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Handle DBG_VALUE mixed with labels when doing PHI

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elimination.  Before a DBG_VALUE could affect codegen.
The solution here is imperfect and not final.

llvm-svn: 96318
This commit is contained in:
Dale Johannesen 2010-02-16 01:57:28 +00:00
parent 8962ca0e05
commit 622053fec3
1 changed files with 18 additions and 1 deletions
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19
lib/CodeGen/PHIElimination.h
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@ -109,12 +109,29 @@ namespace llvm {
// SkipPHIsAndLabels - Copies need to be inserted after phi nodes and
// also after any exception handling labels: in landing pads execution
// starts at the label, so any copies placed before it won't be executed!
// We also deal with DBG_VALUEs, which are a bit tricky:
// PHI
// DBG_VALUE
// LABEL
// Here the DBG_VALUE needs to be skipped, and if it refers to a PHI it
// needs to be annulled or, better, moved to follow the label, as well.
// PHI
// DBG_VALUE
// no label
// Here it is not a good idea to skip the DBG_VALUE.
// FIXME: For now we skip and annul all DBG_VALUEs, maximally simple and
// maximally stupid.
MachineBasicBlock::iterator SkipPHIsAndLabels(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) {
// Rather than assuming that EH labels come before other kinds of labels,
// just skip all labels.
while (I != MBB.end() && (I->isPHI() || I->isLabel()))
while (I != MBB.end() &&
(I->isPHI() || I->isLabel() || I->isDebugValue())) {
if (I->isDebugValue() && I->getNumOperands()==3 &&
I->getOperand(0).isReg())
I->getOperand(0).setReg(0U);
++I;
}
return I;
}