//===----------------------------------------------------------------------===//
//
// This pass mulches exception handling code into a form adapted to code
-// generation. Required if using dwarf exception handling.
+// generation. Required if using dwarf exception handling.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "dwarfehprepare"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/Dominators.h"
-#include "llvm/CodeGen/Passes.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
-#include "llvm/Support/Compiler.h"
-#include "llvm/Support/IRBuilder.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/Support/CallSite.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/PromoteMemToReg.h"
+#include "llvm/Transforms/Utils/SSAUpdater.h"
using namespace llvm;
-STATISTIC(NumExceptionValuesMoved, "Number of eh.exception calls moved");
-STATISTIC(NumLonelyLandingPads, "Number of landing pads with no selector");
-STATISTIC(NumLonelySelectors, "Number of lonely selectors lowered");
STATISTIC(NumLandingPadsSplit, "Number of landing pads split");
-STATISTIC(NumSelectorsAdjusted, "Number of selector results adjusted");
-STATISTIC(NumSelectorsSimplified, "Number of selectors truncated");
-STATISTIC(NumStackTempsIntroduced, "Number of stack temporaries introduced");
STATISTIC(NumUnwindsLowered, "Number of unwind instructions lowered");
+STATISTIC(NumExceptionValuesMoved, "Number of eh.exception calls moved");
namespace {
class DwarfEHPrepare : public FunctionPass {
+ const TargetMachine *TM;
const TargetLowering *TLI;
// The eh.exception intrinsic.
- Function *ExceptionIntrinsic;
+ Function *ExceptionValueIntrinsic;
// The eh.selector intrinsic.
Function *SelectorIntrinsic;
- // The eh.typeid.for intrinsic.
- Function *TypeIdIntrinsic;
+ // _Unwind_Resume_or_Rethrow or _Unwind_SjLj_Resume call.
+ Constant *URoR;
+
+ // The EH language-specific catch-all type.
+ GlobalVariable *EHCatchAllValue;
// _Unwind_Resume or the target equivalent.
Constant *RewindFunction;
- // _Unwind_RaiseException.
- Constant *UnwindFunction;
-
- // Dominator info is used when turning stack temporaries into registers.
+ // We both use and preserve dominator info.
DominatorTree *DT;
- DominanceFrontier *DF;
// The function we are running on.
Function *F;
- // The current context.
- LLVMContext *Context;
-
- // The personality and catch-all value for this function.
- Constant *Personality;
- Constant *CatchAll;
-
// The landing pads for this function.
typedef SmallPtrSet<BasicBlock*, 8> BBSet;
BBSet LandingPads;
- // Stack temporary used to hold eh.exception values.
- AllocaInst *ExceptionValueVar;
-
bool NormalizeLandingPads();
bool LowerUnwinds();
- bool MoveSelectorCalls();
- bool RectifySelectorCalls();
bool MoveExceptionValueCalls();
- bool AddMissingSelectors();
- bool FinishStackTemporaries();
- bool PromoteStackTemporaries();
Instruction *CreateExceptionValueCall(BasicBlock *BB);
- Instruction *CreateValueLoad(BasicBlock *BB);
-
- /// CreateReadOfExceptionValue - Return the result of the eh.exception
- /// intrinsic by calling the intrinsic if in a landing pad, or loading
- /// it from the exception value variable otherwise.
- Instruction *CreateReadOfExceptionValue(BasicBlock *BB) {
- return LandingPads.count(BB) ?
- CreateExceptionValueCall(BB) : CreateValueLoad(BB);
- }
+ /// CleanupSelectors - Any remaining eh.selector intrinsic calls which still
+ /// use the "llvm.eh.catch.all.value" call need to convert to using its
+ /// initializer instead.
+ bool CleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels);
+
+ bool HasCatchAllInSelector(IntrinsicInst *);
+
+ /// FindAllCleanupSelectors - Find all eh.selector calls that are clean-ups.
+ void FindAllCleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels,
+ SmallPtrSet<IntrinsicInst*, 32> &CatchAllSels);
+
+ /// FindAllURoRInvokes - Find all URoR invokes in the function.
+ void FindAllURoRInvokes(SmallPtrSet<InvokeInst*, 32> &URoRInvokes);
+
+ /// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" or
+ /// "_Unwind_SjLj_Resume" calls. The "unwind" part of these invokes jump to
+ /// a landing pad within the current function. This is a candidate to merge
+ /// the selector associated with the URoR invoke with the one from the
+ /// URoR's landing pad.
+ bool HandleURoRInvokes();
+
+ /// FindSelectorAndURoR - Find the eh.selector call and URoR call associated
+ /// with the eh.exception call. This recursively looks past instructions
+ /// which don't change the EH pointer value, like casts or PHI nodes.
+ bool FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke,
+ SmallPtrSet<IntrinsicInst*, 8> &SelCalls,
+ SmallPtrSet<PHINode*, 32> &SeenPHIs);
+
public:
static char ID; // Pass identification, replacement for typeid.
