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Add a restore folder, which shaves a dozen or so machineinstrs off oggenc. Update a testcase to check this.

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llvm-svn: 66029
This commit is contained in:
Owen Anderson 2009-03-04 08:52:31 +00:00
parent f8d2f7429d
commit fb7f64ea0d
2 changed files with 76 additions and 7 deletions
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81
lib/CodeGen/PreAllocSplitting.cpp
View File

@ -159,6 +159,12 @@ namespace {
MachineBasicBlock* MBB,
int& SS,
SmallPtrSet<MachineInstr*, 4>& RefsInMBB);
MachineInstr* FoldRestore(unsigned vreg,
const TargetRegisterClass* RC,
MachineInstr* Barrier,
MachineBasicBlock* MBB,
int SS,
SmallPtrSet<MachineInstr*, 4>& RefsInMBB);
void RenumberValno(VNInfo* VN);
void ReconstructLiveInterval(LiveInterval* LI);
bool removeDeadSpills(SmallPtrSet<LiveInterval*, 8>& split);
@ -1001,6 +1007,59 @@ MachineInstr* PreAllocSplitting::FoldSpill(unsigned vreg,
return FMI;
}
MachineInstr* PreAllocSplitting::FoldRestore(unsigned vreg,
const TargetRegisterClass* RC,
MachineInstr* Barrier,
MachineBasicBlock* MBB,
int SS,
SmallPtrSet<MachineInstr*, 4>& RefsInMBB) {
// Go top down if RefsInMBB is empty.
if (RefsInMBB.empty())
return 0;
// Can't fold a restore between a call stack setup and teardown.
MachineBasicBlock::iterator FoldPt = Barrier;
while (FoldPt != MBB->getFirstTerminator() && !RefsInMBB.count(FoldPt)) {
++FoldPt;
if (FoldPt->getOpcode() == TRI->getCallFrameSetupOpcode()) {
while (FoldPt != MBB->getFirstTerminator() &&
FoldPt->getOpcode() != TRI->getCallFrameDestroyOpcode()) {
if (RefsInMBB.count(FoldPt))
return 0;
++FoldPt;
}
++FoldPt;
}
}
if (FoldPt == MBB->getFirstTerminator())
return 0;
int OpIdx = FoldPt->findRegisterUseOperandIdx(vreg, true);
if (OpIdx == -1)
return 0;
SmallVector<unsigned, 1> Ops;
Ops.push_back(OpIdx);
if (!TII->canFoldMemoryOperand(FoldPt, Ops))
return 0;
MachineInstr* FMI = TII->foldMemoryOperand(*MBB->getParent(),
FoldPt, Ops, SS);
if (FMI) {
LIs->ReplaceMachineInstrInMaps(FoldPt, FMI);
FMI = MBB->insert(MBB->erase(FoldPt), FMI);
++NumFolds;
}
return FMI;
}
/// SplitRegLiveInterval - Split (spill and restore) the given live interval
/// so it would not cross the barrier that's being processed. Shrink wrap
/// (minimize) the live interval to the last uses.
@ -1108,18 +1167,28 @@ bool PreAllocSplitting::SplitRegLiveInterval(LiveInterval *LI) {
Def2SpillMap[ValNo->def] = SpillIndex;
// Add restore.
TII->loadRegFromStackSlot(*BarrierMBB, RestorePt, CurrLI->reg, SS, RC);
MachineInstr *LoadMI = prior(RestorePt);
LIs->InsertMachineInstrInMaps(LoadMI, RestoreIndex);
bool FoldedRestore = false;
if (MachineInstr* LMI = FoldRestore(CurrLI->reg, RC, Barrier,
BarrierMBB, SS, RefsInMBB)) {
RestorePt = LMI;
FoldedRestore = true;
} else {
TII->loadRegFromStackSlot(*BarrierMBB, RestorePt, CurrLI->reg, SS, RC);
MachineInstr *LoadMI = prior(RestorePt);
LIs->InsertMachineInstrInMaps(LoadMI, RestoreIndex);
}
// Update spill stack slot live interval.
UpdateSpillSlotInterval(ValNo, LIs->getUseIndex(SpillIndex)+1,
LIs->getDefIndex(RestoreIndex));
ReconstructLiveInterval(CurrLI);
unsigned RestoreIdx = LIs->getInstructionIndex(prior(RestorePt));
RestoreIdx = LiveIntervals::getDefIndex(RestoreIdx);
RenumberValno(CurrLI->findDefinedVNInfo(RestoreIdx));
if (!FoldedRestore) {
unsigned RestoreIdx = LIs->getInstructionIndex(prior(RestorePt));
RestoreIdx = LiveIntervals::getDefIndex(RestoreIdx);
RenumberValno(CurrLI->findDefinedVNInfo(RestoreIdx));
}
++NumSplits;
return true;

2
test/CodeGen/X86/pre-split6.ll
View File

@ -1,4 +1,4 @@
; RUN: llvm-as < %s | llc -march=x86 -mattr=+sse2 -pre-alloc-split
; RUN: llvm-as < %s | llc -march=x86 -mattr=+sse2 -pre-alloc-split | grep {divsd 8} | count 1
@current_surfaces.b = external global i1 ; <i1*> [#uses=1]