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Compile time decreasing in the case we're dealing with Machine Combiner.

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Before this patch compile time was about 21s (see below). After this patch
we have less than 2s (see bellow).

  Intel(R) Xeon(R) CPU E5-2676 v3 @ 2.40GHz

    DAGCombiner - trunk
        time ./llc spill_fdiv.ll -o /dev/null -enable-unsafe-fp-math
        real  0m1.685s

    DAGCombiner + Speed patch
        time ./llc spill_fdiv.ll -o /dev/null -enable-unsafe-fp-math
        real  0m1.655s

    MachineCombiner w/o Speed patch
        time ./llc spill_fdiv.ll -o /dev/null -enable-unsafe-fp-math
        real  0m21.614s

    MachineCombiner + Speed patch
        time ./llc spill_fdiv.ll -o /dev/null -enable-unsafe-fp-math
        real  0m1.593s

The test spill_fdiv.ll  is attached to D29627
D29627 should be closed.

llvm-svn: 294936
This commit is contained in:
Andrew V. Tischenko 2017-02-13 09:43:37 +00:00
parent 89acda24b8
commit 78f7599134
1 changed files with 27 additions and 15 deletions
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42
lib/CodeGen/MachineCombiner.cpp
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@ -354,6 +354,19 @@ bool MachineCombiner::doSubstitute(unsigned NewSize, unsigned OldSize) {
return false;
}
static void insertDeleteInstructions(MachineBasicBlock *MBB, MachineInstr &MI,
SmallVector<MachineInstr *, 16> InsInstrs,
SmallVector<MachineInstr *, 16> DelInstrs,
MachineTraceMetrics *Traces) {
for (auto *InstrPtr : InsInstrs)
MBB->insert((MachineBasicBlock::iterator)&MI, InstrPtr);
for (auto *InstrPtr : DelInstrs)
InstrPtr->eraseFromParentAndMarkDBGValuesForRemoval();
++NumInstCombined;
Traces->invalidate(MBB);
Traces->verifyAnalysis();
}
/// Substitute a slow code sequence with a faster one by
/// evaluating instruction combining pattern.
/// The prototype of such a pattern is MUl + ADD -> MADD. Performs instruction
@ -408,7 +421,6 @@ bool MachineCombiner::combineInstructions(MachineBasicBlock *MBB) {
DenseMap<unsigned, unsigned> InstrIdxForVirtReg;
if (!MinInstr)
MinInstr = Traces->getEnsemble(MachineTraceMetrics::TS_MinInstrCount);
MachineTraceMetrics::Trace BlockTrace = MinInstr->getTrace(MBB);
Traces->verifyAnalysis();
TII->genAlternativeCodeSequence(MI, P, InsInstrs, DelInstrs,
InstrIdxForVirtReg);
@ -428,23 +440,23 @@ bool MachineCombiner::combineInstructions(MachineBasicBlock *MBB) {
// fewer instructions OR
// the new sequence neither lengthens the critical path nor increases
// resource pressure.
if (SubstituteAlways || doSubstitute(NewInstCount, OldInstCount) ||
(improvesCriticalPathLen(MBB, &MI, BlockTrace, InsInstrs,
DelInstrs, InstrIdxForVirtReg, P) &&
preservesResourceLen(MBB, BlockTrace, InsInstrs, DelInstrs))) {
for (auto *InstrPtr : InsInstrs)
MBB->insert((MachineBasicBlock::iterator) &MI, InstrPtr);
for (auto *InstrPtr : DelInstrs)
InstrPtr->eraseFromParentAndMarkDBGValuesForRemoval();
Changed = true;
++NumInstCombined;
Traces->invalidate(MBB);
Traces->verifyAnalysis();
if (SubstituteAlways || doSubstitute(NewInstCount, OldInstCount)) {
insertDeleteInstructions(MBB, MI, InsInstrs, DelInstrs, Traces);
// Eagerly stop after the first pattern fires.
Changed = true;
break;
} else {
// Calculating the trace metrics may be expensive,
// so only do this when necessary.
MachineTraceMetrics::Trace BlockTrace = MinInstr->getTrace(MBB);
if (improvesCriticalPathLen(MBB, &MI, BlockTrace, InsInstrs, DelInstrs,
InstrIdxForVirtReg, P) &&
preservesResourceLen(MBB, BlockTrace, InsInstrs, DelInstrs)) {
insertDeleteInstructions(MBB, MI, InsInstrs, DelInstrs, Traces);
// Eagerly stop after the first pattern fires.
Changed = true;
break;
}
// Cleanup instructions of the alternative code sequence. There is no
// use for them.
MachineFunction *MF = MBB->getParent();