- DwarfEHPrepare(const TargetLowering *tli) :
- FunctionPass(&ID), TLI(tli), ExceptionIntrinsic(0),
- SelectorIntrinsic(0), TypeIdIntrinsic(0), RewindFunction(0),
- UnwindFunction(0) {}
+ DwarfEHPrepare(const TargetMachine *tm) :
+ FunctionPass(ID), TM(tm), TLI(TM->getTargetLowering()),
+ ExceptionValueIntrinsic(0), SelectorIntrinsic(0),
+ URoR(0), EHCatchAllValue(0), RewindFunction(0) {
+ initializeDominatorTreePass(*PassRegistry::getPassRegistry());
+ }
virtual bool runOnFunction(Function &Fn);
+ // getAnalysisUsage - We need the dominator tree for handling URoR.
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<DominatorTree>();
+ AU.addPreserved<DominatorTree>();
+ }
+
const char *getPassName() const {
return "Exception handling preparation";
}
char DwarfEHPrepare::ID = 0;
-FunctionPass *llvm::createDwarfEHPass(const TargetLowering *tli) {
- return new DwarfEHPrepare(tli);
+FunctionPass *llvm::createDwarfEHPass(const TargetMachine *tm) {
+ return new DwarfEHPrepare(tm);
+}
+
+/// HasCatchAllInSelector - Return true if the intrinsic instruction has a
+/// catch-all.
+bool DwarfEHPrepare::HasCatchAllInSelector(IntrinsicInst *II) {
+ if (!EHCatchAllValue) return false;
+
+ unsigned ArgIdx = II->getNumArgOperands() - 1;
+ GlobalVariable *GV = dyn_cast<GlobalVariable>(II->getArgOperand(ArgIdx));
+ return GV == EHCatchAllValue;
+}
+
+/// FindAllCleanupSelectors - Find all eh.selector calls that are clean-ups.
+void DwarfEHPrepare::
+FindAllCleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels,
+ SmallPtrSet<IntrinsicInst*, 32> &CatchAllSels) {
+ for (Value::use_iterator
+ I = SelectorIntrinsic->use_begin(),
+ E = SelectorIntrinsic->use_end(); I != E; ++I) {
+ IntrinsicInst *II = cast<IntrinsicInst>(*I);
+
+ if (II->getParent()->getParent() != F)
+ continue;
+
+ if (!HasCatchAllInSelector(II))
+ Sels.insert(II);
+ else
+ CatchAllSels.insert(II);
+ }
+}
+
+/// FindAllURoRInvokes - Find all URoR invokes in the function.
+void DwarfEHPrepare::
+FindAllURoRInvokes(SmallPtrSet<InvokeInst*, 32> &URoRInvokes) {
+ for (Value::use_iterator
+ I = URoR->use_begin(),
+ E = URoR->use_end(); I != E; ++I) {
+ if (InvokeInst *II = dyn_cast<InvokeInst>(*I))
+ URoRInvokes.insert(II);
+ }
+}
+
+/// CleanupSelectors - Any remaining eh.selector intrinsic calls which still use
+/// the "llvm.eh.catch.all.value" call need to convert to using its
+/// initializer instead.
+bool DwarfEHPrepare::CleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels) {
+ if (!EHCatchAllValue) return false;
+
+ if (!SelectorIntrinsic) {
+ SelectorIntrinsic =
+ Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_selector);
+ if (!SelectorIntrinsic) return false;
+ }
+
+ bool Changed = false;
+ for (SmallPtrSet<IntrinsicInst*, 32>::iterator
+ I = Sels.begin(), E = Sels.end(); I != E; ++I) {
+ IntrinsicInst *Sel = *I;
+
+ // Index of the "llvm.eh.catch.all.value" variable.
+ unsigned OpIdx = Sel->getNumArgOperands() - 1;
+ GlobalVariable *GV = dyn_cast<GlobalVariable>(Sel->getArgOperand(OpIdx));
+ if (GV != EHCatchAllValue) continue;
+ Sel->setArgOperand(OpIdx, EHCatchAllValue->getInitializer());
+ Changed = true;
+ }
+
+ return Changed;
+}
+
+/// FindSelectorAndURoR - Find the eh.selector call associated with the
+/// eh.exception call. And indicate if there is a URoR "invoke" associated with
+/// the eh.exception call. This recursively looks past instructions which don't
+/// change the EH pointer value, like casts or PHI nodes.
