insertCatchHandler(Action);
DEBUG(dbgs() << " Catch all handler at block " << BB->getName() << "\n");
++HandlersFound;
- continue;
+
+ // Once we reach a catch-all, don't expect to hit a resume instruction.
+ BB = nullptr;
+ break;
}
CatchHandler *CatchAction = findCatchHandler(BB, NextBB, VisitedBlocks);
+ assert(CatchAction);
+
// See if there is any interesting code executed before the dispatch.
- if (auto *CleanupAction =
- findCleanupHandler(BB, CatchAction->getStartBlock())) {
- // Add a cleanup entry to the list
- Actions.insertCleanupHandler(CleanupAction);
- DEBUG(dbgs() << " Found cleanup code in block "
- << CleanupAction->getStartBlock()->getName() << "\n");
- }
+ findCleanupHandlers(Actions, BB, CatchAction->getStartBlock());
- assert(CatchAction);
- ++HandlersFound;
+ // When the source program contains multiple nested try blocks the catch
+ // handlers can get strung together in such a way that we can encounter
+ // a dispatch for a selector that we've already had a handler for.
+ if (CatchAction->getSelector()->stripPointerCasts() == ExpectedSelector) {
+ ++HandlersFound;
- // Add the catch handler to the action list.
- Actions.insertCatchHandler(CatchAction);
- DEBUG(dbgs() << " Found catch dispatch in block "
- << CatchAction->getStartBlock()->getName() << "\n");
+ // Add the catch handler to the action list.
+ DEBUG(dbgs() << " Found catch dispatch in block "
+ << CatchAction->getStartBlock()->getName() << "\n");
+ Actions.insertCatchHandler(CatchAction);
+ } else {
+ // 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
+ // (typically an empty catch). In this case, the handler must be shared
+ // by all remaining clauses.
+ if (isa<ConstantPointerNull>(
+ CatchAction->getSelector()->stripPointerCasts())) {
+ DEBUG(dbgs() << " Applying early catch-all handler in block "
+ << CatchAction->getStartBlock()->getName()
+ << " to all remaining clauses.\n");
+ Actions.insertCatchHandler(CatchAction);
+ return;
+ }
+
+ DEBUG(dbgs() << " Found extra catch dispatch in block "
+ << CatchAction->getStartBlock()->getName() << "\n");
+ }
// Move on to the block after the catch handler.
BB = NextBB;
}
- // See if there is any interesting code executed before the resume.
- if (auto *CleanupAction = findCleanupHandler(BB, BB)) {
- // Add a cleanup entry to the list
- Actions.insertCleanupHandler(CleanupAction);
- DEBUG(dbgs() << " Found cleanup code in block "
- << CleanupAction->getStartBlock()->getName() << "\n");
- }
+ // If we didn't wind up in a catch-all, see if there is any interesting code
+ // executed before the resume.
+ findCleanupHandlers(Actions, BB, BB);
// It's possible that some optimization moved code into a landingpad that
// wasn't
CatchHandlerMap[BB] = Action;
return Action;
}
+ // If we encounter a block containing an llvm.eh.begincatch before we
+ // find a selector dispatch block, the handler is assumed to be
+ // reached unconditionally. This happens for catch-all blocks, but
+ // it can also happen for other catch handlers that have been combined
+ // with the catch-all handler during optimization.
+ if (isCatchBlock(BB)) {
+ PointerType *Int8PtrTy = Type::getInt8PtrTy(BB->getContext());
+ Constant *NullSelector = ConstantPointerNull::get(Int8PtrTy);
+ CatchHandler *Action = new CatchHandler(BB, NullSelector, nullptr);
+ CatchHandlerMap[BB] = Action;
+ return Action;
+ }
}
// Visit each successor, looking for the dispatch.
return nullptr;
}
-// These are helper functions to combine repeated code from findCleanupHandler.
-static CleanupHandler *createCleanupHandler(CleanupHandlerMapTy &CleanupHandlerMap,
- BasicBlock *BB) {
+// These are helper functions to combine repeated code from findCleanupHandlers.
