#include "llvm/ADT/SmallSet.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/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), DT(nullptr) {}
bool runOnFunction(Function &Fn) override;
private:
bool prepareExceptionHandlers(Function &F,
SmallVectorImpl<LandingPadInst *> &LPads);
+ void promoteLandingPadValues(LandingPadInst *LPad);
+ void completeNestedLandingPad(Function *ParentFn,
+ LandingPadInst *OutlinedLPad,
+ const LandingPadInst *OriginalLPad,
+ FrameVarInfoMap &VarInfo);
bool outlineHandler(ActionHandler *Action, Function *SrcFn,
LandingPadInst *LPad, BasicBlock *StartBB,
FrameVarInfoMap &VarInfo);
void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB);
// All fields are reset by runOnFunction.
+ DominatorTree *DT;
EHPersonality Personality;
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;
};
class WinEHFrameVariableMaterializer : public ValueMaterializer {
virtual Value *materializeValueFor(Value *V) override;
+ void escapeCatchObject(Value *V);
+
private:
FrameVarInfoMap &FrameVarInfo;
IRBuilder<> Builder;
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,
+ WinEHCloningDirectorBase(Function *HandlerFn, FrameVarInfoMap &VarInfo,
LandingPadMap &LPadMap)
: Materializer(HandlerFn, VarInfo),
SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())),
virtual CloningAction handleResume(ValueToValueMapTy &VMap,
const ResumeInst *Resume,
BasicBlock *NewBB) = 0;
+ virtual CloningAction handleLandingPad(ValueToValueMapTy &VMap,
+ const LandingPadInst *LPad,
+ BasicBlock *NewBB) = 0;
ValueMaterializer *getValueMaterializer() override { return &Materializer; }
class WinEHCatchDirector : public WinEHCloningDirectorBase {
public:
- WinEHCatchDirector(Function *CatchFn, Value *Selector,
- FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
+ WinEHCatchDirector(
+ Function *CatchFn, Value *Selector, FrameVarInfoMap &VarInfo,
+ LandingPadMap &LPadMap,
+ DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads)
: WinEHCloningDirectorBase(CatchFn, 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 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,
- FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
+ WinEHCleanupDirector(Function *CleanupFn, FrameVarInfoMap &VarInfo,
+ LandingPadMap &LPadMap)
: WinEHCloningDirectorBase(CleanupFn, VarInfo, LPadMap) {}
CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
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), HandlerBlockOrFunc(nullptr) {}
-
- ActionType getType() const { return Type; }
- BasicBlock *getStartBlock() const { return StartBB; }
-
- bool hasBeenProcessed() { return HandlerBlockOrFunc != nullptr; }
-
- void setHandlerBlockOrFunc(Constant *F) { HandlerBlockOrFunc = F; }
- Constant *getHandlerBlockOrFunc() { return HandlerBlockOrFunc; }
-
-private:
- BasicBlock *StartBB;
- ActionType Type;
-
- // Can be either a BlockAddress or a Function depending on the EH personality.
- Constant *HandlerBlockOrFunc;
-};
-
-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 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(); }
// FIXME: Remove this once the backend can handle the prepared IR.
static cl::opt<bool>
-SEHPrepare("sehprepare", cl::Hidden,
- cl::desc("Prepare functions with SEH personalities"));
+ SEHPrepare("sehprepare", cl::Hidden,
+ cl::desc("Prepare functions with SEH personalities"));
bool WinEHPrepare::runOnFunction(Function &Fn) {
SmallVector<LandingPadInst *, 4> LPads;
if (!isMSVCEHPersonality(Personality))
return false;
+ DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+
if (isAsynchronousEHPersonality(Personality) && !SEHPrepare) {
// Replace all resume instructions with unreachable.
// FIXME: Remove this once the backend can handle the prepared IR.
return true;
}
-bool WinEHPrepare::doFinalization(Module &M) {
- return false;
-}
+bool WinEHPrepare::doFinalization(Module &M) { return false; }
-void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {}
+void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<DominatorTreeWrapperPass>();
+}
bool WinEHPrepare::prepareExceptionHandlers(
Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
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);
// 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();
+ auto *NewLPad = cast<LandingPadInst>(LPad->clone());
NewLPadBB->getInstList().push_back(NewLPad);
while (!pred_empty(LPadBB)) {
auto *pred = *pred_begin(LPadBB);
Invoke->setUnwindDest(NewLPadBB);
}
+ // Replace the mapping of any nested landing pad that previously mapped
+ // to this landing pad with a referenced to the cloned version.
+ for (auto &LPadPair : NestedLPtoOriginalLP) {
+ const LandingPadInst *OriginalLPad = LPadPair.second;
+ if (OriginalLPad == LPad) {
+ LPadPair.second = NewLPad;
+ }
+ }
+
// Replace uses of the old lpad in phis with this block and delete the old
// block.
LPadBB->replaceSuccessorsPhiUsesWith(NewLPadBB);
if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
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, 0));
}
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);
+
+ F.addFnAttr("wineh-parent", F.getName());
+
// Delete any blocks that were only used by handlers that were outlined above.
removeUnreachableBlocks(F);
}
}
- // 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) {
+ // If the parent alloca is used by exactly one handler and is not a catch
+ // parameter, erase the parent and leave the copy in the outlined handler.
+ // Catch parameters are indicated by a single null pointer in Allocas.
+ if (ParentAlloca->getNumUses() == 0 && Allocas.size() == 1 &&
+ Allocas[0] != getCatchObjectSentinel()) {
ParentAlloca->eraseFromParent();
+ // FIXME: Put a null entry in the llvm.frameescape call because we've
+ // already created llvm.eh.actions calls with indices into it.