+bool
+DwarfEHPrepare::FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke,
+ SmallPtrSet<IntrinsicInst*, 8> &SelCalls,
+ SmallPtrSet<PHINode*, 32> &SeenPHIs) {
+ bool Changed = false;
+
+ for (Value::use_iterator
+ I = Inst->use_begin(), E = Inst->use_end(); I != E; ++I) {
+ Instruction *II = dyn_cast<Instruction>(*I);
+ if (!II || II->getParent()->getParent() != F) continue;
+
+ if (IntrinsicInst *Sel = dyn_cast<IntrinsicInst>(II)) {
+ if (Sel->getIntrinsicID() == Intrinsic::eh_selector)
+ SelCalls.insert(Sel);
+ } else if (InvokeInst *Invoke = dyn_cast<InvokeInst>(II)) {
+ if (Invoke->getCalledFunction() == URoR)
+ URoRInvoke = true;
+ } else if (CastInst *CI = dyn_cast<CastInst>(II)) {
+ Changed |= FindSelectorAndURoR(CI, URoRInvoke, SelCalls, SeenPHIs);
+ } else if (PHINode *PN = dyn_cast<PHINode>(II)) {
+ if (SeenPHIs.insert(PN))
+ // Don't process a PHI node more than once.
+ Changed |= FindSelectorAndURoR(PN, URoRInvoke, SelCalls, SeenPHIs);
+ }
+ }
+
+ return Changed;
+}
+
+/// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" or
+/// "_Unwind_SjLj_Resume" calls. The "unwind" part of these invokes jump to a
+/// landing pad within the current function. This is a candidate to merge the
+/// selector associated with the URoR invoke with the one from the URoR's
+/// landing pad.
+bool DwarfEHPrepare::HandleURoRInvokes() {
+ if (!EHCatchAllValue) {
+ EHCatchAllValue =
+ F->getParent()->getNamedGlobal("llvm.eh.catch.all.value");
+ if (!EHCatchAllValue) return false;
+ }
+
+ if (!SelectorIntrinsic) {
+ SelectorIntrinsic =
+ Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_selector);
+ if (!SelectorIntrinsic) return false;
+ }
+
+ SmallPtrSet<IntrinsicInst*, 32> Sels;
+ SmallPtrSet<IntrinsicInst*, 32> CatchAllSels;
+ FindAllCleanupSelectors(Sels, CatchAllSels);
+
+ if (!URoR) {
+ URoR = F->getParent()->getFunction("_Unwind_Resume_or_Rethrow");
+ if (!URoR) {
+ URoR = F->getParent()->getFunction("_Unwind_SjLj_Resume");
+ if (!URoR) return CleanupSelectors(CatchAllSels);
+ }
+ }
+
+ SmallPtrSet<InvokeInst*, 32> URoRInvokes;
+ FindAllURoRInvokes(URoRInvokes);
+
+ SmallPtrSet<IntrinsicInst*, 32> SelsToConvert;
+
+ for (SmallPtrSet<IntrinsicInst*, 32>::iterator
+ SI = Sels.begin(), SE = Sels.end(); SI != SE; ++SI) {
+ const BasicBlock *SelBB = (*SI)->getParent();
+ for (SmallPtrSet<InvokeInst*, 32>::iterator
+ UI = URoRInvokes.begin(), UE = URoRInvokes.end(); UI != UE; ++UI) {
+ const BasicBlock *URoRBB = (*UI)->getParent();
+ if (DT->dominates(SelBB, URoRBB)) {
+ SelsToConvert.insert(*SI);
+ break;
+ }
+ }
+ }
+
+ bool Changed = false;
+
+ if (Sels.size() != SelsToConvert.size()) {
+ // If we haven't been able to convert all of the clean-up selectors, then
+ // loop through the slow way to see if they still need to be converted.
+ if (!ExceptionValueIntrinsic) {
+ ExceptionValueIntrinsic =
+ Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_exception);
+ if (!ExceptionValueIntrinsic)
+ return CleanupSelectors(CatchAllSels);
+ }
+
+ for (Value::use_iterator
+ I = ExceptionValueIntrinsic->use_begin(),
+ E = ExceptionValueIntrinsic->use_end(); I != E; ++I) {
+ IntrinsicInst *EHPtr = dyn_cast<IntrinsicInst>(*I);
+ if (!EHPtr || EHPtr->getParent()->getParent() != F) continue;
+
+ bool URoRInvoke = false;
+ SmallPtrSet<IntrinsicInst*, 8> SelCalls;
+ SmallPtrSet<PHINode*, 32> SeenPHIs;
+ Changed |= FindSelectorAndURoR(EHPtr, URoRInvoke, SelCalls, SeenPHIs);
+
+ if (URoRInvoke) {
+ // This EH pointer is being used by an invoke of an URoR instruction and
+ // an eh.selector intrinsic call. If the eh.selector is a 'clean-up', we
+ // need to convert it to a 'catch-all'.
+ for (SmallPtrSet<IntrinsicInst*, 8>::iterator
+ SI = SelCalls.begin(), SE = SelCalls.end(); SI != SE; ++SI)
+ if (!HasCatchAllInSelector(*SI))
+ SelsToConvert.insert(*SI);
+ }
+ }
+ }
+
+ if (!SelsToConvert.empty()) {
+ // Convert all clean-up eh.selectors, which are associated with "invokes" of
+ // URoR calls, into catch-all eh.selectors.
