mirror of
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55e59c1863
than just getting one through a TargetLowering. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101802 91177308-0d34-0410-b5e6-96231b3b80d8
739 lines
26 KiB
C++
739 lines
26 KiB
C++
//===-- DwarfEHPrepare - Prepare exception handling for code generation ---===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass mulches exception handling code into a form adapted to code
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// generation. Required if using dwarf exception handling.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "dwarfehprepare"
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#include "llvm/Function.h"
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#include "llvm/Instructions.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/Target/TargetLowering.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/PromoteMemToReg.h"
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using namespace llvm;
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STATISTIC(NumLandingPadsSplit, "Number of landing pads split");
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STATISTIC(NumUnwindsLowered, "Number of unwind instructions lowered");
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STATISTIC(NumExceptionValuesMoved, "Number of eh.exception calls moved");
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STATISTIC(NumStackTempsIntroduced, "Number of stack temporaries introduced");
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namespace {
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class DwarfEHPrepare : public FunctionPass {
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const TargetMachine *TM;
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const TargetLowering *TLI;
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bool CompileFast;
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// The eh.exception intrinsic.
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Function *ExceptionValueIntrinsic;
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// The eh.selector intrinsic.
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Function *SelectorIntrinsic;
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// _Unwind_Resume_or_Rethrow call.
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Constant *URoR;
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// The EH language-specific catch-all type.
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GlobalVariable *EHCatchAllValue;
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// _Unwind_Resume or the target equivalent.
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Constant *RewindFunction;
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// Dominator info is used when turning stack temporaries into registers.
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DominatorTree *DT;
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DominanceFrontier *DF;
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// The function we are running on.
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Function *F;
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// The landing pads for this function.
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typedef SmallPtrSet<BasicBlock*, 8> BBSet;
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BBSet LandingPads;
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// Stack temporary used to hold eh.exception values.
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AllocaInst *ExceptionValueVar;
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bool NormalizeLandingPads();
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bool LowerUnwinds();
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bool MoveExceptionValueCalls();
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bool FinishStackTemporaries();
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bool PromoteStackTemporaries();
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Instruction *CreateExceptionValueCall(BasicBlock *BB);
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Instruction *CreateValueLoad(BasicBlock *BB);
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/// CreateReadOfExceptionValue - Return the result of the eh.exception
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/// intrinsic by calling the intrinsic if in a landing pad, or loading it
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/// from the exception value variable otherwise.
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Instruction *CreateReadOfExceptionValue(BasicBlock *BB) {
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return LandingPads.count(BB) ?
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CreateExceptionValueCall(BB) : CreateValueLoad(BB);
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}
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/// CleanupSelectors - Any remaining eh.selector intrinsic calls which still
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/// use the ".llvm.eh.catch.all.value" call need to convert to using its
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/// initializer instead.
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bool CleanupSelectors();
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/// FindAllCleanupSelectors - Find all eh.selector calls that are clean-ups.
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void FindAllCleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels);
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/// FindAllURoRInvokes - Find all URoR invokes in the function.
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void FindAllURoRInvokes(SmallPtrSet<InvokeInst*, 32> &URoRInvokes);
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/// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow"
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/// calls. The "unwind" part of these invokes jump to a landing pad within
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/// the current function. This is a candidate to merge the selector
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/// associated with the URoR invoke with the one from the URoR's landing
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/// pad.
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bool HandleURoRInvokes();
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/// FindSelectorAndURoR - Find the eh.selector call and URoR call associated
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/// with the eh.exception call. This recursively looks past instructions
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/// which don't change the EH pointer value, like casts or PHI nodes.
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bool FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke,
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SmallPtrSet<IntrinsicInst*, 8> &SelCalls);
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/// DoMem2RegPromotion - Take an alloca call and promote it from memory to a
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/// register.
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bool DoMem2RegPromotion(Value *V) {
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AllocaInst *AI = dyn_cast<AllocaInst>(V);
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if (!AI || !isAllocaPromotable(AI)) return false;
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// Turn the alloca into a register.
