bool CoalescerPair::setRegisters(const MachineInstr *MI) {
srcReg_ = dstReg_ = subIdx_ = 0;
newRC_ = 0;
- flipped_ = false;
+ flipped_ = crossClass_ = false;
unsigned Src, Dst, SrcSub, DstSub;
if (!isMoveInstr(MI, Src, Dst, SrcSub, DstSub))
std::swap(SrcSub, DstSub);
flipped_ = true;
}
+ origDstReg_ = Dst;
const MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
} else {
// Both registers are virtual.
- // Identical sub to sub.
- if (SrcSub == DstSub)
+ // Both registers have subreg indices.
+ if (SrcSub && DstSub) {
+ // For now we only handle the case of identical indices in commensurate
+ // registers: Dreg:ssub_1 + Dreg:ssub_1 -> Dreg
+ // FIXME: Handle Qreg:ssub_3 + Dreg:ssub_1 as QReg:dsub_1 + Dreg.
+ if (SrcSub != DstSub)
+ return false;
+ const TargetRegisterClass *SrcRC = MRI.getRegClass(Src);
+ const TargetRegisterClass *DstRC = MRI.getRegClass(Dst);
+ if (!getCommonSubClass(DstRC, SrcRC))
+ return false;
SrcSub = DstSub = 0;
- else if (SrcSub && DstSub)
- return false; // FIXME: Qreg:ssub_3 + Dreg:ssub_1 => QReg:dsub_1 + Dreg.
+ }
// There can be no SrcSub.
if (SrcSub) {
newRC_ = getCommonSubClass(DstRC, SrcRC);
if (!newRC_)
return false;
+ crossClass_ = newRC_ != DstRC || newRC_ != SrcRC;
}
// Check our invariants
assert(TargetRegisterInfo::isVirtualRegister(Src) && "Src must be virtual");