+ Changed = true;
+
+ for (SmallPtrSet<IntrinsicInst*, 8>::iterator
+ SI = SelsToConvert.begin(), SE = SelsToConvert.end();
+ SI != SE; ++SI) {
+ IntrinsicInst *II = *SI;
+
+ // Use the exception object pointer and the personality function
+ // from the original selector.
+ CallSite CS(II);
+ IntrinsicInst::op_iterator I = CS.arg_begin();
+ IntrinsicInst::op_iterator E = CS.arg_end();
+ IntrinsicInst::op_iterator B = prior(E);
+
+ // Exclude last argument if it is an integer.
+ if (isa<ConstantInt>(B)) E = B;
+
+ // Add exception object pointer (front).
+ // Add personality function (next).
+ // Add in any filter IDs (rest).
+ SmallVector<Value*, 8> Args(I, E);
+
+ Args.push_back(EHCatchAllValue->getInitializer()); // Catch-all indicator.
+
+ CallInst *NewSelector =
+ CallInst::Create(SelectorIntrinsic, Args.begin(), Args.end(),
+ "eh.sel.catch.all", II);
+
+ NewSelector->setTailCall(II->isTailCall());
+ NewSelector->setAttributes(II->getAttributes());
+ NewSelector->setCallingConv(II->getCallingConv());
+
+ II->replaceAllUsesWith(NewSelector);
+ II->eraseFromParent();
+ }
+ }
+
+ Changed |= CleanupSelectors(CatchAllSels);
+ return Changed;
}
/// NormalizeLandingPads - Normalize and discover landing pads, noting them
bool DwarfEHPrepare::NormalizeLandingPads() {
bool Changed = false;
+ const MCAsmInfo *MAI = TM->getMCAsmInfo();
+ bool usingSjLjEH = MAI->getExceptionHandlingType() == ExceptionHandling::SjLj;
+
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
TerminatorInst *TI = I->getTerminator();
if (!isa<InvokeInst>(TI))
// Check that only invoke unwind edges end at the landing pad.
bool OnlyUnwoundTo = true;
+ bool SwitchOK = usingSjLjEH;
for (pred_iterator PI = pred_begin(LPad), PE = pred_end(LPad);
PI != PE; ++PI) {
TerminatorInst *PT = (*PI)->getTerminator();
+ // The SjLj dispatch block uses a switch instruction. This is effectively
+ // an unwind edge, so we can disregard it here. There will only ever
+ // be one dispatch, however, so if there are multiple switches, one
+ // of them truly is a normal edge, not an unwind edge.
+ if (SwitchOK && isa<SwitchInst>(PT)) {
+ SwitchOK = false;
+ continue;
+ }
if (!isa<InvokeInst>(PT) || LPad == PT->getSuccessor(0)) {
OnlyUnwoundTo = false;
break;
// edges to a new basic block which falls through into this one.
// Create the new basic block.
- BasicBlock *NewBB = BasicBlock::Create(*Context,
+ BasicBlock *NewBB = BasicBlock::Create(F->getContext(),
LPad->getName() + "_unwind_edge");
// Insert it into the function right before the original landing pad.
if (InVal == 0) {
// Different unwind edges have different values. Create a new PHI node
// in NewBB.
- PHINode *NewPN = PHINode::Create(PN->getType(), PN->getName()+".unwind",
- NewBB);
+ PHINode *NewPN = PHINode::Create(PN->getType(),
+ PN->getNumIncomingValues(),
+ PN->getName()+".unwind", NewBB);
// Add an entry for each unwind edge, using the value from the old PHI.
for (pred_iterator PI = PB; PI != PE; ++PI)
NewPN->addIncoming(PN->getIncomingValueForBlock(*PI), *PI);
// Add a fallthrough from NewBB to the original landing pad.
BranchInst::Create(LPad, NewBB);
- // Now update DominatorTree and DominanceFrontier analysis information.
- if (DT)
- DT->splitBlock(NewBB);
- if (DF)
- DF->splitBlock(NewBB);
+ // Now update DominatorTree analysis information.
+ DT->splitBlock(NewBB);
// Remember the newly constructed landing pad. The original landing pad
// LPad is no longer a landing pad now that all unwind edges have been
// Find the rewind function if we didn't already.
if (!RewindFunction) {
+ LLVMContext &Ctx = UnwindInsts[0]->getContext();
std::vector<const Type*>
- Params(1, Type::getInt8PtrTy(*Context));
- FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Context),
+ Params(1, Type::getInt8PtrTy(Ctx));
+ FunctionType *FTy = FunctionType::get(Type::getVoidTy(Ctx),
Params, false);
const char *RewindName = TLI->getLibcallName(RTLIB::UNWIND_RESUME);
RewindFunction = F->getParent()->getOrInsertFunction(RewindName, FTy);
}
+ bool Changed = false;
+
for (SmallVectorImpl<TerminatorInst*>::iterator
I = UnwindInsts.begin(), E = UnwindInsts.end(); I != E; ++I) {
TerminatorInst *TI = *I;
// Create the call...