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std::vector<AllocaInst*> Allocas(1, AI);
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PromoteMemToReg(Allocas, *DT, *DF);
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return true;
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}
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/// PromoteStoreInst - Perform Mem2Reg on a StoreInst.
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bool PromoteStoreInst(StoreInst *SI) {
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if (!SI || !DT || !DF) return false;
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if (DoMem2RegPromotion(SI->getOperand(1)))
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return true;
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return false;
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}
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/// PromoteEHPtrStore - Promote the storing of an EH pointer into a
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/// register. This should get rid of the store and subsequent loads.
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bool PromoteEHPtrStore(IntrinsicInst *II) {
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if (!DT || !DF) return false;
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bool Changed = false;
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StoreInst *SI;
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while (1) {
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SI = 0;
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for (Value::use_iterator
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I = II->use_begin(), E = II->use_end(); I != E; ++I) {
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SI = dyn_cast<StoreInst>(I);
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if (SI) break;
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}
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if (!PromoteStoreInst(SI))
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break;
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Changed = true;
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}
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return false;
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}
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public:
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static char ID; // Pass identification, replacement for typeid.
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DwarfEHPrepare(const TargetMachine *tm, bool fast) :
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FunctionPass(&ID), TM(tm), TLI(TM->getTargetLowering()),
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CompileFast(fast),
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ExceptionValueIntrinsic(0), SelectorIntrinsic(0),
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URoR(0), EHCatchAllValue(0), RewindFunction(0) {}
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virtual bool runOnFunction(Function &Fn);
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// getAnalysisUsage - We need dominance frontiers for memory promotion.
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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if (!CompileFast)
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AU.addRequired<DominatorTree>();
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AU.addPreserved<DominatorTree>();
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if (!CompileFast)
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AU.addRequired<DominanceFrontier>();
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AU.addPreserved<DominanceFrontier>();
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}
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const char *getPassName() const {
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return "Exception handling preparation";
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}
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};
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} // end anonymous namespace
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char DwarfEHPrepare::ID = 0;
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FunctionPass *llvm::createDwarfEHPass(const TargetMachine *tm, bool fast) {
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return new DwarfEHPrepare(tm, fast);
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}
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/// FindAllCleanupSelectors - Find all eh.selector calls that are clean-ups.
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void DwarfEHPrepare::
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FindAllCleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels) {
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for (Value::use_iterator
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I = SelectorIntrinsic->use_begin(),
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E = SelectorIntrinsic->use_end(); I != E; ++I) {
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IntrinsicInst *SI = cast<IntrinsicInst>(I);
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if (!SI || SI->getParent()->getParent() != F) continue;
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unsigned NumOps = SI->getNumOperands();
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if (NumOps > 4) continue;
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bool IsCleanUp = (NumOps == 3);
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if (!IsCleanUp)
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if (ConstantInt *CI = dyn_cast<ConstantInt>(SI->getOperand(3)))
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IsCleanUp = (CI->getZExtValue() == 0);
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if (IsCleanUp)
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Sels.insert(SI);
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}
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}
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/// FindAllURoRInvokes - Find all URoR invokes in the function.
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void DwarfEHPrepare::
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FindAllURoRInvokes(SmallPtrSet<InvokeInst*, 32> &URoRInvokes) {
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for (Value::use_iterator
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I = URoR->use_begin(),
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E = URoR->use_end(); I != E; ++I) {
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if (InvokeInst *II = dyn_cast<InvokeInst>(I))
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URoRInvokes.insert(II);
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}
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}
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/// CleanupSelectors - Any remaining eh.selector intrinsic calls which still use
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/// the ".llvm.eh.catch.all.value" call need to convert to using its
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/// initializer instead.
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bool DwarfEHPrepare::CleanupSelectors() {
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if (!EHCatchAllValue) return false;
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if (!SelectorIntrinsic) {
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SelectorIntrinsic =
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Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_selector);
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if (!SelectorIntrinsic) return false;
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}
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bool Changed = false;
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for (Value::use_iterator
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I = SelectorIntrinsic->use_begin(),
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E = SelectorIntrinsic->use_end(); I != E; ++I) {
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IntrinsicInst *Sel = dyn_cast<IntrinsicInst>(I);
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if (!Sel || Sel->getParent()->getParent() != F) continue;
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// Index of the ".llvm.eh.catch.all.value" variable.
