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Add f16 and f128 const eval for casting operations #126718

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Add f16 and f128 const eval for casting operations #126718

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7a38cac
Enable const casting for `f16` and `f128`
tgross35 Jun 13, 2024
006d6e8
Update Miri casting tests with `f16` and `f128`
tgross35 Jun 13, 2024
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27 changes: 17 additions & 10 deletions compiler/rustc_const_eval/src/interpret/cast.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
use std::assert_matches::assert_matches;

use rustc_apfloat::ieee::{Double, Single};
use rustc_apfloat::ieee::{Double, Half, Quad, Single};
use rustc_apfloat::{Float, FloatConvert};
use rustc_middle::mir::interpret::{InterpResult, PointerArithmetic, Scalar};
use rustc_middle::mir::CastKind;
Expand Down Expand Up @@ -189,10 +189,10 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
bug!("FloatToFloat/FloatToInt cast: source type {} is not a float type", src.layout.ty)
};
let val = match fty {
FloatTy::F16 => unimplemented!("f16_f128"),
FloatTy::F16 => self.cast_from_float(src.to_scalar().to_f16()?, cast_to.ty),
FloatTy::F32 => self.cast_from_float(src.to_scalar().to_f32()?, cast_to.ty),
FloatTy::F64 => self.cast_from_float(src.to_scalar().to_f64()?, cast_to.ty),
FloatTy::F128 => unimplemented!("f16_f128"),
FloatTy::F128 => self.cast_from_float(src.to_scalar().to_f128()?, cast_to.ty),
};
Ok(ImmTy::from_scalar(val, cast_to))
}
Expand Down Expand Up @@ -298,18 +298,18 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
Float(fty) if signed => {
let v = v as i128;
match fty {
FloatTy::F16 => unimplemented!("f16_f128"),
FloatTy::F16 => Scalar::from_f16(Half::from_i128(v).value),
FloatTy::F32 => Scalar::from_f32(Single::from_i128(v).value),
FloatTy::F64 => Scalar::from_f64(Double::from_i128(v).value),
FloatTy::F128 => unimplemented!("f16_f128"),
FloatTy::F128 => Scalar::from_f128(Quad::from_i128(v).value),
}
}
// unsigned int -> float
Float(fty) => match fty {
FloatTy::F16 => unimplemented!("f16_f128"),
FloatTy::F16 => Scalar::from_f16(Half::from_u128(v).value),
FloatTy::F32 => Scalar::from_f32(Single::from_u128(v).value),
FloatTy::F64 => Scalar::from_f64(Double::from_u128(v).value),
FloatTy::F128 => unimplemented!("f16_f128"),
FloatTy::F128 => Scalar::from_f128(Quad::from_u128(v).value),
},

// u8 -> char
Expand All @@ -323,7 +323,12 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
/// Low-level cast helper function. Converts an apfloat `f` into int or float types.
fn cast_from_float<F>(&self, f: F, dest_ty: Ty<'tcx>) -> Scalar<M::Provenance>
where
F: Float + Into<Scalar<M::Provenance>> + FloatConvert<Single> + FloatConvert<Double>,
F: Float
+ Into<Scalar<M::Provenance>>
+ FloatConvert<Half>
+ FloatConvert<Single>
+ FloatConvert<Double>
+ FloatConvert<Quad>,
{
use rustc_type_ir::TyKind::*;

Expand Down Expand Up @@ -360,10 +365,12 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
}
// float -> float
Float(fty) => match fty {
FloatTy::F16 => unimplemented!("f16_f128"),
FloatTy::F16 => Scalar::from_f16(adjust_nan(self, f, f.convert(&mut false).value)),
FloatTy::F32 => Scalar::from_f32(adjust_nan(self, f, f.convert(&mut false).value)),
FloatTy::F64 => Scalar::from_f64(adjust_nan(self, f, f.convert(&mut false).value)),
FloatTy::F128 => unimplemented!("f16_f128"),
FloatTy::F128 => {
Scalar::from_f128(adjust_nan(self, f, f.convert(&mut false).value))
}
},
// That's it.
_ => span_bug!(self.cur_span(), "invalid float to {} cast", dest_ty),
Expand Down
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