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Drop <def,dead> flags when merging into an unused lane.

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The new coalescer can merge a dead def into an unused lane of an
otherwise live vector register.

Clear the <dead> flag when that happens since the flag refers to the
full virtual register which is still live after the partial dead def.

This fixes PR14079.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165877 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2012-10-13 17:26:47 +00:00
parent 186f8d90df
commit d86296a4ae
2 changed files with 36 additions and 5 deletions
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13
lib/CodeGen/RegisterCoalescer.cpp
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@@ -1739,15 +1739,20 @@ void JoinVals::pruneValues(JoinVals &Other,
// has been replaced.
Val &OtherV = Other.Vals[Vals[i].OtherVNI->id];
bool EraseImpDef = OtherV.IsImplicitDef && OtherV.Resolution == CR_Keep;
if (!EraseImpDef && !Def.isBlock()) {
if (!Def.isBlock()) {
// Remove <def,read-undef> flags. This def is now a partial redef.
// Also remove <def,dead> flags since the joined live range will
// continue past this instruction.
for (MIOperands MO(Indexes->getInstructionFromIndex(Def));
MO.isValid(); ++MO)
if (MO->isReg() && MO->isDef() && MO->getReg() == LI.reg)
MO->setIsUndef(false);
if (MO->isReg() && MO->isDef() && MO->getReg() == LI.reg) {
MO->setIsUndef(EraseImpDef);
MO->setIsDead(false);
}
// This value will reach instructions below, but we need to make sure
// the live range also reaches the instruction at Def.
EndPoints.push_back(Def);
if (!EraseImpDef)
EndPoints.push_back(Def);
}
DEBUG(dbgs() << "\t\tpruned " << PrintReg(Other.LI.reg) << " at " << Def
<< ": " << Other.LI << '\n');