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unsigned OpIdx = Sel->getNumOperands() - 1;
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GlobalVariable *GV = dyn_cast<GlobalVariable>(Sel->getOperand(OpIdx));
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if (GV != EHCatchAllValue) continue;
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Sel->setOperand(OpIdx, EHCatchAllValue->getInitializer());
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Changed = true;
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}
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return Changed;
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}
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/// FindSelectorAndURoR - Find the eh.selector call associated with the
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/// eh.exception call. And indicate if there is a URoR "invoke" associated with
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/// the eh.exception call. This recursively looks past instructions which don't
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/// change the EH pointer value, like casts or PHI nodes.
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bool
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DwarfEHPrepare::FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke,
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SmallPtrSet<IntrinsicInst*, 8> &SelCalls) {
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SmallPtrSet<PHINode*, 32> SeenPHIs;
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bool Changed = false;
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restart:
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for (Value::use_iterator
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I = Inst->use_begin(), E = Inst->use_end(); I != E; ++I) {
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Instruction *II = dyn_cast<Instruction>(I);
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if (!II || II->getParent()->getParent() != F) continue;
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if (IntrinsicInst *Sel = dyn_cast<IntrinsicInst>(II)) {
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if (Sel->getIntrinsicID() == Intrinsic::eh_selector)
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SelCalls.insert(Sel);
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} else if (InvokeInst *Invoke = dyn_cast<InvokeInst>(II)) {
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if (Invoke->getCalledFunction() == URoR)
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URoRInvoke = true;
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} else if (CastInst *CI = dyn_cast<CastInst>(II)) {
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Changed |= FindSelectorAndURoR(CI, URoRInvoke, SelCalls);
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} else if (StoreInst *SI = dyn_cast<StoreInst>(II)) {
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if (!PromoteStoreInst(SI)) continue;
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Changed = true;
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SeenPHIs.clear();
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goto restart; // Uses may have changed, restart loop.
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} else if (PHINode *PN = dyn_cast<PHINode>(II)) {
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if (SeenPHIs.insert(PN))
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// Don't process a PHI node more than once.
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Changed |= FindSelectorAndURoR(PN, URoRInvoke, SelCalls);
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}
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}
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return Changed;
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}
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/// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" calls. The
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/// "unwind" part of these invokes jump to a landing pad within the current
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/// function. This is a candidate to merge the selector associated with the URoR
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/// invoke with the one from the URoR's landing pad.
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bool DwarfEHPrepare::HandleURoRInvokes() {
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if (!DT) return CleanupSelectors(); // We require DominatorTree information.
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if (!EHCatchAllValue) {
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EHCatchAllValue =
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F->getParent()->getNamedGlobal(".llvm.eh.catch.all.value");
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if (!EHCatchAllValue) return false;
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}
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if (!SelectorIntrinsic) {
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SelectorIntrinsic =
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Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_selector);
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if (!SelectorIntrinsic) return false;
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}
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if (!URoR) {
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URoR = F->getParent()->getFunction("_Unwind_Resume_or_Rethrow");
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if (!URoR) return CleanupSelectors();
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}
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SmallPtrSet<IntrinsicInst*, 32> Sels;
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SmallPtrSet<InvokeInst*, 32> URoRInvokes;
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FindAllCleanupSelectors(Sels);
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FindAllURoRInvokes(URoRInvokes);
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SmallPtrSet<IntrinsicInst*, 32> SelsToConvert;
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for (SmallPtrSet<IntrinsicInst*, 32>::iterator
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SI = Sels.begin(), SE = Sels.end(); SI != SE; ++SI) {
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const BasicBlock *SelBB = (*SI)->getParent();
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for (SmallPtrSet<InvokeInst*, 32>::iterator
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UI = URoRInvokes.begin(), UE = URoRInvokes.end(); UI != UE; ++UI) {
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const BasicBlock *URoRBB = (*UI)->getParent();
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if (SelBB == URoRBB || DT->dominates(SelBB, URoRBB)) {
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SelsToConvert.insert(*SI);
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break;
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}
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}
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}
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bool Changed = false;
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if (Sels.size() != SelsToConvert.size()) {
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// If we haven't been able to convert all of the clean-up selectors, then
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// loop through the slow way to see if they still need to be converted.
