Rollup merge of #121997 - RalfJung:cast-float-ty, r=compiler-errors

interpret/cast: make more matches on FloatTy properly exhaustive Actually implementing these is pretty trivial (at least once all the scalar methods are added, which happens in #121926), but I'm staying consistent with the other f16/f128 PRs. Also adding adding all the tests to Miri would be quite a lot of work. There's probably some way to reduce the code duplication here with more use of generics... but that's a future refactor.^^ r? `@tgross35`
rust-lang · Mar 5, 2024 · 4a65a53 · 4a65a53
2 parents ac4eb31 681dc38
commit 4a65a53
Showing 1 changed file with 35 additions and 23 deletions.
diff --git a/compiler/rustc_const_eval/src/interpret/cast.rs b/compiler/rustc_const_eval/src/interpret/cast.rs
@@ -182,13 182,14 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
  ) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
  use rustc_type_ir::TyKind::*;
 
- let val = match src.layout.ty.kind() {
- // Floating point
- Float(FloatTy::F32) => self.cast_from_float(src.to_scalar().to_f32()?, cast_to.ty),
- Float(FloatTy::F64) => self.cast_from_float(src.to_scalar().to_f64()?, cast_to.ty),
- _ => {
- bug!("Can't cast 'Float' type into {}", cast_to.ty);
- }
  let Float(fty) = src.layout.ty.kind() else {
  bug!("FloatToFloat/FloatToInt cast: source type {} is not a float type", src.layout.ty)
  };
  let val = match fty {
  FloatTy::F16 => unimplemented!("f16_f128"),
  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"),
  };
  Ok(ImmTy::from_scalar(val, cast_to))
  }
@@ -275,6 276,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
  trace!("cast_from_scalar: {}, {} -> {}", v, src_layout.ty, cast_ty);
 
  Ok(match *cast_ty.kind() {
  // int -> int
  Int(_) | Uint(_) => {
  let size = match *cast_ty.kind() {
  Int(t) => Integer::from_int_ty(self, t).size(),
@@ -285,15 287,26 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
  Scalar::from_uint(v, size)
  }
 
- Float(FloatTy::F32) if signed => Scalar::from_f32(Single::from_i128(v as i128).value),
- Float(FloatTy::F64) if signed => Scalar::from_f64(Double::from_i128(v as i128).value),
- Float(FloatTy::F32) => Scalar::from_f32(Single::from_u128(v).value),
- Float(FloatTy::F64) => Scalar::from_f64(Double::from_u128(v).value),
-
- Char => {
- // `u8` to `char` cast
- Scalar::from_u32(u8::try_from(v).unwrap().into())
  // signed int -> float
  Float(fty) if signed => {
  let v = v as i128;
  match fty {
  FloatTy::F16 => unimplemented!("f16_f128"),
  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"),
  }
  }
  // unsigned int -> float
  Float(fty) => match fty {
  FloatTy::F16 => unimplemented!("f16_f128"),
  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"),
  },
 
  // u8 -> char
  Char => Scalar::from_u32(u8::try_from(v).unwrap().into()),
 
  // Casts to bool are not permitted by rustc, no need to handle them here.
  _ => span_bug!(self.cur_span(), "invalid int to {} cast", cast_ty),
@@ -339,14 352,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
  let v = f.to_i128(size.bits_usize()).value;
  Scalar::from_int(v, size)
  }
- // float -> f32
- Float(FloatTy::F32) => {
- Scalar::from_f32(adjust_nan(self, f, f.convert(&mut false).value))
- }
- // float -> f64
- Float(FloatTy::F64) => {
- Scalar::from_f64(adjust_nan(self, f, f.convert(&mut false).value))
- }
  // float -> float
  Float(fty) => match fty {
  FloatTy::F16 => unimplemented!("f16_f128"),
  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"),
  },
  // That's it.
  _ => span_bug!(self.cur_span(), "invalid float to {} cast", dest_ty),
  }