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machinst x64: generate copies of constants during lowering;

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This commit is contained in:
Benjamin Bouvier
2020-09-08 16:19:06 +02:00
parent cace32746f
commit d9052d0a9c
2 changed files with 24 additions and 2 deletions
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2
cranelift/codegen/src/isa/aarch64/lower.rs
View File

@@ -185,12 +185,12 @@ pub(crate) fn put_input_in_reg<C: LowerCtx<I = Inst>>(
let from_bits = ty_bits(ty) as u8;
let inputs = ctx.get_input(input.insn, input.input);
let in_reg = if let Some(c) = inputs.constant {
// Generate constants fresh at each use to minimize long-range register pressure.
let masked = if from_bits < 64 {
c & ((1u64 << from_bits) - 1)
} else {
c
};
// Generate constants fresh at each use to minimize long-range register pressure.
let to_reg = ctx.alloc_tmp(Inst::rc_for_type(ty).unwrap(), ty);
for inst in Inst::gen_constant(to_reg, masked, ty, |reg_class, ty| {
ctx.alloc_tmp(reg_class, ty)

22
cranelift/codegen/src/isa/x64/lower.rs
View File

@@ -79,7 +79,29 @@ fn lowerinput_to_reg(ctx: Ctx, input: LowerInput) -> Reg {
/// Put the given input into a register, and mark it as used (side-effect).
fn put_input_in_reg(ctx: Ctx, spec: InsnInput) -> Reg {
let input = ctx.get_input(spec.insn, spec.input);
if let Some(c) = input.constant {
// Generate constants fresh at each use to minimize long-range register pressure.
let ty = ctx.input_ty(spec.insn, spec.input);
let from_bits = ty_bits(ty);
let masked = if from_bits < 64 {
c & ((1u64 << from_bits) - 1)
} else {
c
};
let cst_copy = ctx.alloc_tmp(Inst::rc_for_type(ty).unwrap(), ty);
for inst in Inst::gen_constant(cst_copy, masked, ty, |reg_class, ty| {
ctx.alloc_tmp(reg_class, ty)
})
.into_iter()
{
ctx.emit(inst);
}
cst_copy.to_reg()
} else {
lowerinput_to_reg(ctx, input)
}
}
/// An extension specification for `extend_input_to_reg`.