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Fix for http://llvm.org/bugs/show_bug.cgi?id=18590

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This patch fixes the bug in peephole optimization that folds a load which defines one vreg into the one and only use of that vreg. With debug info, a DBG_VALUE that referenced the vreg considered to be a use, preventing the optimization. The fix is to ignore DBG_VALUE's during the optimization, and undef a DBG_VALUE that references a vreg that gets removed.
Patch by Trevor Smigiel!



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203829 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ekaterina Romanova
2014-03-13 18:47:12 +00:00
parent 4ad41871eb
commit ed2ca70ccf
5 changed files with 114 additions and 14 deletions
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12
lib/CodeGen/DeadMachineInstructionElim.cpp
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@@ -127,17 +127,7 @@ bool DeadMachineInstructionElim::runOnMachineFunction(MachineFunction &MF) {
unsigned Reg = MO.getReg();
if (!TargetRegisterInfo::isVirtualRegister(Reg))
continue;
MachineRegisterInfo::use_iterator nextI;
for (MachineRegisterInfo::use_iterator I = MRI->use_begin(Reg),
E = MRI->use_end(); I!=E; I=nextI) {
nextI = std::next(I); // I is invalidated by the setReg
MachineOperand& Use = I.getOperand();
MachineInstr *UseMI = Use.getParent();
if (UseMI==MI)
continue;
assert(Use.isDebug());
UseMI->getOperand(0).setReg(0U);
}
MRI->markUsesInDebugValueAsUndef(Reg);
}
AnyChanges = true;
MI->eraseFromParent();