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if (!ExceptionValueIntrinsic) {
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ExceptionValueIntrinsic =
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Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_exception);
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if (!ExceptionValueIntrinsic) return CleanupSelectors();
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}
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for (Value::use_iterator
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I = ExceptionValueIntrinsic->use_begin(),
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E = ExceptionValueIntrinsic->use_end(); I != E; ++I) {
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IntrinsicInst *EHPtr = dyn_cast<IntrinsicInst>(I);
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if (!EHPtr || EHPtr->getParent()->getParent() != F) continue;
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Changed |= PromoteEHPtrStore(EHPtr);
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bool URoRInvoke = false;
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SmallPtrSet<IntrinsicInst*, 8> SelCalls;
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Changed |= FindSelectorAndURoR(EHPtr, URoRInvoke, SelCalls);
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if (URoRInvoke) {
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// This EH pointer is being used by an invoke of an URoR instruction and
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// an eh.selector intrinsic call. If the eh.selector is a 'clean-up', we
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// need to convert it to a 'catch-all'.
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for (SmallPtrSet<IntrinsicInst*, 8>::iterator
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SI = SelCalls.begin(), SE = SelCalls.end(); SI != SE; ++SI) {
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IntrinsicInst *II = *SI;
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unsigned NumOps = II->getNumOperands();
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if (NumOps <= 4) {
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bool IsCleanUp = (NumOps == 3);
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if (!IsCleanUp)
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if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getOperand(3)))
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IsCleanUp = (CI->getZExtValue() == 0);
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if (IsCleanUp)
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SelsToConvert.insert(II);
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}
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}
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}
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}
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}
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if (!SelsToConvert.empty()) {
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// Convert all clean-up eh.selectors, which are associated with "invokes" of
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// URoR calls, into catch-all eh.selectors.
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Changed = true;
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for (SmallPtrSet<IntrinsicInst*, 8>::iterator
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SI = SelsToConvert.begin(), SE = SelsToConvert.end();
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SI != SE; ++SI) {
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IntrinsicInst *II = *SI;
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SmallVector<Value*, 8> Args;
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// Use the exception object pointer and the personality function
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// from the original selector.
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Args.push_back(II->getOperand(1)); // Exception object pointer.
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Args.push_back(II->getOperand(2)); // Personality function.
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Args.push_back(EHCatchAllValue->getInitializer()); // Catch-all indicator.
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CallInst *NewSelector =
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CallInst::Create(SelectorIntrinsic, Args.begin(), Args.end(),
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"eh.sel.catch.all", II);
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NewSelector->setTailCall(II->isTailCall());
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NewSelector->setAttributes(II->getAttributes());
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NewSelector->setCallingConv(II->getCallingConv());
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II->replaceAllUsesWith(NewSelector);
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II->eraseFromParent();
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}
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}
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Changed |= CleanupSelectors();
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return Changed;
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}
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/// NormalizeLandingPads - Normalize and discover landing pads, noting them
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/// in the LandingPads set. A landing pad is normal if the only CFG edges
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/// that end at it are unwind edges from invoke instructions. If we inlined
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/// through an invoke we could have a normal branch from the previous
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/// unwind block through to the landing pad for the original invoke.
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/// Abnormal landing pads are fixed up by redirecting all unwind edges to
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/// a new basic block which falls through to the original.
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bool DwarfEHPrepare::NormalizeLandingPads() {
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bool Changed = false;
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const MCAsmInfo *MAI = TM->getMCAsmInfo();
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bool usingSjLjEH = MAI->getExceptionHandlingType() == ExceptionHandling::SjLj;
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for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
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TerminatorInst *TI = I->getTerminator();
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if (!isa<InvokeInst>(TI))
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continue;
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BasicBlock *LPad = TI->getSuccessor(1);
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// Skip landing pads that have already been normalized.
