Introduce InstanceKind::LlvmIntrinsic by bjorn3 · Pull Request #159183 · rust-lang/rust

bjorn3 · 2026-07-12T16:20:18Z

This way codegen backends don't have to check for a magic symbol name prefix to detect LLVM intrinsic calls and thus can more easily handle them separately as necessary.

rustbot · 2026-07-12T16:20:21Z

miri is developed in its own repository. If possible, consider making this change to rust-lang/miri instead.

cc @rust-lang/miri

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

This PR changes rustc_public

cc @oli-obk, @celinval, @ouz-a, @makai410

rustbot · 2026-07-12T16:20:23Z

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bjorn3 · 2026-07-12T16:24:57Z

+                    this, link_name, args, &dest,
+                ),
+            _ => interp_ok(EmulateItemResult::NotSupported),
+        };


@RalfJung would you prefer if this match was a method in shims/mod.rs?

View changes since the review

Eventually, all the LLVM shims should be moved to intrinsics.

Up to you if you want to do that in this PR. But if you don't, then please leave the logic entirely inside shims rather than splitting it between shims and intrinsics.

I've moved it back to shims for now with a FIXME to move it to intrinsics.

RalfJung · 2026-07-13T10:28:34Z

+                    this, link_name, args, &dest,
+                ),
+            _ => interp_ok(EmulateItemResult::NotSupported),
+        };


Eventually, all the LLVM shims should be moved to intrinsics.

Up to you if you want to do that in this PR. But if you don't, then please leave the logic entirely inside shims rather than splitting it between shims and intrinsics.

RalfJung

r=me on the Miri changes

View changes since this review

RalfJung · 2026-07-13T14:01:23Z

Oh wait nvm there was the EmulateItemResult discussion.

bjorn3 · 2026-07-13T14:18:02Z

Ok if I squash the first four commits?

RalfJung

Now for real, r=me on the Miri parts. :)

And yeah fine for me to squash.

View changes since this review

This way codegen backends don't have to check for a magic symbol name prefix to detect LLVM intrinsic calls and thus can more easily handle them separately as necessary.

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jul 12, 2026

rustbot assigned folkertdev Jul 12, 2026

bjorn3 force-pushed the instance_llvm_intrinsic branch from e14ca78 to b7990f6 Compare July 12, 2026 16:24

bjorn3 commented Jul 12, 2026

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