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release/18.x: [Mips] Fix missing sign extension in expansion of sub-word atomic max (#77072) #84566

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release/18.x: [Mips] Fix missing sign extension in expansion of sub-word atomic max (#77072) #84566

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51 changes: 42 additions & 9 deletions llvm/lib/Target/Mips/MipsExpandPseudo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -388,18 +388,32 @@ bool MipsExpandPseudo::expandAtomicBinOpSubword(
Opcode = Mips::XOR;
break;
case Mips::ATOMIC_LOAD_UMIN_I8_POSTRA:
IsUnsigned = true;
IsMin = true;
break;
case Mips::ATOMIC_LOAD_UMIN_I16_POSTRA:
IsUnsigned = true;
[[fallthrough]];
IsMin = true;
break;
case Mips::ATOMIC_LOAD_MIN_I8_POSTRA:
SEOp = Mips::SEB;
IsMin = true;
break;
case Mips::ATOMIC_LOAD_MIN_I16_POSTRA:
IsMin = true;
break;
case Mips::ATOMIC_LOAD_UMAX_I8_POSTRA:
IsUnsigned = true;
IsMax = true;
break;
case Mips::ATOMIC_LOAD_UMAX_I16_POSTRA:
IsUnsigned = true;
[[fallthrough]];
IsMax = true;
break;
case Mips::ATOMIC_LOAD_MAX_I8_POSTRA:
SEOp = Mips::SEB;
IsMax = true;
break;
case Mips::ATOMIC_LOAD_MAX_I16_POSTRA:
IsMax = true;
break;
Expand Down Expand Up @@ -461,14 +475,33 @@ bool MipsExpandPseudo::expandAtomicBinOpSubword(

// For little endian we need to clear uninterested bits.
if (STI->isLittle()) {
// and OldVal, OldVal, Mask
// and Incr, Incr, Mask
BuildMI(loopMBB, DL, TII->get(Mips::AND), OldVal)
.addReg(OldVal)
.addReg(Mask);
BuildMI(loopMBB, DL, TII->get(Mips::AND), Incr).addReg(Incr).addReg(Mask);
if (!IsUnsigned) {
BuildMI(loopMBB, DL, TII->get(Mips::SRAV), OldVal)
.addReg(OldVal)
.addReg(ShiftAmnt);
BuildMI(loopMBB, DL, TII->get(Mips::SRAV), Incr)
.addReg(Incr)
.addReg(ShiftAmnt);
if (STI->hasMips32r2()) {
BuildMI(loopMBB, DL, TII->get(SEOp), OldVal).addReg(OldVal);
BuildMI(loopMBB, DL, TII->get(SEOp), Incr).addReg(Incr);
} else {
const unsigned ShiftImm = SEOp == Mips::SEH ? 16 : 24;
BuildMI(loopMBB, DL, TII->get(Mips::SLL), OldVal)
.addReg(OldVal, RegState::Kill)
.addImm(ShiftImm);
BuildMI(loopMBB, DL, TII->get(Mips::SRA), OldVal)
.addReg(OldVal, RegState::Kill)
.addImm(ShiftImm);
BuildMI(loopMBB, DL, TII->get(Mips::SLL), Incr)
.addReg(Incr, RegState::Kill)
.addImm(ShiftImm);
BuildMI(loopMBB, DL, TII->get(Mips::SRA), Incr)
.addReg(Incr, RegState::Kill)
.addImm(ShiftImm);
}
}
}

// unsigned: sltu Scratch4, oldVal, Incr
// signed: slt Scratch4, oldVal, Incr
BuildMI(loopMBB, DL, TII->get(SLTScratch4), Scratch4)
Expand Down
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