+static void createCleanupHandler(LandingPadActions &Actions,
+ CleanupHandlerMapTy &CleanupHandlerMap,
+ BasicBlock *BB) {
CleanupHandler *Action = new CleanupHandler(BB);
CleanupHandlerMap[BB] = Action;
- return Action;
+ Actions.insertCleanupHandler(Action);
+ DEBUG(dbgs() << " Found cleanup code in block "
+ << Action->getStartBlock()->getName() << "\n");
+}
+
+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)
+ // call void @"fin$parent"(iN 1, i8* %fp)
+ if (isFrameAddressCall(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)))
+ return CallSite();
+ return FinallyCall;
+}
+
+static BasicBlock *followSingleUnconditionalBranches(BasicBlock *BB) {
+ // Skip single ubr blocks.
+ while (BB->getFirstNonPHIOrDbg() == BB->getTerminator()) {
+ auto *Br = dyn_cast<BranchInst>(BB->getTerminator());
+ if (Br && Br->isUnconditional())
+ BB = Br->getSuccessor(0);
+ else
+ return BB;
+ }
+ return BB;
}
// This function searches starting with the input block for the next block that
// contains code that is not part of a catch handler and would not be eliminated
// during handler outlining.
//
-CleanupHandler *WinEHPrepare::findCleanupHandler(BasicBlock *StartBB,
- BasicBlock *EndBB) {
+void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions,
+ BasicBlock *StartBB, BasicBlock *EndBB) {
// Here we will skip over the following:
//
// landing pad prolog:
// Anything other than an unconditional branch will kick us out of this loop
// one way or another.
while (BB) {
+ BB = followSingleUnconditionalBranches(BB);
// If we've already scanned this block, don't scan it again. If it is
// a cleanup block, there will be an action in the CleanupHandlerMap.
// If we've scanned it and it is not a cleanup block, there will be a
// avoid creating a null entry for blocks we haven't scanned.
if (CleanupHandlerMap.count(BB)) {
if (auto *Action = CleanupHandlerMap[BB]) {
- return cast<CleanupHandler>(Action);
+ Actions.insertCleanupHandler(Action);
+ DEBUG(dbgs() << " Found cleanup code in block "
+ << Action->getStartBlock()->getName() << "\n");
+ // FIXME: This cleanup might chain into another, and we need to discover
+ // that.
+ return;
} else {
// Here we handle the case where the cleanup handler map contains a
// value for this block but the value is a nullptr. This means that
// would terminate the search for cleanup code, so the unconditional
// branch is the only case for which we might need to continue
// searching.
- if (BB == EndBB)
- return nullptr;
- BasicBlock *SuccBB;
- if (!match(BB->getTerminator(), m_UnconditionalBr(SuccBB)))
- return nullptr;
+ BasicBlock *SuccBB = followSingleUnconditionalBranches(BB);
+ if (SuccBB == BB || SuccBB == EndBB)
+ return;
BB = SuccBB;
continue;
}
}
// Look for the bare resume pattern:
- // %exn2 = load i8** %exn.slot
- // %sel2 = load i32* %ehselector.slot
- // %lpad.val1 = insertvalue { i8*, i32 } undef, i8* %exn2, 0
- // %lpad.val2 = insertvalue { i8*, i32 } %lpad.val1, i32 %sel2, 1
+ // %lpad.val1 = insertvalue { i8*, i32 } undef, i8* %exn, 0
+ // %lpad.val2 = insertvalue { i8*, i32 } %lpad.val1, i32 %sel, 1
// resume { i8*, i32 } %lpad.val2
if (auto *Resume = dyn_cast<ResumeInst>(Terminator)) {
InsertValueInst *Insert1 = nullptr;
InsertValueInst *Insert2 = nullptr;
- if (!isa<PHINode>(Resume->getOperand(0))) {
- Insert2 = dyn_cast<InsertValueInst>(Resume->getOperand(0));
+ Value *ResumeVal = Resume->getOperand(0);
+ // If the resume value isn't a phi or landingpad value, it should be a
+ // series of insertions. Identify them so we can avoid them when scanning
+ // for cleanups.
