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Only erase virtregs with no uses left.

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Also make sure registers aren't erased twice if the dead def mentions
the register twice.

This fixes PR12911.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157254 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2012-05-22 14:52:12 +00:00
parent 5cdbb1de7d
commit 76ff741836
2 changed files with 133 additions and 4 deletions
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lib/CodeGen/LiveRangeEdit.cpp
+15 -4
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@@ -220,6 +220,9 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
DEBUG(dbgs() << "Deleting dead def " << Idx << '\t' << *MI);
// Collect virtual registers to be erased after MI is gone.
SmallVector<unsigned, 8> RegsToErase;
// Check for live intervals that may shrink
for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
MOE = MI->operands_end(); MOI != MOE; ++MOI) {
@@ -245,10 +248,8 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
if (TheDelegate)
TheDelegate->LRE_WillShrinkVirtReg(LI.reg);
LI.removeValNo(VNI);
if (LI.empty()) {
ToShrink.remove(&LI);
eraseVirtReg(Reg);
}
if (LI.empty())
RegsToErase.push_back(Reg);
}
}
}
@@ -258,6 +259,16 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
LIS.RemoveMachineInstrFromMaps(MI);
MI->eraseFromParent();
++NumDCEDeleted;
// Erase any virtregs that are now empty and unused. There may be <undef>
// uses around. Keep the empty live range in that case.
for (unsigned i = 0, e = RegsToErase.size(); i != e; ++i) {
unsigned Reg = RegsToErase[i];
if (LIS.hasInterval(Reg) && MRI.reg_nodbg_empty(Reg)) {
ToShrink.remove(&LIS.getInterval(Reg));
eraseVirtReg(Reg);
}
}
}
if (ToShrink.empty())