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if (LandingPads.count(LPad))
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continue;
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// Check that only invoke unwind edges end at the landing pad.
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bool OnlyUnwoundTo = true;
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bool SwitchOK = usingSjLjEH;
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for (pred_iterator PI = pred_begin(LPad), PE = pred_end(LPad);
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PI != PE; ++PI) {
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TerminatorInst *PT = (*PI)->getTerminator();
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// The SjLj dispatch block uses a switch instruction. This is effectively
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// an unwind edge, so we can disregard it here. There will only ever
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// be one dispatch, however, so if there are multiple switches, one
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// of them truly is a normal edge, not an unwind edge.
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if (SwitchOK && isa<SwitchInst>(PT)) {
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SwitchOK = false;
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continue;
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}
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if (!isa<InvokeInst>(PT) || LPad == PT->getSuccessor(0)) {
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OnlyUnwoundTo = false;
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break;
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}
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}
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if (OnlyUnwoundTo) {
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// Only unwind edges lead to the landing pad. Remember the landing pad.
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LandingPads.insert(LPad);
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continue;
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}
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// At least one normal edge ends at the landing pad. Redirect the unwind
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// edges to a new basic block which falls through into this one.
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// Create the new basic block.
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BasicBlock *NewBB = BasicBlock::Create(F->getContext(),
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LPad->getName() + "_unwind_edge");
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// Insert it into the function right before the original landing pad.
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LPad->getParent()->getBasicBlockList().insert(LPad, NewBB);
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// Redirect unwind edges from the original landing pad to NewBB.
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for (pred_iterator PI = pred_begin(LPad), PE = pred_end(LPad); PI != PE; ) {
|
|
TerminatorInst *PT = (*PI++)->getTerminator();
|
|
if (isa<InvokeInst>(PT) && PT->getSuccessor(1) == LPad)
|
|
// Unwind to the new block.
|
|
PT->setSuccessor(1, NewBB);
|
|
}
|
|
|
|
// If there are any PHI nodes in LPad, we need to update them so that they
|
|
// merge incoming values from NewBB instead.
|
|
for (BasicBlock::iterator II = LPad->begin(); isa<PHINode>(II); ++II) {
|
|
PHINode *PN = cast<PHINode>(II);
|
|
pred_iterator PB = pred_begin(NewBB), PE = pred_end(NewBB);
|
|
|
|
// Check to see if all of the values coming in via unwind edges are the
|
|
// same. If so, we don't need to create a new PHI node.
|
|
Value *InVal = PN->getIncomingValueForBlock(*PB);
|
|
for (pred_iterator PI = PB; PI != PE; ++PI) {
|
|
if (PI != PB && InVal != PN->getIncomingValueForBlock(*PI)) {
|
|
InVal = 0;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (InVal == 0) {
|
|
// Different unwind edges have different values. Create a new PHI node
|
|
// in NewBB.
|
|
PHINode *NewPN = PHINode::Create(PN->getType(), PN->getName()+".unwind",
|
|
NewBB);
|
|
// Add an entry for each unwind edge, using the value from the old PHI.
|
|
for (pred_iterator PI = PB; PI != PE; ++PI)
|
|
NewPN->addIncoming(PN->getIncomingValueForBlock(*PI), *PI);
|
|
|
|
// Now use this new PHI as the common incoming value for NewBB in PN.
|
|
InVal = NewPN;
|
|
}
|
|
|
|
// Revector exactly one entry in the PHI node to come from NewBB
|
|
// and delete all other entries that come from unwind edges. If
|
|
// there are both normal and unwind edges from the same predecessor,
|
|
// this leaves an entry for the normal edge.
|
|
for (pred_iterator PI = PB; PI != PE; ++PI)
|
|
PN->removeIncomingValue(*PI);
|
|
PN->addIncoming(InVal, NewBB);
|
|
}
|
|
|
|
// Add a fallthrough from NewBB to the original landing pad.
|
|
BranchInst::Create(LPad, NewBB);
|
|
|
|
// Now update DominatorTree and DominanceFrontier analysis information.