CallInst *CI = CallInst::Create(RewindFunction,
- CreateReadOfExceptionValue(TI->getParent()),
+ CreateExceptionValueCall(TI->getParent()),
"", TI);
CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
// ...followed by an UnreachableInst.
- new UnreachableInst(*Context, TI);
+ new UnreachableInst(TI->getContext(), TI);
// Nuke the unwind instruction.
TI->eraseFromParent();
++NumUnwindsLowered;
- }
-
- return true;
-}
-
-/// MoveSelectorCalls - Make sure that every call to eh.selector occurs in its
-/// own landing pad, the landing pad corresponding to the exception object.
-bool DwarfEHPrepare::MoveSelectorCalls() {
- // If the eh.selector intrinsic is not declared in the module then there is
- // nothing to do. Speed up compilation by checking for this common case.
- if (!F->getParent()->getFunction(Intrinsic::getName(Intrinsic::eh_selector)))
- return false;
-
- // TODO: There is a lot of room for optimization here.
-
- bool Changed = false;
- BasicBlock *UnrBB = 0;
-
- for (Function::iterator BB = F->begin(); BB != F->end(); ++BB) {
- // If this basic block is not a landing pad then synthesize a landing pad
- // for every selector in it.
- bool SynthesizeLandingPad = !LandingPads.count(BB);
-
- for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE; ++II) {
- EHSelectorInst *SI = dyn_cast<EHSelectorInst>(II);
- // Only interested in eh.selector calls.
- if (!SI)
- continue;
-
- // Note the personality and catch-all for later use.
- Personality = cast<Constant>(SI->getOperand(2));
- CatchAll = cast<Constant>(SI->getOperand(SI->getNumOperands() - 1)
- ->stripPointerCasts());
-
- // The exception object.
- Value *Exception = SI->getOperand(1);
-
- if (!SynthesizeLandingPad) {
- // Did the exception come from unwinding to this landing pad or another?
- // If it comes from a different landing pad then we need to synthesize a
- // new landing pad for the selector.
- EHExceptionInst *EI = dyn_cast<EHExceptionInst>(Exception);
- SynthesizeLandingPad = !EI || EI->getParent() != BB;
- }
-
- if (!SynthesizeLandingPad) {
- // This is the first selector in this landing pad, and it is the landing
- // pad corresponding to the exception object. No need to do anything to
- // this selector, but any subsequent selectors in this landing pad will
- // need their own invoke in order to make them independent of this one.
- SynthesizeLandingPad = true;
- continue;
- }
-
- // Rethrow the exception and catch it again, generating a landing pad for
- // this selector to live in.
-
- // Find _Unwind_RaiseException if we didn't already.
- if (!UnwindFunction) {
- std::vector<const Type*> ArgTys(1, Type::getInt8PtrTy(*Context));
- const FunctionType *FTy =
- FunctionType::get(Type::getInt32Ty(*Context), ArgTys, true);
-
- const char *Name = "_Unwind_RaiseException";
- UnwindFunction = F->getParent()->getOrInsertFunction(Name, FTy);
- }
-
- // Create a basic block containing only an unreachable instruction if we
- // didn't already.
- if (!UnrBB) {
- UnrBB = BasicBlock::Create(*Context, "unreachable", F);
- new UnreachableInst(*Context, UnrBB);
- }
-
- // Split the basic block before the selector.
- BasicBlock *NewBB = SplitBlock(BB, SI, this);
-
- // Replace the terminator with an invoke of _Unwind_RaiseException.
- BB->getTerminator()->eraseFromParent();
- InvokeInst::Create(UnwindFunction, UnrBB, NewBB, &Exception,
- 1 + &Exception, "", BB);
-
- // The split off basic block is now a landing pad.
- LandingPads.insert(NewBB);
-
- // Replace the exception argument in the selector call with a call to
- // eh.exception. This is not really necessary but it makes things more
- // regular.
- Exception = CreateExceptionValueCall(NewBB);
- SI->setOperand(1, Exception);
-
- ++NumLonelySelectors;
- Changed = true;
-
- // All instructions still in the original basic block have been scanned.
- // Move on to the next basic block.
- break;
- }
- }
-
- return Changed;
-}
-
-/// RectifySelectorCalls - Remove useless catch-all clauses from the ends of
-/// selectors, or correct the selector result for the presence of the catch-all
-/// if it is really needed.
-bool DwarfEHPrepare::RectifySelectorCalls() {
- // If the eh.selector intrinsic is not declared in the module then there is
- // nothing to do. Speed up compilation by checking for this common case.
