Fix inverted conflict test in -early-coalesce.
A non-identity copy cannot be coalesced when the phi join destination register
is live at the copy site.
Also verify the condition that the PHI join source register is only used in
the PHI join. Otherwise the coalescing is invalid.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86322 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 2a93a35..854fb4d 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -646,17 +646,17 @@
0, false, VNInfoAllocator);
vni->setIsPHIDef(true);
LiveRange LR(start, end, vni);
-
+
interval.addRange(LR);
LR.valno->addKill(end);
DEBUG(errs() << " +" << LR << '\n');
}
-bool
-LiveIntervals::isProfitableToCoalesce(LiveInterval &DstInt, LiveInterval &SrcInt,
- SmallVector<MachineInstr*,16> &IdentCopies,
- SmallVector<MachineInstr*,16> &OtherCopies) {
- bool HaveConflict = false;
+bool LiveIntervals::
+isSafeAndProfitableToCoalesce(LiveInterval &DstInt,
+ LiveInterval &SrcInt,
+ SmallVector<MachineInstr*,16> &IdentCopies,
+ SmallVector<MachineInstr*,16> &OtherCopies) {
unsigned NumIdent = 0;
for (MachineRegisterInfo::def_iterator ri = mri_->def_begin(SrcInt.reg),
re = mri_->def_end(); ri != re; ++ri) {
@@ -665,16 +665,16 @@
if (!tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubReg, DstSubReg))
return false;
if (SrcReg != DstInt.reg) {
+ // Non-identity copy - we cannot handle overlapping intervals
+ if (DstInt.liveAt(getInstructionIndex(MI)))
+ return false;
OtherCopies.push_back(MI);
- HaveConflict |= DstInt.liveAt(getInstructionIndex(MI));
} else {
IdentCopies.push_back(MI);
++NumIdent;
}
}
- if (!HaveConflict)
- return false; // Let coalescer handle it
return IdentCopies.size() > OtherCopies.size();
}
@@ -701,19 +701,21 @@
LiveInterval &SrcInt = getInterval(PHISrc);
SmallVector<MachineInstr*, 16> IdentCopies;
SmallVector<MachineInstr*, 16> OtherCopies;
- if (!isProfitableToCoalesce(DstInt, SrcInt, IdentCopies, OtherCopies))
+ if (!isSafeAndProfitableToCoalesce(DstInt, SrcInt,
+ IdentCopies, OtherCopies))
continue;
DEBUG(errs() << "PHI Join: " << *Join);
assert(DstInt.containsOneValue() && "PHI join should have just one val#!");
+ assert(std::distance(mri_->use_begin(PHISrc), mri_->use_end()) == 1 &&
+ "PHI join src should not be used elsewhere");
VNInfo *VNI = DstInt.getValNumInfo(0);
// Change the non-identity copies to directly target the phi destination.
for (unsigned i = 0, e = OtherCopies.size(); i != e; ++i) {
MachineInstr *PHICopy = OtherCopies[i];
- DEBUG(errs() << "Moving: " << *PHICopy);
-
SlotIndex MIIndex = getInstructionIndex(PHICopy);
+ DEBUG(errs() << "Moving: " << MIIndex << ' ' << *PHICopy);
SlotIndex DefIndex = MIIndex.getDefIndex();
LiveRange *SLR = SrcInt.getLiveRangeContaining(DefIndex);
SlotIndex StartIndex = SLR->start;
@@ -724,8 +726,7 @@
SrcInt.removeValNo(SLR->valno);
DEBUG(errs() << " added range [" << StartIndex << ','
<< EndIndex << "] to reg" << DstInt.reg << '\n');
- if (DstInt.liveAt(StartIndex))
- DstInt.removeRange(StartIndex, EndIndex);
+ assert (!DstInt.liveAt(StartIndex) && "Cannot coalesce when dst live!");
VNInfo *NewVNI = DstInt.getNextValue(DefIndex, PHICopy, true,
VNInfoAllocator);
NewVNI->setHasPHIKill(true);