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When lowering the 'resume' instruction, look to see if we can eliminate the

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'insertvalue' instructions that recreate the structure returned by the
'landingpad' instruction. Because the 'insertvalue' instruction isn't supported
by FastISel, this can save a bit of time during -O0 compilation.

llvm-svn: 148520
This commit is contained in:
Bill Wendling 2012-01-20 00:53:28 +00:00
parent ffa3b8b5f1
commit f599e9d12a
1 changed files with 32 additions and 2 deletions
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34
lib/CodeGen/DwarfEHPrepare.cpp
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@ -101,10 +101,40 @@ bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) {
I = Resumes.begin(), E = Resumes.end(); I != E; ++I) {
ResumeInst *RI = *I;
BranchInst::Create(UnwindBB, RI->getParent());
ExtractValueInst *ExnObj = ExtractValueInst::Create(RI->getOperand(0),
0, "exn.obj", RI);
Value *V = RI->getOperand(0);
Instruction *ExnObj = 0;
InsertValueInst *SelIVI = dyn_cast<InsertValueInst>(V);
LoadInst *SelLoad = 0;
InsertValueInst *ExcIVI = 0;
bool EraseIVIs = false;
if (SelIVI) {
if (SelIVI->getNumIndices() == 1 && *SelIVI->idx_begin() == 1) {
ExcIVI = dyn_cast<InsertValueInst>(SelIVI->getOperand(0));
if (ExcIVI && isa<UndefValue>(ExcIVI->getOperand(0)) &&
ExcIVI->getNumIndices() == 1 && *ExcIVI->idx_begin() == 0) {
ExnObj = cast<Instruction>(ExcIVI->getOperand(1));
SelLoad = dyn_cast<LoadInst>(SelIVI->getOperand(1));
EraseIVIs = true;
}
}
}
if (!ExnObj)
ExnObj = ExtractValueInst::Create(RI->getOperand(0), 0, "exn.obj", RI);
PN->addIncoming(ExnObj, RI->getParent());
RI->eraseFromParent();
if (EraseIVIs) {
if (SelIVI->getNumUses() == 0)
SelIVI->eraseFromParent();
if (ExcIVI->getNumUses() == 0)
ExcIVI->eraseFromParent();
if (SelLoad && SelLoad->getNumUses() == 0)
SelLoad->eraseFromParent();
}
++NumResumesLowered;
}