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float-to-float casts also have non-deterministic NaN results

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This commit is contained in:
Ralf Jung 2023-10-09 07:38:00 +02:00
parent 615d738abe
commit 08deb0daed
6 changed files with 150 additions and 17 deletions
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23
compiler/rustc_const_eval/src/interpret/cast.rs
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@ -311,6 +311,21 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
F: Float + Into<Scalar<M::Provenance>> + FloatConvert<Single> + FloatConvert<Double>,
{
use rustc_type_ir::sty::TyKind::*;
fn adjust_nan<
'mir,
'tcx: 'mir,
M: Machine<'mir, 'tcx>,
F1: rustc_apfloat::Float + FloatConvert<F2>,
F2: rustc_apfloat::Float,
>(
ecx: &InterpCx<'mir, 'tcx, M>,
f1: F1,
f2: F2,
) -> F2 {
if f2.is_nan() { M::generate_nan(ecx, &[f1]) } else { f2 }
}
match *dest_ty.kind() {
// float -> uint
Uint(t) => {
@ -330,9 +345,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
Scalar::from_int(v, size)
}
// float -> f32
Float(FloatTy::F32) => Scalar::from_f32(f.convert(&mut false).value),
Float(FloatTy::F32) => {
Scalar::from_f32(adjust_nan(self, f, f.convert(&mut false).value))
}
// float -> f64
Float(FloatTy::F64) => Scalar::from_f64(f.convert(&mut false).value),
Float(FloatTy::F64) => {
Scalar::from_f64(adjust_nan(self, f, f.convert(&mut false).value))
}
// That's it.
_ => span_bug!(self.cur_span(), "invalid float to {} cast", dest_ty),
}