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Stage two of fixing pre-alloc-splitting's code size issues: filter out restores that are just

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going to be re-spilled again.

This also helps performance.  Pre-alloc-splitting now seems to be an overall win on SPEC.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62834 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2009-01-23 03:28:53 +00:00
parent 8c08d8c77c
commit 9ce499ab36
1 changed files with 37 additions and 9 deletions
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46
lib/CodeGen/PreAllocSplitting.cpp
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@ -1388,7 +1388,7 @@ bool PreAllocSplitting::removeDeadSpills(SmallPtrSet<LiveInterval*, 8>& split) {
for (SmallPtrSet<LiveInterval*, 8>::iterator LI = split.begin(),
LE = split.end(); LI != LE; ++LI) {
DenseMap<VNInfo*, unsigned > VNUseCount;
DenseMap<VNInfo*, SmallPtrSet<MachineInstr*, 4> > VNUseCount;
for (MachineRegisterInfo::use_iterator UI = MRI->use_begin((*LI)->reg),
UE = MRI->use_end(); UI != UE; ++UI) {
@ -1396,27 +1396,55 @@ bool PreAllocSplitting::removeDeadSpills(SmallPtrSet<LiveInterval*, 8>& split) {
index = LiveIntervals::getUseIndex(index);
const LiveRange* LR = (*LI)->getLiveRangeContaining(index);
VNUseCount[LR->valno]++;
VNUseCount[LR->valno].insert(&*UI);
}
for (LiveInterval::vni_iterator VI = (*LI)->vni_begin(),
VE = (*LI)->vni_end(); VI != VE; ++VI) {
VNInfo* CurrVN = *VI;
if (CurrVN->hasPHIKill) continue;
if (VNUseCount[CurrVN] > 0) continue;
unsigned DefIdx = CurrVN->def;
if (DefIdx == ~0U || DefIdx == ~1U) continue;
MachineInstr* DefMI = LIs->getInstructionFromIndex(DefIdx);
int FrameIndex;
if (!TII->isLoadFromStackSlot(DefMI, FrameIndex)) continue;
LIs->RemoveMachineInstrFromMaps(DefMI);
(*LI)->removeValNo(CurrVN);
DefMI->eraseFromParent();
NumDeadSpills++;
changed = true;
if (VNUseCount[CurrVN].size() == 0) {
LIs->RemoveMachineInstrFromMaps(DefMI);
(*LI)->removeValNo(CurrVN);
DefMI->eraseFromParent();
NumDeadSpills++;
changed = true;
} else {
bool NonRestore = false;
for (SmallPtrSet<MachineInstr*, 4>::iterator UI =
VNUseCount[CurrVN].begin(), UE = VNUseCount[CurrVN].end();
UI != UI; ++UI) {
int StoreFrameIndex;
unsigned StoreVReg = TII->isStoreToStackSlot(*UI, StoreFrameIndex);
if (StoreVReg != (*LI)->reg || StoreFrameIndex != FrameIndex) {
NonRestore = false;
break;
}
}
if (NonRestore) continue;
for (SmallPtrSet<MachineInstr*, 4>::iterator UI =
VNUseCount[CurrVN].begin(), UE = VNUseCount[CurrVN].end();
UI != UI; ++UI) {
LIs->RemoveMachineInstrFromMaps(*UI);
(*UI)->eraseFromParent();
}
LIs->RemoveMachineInstrFromMaps(DefMI);
(*LI)->removeValNo(CurrVN);
DefMI->eraseFromParent();
NumDeadSpills++;
changed = true;
}
}
}