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llvm-mirror/lib/CodeGen/DwarfEHPrepare.cpp
Owen Anderson 46990c17f7 Get rid of static constructors for pass registration. Instead, every pass exposes an initializeMyPassFunction(), which 
must be called in the pass's constructor.  This function uses static dependency declarations to recursively initialize
the pass's dependencies.

Clients that only create passes through the createFooPass() APIs will require no changes.  Clients that want to use the
CommandLine options for passes will need to manually call the appropriate initialization functions in PassInitialization.h
before parsing commandline arguments.

I have tested this with all standard configurations of clang and llvm-gcc on Darwin.  It is possible that there are problems
with the static dependencies that will only be visible with non-standard options.  If you encounter any crash in pass
registration/creation, please send the testcase to me directly.

llvm-svn: 116820
2010-10-19 17:21:58 +00:00

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//===-- DwarfEHPrepare - Prepare exception handling for code generation ---===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass mulches exception handling code into a form adapted to code
// generation. Required if using dwarf exception handling.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "dwarfehprepare"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Module.h"
#include "llvm/Pass.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/SSAUpdater.h"
using namespace llvm;
STATISTIC(NumLandingPadsSplit, "Number of landing pads split");
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 *ExceptionValueIntrinsic;
// The eh.selector intrinsic.
Function *SelectorIntrinsic;
// _Unwind_Resume_or_Rethrow call.
Constant *URoR;
// The EH language-specific catch-all type.
GlobalVariable *EHCatchAllValue;
// _Unwind_Resume or the target equivalent.
Constant *RewindFunction;
// We both use and preserve dominator info.
DominatorTree *DT;
// The function we are running on.
Function *F;
// The landing pads for this function.
typedef SmallPtrSet<BasicBlock*, 8> BBSet;
BBSet LandingPads;
bool NormalizeLandingPads();
bool LowerUnwinds();
bool MoveExceptionValueCalls();
Instruction *CreateExceptionValueCall(BasicBlock *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"
/// 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);
public:
static char ID; // Pass identification, replacement for typeid.
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";
}
};
} // end anonymous namespace
char DwarfEHPrepare::ID = 0;
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);
} 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);
}
}
return Changed;
}
/// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" 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) 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;
Changed |= FindSelectorAndURoR(EHPtr, URoRInvoke, SelCalls);
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
/// in the LandingPads set. A landing pad is normal if the only CFG edges
/// that end at it are unwind edges from invoke instructions. If we inlined
/// through an invoke we could have a normal branch from the previous
/// unwind block through to the landing pad for the original invoke.
/// Abnormal landing pads are fixed up by redirecting all unwind edges to
/// a new basic block which falls through to the original.
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))
continue;
BasicBlock *LPad = TI->getSuccessor(1);
// Skip landing pads that have already been normalized.
if (LandingPads.count(LPad))
continue;
// 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;
}
}
if (OnlyUnwoundTo) {
// Only unwind edges lead to the landing pad. Remember the landing pad.
LandingPads.insert(LPad);
continue;
}
// At least one normal edge ends at the landing pad. Redirect the unwind
// edges to a new basic block which falls through into this one.
// Create the new basic block.
BasicBlock *NewBB = BasicBlock::Create(F->getContext(),
LPad->getName() + "_unwind_edge");
// Insert it into the function right before the original landing pad.
LPad->getParent()->getBasicBlockList().insert(LPad, NewBB);
// Redirect unwind edges from the original landing pad to NewBB.
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 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
// 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,
CreateExceptionValueCall(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 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 (!ExceptionValueIntrinsic &&
!F->getParent()->getFunction(Intrinsic::getName(Intrinsic::eh_exception)))
return false;
bool Changed = false;
// 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;
}
}
// 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;
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;
}
if (FoundCallOutsideLandingPad)
break;
}
// If all calls to eh.exception are in landing pads then we are done.
if (!FoundCallOutsideLandingPad)
return Changed;
// 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 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->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);
}
bool DwarfEHPrepare::runOnFunction(Function &Fn) {
bool Changed = false;
// Initialize internal state.
DT = &getAnalysis<DominatorTree>();
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();
Changed |= HandleURoRInvokes();
LandingPads.clear();
return Changed;
}
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