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Rollup merge of #128731 - RalfJung:simd-shuffle-vector, r=workingjubilee

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simd_shuffle intrinsic: allow argument to be passed as vector

See https://github.com/rust-lang/rust/issues/128738 for context.

I'd like to get rid of [this hack](6c0b89dfac/compiler/rustc_codegen_ssa/src/mir/block.rs (L922-L935)). https://github.com/rust-lang/rust/pull/128537 almost lets us do that since constant SIMD vectors will then be passed as immediate arguments. However, simd_shuffle for some reason actually takes an *array* as argument, not a vector, so the hack is still required to ensure that the array becomes an immediate (which then later stages of codegen convert into a vector, as that's what LLVM needs).

This PR prepares simd_shuffle to also support a vector as the `idx` argument. Once this lands, stdarch can hopefully be updated to pass `idx` as a vector, and then support for arrays can be removed, which finally lets us get rid of that hack.
This commit is contained in:
Trevor Gross 2024-08-27 01:46:50 -05:00 • committed by GitHub
commit d2ff033302
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6 changed files with 90 additions and 31 deletions
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19
compiler/rustc_codegen_llvm/src/intrinsic.rs
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@ -1287,19 +1287,24 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
}
if name == sym::simd_shuffle {
// Make sure this is actually an array, since typeck only checks the length-suffixed
// Make sure this is actually an array or SIMD vector, since typeck only checks the length-suffixed
// version of this intrinsic.
let n: u64 = match args[2].layout.ty.kind() {
let idx_ty = args[2].layout.ty;
let n: u64 = match idx_ty.kind() {
ty::Array(ty, len) if matches!(ty.kind(), ty::Uint(ty::UintTy::U32)) => {
len.try_eval_target_usize(bx.cx.tcx, ty::ParamEnv::reveal_all()).unwrap_or_else(
|| span_bug!(span, "could not evaluate shuffle index array length"),
)
}
_ => return_error!(InvalidMonomorphization::SimdShuffle {
span,
name,
ty: args[2].layout.ty
}),
_ if idx_ty.is_simd()
&& matches!(
idx_ty.simd_size_and_type(bx.cx.tcx).1.kind(),
ty::Uint(ty::UintTy::U32)
) =>
{
idx_ty.simd_size_and_type(bx.cx.tcx).0
}
_ => return_error!(InvalidMonomorphization::SimdShuffle { span, name, ty: idx_ty }),
};
let (out_len, out_ty) = require_simd!(ret_ty, SimdReturn);