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Split the landing pad's edge. Then for all uses of a landingpad instruction's 

value, we insert a load of the exception object and selector object from memory,
which is where it actually resides. If it's used by a PHI node, we follow that
to where it is being used. Eventually, all landingpad instructions should have
no uses. Any PHI nodes that were associated with those landingpads should be
removed.

llvm-svn: 138302
This commit is contained in:
Bill Wendling 2011-08-22 23:38:40 +00:00
parent 1346d79b4b
commit f0d2dfde4f
1 changed files with 74 additions and 2 deletions
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76
llvm/lib/CodeGen/SjLjEHPrepare.cpp
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@ -26,6 +26,7 @@
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include <set>
@ -52,6 +53,7 @@ namespace {
Constant *CallSiteFn;
Constant *DispatchSetupFn;
Value *CallSite;
DenseMap<InvokeInst*, BasicBlock*> LPadSuccMap;
public:
static char ID; // Pass identification, replacement for typeid
explicit SjLjEHPass(const TargetLowering *tli = NULL)
@ -158,7 +160,12 @@ void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo,
CallInst::Create(CallSiteFn, CallSiteNoC, "", II);
// Add a switch case to our unwind block.
CatchSwitch->addCase(SwitchValC, II->getUnwindDest());
if (BasicBlock *SuccBB = LPadSuccMap[II]) {
CatchSwitch->addCase(SwitchValC, SuccBB);
} else {
CatchSwitch->addCase(SwitchValC, II->getUnwindDest());
}
// We still want this to look like an invoke so we emit the LSDA properly,
// so we don't transform the invoke into a call here.
}
@ -184,7 +191,17 @@ splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) {
for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
InvokeInst *II = Invokes[i];
SplitCriticalEdge(II, 0, this);
SplitCriticalEdge(II, 1, this);
// FIXME: New EH - This if-condition will be always true in the new scheme.
if (II->getUnwindDest()->isLandingPad()) {
SmallVector<BasicBlock*, 2> NewBBs;
SplitLandingPadPredecessors(II->getUnwindDest(), II->getParent(),
".1", ".2", this, NewBBs);
LPadSuccMap[II] = *succ_begin(NewBBs[0]);
} else {
SplitCriticalEdge(II, 1, this);
}
assert(!isa<PHINode>(II->getNormalDest()) &&
!isa<PHINode>(II->getUnwindDest()) &&
"Critical edge splitting left single entry phi nodes?");
@ -296,6 +313,44 @@ splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) {
}
}
/// CreateLandingPadLoad - Load the exception handling values and insert them
/// into a structure.
static Instruction *CreateLandingPadLoad(Function &F, Value *ExnAddr,
Value *SelAddr,
BasicBlock::iterator InsertPt) {
Value *Exn = new LoadInst(ExnAddr, "exn", false,
InsertPt);
Type *Ty = Type::getInt8PtrTy(F.getContext());
Exn = CastInst::Create(Instruction::IntToPtr, Exn, Ty, "", InsertPt);
Value *Sel = new LoadInst(SelAddr, "sel", false, InsertPt);
Ty = StructType::get(Exn->getType(), Sel->getType(), NULL);
InsertValueInst *LPadVal = InsertValueInst::Create(llvm::UndefValue::get(Ty),
Exn, 0,
"lpad.val", InsertPt);
return InsertValueInst::Create(LPadVal, Sel, 1, "lpad.val", InsertPt);
}
/// ReplaceLandingPadVal - Replace the landingpad instruction's value with a
/// load from the stored values (via CreateLandingPadLoad). This looks through
/// PHI nodes, and removes them if they are dead.
static void ReplaceLandingPadVal(Function &F, Instruction *Inst, Value *ExnAddr,
Value *SelAddr) {
if (Inst->use_empty()) return;
while (!Inst->use_empty()) {
Instruction *I = cast<Instruction>(Inst->use_back());
if (PHINode *PN = dyn_cast<PHINode>(I)) {
ReplaceLandingPadVal(F, PN, ExnAddr, SelAddr);
if (PN->use_empty()) PN->eraseFromParent();
continue;
}
Inst->replaceAllUsesWith(CreateLandingPadLoad(F, ExnAddr, SelAddr, I));
}
}
bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
SmallVector<ReturnInst*,16> Returns;
SmallVector<UnwindInst*,16> Unwinds;
@ -350,6 +405,10 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
}
} else if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
JmpbufUpdatePoints.push_back(AI);
} else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
// FIXME: This will be always non-NULL in the new EH.
if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst())
if (!PersonalityFn) PersonalityFn = LPI->getPersonalityFn();
}
}
}
@ -368,6 +427,16 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
// invoke's.
splitLiveRangesAcrossInvokes(Invokes);
SmallVector<LandingPadInst*, 16> LandingPads;
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator()))
// FIXME: This will be always non-NULL in the new EH.
if (LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst())
LandingPads.push_back(LPI);
}
BasicBlock *EntryBB = F.begin();
// Create an alloca for the incoming jump buffer ptr and the new jump buffer
// that needs to be restored on all exits from the function. This is an
@ -425,6 +494,9 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
I->eraseFromParent();
}
for (unsigned i = 0, e = LandingPads.size(); i != e; ++i)
ReplaceLandingPadVal(F, LandingPads[i], ExceptionAddr, SelectorAddr);
// The entry block changes to have the eh.sjlj.setjmp, with a conditional
// branch to a dispatch block for non-zero returns. If we return normally,
// we're not handling an exception and just register the function context and