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compare_const_vals: Use infallible evaluation.

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Because these evaluations can never fail.
This commit is contained in:
Nicholas Nethercote 2022-06-09 11:15:03 +10:00
parent 246a5e08bf
commit 73c52b724a
1 changed files with 22 additions and 26 deletions
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48
compiler/rustc_mir_build/src/thir/pattern/mod.rs
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@ -760,32 +760,28 @@ pub(crate) fn compare_const_vals<'tcx>(
}
let ty = a.ty();
let a_bits = a.try_eval_bits(tcx, param_env, ty);
let b_bits = b.try_eval_bits(tcx, param_env, ty);
let a = a.eval_bits(tcx, param_env, ty);
let b = b.eval_bits(tcx, param_env, ty);
if let (Some(a), Some(b)) = (a_bits, b_bits) {
use rustc_apfloat::Float;
return match *ty.kind() {
ty::Float(ty::FloatTy::F32) => {
let l = rustc_apfloat::ieee::Single::from_bits(a);
let r = rustc_apfloat::ieee::Single::from_bits(b);
l.partial_cmp(&r)
}
ty::Float(ty::FloatTy::F64) => {
let l = rustc_apfloat::ieee::Double::from_bits(a);
let r = rustc_apfloat::ieee::Double::from_bits(b);
l.partial_cmp(&r)
}
ty::Int(ity) => {
use rustc_middle::ty::layout::IntegerExt;
let size = rustc_target::abi::Integer::from_int_ty(&tcx, ity).size();
let a = size.sign_extend(a);
let b = size.sign_extend(b);
Some((a as i128).cmp(&(b as i128)))
}
_ => Some(a.cmp(&b)),
};
use rustc_apfloat::Float;
match *ty.kind() {
ty::Float(ty::FloatTy::F32) => {
let a = rustc_apfloat::ieee::Single::from_bits(a);
let b = rustc_apfloat::ieee::Single::from_bits(b);
a.partial_cmp(&b)
}
ty::Float(ty::FloatTy::F64) => {
let a = rustc_apfloat::ieee::Double::from_bits(a);
let b = rustc_apfloat::ieee::Double::from_bits(b);
a.partial_cmp(&b)
}
ty::Int(ity) => {
use rustc_middle::ty::layout::IntegerExt;
let size = rustc_target::abi::Integer::from_int_ty(&tcx, ity).size();
let a = size.sign_extend(a);
let b = size.sign_extend(b);
Some((a as i128).cmp(&(b as i128)))
}
_ => Some(a.cmp(&b)),
}
None
}