Bug fix for PR1279. When isDead is propagate by copy coalescing, we keep length
of dead def live interval at 1 to avoid multiple def's targeting the same
register. The previous patch missed a case where the source operand is live-in.
In that case, remove the whole interval.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35512 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index ff7b555..bc4f601 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -915,6 +915,7 @@
// Check if it is necessary to propagate "isDead" property before intervals
// are joined.
+ MachineBasicBlock *CopyBB = CopyMI->getParent();
MachineOperand *mopd = CopyMI->findRegisterDefOperand(DstReg);
bool isDead = mopd->isDead();
bool isShorten = false;
@@ -941,9 +942,15 @@
isShorten = true;
RemoveStart = getDefIndex(getInstructionIndex(LastUse));
RemoveEnd = SrcEnd;
- } else if (RemoveStart > 0)
- // A dead def should have a single cycle interval.
- ++RemoveStart;
+ } else {
+ MachineInstr *SrcMI = getInstructionFromIndex(SrcStart);
+ if (SrcMI) {
+ MachineOperand *mops = SrcMI->findRegisterDefOperand(SrcReg);
+ if (mops)
+ // A dead def should have a single cycle interval.
+ ++RemoveStart;
+ }
+ }
}
}
@@ -959,7 +966,6 @@
LiveVariables::VarInfo& dvi = lv_->getVarInfo(repDstReg);
// Is the value used in the current BB or any immediate successroe BB?
- MachineBasicBlock *CopyBB = CopyMI->getParent();
if (dvi.UsedBlocks[CopyBB->getNumber()])
goto TryJoin;
for (MachineBasicBlock::succ_iterator SI = CopyBB->succ_begin(),
@@ -1018,7 +1024,6 @@
if (SrcMI) {
MachineOperand *mops = SrcMI->findRegisterDefOperand(SrcReg);
if (mops)
- // FIXME: mops == NULL means SrcMI defines a subregister?
mops->setIsDead();
}
}