+ if (!isa<PHINode>(ResumeVal) && !isa<LandingPadInst>(ResumeVal)) {
+ Insert2 = dyn_cast<InsertValueInst>(ResumeVal);
if (!Insert2)
- return createCleanupHandler(CleanupHandlerMap, BB);
+ return createCleanupHandler(Actions, CleanupHandlerMap, BB);
Insert1 = dyn_cast<InsertValueInst>(Insert2->getAggregateOperand());
if (!Insert1)
- return createCleanupHandler(CleanupHandlerMap, BB);
+ return createCleanupHandler(Actions, CleanupHandlerMap, BB);
}
for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
II != IE; ++II) {
continue;
if (!Inst->hasOneUse() ||
(Inst->user_back() != Insert1 && Inst->user_back() != Insert2)) {
- return createCleanupHandler(CleanupHandlerMap, BB);
+ return createCleanupHandler(Actions, CleanupHandlerMap, BB);
}
}
- return nullptr;
+ return;
}
BranchInst *Branch = dyn_cast<BranchInst>(Terminator);
- if (Branch) {
- if (Branch->isConditional()) {
- // Look for the selector dispatch.
- // %sel = load i32* %ehselector.slot
- // %2 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
- // %matches = icmp eq i32 %sel12, %2
- // br i1 %matches, label %catch14, label %eh.resume
- CmpInst *Compare = dyn_cast<CmpInst>(Branch->getCondition());
- if (!Compare || !Compare->isEquality())
- return createCleanupHandler(CleanupHandlerMap, BB);
- for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(),
- IE = BB->end();
- II != IE; ++II) {
- Instruction *Inst = II;
- if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
- continue;
- if (Inst == Compare || Inst == Branch)
- continue;
- if (!Inst->hasOneUse() || (Inst->user_back() != Compare))
- return createCleanupHandler(CleanupHandlerMap, BB);
- if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
- continue;
- if (!isa<LoadInst>(Inst))
- return createCleanupHandler(CleanupHandlerMap, BB);
- }
- // The selector dispatch block should always terminate our search.
- assert(BB == EndBB);
- return nullptr;
- } else {
- // Look for empty blocks with unconditional branches.
- for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(),
- IE = BB->end();
- II != IE; ++II) {
- Instruction *Inst = II;
- if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
- continue;
- if (Inst == Branch)
- continue;
- if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
- continue;
- // Anything else makes this interesting cleanup code.
- return createCleanupHandler(CleanupHandlerMap, BB);
+ if (Branch && Branch->isConditional()) {
+ // Look for the selector dispatch.
+ // %2 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
+ // %matches = icmp eq i32 %sel, %2
+ // br i1 %matches, label %catch14, label %eh.resume
+ CmpInst *Compare = dyn_cast<CmpInst>(Branch->getCondition());
+ if (!Compare || !Compare->isEquality())
+ return createCleanupHandler(Actions, CleanupHandlerMap, BB);
+ for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
+ II != IE; ++II) {
+ Instruction *Inst = II;
+ if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
+ continue;
+ if (Inst == Compare || Inst == Branch)
+ continue;
+ if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
+ continue;
+ return createCleanupHandler(Actions, CleanupHandlerMap, BB);
+ }
+ // The selector dispatch block should always terminate our search.
+ assert(BB == EndBB);
+ return;
+ }
+
+ if (isAsynchronousEHPersonality(Personality)) {
+ // If this is a landingpad block, split the block at the first non-landing
+ // pad instruction.
+ Instruction *MaybeCall = BB->getFirstNonPHIOrDbg();
+ if (LPadMap) {
+ while (MaybeCall != BB->getTerminator() &&
+ LPadMap->isLandingPadSpecificInst(MaybeCall))
+ MaybeCall = MaybeCall->getNextNode();
+ }
+
+ // Look for outlined finally calls.
