Jonathan Brouwer cccf996225 Rollup merge of #155264 - sayantn:amx-autocast, r=dianqk ...

Add autocast support for `x86amx`

Builds on rust-lang/rust#140763 by further adding autocasts for `x86amx` from/to vectors of size 8192 bits.

This also disables SIMD vector abi checks for the `"unadjusted"` abi because
 - This is primarily used to link with LLVM intrinsics, which don't actually lower to function calls with vector arguments. Even with other cg backends, this is true.
 - This ABI is internal and perma-unstable (and also super specific), so it is very unlikely that this will cause breakages.
 - (The primary reason) Without doing this we can't actually use 8192 bit long vectors to represent `x86amx`

> Why do we need a bypass for `x86amx`? Can't we use a `#[lang_item]` or something?

If `x86amx` was a normal LLVM type, this approach would've worked and I would also prefer it. But LLVM specifies that

> No instruction is allowed for this type. There are no arguments, arrays, pointers, vectors or constants of this type.

So we can't treat it like a normal type at all -- even if we add it like a lang-item, we would still have to special-case everywhere to check if we are passing to the correct LLVM intrinsic, and only then use the `x86amx` type. IMO this is needlessly complex, and way worse than this solution, which just adds it to the autocast list in cg_llvm

r? codegen

2026-04-20 08:14:10 +02:00

..

src

Rollup merge of #155264 - sayantn:amx-autocast, r=dianqk

2026-04-20 08:14:10 +02:00

Cargo.toml

Convert to inline diagnostics in rustc_monomorphize

2026-02-03 22:44:22 +01:00