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[TargetLowering][NFC] More efficient emitPatchpoint(). 

Current implementation of emitPatchpoint() is very inefficient:
for every FrameIndex operand if creates new MachineInstr with
that operand expanded and all other copied as is.
Since PATCHPOINT/STATEPOINT instructions may have *a lot* of
FrameIndex operands, we end up creating and erasing many
machine instructions. But we can do it in single pass, with only
one new machine instruction generated.

Reviewed By: reames
Differential Revision: https://reviews.llvm.org/D81181
This commit is contained in:
Denis Antrushin 2020-06-04 19:11:13 +03:00
parent c6aa829644
commit 66a1b83bf9
1 changed files with 15 additions and 19 deletions
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34
llvm/lib/CodeGen/TargetLoweringBase.cpp
View File

@ -1023,20 +1023,25 @@ TargetLoweringBase::emitPatchPoint(MachineInstr &InitialMI,
// all stack slots), but we need to handle the different type of stackmap
// operands and memory effects here.
// MI changes inside this loop as we grow operands.
for(unsigned OperIdx = 0; OperIdx != MI->getNumOperands(); ++OperIdx) {
MachineOperand &MO = MI->getOperand(OperIdx);
if (!MO.isFI())
if (!llvm::any_of(MI->operands(),
[](MachineOperand &Operand) { return Operand.isFI(); }))
return MBB;
MachineInstrBuilder MIB = BuildMI(MF, MI->getDebugLoc(), MI->getDesc());
// Inherit previous memory operands.
MIB.cloneMemRefs(*MI);
for (auto &MO : MI->operands()) {
if (!MO.isFI()) {
MIB.add(MI->getOperand(OperIdx));
continue;
}
// foldMemoryOperand builds a new MI after replacing a single FI operand
// with the canonical set of five x86 addressing-mode operands.
int FI = MO.getIndex();
MachineInstrBuilder MIB = BuildMI(MF, MI->getDebugLoc(), MI->getDesc());
// Copy operands before the frame-index.
for (unsigned i = 0; i < OperIdx; ++i)
MIB.add(MI->getOperand(i));
// Add frame index operands recognized by stackmaps.cpp
if (MFI.isStatepointSpillSlotObjectIndex(FI)) {
// indirect-mem-ref tag, size, #FI, offset.
@ -1055,12 +1060,7 @@ TargetLoweringBase::emitPatchPoint(MachineInstr &InitialMI,
MIB.add(MI->getOperand(OperIdx));
MIB.addImm(0);
}
// Copy the operands after the frame index.
for (unsigned i = OperIdx + 1; i != MI->getNumOperands(); ++i)
MIB.add(MI->getOperand(i));
// Inherit previous memory operands.
MIB.cloneMemRefs(*MI);
assert(MIB->mayLoad() && "Folded a stackmap use to a non-load!");
// Add a new memory operand for this FI.
@ -1075,13 +1075,9 @@ TargetLoweringBase::emitPatchPoint(MachineInstr &InitialMI,
MF.getDataLayout().getPointerSize(), MFI.getObjectAlign(FI));
MIB->addMemOperand(MF, MMO);
}
// Replace the instruction and update the operand index.
MBB->insert(MachineBasicBlock::iterator(MI), MIB);
OperIdx += (MIB->getNumOperands() - MI->getNumOperands()) - 1;
MI->eraseFromParent();
MI = MIB;
}
MBB->insert(MachineBasicBlock::iterator(MI), MIB);
MI->eraseFromParent();
return MBB;
}