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Stop moving Early FixedReg Use operands in certain conditions when Reuse operands are present. #190

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Stop moving Early FixedReg Use operands in certain conditions when Reuse operands are present. #190

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ab3c0a4
Added support for multiple OperandConstraint::Reuse operands.
Iizerd Jul 18, 2024
f9bdffc
Stop moving fixed reg operands to after if there is a clobber or late…
Iizerd Sep 6, 2024
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23 changes: 16 additions & 7 deletions src/ion/liveranges.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -460,15 +460,14 @@ impl<'a, F: Function> Env<'a, F> {
// Does the instruction have any input-reusing
// outputs? This is important below to establish
// proper interference wrt other inputs. We note the
// *vreg* that is reused, not the index.
let mut reused_input = None;
// *vreg*s that are reused, not the index.
let mut reused_inputs: SmallVec<[VReg; 4]> = smallvec![];
for op in self.func.inst_operands(inst) {
if let OperandConstraint::Reuse(i) = op.constraint() {
debug_assert!(self.func.inst_operands(inst)[i]
.as_fixed_nonallocatable()
.is_none());
reused_input = Some(self.func.inst_operands(inst)[i].vreg());
break;
reused_inputs.push(self.func.inst_operands(inst)[i].vreg())
}
}

Expand Down Expand Up @@ -592,10 +591,20 @@ impl<'a, F: Function> Env<'a, F> {
// the other inputs and the
// input-that-is-reused/output.
(OperandKind::Use, OperandPos::Early)
if reused_input.is_some()
&& reused_input.unwrap() != operand.vreg() =>
if !reused_inputs.is_empty()
&& !reused_inputs.contains(&operand.vreg()) =>
{
ProgPoint::after(inst)
if let OperandConstraint::FixedReg(preg) = operand.constraint() {
if self.func.inst_clobbers(inst).contains(preg)
|| late_def_fixed.contains(&preg)
{
ProgPoint::before(inst)
} else {
ProgPoint::after(inst)
}
} else {
ProgPoint::after(inst)
}
}
(OperandKind::Use, OperandPos::Early) => ProgPoint::before(inst),
};
Expand Down
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