- if (!F->getParent()->getFunction(Intrinsic::getName(Intrinsic::eh_selector)))
- return false;
-
- bool Changed = false;
-
- for (BBSet::iterator I = LandingPads.begin(), E = LandingPads.end(); I != E;
- ++I)
- for (BasicBlock::iterator II = (*I)->begin(), IE = (*I)->end(); II != IE; )
- if (EHSelectorInst *SI = dyn_cast<EHSelectorInst>(II++)) {
- // Found a call to eh.selector. Check whether it has a catch-all in the
- // middle.
- unsigned LastIndex = 0;
- for (unsigned i = 3, e = SI->getNumOperands() - 1; i < e; ++i) {
- Value *V = SI->getOperand(i);
- if (V->stripPointerCasts() == CatchAll) {
- // A catch-all. The catch-all at the end was not needed.
- LastIndex = i;
- break;
- } else if (ConstantInt *FilterLength = dyn_cast<ConstantInt>(V)) {
- // A cleanup or a filter.
- unsigned Length = FilterLength->getZExtValue();
- if (Length == 0)
- // A cleanup - skip it.
- continue;
- if (Length == 1) {
- // A catch-all filter. Drop everything that follows.
- LastIndex = i;
- break;
- }
- // A filter, skip over the typeinfos.
- i += Length - 1;
- }
- }
-
- if (LastIndex) {
- // Drop the pointless catch-all from the end. In fact drop everything
- // after LastIndex as an optimization.
- SmallVector<Value*, 16> Args;
- Args.reserve(LastIndex);
- for (unsigned i = 1; i <= LastIndex; ++i)
- Args.push_back(SI->getOperand(i));
- CallInst *CI = CallInst::Create(SI->getOperand(0), Args.begin(),
- Args.end(), "", SI);
- CI->takeName(SI);
- SI->replaceAllUsesWith(CI);
- SI->eraseFromParent();
- ++NumSelectorsSimplified;
- } else if (!isa<ConstantInt>(CatchAll) && // Not a cleanup.
- !SI->use_empty()) {
- // Correct the selector value to return zero if the catch-all matches.
- Constant *Zero = ConstantInt::getNullValue(Type::getInt32Ty(*Context));
-
- // Create the new selector value, with placeholders instead of the
- // real operands and make everyone use it. The reason for this round
- // about approach is that the computation of the new value makes use
- // of the old value, so we can't just compute it then do RAUW.
- SelectInst *S = SelectInst::Create(ConstantInt::getFalse(*Context),
- Zero, Zero, "", II);
- SI->replaceAllUsesWith(S);
-
- // Now calculate the operands of the select.
- IRBuilder<> Builder(*I, S);
-
- // Find the eh.typeid.for intrinsic if we didn't already.
- if (!TypeIdIntrinsic)
- TypeIdIntrinsic = Intrinsic::getDeclaration(F->getParent(),
- Intrinsic::eh_typeid_for);
-
- // Obtain the id of the catch-all.
- Value *CatchAllId = Builder.CreateCall(TypeIdIntrinsic,
- ConstantExpr::getBitCast(CatchAll, Type::getInt8PtrTy(*Context)));
-
- // Compare it with the original selector result. If it matched then
- // the selector result is zero, otherwise it is the original selector.
- Value *MatchesCatchAll = Builder.CreateICmpEQ(SI, CatchAllId);
- S->setOperand(0, MatchesCatchAll);
- S->setOperand(2, SI);
- ++NumSelectorsAdjusted;
- }
-
- Changed = true;
- break;
- }
-
- return Changed;
-}
-
-/// Make sure every landing pad has a selector in it.
-bool DwarfEHPrepare::AddMissingSelectors() {
- if (!Personality)
- // We only know how to codegen invokes if there is a personality.
- // FIXME: This results in wrong code.
- return false;
-
- bool Changed = false;
-
- for (BBSet::iterator I = LandingPads.begin(), E = LandingPads.end(); I != E;
- ++I) {
- bool FoundSelector = false;
-
- // Check whether the landing pad already contains a call to eh.selector.
- for (BasicBlock::iterator II = (*I)->begin(), IE = (*I)->end(); II != IE;
- ++II)
- if (isa<EHSelectorInst>(II)) {
- FoundSelector = true;
- break;
- }
-
- if (FoundSelector)
- continue;
-
- // Find the eh.selector intrinsic if we didn't already.
- if (!SelectorIntrinsic)
- SelectorIntrinsic = Intrinsic::getDeclaration(F->getParent(),
- Intrinsic::eh_selector);
-
- // Get the exception object.
- Instruction *Exception = CreateExceptionValueCall(*I);
-
- Value *Args[3] = { Exception, Personality, CatchAll };
- CallInst *Selector = CallInst::Create(SelectorIntrinsic, Args, Args + 3);
- Selector->insertAfter(Exception);
-
- ++NumLonelyLandingPads;
Changed = true;
}
}
/// MoveExceptionValueCalls - Ensure that eh.exception is only ever called from
-/// landing pads by replacing calls outside of landing pads with loads from a
-/// stack temporary. Move eh.exception calls inside landing pads to the start
-/// of the landing pad (optional, but may make things simpler for later passes).
