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Fix PR8854. Track inserted copies to avoid read before write. Sorry, it's hard to reduce a sensible small test case. 

llvm-svn: 125523
This commit is contained in:
Evan Cheng 2011-02-14 21:50:37 +00:00
parent c2448f6175
commit 9bf3f8e08b
1 changed files with 16 additions and 4 deletions
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20
llvm/lib/CodeGen/PeepholeOptimizer.cpp
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@ -331,25 +331,37 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
ImmDefRegs.clear();
ImmDefMIs.clear();
MachineBasicBlock::iterator PMII = I->begin();
for (MachineBasicBlock::iterator
MII = I->begin(), MIE = I->end(); MII != MIE; ) {
MachineInstr *MI = &*MII++;
MachineInstr *MI = &*MII;
LocalMIs.insert(MI);
if (MI->isLabel() || MI->isPHI() || MI->isImplicitDef() ||
MI->isKill() || MI->isInlineAsm() || MI->isDebugValue() ||
MI->hasUnmodeledSideEffects())
MI->hasUnmodeledSideEffects()) {
++MII;
continue;
}
if (MI->getDesc().isCompare()) {
Changed |= OptimizeCmpInstr(MI, MBB);
} else if (isMoveImmediate(MI, ImmDefRegs, ImmDefMIs)) {
if (OptimizeCmpInstr(MI, MBB)) {
// MI is deleted.
Changed = true;
MII = llvm::next(PMII);
continue;
}
}
if (isMoveImmediate(MI, ImmDefRegs, ImmDefMIs)) {
SeenMoveImm = true;
} else {
Changed |= OptimizeExtInstr(MI, MBB, LocalMIs);
if (SeenMoveImm)
Changed |= FoldImmediate(MI, MBB, ImmDefRegs, ImmDefMIs);
}
PMII = MII;
++MII;
}
}