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Properly handle multiple definitions of a virtual register in the same

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instruction.

This can happen on ARM:

>> %reg1035:5<def>, %reg1035:6<def> = VLD1q16 %reg1028, 0, pred:14, pred:%reg0
Regs: Q0=%reg1032* R0=%reg1028* R1=%reg1029* R2 R3=%reg1031*
Killing last use: %reg1028
Allocating %reg1035 from QPR
Assigning %reg1035 to Q1
<< %D2<def>, %D3<def> = VLD1q16 %R0<kill>, 0, pred:14, pred:%reg0, %Q1<imp-def>

llvm-svn: 104056
This commit is contained in:
Jakob Stoklund Olesen 2010-05-18 21:10:50 +00:00
parent 6b88a14922
commit 1d0a54cb9d
1 changed files with 41 additions and 21 deletions
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62
lib/CodeGen/RegAllocFast.cpp
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@ -154,7 +154,7 @@ namespace {
LiveRegMap::iterator reloadVirtReg(MachineInstr *MI, unsigned OpNum,
unsigned VirtReg, unsigned Hint);
void spillAll(MachineInstr *MI);
bool setPhysReg(MachineOperand &MO, unsigned PhysReg);
bool setPhysReg(MachineInstr *MI, unsigned OpNum, unsigned PhysReg);
};
char RAFast::ID = 0;
}
@ -200,10 +200,17 @@ bool RAFast::isLastUseOfLocalReg(MachineOperand &MO) {
void RAFast::addKillFlag(const LiveReg &LR) {
if (!LR.LastUse) return;
MachineOperand &MO = LR.LastUse->getOperand(LR.LastOpNum);
if (MO.isDef())
MO.setIsDead();
else if (!LR.LastUse->isRegTiedToDefOperand(LR.LastOpNum))
MO.setIsKill();
if (MO.getReg() == LR.PhysReg) {
if (MO.isDef())
MO.setIsDead();
else if (!LR.LastUse->isRegTiedToDefOperand(LR.LastOpNum))
MO.setIsKill();
} else {
if (MO.isDef())
LR.LastUse->addRegisterDead(LR.PhysReg, TRI, true);
else
LR.LastUse->addRegisterKilled(LR.PhysReg, TRI, true);
}
}
/// killVirtReg - Mark virtreg as no longer available.
@ -517,8 +524,12 @@ RAFast::defineVirtReg(MachineInstr *MI, unsigned OpNum,
Hint = DstReg;
}
allocVirtReg(MI, *LRI, Hint);
} else
addKillFlag(LR); // Kill before redefine.
} else if (LR.LastUse) {
// 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())
addKillFlag(LR);
}
assert(LR.PhysReg && "Register not assigned");
LR.LastUse = MI;
LR.LastOpNum = OpNum;
@ -569,11 +580,11 @@ RAFast::reloadVirtReg(MachineInstr *MI, unsigned OpNum,
return LRI;
}
// setPhysReg - Change MO the refer the PhysReg, considering subregs.
// This may invalidate MO if it is necessary to add implicit kills for a
// superregister.
// Return tru if MO kills its register.
bool RAFast::setPhysReg(MachineOperand &MO, unsigned PhysReg) {
// setPhysReg - Change operand OpNum in MI the refer the PhysReg, considering
// subregs. This may invalidate any operand pointers.
// Return true if the operand kills its register.
bool RAFast::setPhysReg(MachineInstr *MI, unsigned OpNum, unsigned PhysReg) {
MachineOperand &MO = MI->getOperand(OpNum);
if (!MO.getSubReg()) {
MO.setReg(PhysReg);
return MO.isKill() || MO.isDead();
@ -584,17 +595,17 @@ bool RAFast::setPhysReg(MachineOperand &MO, unsigned PhysReg) {
MO.setSubReg(0);
if (MO.isUse()) {
if (MO.isKill()) {
MO.getParent()->addRegisterKilled(PhysReg, TRI, true);
MI->addRegisterKilled(PhysReg, TRI, true);
return true;
}
return false;
}
// A subregister def implicitly defines the whole physreg.
if (MO.isDead()) {
MO.getParent()->addRegisterDead(PhysReg, TRI, true);
MI->addRegisterDead(PhysReg, TRI, true);
return true;
}
MO.getParent()->addRegisterDefined(PhysReg, TRI);
MI->addRegisterDefined(PhysReg, TRI);
return false;
}
@ -611,7 +622,7 @@ void RAFast::AllocateBasicBlock() {
E = MBB->livein_end(); I != E; ++I)
definePhysReg(MII, *I, regReserved);
SmallVector<unsigned, 8> PhysECs;
SmallVector<unsigned, 8> PhysECs, VirtDead;
SmallVector<MachineInstr*, 32> Coalesced;
// Otherwise, sequentially allocate each instruction in the MBB.
@ -660,7 +671,7 @@ void RAFast::AllocateBasicBlock() {
if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
LiveRegMap::iterator LRI = LiveVirtRegs.find(Reg);
if (LRI != LiveVirtRegs.end())
setPhysReg(MO, LRI->second.PhysReg);
setPhysReg(MI, i, LRI->second.PhysReg);
else
MO.setReg(0); // We can't allocate a physreg for a DebugValue, sorry!
}
@ -711,12 +722,13 @@ void RAFast::AllocateBasicBlock() {
LiveRegMap::iterator LRI = reloadVirtReg(MI, i, Reg, CopyDst);
unsigned PhysReg = LRI->second.PhysReg;
CopySrc = (CopySrc == Reg || CopySrc == PhysReg) ? PhysReg : 0;
if (setPhysReg(MO, PhysReg))
if (setPhysReg(MI, i, PhysReg))
killVirtReg(LRI);
} else if (MO.isEarlyClobber()) {
// Note: defineVirtReg may invalidate MO.
LiveRegMap::iterator LRI = defineVirtReg(MI, i, Reg, 0);
unsigned PhysReg = LRI->second.PhysReg;
setPhysReg(MO, PhysReg);
setPhysReg(MI, i, PhysReg);
PhysECs.push_back(PhysReg);
}
}
@ -759,13 +771,21 @@ void RAFast::AllocateBasicBlock() {
}
LiveRegMap::iterator LRI = defineVirtReg(MI, i, Reg, CopySrc);
unsigned PhysReg = LRI->second.PhysReg;
if (setPhysReg(MO, PhysReg)) {
killVirtReg(LRI);
if (setPhysReg(MI, i, PhysReg)) {
VirtDead.push_back(Reg);
CopyDst = 0; // cancel coalescing;
} else
CopyDst = (CopyDst == Reg || CopyDst == PhysReg) ? PhysReg : 0;
}
// Kill dead defs after the scan to ensure that multiple defs of the same
// register are allocated identically. We didn't need to do this for uses
// because we are crerating our own kill flags, and they are always at the
// last use.
for (unsigned i = 0, e = VirtDead.size(); i != e; ++i)
killVirtReg(VirtDead[i]);
VirtDead.clear();
MRI->addPhysRegsUsed(UsedInInstr);
if (CopyDst && CopyDst == CopySrc && CopyDstSub == CopySrcSub) {