#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");
-STATISTIC(NumStackTempsIntroduced, "Number of stack temporaries introduced");
namespace {
class DwarfEHPrepare : public FunctionPass {
// The eh.selector intrinsic.
Function *SelectorIntrinsic;
- // _Unwind_Resume_or_Rethrow call.
+ // _Unwind_Resume_or_Rethrow or _Unwind_SjLj_Resume call.
Constant *URoR;
// The EH language-specific catch-all type.
typedef SmallPtrSet<BasicBlock*, 8> BBSet;
BBSet LandingPads;
- // Stack temporary used to hold eh.exception values.
- AllocaInst *ExceptionValueVar;
-
bool NormalizeLandingPads();
bool LowerUnwinds();
bool MoveExceptionValueCalls();
- bool FinishStackTemporaries();
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
/// 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.
+ /// 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<IntrinsicInst*, 8> &SelCalls,
+ SmallPtrSet<PHINode*, 32> &SeenPHIs);
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) {}
+ URoR(0), EHCatchAllValue(0), RewindFunction(0) {
+ initializeDominatorTreePass(*PassRegistry::getPassRegistry());
+ }
virtual bool runOnFunction(Function &Fn);
- // getAnalysisUsage - We need dominance frontiers for memory promotion.
+ // getAnalysisUsage - We need the dominator tree for handling URoR.
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<DominatorTree>();
AU.addPreserved<DominatorTree>();
/// 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;
+ SmallPtrSet<IntrinsicInst*, 8> &SelCalls,
+ SmallPtrSet<PHINode*, 32> &SeenPHIs) {
bool Changed = false;
for (Value::use_iterator
if (Invoke->getCalledFunction() == URoR)
URoRInvoke = true;
} else if (CastInst *CI = dyn_cast<CastInst>(II)) {
- Changed |= FindSelectorAndURoR(CI, URoRInvoke, SelCalls);
+ 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);
+ Changed |= FindSelectorAndURoR(PN, URoRInvoke, SelCalls, SeenPHIs);
}
}
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.
+/// 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 =
if (!URoR) {
URoR = F->getParent()->getFunction("_Unwind_Resume_or_Rethrow");
- if (!URoR) return CleanupSelectors(CatchAllSels);
+ if (!URoR) {
+ URoR = F->getParent()->getFunction("_Unwind_SjLj_Resume");
+ if (!URoR) return CleanupSelectors(CatchAllSels);
+ }
}
SmallPtrSet<InvokeInst*, 32> URoRInvokes;
bool URoRInvoke = false;
SmallPtrSet<IntrinsicInst*, 8> SelCalls;
- Changed |= FindSelectorAndURoR(EHPtr, URoRInvoke, 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
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);
// 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.
}
/// 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.
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;
-}
+ // 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;
-/// 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;
+ 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;
+ }
- bool Changed = false;
+ if (FoundCallOutsideLandingPad)
+ break;
+ }
- // Make sure that there is a store of the exception value at the start of
- // each landing pad.
+ // 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) {
- Instruction *ExceptionValue = CreateReadOfExceptionValue(*LI);
- Instruction *Store = new StoreInst(ExceptionValue, ExceptionValueVar);
- Store->insertAfter(ExceptionValue);
- Changed = true;
+ 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 Changed;
+ return true;
}
/// CreateExceptionValueCall - Insert a call to the eh.exception intrinsic at
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 = &getAnalysis<DominatorTree>();
- ExceptionValueVar = 0;
F = &Fn;
// Ensure that only unwind edges end at landing pads (a landing pad is a
// Move eh.exception calls to landing pads.
Changed |= MoveExceptionValueCalls();
- // Initialize any stack temporaries we introduced.
- Changed |= FinishStackTemporaries();
-
- // TODO: Turn any stack temporaries into registers if possible.
-
Changed |= HandleURoRInvokes();
LandingPads.clear();
projects / oota-llvm.git / blobdiff