+/// landing pads by replacing calls outside of landing pads with direct use of
+/// a register holding the appropriate value; this requires adding calls inside
+/// all landing pads to initialize the register. Also, move eh.exception calls
+/// inside landing pads to the start of the landing pad (optional, but may make
+/// things simpler for later passes).
bool DwarfEHPrepare::MoveExceptionValueCalls() {
// If the eh.exception intrinsic is not declared in the module then there is
// nothing to do. Speed up compilation by checking for this common case.
- if (!ExceptionIntrinsic &&
+ if (!ExceptionValueIntrinsic &&
!F->getParent()->getFunction(Intrinsic::getName(Intrinsic::eh_exception)))
return false;
bool Changed = false;
- for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
- for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E;)
- if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(II++))
- if (CI->getIntrinsicID() == Intrinsic::eh_exception) {
- if (!CI->use_empty()) {
- Value *ExceptionValue = CreateReadOfExceptionValue(BB);
- if (CI == ExceptionValue) {
- // The call was at the start of a landing pad - leave it alone.
- assert(LandingPads.count(BB) &&
- "Created eh.exception call outside landing pad!");
- continue;
- }
- CI->replaceAllUsesWith(ExceptionValue);
- }
- CI->eraseFromParent();
- ++NumExceptionValuesMoved;
- Changed = true;
+ // Move calls to eh.exception that are inside a landing pad to the start of
+ // the landing pad.
+ for (BBSet::const_iterator LI = LandingPads.begin(), LE = LandingPads.end();
+ LI != LE; ++LI) {
+ BasicBlock *LP = *LI;
+ for (BasicBlock::iterator II = LP->getFirstNonPHIOrDbg(), IE = LP->end();
+ II != IE;)
+ if (EHExceptionInst *EI = dyn_cast<EHExceptionInst>(II++)) {
+ // Found a call to eh.exception.
+ if (!EI->use_empty()) {
+ // If there is already a call to eh.exception at the start of the
+ // landing pad, then get hold of it; otherwise create such a call.
+ Value *CallAtStart = CreateExceptionValueCall(LP);
+
+ // If the call was at the start of a landing pad then leave it alone.
+ if (EI == CallAtStart)
+ continue;
+ EI->replaceAllUsesWith(CallAtStart);
}
+ EI->eraseFromParent();
+ ++NumExceptionValuesMoved;
+ Changed = true;
+ }
}
- return Changed;
-}
-
-/// FinishStackTemporaries - If we introduced a stack variable to hold the
-/// exception value then initialize it in each landing pad.
-bool DwarfEHPrepare::FinishStackTemporaries() {
- if (!ExceptionValueVar)
- // Nothing to do.
- return false;
+ // Look for calls to eh.exception that are not in a landing pad. If one is
+ // found, then a register that holds the exception value will be created in
+ // each landing pad, and the SSAUpdater will be used to compute the values
+ // returned by eh.exception calls outside of landing pads.
+ SSAUpdater SSA;
+
+ // Remember where we found the eh.exception call, to avoid rescanning earlier
+ // basic blocks which we already know contain no eh.exception calls.
+ bool FoundCallOutsideLandingPad = false;
+ Function::iterator BB = F->begin();
+ for (Function::iterator BE = F->end(); BB != BE; ++BB) {
+ // Skip over landing pads.
+ if (LandingPads.count(BB))
+ continue;
- bool Changed = false;
+ for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
+ II != IE; ++II)
+ if (isa<EHExceptionInst>(II)) {
+ SSA.Initialize(II->getType(), II->getName());
+ FoundCallOutsideLandingPad = true;
+ break;
+ }
- // Make sure that there is a store of the exception value at the start of
- // each landing pad.
- for (BBSet::iterator LI = LandingPads.begin(), LE = LandingPads.end();
- LI != LE; ++LI) {
- Instruction *ExceptionValue = CreateReadOfExceptionValue(*LI);
- Instruction *Store = new StoreInst(ExceptionValue, ExceptionValueVar);
- Store->insertAfter(ExceptionValue);
- Changed = true;
+ if (FoundCallOutsideLandingPad)
+ break;
}
- return Changed;
-}
+ // If all calls to eh.exception are in landing pads then we are done.
+ if (!FoundCallOutsideLandingPad)
+ return Changed;
-/// PromoteStackTemporaries - Turn any stack temporaries we introduced into
-/// registers if possible.
-bool DwarfEHPrepare::PromoteStackTemporaries() {
- if (ExceptionValueVar && DT && DF && isAllocaPromotable(ExceptionValueVar)) {
- // Turn the exception temporary into registers and phi nodes if possible.
