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Add support for partial redefs to the fast register allocator.

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A partial redef now triggers a reload if required. Also don't add
<imp-def,dead> operands for physical superregisters.

Kill flags are still treated as full register kills, and <imp-use,kill> operands
are added for physical superregisters as before.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104167 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2010-05-19 21:36:05 +00:00
parent f4ccaeaef9
commit d32e735ae6
1 changed files with 18 additions and 20 deletions
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38
lib/CodeGen/RegAllocFast.cpp
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@ -200,14 +200,9 @@ bool RAFast::isLastUseOfLocalReg(MachineOperand &MO) {
void RAFast::addKillFlag(const LiveReg &LR) {
if (!LR.LastUse) return;
MachineOperand &MO = LR.LastUse->getOperand(LR.LastOpNum);
if (MO.getReg() == LR.PhysReg) {
if (MO.isDef())
MO.setIsDead();
else if (!LR.LastUse->isRegTiedToDefOperand(LR.LastOpNum))
if (MO.isUse() && !LR.LastUse->isRegTiedToDefOperand(LR.LastOpNum)) {
if (MO.getReg() == LR.PhysReg)
MO.setIsKill();
} else {
if (MO.isDef())
LR.LastUse->addRegisterDead(LR.PhysReg, TRI, true);
else
LR.LastUse->addRegisterKilled(LR.PhysReg, TRI, true);
}
@ -513,6 +508,7 @@ RAFast::defineVirtReg(MachineInstr *MI, unsigned OpNum,
bool New;
tie(LRI, New) = LiveVirtRegs.insert(std::make_pair(VirtReg, LiveReg()));
LiveReg &LR = LRI->second;
bool PartialRedef = MI->getOperand(OpNum).getSubReg();
if (New) {
// If there is no hint, peek at the only use of this register.
if ((!Hint || !TargetRegisterInfo::isPhysicalRegister(Hint)) &&
@ -524,7 +520,15 @@ RAFast::defineVirtReg(MachineInstr *MI, unsigned OpNum,
Hint = DstReg;
}
allocVirtReg(MI, *LRI, Hint);
} else if (LR.LastUse) {
// If this is only a partial redefinition, we must reload the other parts.
if (PartialRedef && MI->readsVirtualRegister(VirtReg)) {
const TargetRegisterClass *RC = MRI->getRegClass(VirtReg);
int FI = getStackSpaceFor(VirtReg, RC);
DEBUG(dbgs() << "Reloading for partial redef: %reg" << VirtReg << "\n");
TII->loadRegFromStackSlot(*MBB, MI, LR.PhysReg, FI, RC, TRI);
++NumLoads;
}
} else if (LR.LastUse && !PartialRedef) {
// Redefining a live register - kill at the last use, unless it is this
// instruction defining VirtReg multiple times.
if (LR.LastUse != MI || LR.LastUse->getOperand(LR.LastOpNum).isUse())
@ -593,20 +597,14 @@ bool RAFast::setPhysReg(MachineInstr *MI, unsigned OpNum, unsigned PhysReg) {
// Handle subregister index.
MO.setReg(PhysReg ? TRI->getSubReg(PhysReg, MO.getSubReg()) : 0);
MO.setSubReg(0);
if (MO.isUse()) {
if (MO.isKill()) {
MI->addRegisterKilled(PhysReg, TRI, true);
return true;
}
return false;
}
// A subregister def implicitly defines the whole physreg.
if (MO.isDead()) {
MI->addRegisterDead(PhysReg, TRI, true);
// A kill flag implies killing the full register. Add corresponding super
// register kill.
if (MO.isKill()) {
MI->addRegisterKilled(PhysReg, TRI, true);
return true;
}
MI->addRegisterDefined(PhysReg, TRI);
return false;
return MO.isDead();
}
void RAFast::AllocateBasicBlock() {