+ AllocasToEscape.push_back(Constant::getNullValue(Int8PtrType));
continue;
}
// 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.
Builder.SetInsertPoint(TempAlloca);
Builder.SetInsertPoint(&F.getEntryBlock().back());
Builder.CreateCall(FrameEscapeFn, AllocasToEscape);
+ // Insert an alloca for the EH state in the entry block. On x86, we will also
+ // insert stores to update the EH state, but on other ISAs, the runtime does
+ // it for us.
+ // FIXME: This record is different on x86.
+ Type *UnwindHelpTy = Type::getInt64Ty(Context);
+ AllocaInst *UnwindHelp =
+ new AllocaInst(UnwindHelpTy, "unwindhelp", &F.getEntryBlock().front());
+ Builder.CreateStore(llvm::ConstantInt::get(UnwindHelpTy, -2), UnwindHelp,
+ /*isVolatile=*/true);
+ Function *UnwindHelpFn =
+ Intrinsic::getDeclaration(M, Intrinsic::eh_unwindhelp);
+ Builder.CreateCall(UnwindHelpFn,
+ Builder.CreateBitCast(UnwindHelp, Int8PtrType));
+
// Clean up the handler action maps we created for this function
DeleteContainerSeconds(CatchHandlerMap);
CatchHandlerMap.clear();
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();
+ }
+}
+
+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.
+ WinEHFrameVariableMaterializer Materializer(OutlinedHandlerFn, FrameVarInfo);
+ SmallVector<BlockAddress *, 4> ActionTargets;
+ SmallVector<ActionHandler *, 4> ActionList;
+ parseEHActions(EHActions, ActionList);
+ for (auto *Action : ActionList) {
+ auto *Catch = dyn_cast<CatchHandler>(Action);
+ 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);
+ }
+ }
+ 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
SrcFn->getName() + ".cleanup", M);
}
+ Handler->addFnAttr("wineh-parent", SrcFn->getName());
+
// Generate a standard prolog to setup the frame recovery structure.
IRBuilder<> Builder(Context);
BasicBlock *Entry = BasicBlock::Create(Context, "entry");
LPadMap.mapLandingPad(LPad);
if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
Constant *Sel = CatchAction->getSelector();
- Director.reset(new WinEHCatchDirector(Handler, Sel, VarInfo, LPadMap));
- LPadMap.remapSelector(VMap, ConstantInt::get(Type::getInt32Ty(Context), 1));
+ Director.reset(new WinEHCatchDirector(Handler, Sel, VarInfo, LPadMap,
+ NestedLPtoOriginalLP));
+ LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
+ ConstantInt::get(Type::getInt32Ty(Context), 1));
} else {
Director.reset(new WinEHCleanupDirector(Handler, VarInfo, LPadMap));
+ LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
+ UndefValue::get(Type::getInt32Ty(Context)));
}
SmallVector<ReturnInst *, 8> Returns;
reinterpret_cast<WinEHCatchDirector *>(Director.get());
CatchAction->setExceptionVar(CatchDirector->getExceptionVar());
CatchAction->setReturnTargets(CatchDirector->getReturnTargets());
- }
+
+ // 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 (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);
// 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;
-}
-
-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;
+ VMap[Extract] = SelectorValue;
}
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))
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 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.
WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer(
Function *OutlinedFn, FrameVarInfoMap &FrameVarInfo)
: FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) {
- Builder.SetInsertPoint(&OutlinedFn->getEntryBlock());
+ BasicBlock *EntryBB = &OutlinedFn->getEntryBlock();
+ Builder.SetInsertPoint(EntryBB, EntryBB->getFirstInsertionPt());
}
Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) {
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:
//
}
// These are helper functions to combine repeated code from findCleanupHandler.
-static CleanupHandler *createCleanupHandler(CleanupHandlerMapTy &CleanupHandlerMap,
- BasicBlock *BB) {
+static CleanupHandler *
+createCleanupHandler(CleanupHandlerMapTy &CleanupHandlerMap, BasicBlock *BB) {
CleanupHandler *Action = new CleanupHandler(BB);
CleanupHandlerMap[BB] = Action;
return Action;
}
// 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;
}
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 (BB == EndBB)
- return nullptr;
- // The branch was unconditional.
- BB = Branch->getSuccessor(0);
+ 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(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(CleanupHandlerMap, BB);
+ }
+ // The selector dispatch block should always terminate our search.
+ assert(BB == EndBB);
+ return nullptr;
+ }
+
+ // 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 nullptr;
+ // If this a nested landing pad, it may contain an endcatch call.
+ if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
+ return nullptr;
+ // Anything else makes this interesting cleanup code.
+ return createCleanupHandler(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 nullptr;
+ 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<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 = new CatchHandler(/*BB=*/nullptr, Selector, /*NextBB=*/nullptr);
+ CH->setHandlerBlockOrFunc(Handler);
+ CH->setExceptionVarIndex(EHObjIndexVal);
+ Actions.push_back(CH);
+ }
+ else {
+ assert(ActionKind == 0 && "expected a cleanup or a catch action!");
+ Constant *Handler = cast<Constant>(II->getArgOperand(I + 1));
+ I += 2;
+ auto *CH = new CleanupHandler(/*BB=*/nullptr);
+ CH->setHandlerBlockOrFunc(Handler);
+ Actions.push_back(CH);
+ }
+ }
+ std::reverse(Actions.begin(), Actions.end());
+}
+
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