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Miri float->int casts: be explicit that this is saturating

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This commit is contained in:
Ralf Jung 2020-03-26 19:09:31 +01:00
parent 2fbb07525e
commit 27777e2e7b
1 changed files with 4 additions and 0 deletions
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4
src/librustc_mir/interpret/cast.rs
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@ -229,6 +229,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// float -> uint
Uint(t) => {
let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits());
// `to_u128` is a saturating cast, which is what we need
// (https://doc.rust-lang.org/nightly/nightly-rustc/rustc_apfloat/trait.Float.html#method.to_i128_r).
let v = f.to_u128(usize::try_from(width).unwrap()).value;
// This should already fit the bit width
Ok(Scalar::from_uint(v, Size::from_bits(width)))
@ -236,6 +238,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// float -> int
Int(t) => {
let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits());
// `to_i128` is a saturating cast, which is what we need
// (https://doc.rust-lang.org/nightly/nightly-rustc/rustc_apfloat/trait.Float.html#method.to_i128_r).
let v = f.to_i128(usize::try_from(width).unwrap()).value;
Ok(Scalar::from_int(v, Size::from_bits(width)))
}