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Fix for PR1257. Bug in live range shortening as a result of copy coalescing
where the destination is dead. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35252 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -924,14 +924,14 @@ bool LiveIntervals::JoinCopy(MachineInstr *CopyMI,
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MachineOperand *mopd = CopyMI->findRegisterDefOperand(DstReg);
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bool isDead = mopd->isDead();
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bool isShorten = false;
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unsigned SrcStart = 0;
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unsigned SrcEnd = 0;
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unsigned SrcStart = 0, RemoveStart = 0;
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unsigned SrcEnd = 0, RemoveEnd = 0;
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if (isDead) {
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unsigned CopyIdx = getInstructionIndex(CopyMI);
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LiveInterval::iterator SrcLR =
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SrcInt.FindLiveRangeContaining(getUseIndex(CopyIdx));
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SrcStart = SrcLR->start;
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SrcEnd = SrcLR->end;
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RemoveStart = SrcStart = SrcLR->start;
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RemoveEnd = SrcEnd = SrcLR->end;
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// The instruction which defines the src is only truly dead if there are
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// no intermediate uses and there isn't a use beyond the copy.
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// FIXME: find the last use, mark is kill and shorten the live range.
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@ -939,18 +939,16 @@ bool LiveIntervals::JoinCopy(MachineInstr *CopyMI,
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isDead = false;
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else {
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MachineOperand *MOU;
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MachineInstr *LastUse =
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lastRegisterUse(repSrcReg, SrcStart, CopyIdx, MOU);
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MachineInstr *LastUse= lastRegisterUse(repSrcReg, SrcStart, CopyIdx, MOU);
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if (LastUse) {
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// Shorten the liveinterval to the end of last use.
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MOU->setIsKill();
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isDead = false;
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isShorten = true;
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SrcEnd = getUseIndex(getInstructionIndex(LastUse));
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RemoveStart = getDefIndex(getInstructionIndex(LastUse));
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RemoveEnd = SrcEnd;
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}
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}
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if (isDead)
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isShorten = true;
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}
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// We need to be careful about coalescing a source physical register with a
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@ -1030,10 +1028,10 @@ TryJoin:
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}
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}
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if (isShorten) {
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if (isShorten || isDead) {
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// Shorten the live interval.
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LiveInterval &LiveInInt = (repSrcReg == DestInt.reg) ? DestInt : SrcInt;
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LiveInInt.removeRange(SrcStart, SrcEnd);
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LiveInInt.removeRange(RemoveStart, RemoveEnd);
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}
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} else {
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// Coallescing failed.
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