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Rollup merge of #90999 - RalfJung:miri_simd, r=oli-obk

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fix CTFE/Miri simd_insert/extract on array-style repr(simd) types

The changed test would previously fail since `place_index` would just return the only field of `f32x4`, i.e., the array -- rather than *indexing into* the array which is what we have to do.

The new helper methods will also be needed for https://github.com/rust-lang/miri/issues/1912.

r? ``````@oli-obk``````
This commit is contained in:
Matthias Krüger 2021-11-20 01:09:41 +01:00 • committed by GitHub
commit cf69f9e220
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5 changed files with 76 additions and 38 deletions
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5
compiler/rustc_middle/src/ty/sty.rs
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@ -1805,10 +1805,13 @@ impl<'tcx> TyS<'tcx> {
pub fn simd_size_and_type(&self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
match self.kind() {
Adt(def, substs) => {
assert!(def.repr.simd(), "`simd_size_and_type` called on non-SIMD type");
let variant = def.non_enum_variant();
let f0_ty = variant.fields[0].ty(tcx, substs);
match f0_ty.kind() {
// If the first field is an array, we assume it is the only field and its
// elements are the SIMD components.
Array(f0_elem_ty, f0_len) => {
// FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
// The way we evaluate the `N` in `[T; N]` here only works since we use
@ -1816,6 +1819,8 @@ impl<'tcx> TyS<'tcx> {
// if we use it in generic code. See the `simd-array-trait` ui test.
(f0_len.eval_usize(tcx, ParamEnv::empty()) as u64, f0_elem_ty)
}
// Otherwise, the fields of this Adt are the SIMD components (and we assume they
// all have the same type).
_ => (variant.fields.len() as u64, f0_ty),
}
}