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Rollup merge of #127032 - tgross35:f16-f128-const-eval-cast, r=oli-obk

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Enable const casting for `f16` and `f128`

I have an open PR to the Miri repo adding tests for this behavior https://github.com/rust-lang/miri/pull/3688, but that unfortunately hits the ICE path here. The changes seem reasonably low risk that it might be okay to merge separately from the tests, and I tested the result locally against an older version of https://github.com/rust-lang/miri/pull/3688.

Cc ``````@RalfJung``````
This commit is contained in:
Matthias Krüger 2024-06-28 22:04:17 +02:00 committed by GitHub
commit 93ca5ff900
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1 changed files with 17 additions and 10 deletions
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27
compiler/rustc_const_eval/src/interpret/cast.rs
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@ -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;
@ -187,10 +187,10 @@ 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))
}
@ -296,18 +296,18 @@ 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
@ -321,7 +321,12 @@ 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::*;
@ -358,10 +363,12 @@ 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),