|
|
if (DT)
|
|
DT->splitBlock(NewBB);
|
|
if (DF)
|
|
DF->splitBlock(NewBB);
|
|
|
|
// Remember the newly constructed landing pad. The original landing pad
|
|
// LPad is no longer a landing pad now that all unwind edges have been
|
|
// revectored to NewBB.
|
|
LandingPads.insert(NewBB);
|
|
++NumLandingPadsSplit;
|
|
Changed = true;
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
/// LowerUnwinds - Turn unwind instructions into calls to _Unwind_Resume,
|
|
/// rethrowing any previously caught exception. This will crash horribly
|
|
/// at runtime if there is no such exception: using unwind to throw a new
|
|
/// exception is currently not supported.
|
|
bool DwarfEHPrepare::LowerUnwinds() {
|
|
SmallVector<TerminatorInst*, 16> UnwindInsts;
|
|
|
|
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
|
|
TerminatorInst *TI = I->getTerminator();
|
|
if (isa<UnwindInst>(TI))
|
|
UnwindInsts.push_back(TI);
|
|
}
|
|
|
|
if (UnwindInsts.empty()) return false;
|
|
|
|
// Find the rewind function if we didn't already.
|
|
if (!RewindFunction) {
|
|
LLVMContext &Ctx = UnwindInsts[0]->getContext();
|
|
std::vector<const Type*>
|
|
Params(1, Type::getInt8PtrTy(Ctx));
|
|
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;
|
|
|
|
// Replace the unwind instruction with a call to _Unwind_Resume (or the
|
|
// appropriate target equivalent) followed by an UnreachableInst.
|
|
|
|
// Create the call...
|
|
CallInst *CI = CallInst::Create(RewindFunction,
|
|
CreateReadOfExceptionValue(TI->getParent()),
|
|
"", TI);
|
|
CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
|
|
// ...followed by an UnreachableInst.
|
|
new UnreachableInst(TI->getContext(), TI);
|
|
|
|
// Nuke the unwind instruction.
|
|
TI->eraseFromParent();
|
|
++NumUnwindsLowered;
|
|
Changed = true;
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
/// MoveExceptionValueCalls - Ensure that eh.exception is only ever called from
|
|
/// landing pads by replacing calls outside of landing pads with loads from a
|
|
/// stack temporary. Move eh.exception calls inside landing pads to the start
|
|
/// of the landing pad (optional, but may make things simpler for later passes).
|
|
bool DwarfEHPrepare::MoveExceptionValueCalls() {
|
|
// If the eh.exception intrinsic is not declared in the module then there is
|
|
// nothing to do. Speed up compilation by checking for this common case.
|
|
if (!ExceptionValueIntrinsic &&
|
|
!F->getParent()->getFunction(Intrinsic::getName(Intrinsic::eh_exception)))
|
|
return false;
|
|
|
|
bool Changed = false;
|
|
|
|
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
|
|
for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E;)
|
|
if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(II++))
|
|
if (CI->getIntrinsicID() == Intrinsic::eh_exception) {
|
|
if (!CI->use_empty()) {
|
|
Value *ExceptionValue = CreateReadOfExceptionValue(BB);
|
|
if (CI == ExceptionValue) {
|
|
// The call was at the start of a landing pad - leave it alone.
|
|
assert(LandingPads.count(BB) &&
|
|
"Created eh.exception call outside landing pad!");
|
|
continue;
|
|
}
|
|
CI->replaceAllUsesWith(ExceptionValue);
|
|
}
|
|
CI->eraseFromParent();
|
|
++NumExceptionValuesMoved;
|
|
Changed = true;
|
|
}
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
/// FinishStackTemporaries - If we introduced a stack variable to hold the
|
|
/// exception value then initialize it in each landing pad.
|
|
bool DwarfEHPrepare::FinishStackTemporaries() {
|
|
if (!ExceptionValueVar)
|
|
// Nothing to do.
|
|
return false;
|
|
|
|
bool Changed = false;
|
|
|
|
// Make sure that there is a store of the exception value at the start of
|
|
// each landing pad.
