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
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index a968063..ab8a18d 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -924,14 +924,14 @@
MachineOperand *mopd = CopyMI->findRegisterDefOperand(DstReg);
bool isDead = mopd->isDead();
bool isShorten = false;
- unsigned SrcStart = 0;
- unsigned SrcEnd = 0;
+ unsigned SrcStart = 0, RemoveStart = 0;
+ unsigned SrcEnd = 0, RemoveEnd = 0;
if (isDead) {
unsigned CopyIdx = getInstructionIndex(CopyMI);
LiveInterval::iterator SrcLR =
SrcInt.FindLiveRangeContaining(getUseIndex(CopyIdx));
- SrcStart = SrcLR->start;
- SrcEnd = SrcLR->end;
+ RemoveStart = SrcStart = SrcLR->start;
+ RemoveEnd = SrcEnd = SrcLR->end;
// The instruction which defines the src is only truly dead if there are
// no intermediate uses and there isn't a use beyond the copy.
// FIXME: find the last use, mark is kill and shorten the live range.
@@ -939,18 +939,16 @@
isDead = false;
else {
MachineOperand *MOU;
- MachineInstr *LastUse =
- lastRegisterUse(repSrcReg, SrcStart, CopyIdx, MOU);
+ MachineInstr *LastUse= lastRegisterUse(repSrcReg, SrcStart, CopyIdx, MOU);
if (LastUse) {
// Shorten the liveinterval to the end of last use.
MOU->setIsKill();
isDead = false;
isShorten = true;
- SrcEnd = getUseIndex(getInstructionIndex(LastUse));
+ RemoveStart = getDefIndex(getInstructionIndex(LastUse));
+ RemoveEnd = SrcEnd;
}
}
- if (isDead)
- isShorten = true;
}
// We need to be careful about coalescing a source physical register with a
@@ -1030,10 +1028,10 @@
}
}
- if (isShorten) {
+ if (isShorten || isDead) {
// Shorten the live interval.
LiveInterval &LiveInInt = (repSrcReg == DestInt.reg) ? DestInt : SrcInt;
- LiveInInt.removeRange(SrcStart, SrcEnd);
+ LiveInInt.removeRange(RemoveStart, RemoveEnd);
}
} else {
// Coallescing failed.