+ if (CallSite FinallyCall = matchOutlinedFinallyCall(BB, MaybeCall)) {
+ Function *Fin = FinallyCall.getCalledFunction();
+ assert(Fin && "outlined finally call should be direct");
+ auto *Action = new CleanupHandler(BB);
+ Action->setHandlerBlockOrFunc(Fin);
+ Actions.insertCleanupHandler(Action);
+ CleanupHandlerMap[BB] = Action;
+ DEBUG(dbgs() << " Found frontend-outlined finally call to "
+ << Fin->getName() << " in block "
+ << Action->getStartBlock()->getName() << "\n");
+
+ // Split the block if there were more interesting instructions and look
+ // for finally calls in the normal successor block.
+ BasicBlock *SuccBB = BB;
+ if (FinallyCall.getInstruction() != BB->getTerminator() &&
+ FinallyCall.getInstruction()->getNextNode() !=
+ BB->getTerminator()) {
+ SuccBB =
+ SplitBlock(BB, FinallyCall.getInstruction()->getNextNode(), DT);
+ } else {
+ if (FinallyCall.isInvoke()) {
+ SuccBB =
+ cast<InvokeInst>(FinallyCall.getInstruction())->getNormalDest();
+ } else {
+ SuccBB = BB->getUniqueSuccessor();
+ assert(SuccBB &&
+ "splitOutlinedFinallyCalls didn't insert a branch");
+ }
}
+ BB = SuccBB;
if (BB == EndBB)
- return nullptr;
- // The branch was unconditional.
- BB = Branch->getSuccessor(0);
+ return;
+ continue;
+ }
+ }
+
+ // Anything else is either a catch block or interesting cleanup code.
+ for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
+ II != IE; ++II) {
+ Instruction *Inst = II;
+ if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
+ continue;
+ // Unconditional branches fall through to this loop.
+ if (Inst == Branch)
continue;
- } // End else of if branch was conditional
- } // End if Branch
+ // If this is a catch block, there is no cleanup code to be found.
+ if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
+ return;
+ // If this a nested landing pad, it may contain an endcatch call.
+ if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
+ return;
+ // Anything else makes this interesting cleanup code.
+ return createCleanupHandler(Actions, CleanupHandlerMap, BB);
+ }
- // Anything else makes this interesting cleanup code.
- return createCleanupHandler(CleanupHandlerMap, BB);
+ // Only unconditional branches in empty blocks should get this far.
+ assert(Branch && Branch->isUnconditional());
+ if (BB == EndBB)
+ return;
+ BB = Branch->getSuccessor(0);
}
- return nullptr;
+}
+
+// This is a public function, declared in WinEHFuncInfo.h and is also
+// referenced by WinEHNumbering in FunctionLoweringInfo.cpp.
+void llvm::parseEHActions(
+ const IntrinsicInst *II,
+ SmallVectorImpl<std::unique_ptr<ActionHandler>> &Actions) {
+ for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) {
+ uint64_t ActionKind =
+ cast<ConstantInt>(II->getArgOperand(I))->getZExtValue();
+ if (ActionKind == /*catch=*/1) {
+ auto *Selector = cast<Constant>(II->getArgOperand(I + 1));
+ ConstantInt *EHObjIndex = cast<ConstantInt>(II->getArgOperand(I + 2));
+ int64_t EHObjIndexVal = EHObjIndex->getSExtValue();
+ Constant *Handler = cast<Constant>(II->getArgOperand(I + 3));
+ I += 4;
+ auto CH = make_unique<CatchHandler>(/*BB=*/nullptr, Selector,
+ /*NextBB=*/nullptr);
+ CH->setHandlerBlockOrFunc(Handler);
+ CH->setExceptionVarIndex(EHObjIndexVal);
+ Actions.push_back(std::move(CH));
+ } else if (ActionKind == 0) {
+ Constant *Handler = cast<Constant>(II->getArgOperand(I + 1));
+ I += 2;
+ auto CH = make_unique<CleanupHandler>(/*BB=*/nullptr);
+ CH->setHandlerBlockOrFunc(Handler);
+ Actions.push_back(std::move(CH));
+ } else {
+ llvm_unreachable("Expected either a catch or cleanup handler!");
+ }
+ }
+ std::reverse(Actions.begin(), Actions.end());
}
projects / oota-llvm.git / blobdiff