|
|
for (BBSet::iterator LI = LandingPads.begin(), LE = LandingPads.end();
|
|
LI != LE; ++LI) {
|
|
Instruction *ExceptionValue = CreateReadOfExceptionValue(*LI);
|
|
Instruction *Store = new StoreInst(ExceptionValue, ExceptionValueVar);
|
|
Store->insertAfter(ExceptionValue);
|
|
Changed = true;
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
/// PromoteStackTemporaries - Turn any stack temporaries we introduced into
|
|
/// registers if possible.
|
|
bool DwarfEHPrepare::PromoteStackTemporaries() {
|
|
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);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// CreateExceptionValueCall - Insert a call to the eh.exception intrinsic at
|
|
/// the start of the basic block (unless there already is one, in which case
|
|
/// the existing call is returned).
|
|
Instruction *DwarfEHPrepare::CreateExceptionValueCall(BasicBlock *BB) {
|
|
Instruction *Start = BB->getFirstNonPHIOrDbg();
|
|
// Is this a call to eh.exception?
|
|
if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(Start))
|
|
if (CI->getIntrinsicID() == Intrinsic::eh_exception)
|
|
// Reuse the existing call.
|
|
return Start;
|
|
|
|
// Find the eh.exception intrinsic if we didn't already.
|
|
if (!ExceptionValueIntrinsic)
|
|
ExceptionValueIntrinsic = Intrinsic::getDeclaration(F->getParent(),
|
|
Intrinsic::eh_exception);
|
|
|
|
// Create the call.
|
|
return CallInst::Create(ExceptionValueIntrinsic, "eh.value.call", Start);
|
|
}
|
|
|
|
/// CreateValueLoad - Insert a load of the exception value stack variable
|
|
/// (creating it if necessary) at the start of the basic block (unless
|
|
/// there already is a load, in which case the existing load is returned).
|
|
Instruction *DwarfEHPrepare::CreateValueLoad(BasicBlock *BB) {
|
|
Instruction *Start = BB->getFirstNonPHIOrDbg();
|
|
// Is this a load of the exception temporary?
|
|
if (ExceptionValueVar)
|
|
if (LoadInst* LI = dyn_cast<LoadInst>(Start))
|
|
if (LI->getPointerOperand() == ExceptionValueVar)
|
|
// Reuse the existing load.
|
|
return Start;
|
|
|
|
// Create the temporary if we didn't already.
|
|
if (!ExceptionValueVar) {
|
|
ExceptionValueVar = new AllocaInst(PointerType::getUnqual(
|
|
Type::getInt8Ty(BB->getContext())), "eh.value", F->begin()->begin());
|
|
++NumStackTempsIntroduced;
|
|
}
|
|
|
|
// Load the value.
|
|
return new LoadInst(ExceptionValueVar, "eh.value.load", Start);
|
|
}
|
|
|
|
bool DwarfEHPrepare::runOnFunction(Function &Fn) {
|
|
bool Changed = false;
|
|
|
|
// Initialize internal state.
|
|
DT = getAnalysisIfAvailable<DominatorTree>();
|
|
DF = getAnalysisIfAvailable<DominanceFrontier>();
|
|
ExceptionValueVar = 0;
|
|
F = &Fn;
|
|
|
|
// Ensure that only unwind edges end at landing pads (a landing pad is a
|
|
// basic block where an invoke unwind edge ends).
|
|
Changed |= NormalizeLandingPads();
|
|
|
|
// Turn unwind instructions into libcalls.
|
|
Changed |= LowerUnwinds();
|
|
|
|
// TODO: Move eh.selector calls to landing pads and combine them.
|
|
|
|
// Move eh.exception calls to landing pads.
|
|
Changed |= MoveExceptionValueCalls();
|
|
|
|
// Initialize any stack temporaries we introduced.
|
|
Changed |= FinishStackTemporaries();
|
|
|
|
// Turn any stack temporaries into registers if possible.
|
|
if (!CompileFast)
|
|
Changed |= PromoteStackTemporaries();
|
|
|
|
Changed |= HandleURoRInvokes();
|
|
|
|
LandingPads.clear();
|
|
|
|
return Changed;
|
|
}
|