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Dead code elimination may separate the live interval into multiple connected components.

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I have convinced myself that it can only happen when a phi value dies. When it
happens, allocate new virtual registers for the components.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127827 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2011-03-17 20:37:07 +00:00
parent c74513d1b6
commit 6a3dbd3b25
6 changed files with 47 additions and 23 deletions
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lib/CodeGen/LiveRangeEdit.cpp
+25 -12
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@@ -22,16 +22,16 @@
using namespace llvm;
LiveInterval &LiveRangeEdit::create(MachineRegisterInfo &mri,
LiveIntervals &lis,
VirtRegMap &vrm) {
const TargetRegisterClass *RC = mri.getRegClass(getReg());
unsigned VReg = mri.createVirtualRegister(RC);
vrm.grow();
vrm.setIsSplitFromReg(VReg, vrm.getOriginal(getReg()));
LiveInterval &li = lis.getOrCreateInterval(VReg);
newRegs_.push_back(&li);
return li;
LiveInterval &LiveRangeEdit::createFrom(unsigned OldReg,
LiveIntervals &LIS,
VirtRegMap &VRM) {
MachineRegisterInfo &MRI = VRM.getRegInfo();
unsigned VReg = MRI.createVirtualRegister(MRI.getRegClass(OldReg));
VRM.grow();
VRM.setIsSplitFromReg(VReg, VRM.getOriginal(OldReg));
LiveInterval &LI = LIS.getOrCreateInterval(VReg);
newRegs_.push_back(&LI);
return LI;
}
void LiveRangeEdit::scanRemattable(LiveIntervals &lis,
@@ -137,7 +137,7 @@ void LiveRangeEdit::eraseVirtReg(unsigned Reg, LiveIntervals &LIS) {
}
void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
LiveIntervals &LIS,
LiveIntervals &LIS, VirtRegMap &VRM,
const TargetInstrInfo &TII) {
SetVector<LiveInterval*,
SmallVector<LiveInterval*, 8>,
@@ -205,7 +205,20 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
ToShrink.pop_back();
if (delegate_)
delegate_->LRE_WillShrinkVirtReg(LI->reg);
LIS.shrinkToUses(LI, &Dead);
if (!LIS.shrinkToUses(LI, &Dead))
continue;
// LI may have been separated, create new intervals.
LI->RenumberValues(LIS);
ConnectedVNInfoEqClasses ConEQ(LIS);
unsigned NumComp = ConEQ.Classify(LI);
if (NumComp <= 1)
continue;
DEBUG(dbgs() << NumComp << " components: " << *LI << '\n');
SmallVector<LiveInterval*, 8> Dups(1, LI);
for (unsigned i = 1; i != NumComp; ++i)
Dups.push_back(&createFrom(LI->reg, LIS, VRM));
ConEQ.Distribute(&Dups[0], VRM.getRegInfo());
}
}