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machinst x64: fix generation of RegMemImm immediate operands;

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This commit is contained in:
Benjamin Bouvier
2020-07-08 16:49:44 +02:00
parent 1430c5e436
commit 00b38c91f6
1 changed files with 5 additions and 5 deletions
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10
cranelift/codegen/src/isa/x64/lower.rs
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@@ -175,11 +175,11 @@ fn input_to_reg_mem(ctx: Ctx, spec: InsnInput) -> RegMem {
/// TODO: handle memory as well!
fn input_to_reg_mem_imm(ctx: Ctx, spec: InsnInput) -> RegMemImm {
let imm = ctx.get_input(spec.insn, spec.input).constant.and_then(|x| {
let as_u32 = x as u32;
let extended = as_u32 as u64;
// If the truncation and sign-extension don't change the value, use it.
if extended == x {
Some(as_u32)
// For i64 instructions (prefixed with REX.W), require that the immediate will sign-extend
// to 64 bits. For other sizes, it doesn't matter and we can just use the plain
// constant.
if ctx.input_ty(spec.insn, spec.input).bytes() != 8 || low32_will_sign_extend_to_64(x) {
Some(x as u32)
} else {
None
}