- std::vector<AllocaInst*> Allocas(1, ExceptionValueVar);
- PromoteMemToReg(Allocas, *DT, *DF, *Context);
- return true;
+ // Add a call to eh.exception at the start of each landing pad, and tell the
+ // SSAUpdater that this is the value produced by the landing pad.
+ for (BBSet::iterator LI = LandingPads.begin(), LE = LandingPads.end();
+ LI != LE; ++LI)
+ SSA.AddAvailableValue(*LI, CreateExceptionValueCall(*LI));
+
+ // Now turn all calls to eh.exception that are not in a landing pad into a use
+ // of the appropriate register.
+ for (Function::iterator BE = F->end(); BB != BE; ++BB) {
+ // Skip over landing pads.
+ if (LandingPads.count(BB))
+ continue;
+
+ for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
+ II != IE;)
+ if (EHExceptionInst *EI = dyn_cast<EHExceptionInst>(II++)) {
+ // Found a call to eh.exception, replace it with the value from any
+ // upstream landing pad(s).
+ EI->replaceAllUsesWith(SSA.GetValueAtEndOfBlock(BB));
+ EI->eraseFromParent();
+ ++NumExceptionValuesMoved;
+ }
}
- return false;
+
+ return true;
}
/// CreateExceptionValueCall - Insert a call to the eh.exception intrinsic at
/// the start of the basic block (unless there already is one, in which case
/// the existing call is returned).
Instruction *DwarfEHPrepare::CreateExceptionValueCall(BasicBlock *BB) {
- Instruction *Start = BB->getFirstNonPHI();
+ Instruction *Start = BB->getFirstNonPHIOrDbg();
// Is this a call to eh.exception?
if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(Start))
if (CI->getIntrinsicID() == Intrinsic::eh_exception)
return Start;
// Find the eh.exception intrinsic if we didn't already.
- if (!ExceptionIntrinsic)
- ExceptionIntrinsic = Intrinsic::getDeclaration(F->getParent(),
+ if (!ExceptionValueIntrinsic)
+ ExceptionValueIntrinsic = Intrinsic::getDeclaration(F->getParent(),
Intrinsic::eh_exception);
// Create the call.
- return CallInst::Create(ExceptionIntrinsic, "eh.value.call", Start);
-}
-
-/// CreateValueLoad - Insert a load of the exception value stack variable
-/// (creating it if necessary) at the start of the basic block (unless
-/// there already is a load, in which case the existing load is returned).
-Instruction *DwarfEHPrepare::CreateValueLoad(BasicBlock *BB) {
- Instruction *Start = BB->getFirstNonPHI();
- // Is this a load of the exception temporary?
- if (ExceptionValueVar)
- if (LoadInst* LI = dyn_cast<LoadInst>(Start))
- if (LI->getPointerOperand() == ExceptionValueVar)
- // Reuse the existing load.
- return Start;
-
- // Create the temporary if we didn't already.
- if (!ExceptionValueVar) {
- ExceptionValueVar = new AllocaInst(PointerType::getUnqual(
- Type::getInt8Ty(*Context)), "eh.value", F->begin()->begin());
- ++NumStackTempsIntroduced;
- }
-
- // Load the value.
- return new LoadInst(ExceptionValueVar, "eh.value.load", Start);
+ return CallInst::Create(ExceptionValueIntrinsic, "eh.value.call", Start);
}
bool DwarfEHPrepare::runOnFunction(Function &Fn) {
bool Changed = false;
// Initialize internal state.
- DT = getAnalysisIfAvailable<DominatorTree>();
- DF = getAnalysisIfAvailable<DominanceFrontier>();
- ExceptionValueVar = 0;
- Personality = 0;
- CatchAll = 0;
- Context = &Fn.getContext();
+ DT = &getAnalysis<DominatorTree>();
F = &Fn;
// Ensure that only unwind edges end at landing pads (a landing pad is a
// Turn unwind instructions into libcalls.
Changed |= LowerUnwinds();
- // Make sure that every call to eh.selector occurs in its own landing pad.
- Changed |= MoveSelectorCalls();
-
- // Remove useless catch-all clauses from the ends of selectors, or correct the
- // selector result for the presence of the catch-all if it is really needed.
- Changed |= RectifySelectorCalls();
-
- // Make sure every landing pad has a selector in it.
- Changed |= AddMissingSelectors();
+ // TODO: Move eh.selector calls to landing pads and combine them.
// Move eh.exception calls to landing pads.
Changed |= MoveExceptionValueCalls();
- // Initialize any stack temporaries we introduced.
- Changed |= FinishStackTemporaries();
-
- // Turn any stack temporaries into registers if possible.
-//TODO if (!CompileFast)
-//TODO Changed |= PromoteStackTemporaries();
+ Changed |= HandleURoRInvokes();
LandingPads.clear();
projects / oota-llvm.git / blobdiff