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Rollup merge of #126184 - RalfJung:interpret-simd-nonpow2, r=oli-obk

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interpret: do not ICE on padded non-pow2 SIMD vectors

Fixes https://github.com/rust-lang/miri/issues/3458

r? ``@oli-obk``
This commit is contained in:
Matthias Krüger 2024-06-10 21:12:25 +02:00 committed by GitHub
commit 07bb7ca9fa
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3 changed files with 30 additions and 6 deletions
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13
compiler/rustc_const_eval/src/interpret/place.rs
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@ -499,13 +499,14 @@ where
&self,
mplace: &MPlaceTy<'tcx, M::Provenance>,
) -> InterpResult<'tcx, (MPlaceTy<'tcx, M::Provenance>, u64)> {
// Basically we just transmute this place into an array following simd_size_and_type.
// (Transmuting is okay since this is an in-memory place. We also double-check the size
// stays the same.)
// Basically we want to transmute this place into an array following simd_size_and_type.
let (len, e_ty) = mplace.layout.ty.simd_size_and_type(*self.tcx);
let array = Ty::new_array(self.tcx.tcx, e_ty, len);
let layout = self.layout_of(array)?;
let mplace = mplace.transmute(layout, self)?;
// Some SIMD types have padding, so `len` many `e_ty` does not cover the entire place.
// Therefore we cannot transmute, and instead we project at offset 0, which side-steps
// the size check.
let array_layout = self.layout_of(Ty::new_array(self.tcx.tcx, e_ty, len))?;
assert!(array_layout.size <= mplace.layout.size);
let mplace = mplace.offset(Size::ZERO, array_layout, self)?;
Ok((mplace, len))
}

2
compiler/rustc_const_eval/src/interpret/projection.rs
View File

@ -81,6 +81,8 @@ pub trait Projectable<'tcx, Prov: Provenance>: Sized + std::fmt::Debug {
ecx: &InterpCx<'tcx, M>,
) -> InterpResult<'tcx, Self> {
assert!(layout.is_sized());
// We sometimes do pointer arithmetic with this function, disregarding the source type.
// So we don't check the sizes here.
self.offset_with_meta(offset, OffsetMode::Inbounds, MemPlaceMeta::None, layout, ecx)
}

21
src/tools/miri/tests/pass/intrinsics/portable-simd.rs
View File

@ -658,11 +658,32 @@ fn simd_masked_loadstore() {
assert_eq!(buf, [2, 3, 4]);
}
fn simd_ops_non_pow2() {
// Just a little smoke test for operations on non-power-of-two vectors.
#[repr(simd, packed)]
#[derive(Copy, Clone)]
pub struct SimdPacked<T, const N: usize>([T; N]);
#[repr(simd)]
#[derive(Copy, Clone)]
pub struct SimdPadded<T, const N: usize>([T; N]);
let x = SimdPacked([1u32; 3]);
let y = SimdPacked([2u32; 3]);
let z = unsafe { intrinsics::simd_add(x, y) };
assert_eq!({ z.0 }, [3u32; 3]);
let x = SimdPadded([1u32; 3]);
let y = SimdPadded([2u32; 3]);
let z = unsafe { intrinsics::simd_add(x, y) };
assert_eq!(z.0, [3u32; 3]);
}
fn main() {
simd_mask();
simd_ops_f32();
simd_ops_f64();
simd_ops_i32();
simd_ops_non_pow2();
simd_cast();
simd_swizzle();
simd_gather_scatter();