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Add full register <imp-def> operands when the coalescer is creating partial 

register updates.

These operands tell the spiller that the other parts of the partially defined
register are don't-care, and a reload is not necessary.

llvm-svn: 105361
This commit is contained in:
Jakob Stoklund Olesen 2010-06-02 23:22:11 +00:00
parent df84e8baf7
commit 42c642cd24
1 changed files with 52 additions and 52 deletions
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104
llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp
View File

@ -792,63 +792,63 @@ SimpleRegisterCoalescing::UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg,
SubIdx = 0;
}
// Copy the register use-list before traversing it. We may be adding operands
// and invalidating pointers.
SmallVector<std::pair<MachineInstr*, unsigned>, 32> reglist;
// Collect all the instructions using SrcReg.
SmallPtrSet<MachineInstr*, 32> Instrs;
for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(SrcReg),
E = mri_->reg_end(); I != E; ++I)
reglist.push_back(std::make_pair(&*I, I.getOperandNo()));
Instrs.insert(&*I);
for (unsigned N=0; N != reglist.size(); ++N) {
MachineInstr *UseMI = reglist[N].first;
MachineOperand &O = UseMI->getOperand(reglist[N].second);
unsigned OldSubIdx = O.getSubReg();
for (SmallPtrSet<MachineInstr*, 32>::const_iterator I = Instrs.begin(),
E = Instrs.end(); I != E; ++I) {
MachineInstr *UseMI = *I;
// A PhysReg copy that won't be coalesced can perhaps be rematerialized
// instead.
if (DstIsPhys) {
unsigned UseDstReg = DstReg;
if (OldSubIdx)
UseDstReg = tri_->getSubReg(DstReg, OldSubIdx);
unsigned CopySrcReg, CopyDstReg, CopySrcSubIdx, CopyDstSubIdx;
if (tii_->isMoveInstr(*UseMI, CopySrcReg, CopyDstReg,
CopySrcSubIdx, CopyDstSubIdx) &&
CopySrcSubIdx == 0 &&
CopyDstSubIdx == 0 &&
CopySrcReg != CopyDstReg &&
CopySrcReg == SrcReg && CopyDstReg != UseDstReg) {
// If the use is a copy and it won't be coalesced away, and its source
// is defined by a trivial computation, try to rematerialize it instead.
if (!JoinedCopies.count(UseMI) &&
ReMaterializeTrivialDef(li_->getInterval(SrcReg), CopyDstReg,
CopyDstSubIdx, UseMI))
continue;
}
O.setReg(UseDstReg);
O.setSubReg(0);
if (OldSubIdx) {
// Def and kill of subregister of a virtual register actually defs and
// kills the whole register. Add imp-defs and imp-kills as needed.
if (O.isDef()) {
if(O.isDead())
UseMI->addRegisterDead(DstReg, tri_, true);
else
UseMI->addRegisterDefined(DstReg, tri_);
} else if (!O.isUndef() &&
(O.isKill() ||
UseMI->isRegTiedToDefOperand(&O-&UseMI->getOperand(0))))
UseMI->addRegisterKilled(DstReg, tri_, true);
}
DEBUG({
dbgs() << "\t\tupdated: ";
if (!UseMI->isDebugValue())
dbgs() << li_->getInstructionIndex(UseMI) << "\t";
dbgs() << *UseMI;
});
continue;
CopySrcSubIdx == 0 && CopyDstSubIdx == 0 &&
CopySrcReg != CopyDstReg && CopySrcReg == SrcReg &&
CopyDstReg != DstReg && !JoinedCopies.count(UseMI) &&
ReMaterializeTrivialDef(li_->getInterval(SrcReg), CopyDstReg, 0,
UseMI))
continue;
}
O.substVirtReg(DstReg, SubIdx, *tri_);
SmallVector<unsigned,8> Ops;
bool Reads, Writes;
tie(Reads, Writes) = UseMI->readsWritesVirtualRegister(SrcReg, &Ops);
bool Kills = false, Deads = false;
// Replace SrcReg with DstReg in all UseMI operands.
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
MachineOperand &MO = UseMI->getOperand(Ops[i]);
Kills |= MO.isKill();
Deads |= MO.isDead();
if (DstIsPhys)
MO.substPhysReg(DstReg, *tri_);
else
MO.substVirtReg(DstReg, SubIdx, *tri_);
}
// This instruction is a copy that will be removed.
if (JoinedCopies.count(UseMI))
continue;
if (SubIdx) {
// If UseMI was a simple SrcReg def, make sure we didn't turn it into a
// read-modify-write of DstReg.
if (Deads)
UseMI->addRegisterDead(DstReg, tri_);
else if (!Reads && Writes)
UseMI->addRegisterDefined(DstReg, tri_);
// Kill flags apply to the whole physical register.
if (DstIsPhys && Kills)
UseMI->addRegisterKilled(DstReg, tri_);
}
DEBUG({
dbgs() << "\t\tupdated: ";
@ -857,15 +857,15 @@ SimpleRegisterCoalescing::UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg,
dbgs() << *UseMI;
});
// After updating the operand, check if the machine instruction has
// become a copy. If so, update its val# information.
if (JoinedCopies.count(UseMI))
const TargetInstrDesc &TID = UseMI->getDesc();
if (DstIsPhys || TID.getNumDefs() != 1 || TID.getNumOperands() <= 2)
continue;
const TargetInstrDesc &TID = UseMI->getDesc();
unsigned CopySrcReg, CopyDstReg, CopySrcSubIdx, CopyDstSubIdx;
if (TID.getNumDefs() == 1 && TID.getNumOperands() > 2 &&
tii_->isMoveInstr(*UseMI, CopySrcReg, CopyDstReg,
if (tii_->isMoveInstr(*UseMI, CopySrcReg, CopyDstReg,
CopySrcSubIdx, CopyDstSubIdx) &&
CopySrcReg != CopyDstReg &&
(TargetRegisterInfo::isVirtualRegister(CopyDstReg) ||