rustup: update to `nightly-2025-05-09` (~1.88) and Rust 2024 edition. #249

eddyb · 2025-05-12T18:40:33Z

_{This PR supersedes (and includes many of the changes from):

rustup to nightly-2025-04-28 #246}

This brings us 4 whole Rust releases ahead, to a 1.88-equivalent nightly.
_{(Rust 1.88.0 stable will be released on June 26th, 2025)}

The many commits exist in part because of nightly bisection (to find nightly-2024-12-16, containing the GEP array change), but also because there have been several changes of note:

target specs no longer spuriously claim an OS of unknown
- (the sole unknown component in e.g. spirv-unknown-vulkan1.1 is the vendor, whereas the OS is none and omitted in the "triple")
maybe_inbounds_gep had to be made more flexible, due to:
Modifies the index instruction from gep [0 x %Type] to gep %Type rust-lang/rust#134117
- (supporting that pattern was achieved by attempting pointercast first, which can itself produce a "first element of array" GEP that can then be merged with an "intra-array indexing GEP")
f16/f128 required some stubbing out (i.e. intrinsics)
- it may be possible to support f16, but I've not attempted that in this PR
had to re-enable niches for bool (i.e. making Option<bool> byte-sized), due a transmute (from ControlFlow<bool> to u8) added to core::cmp in:
Use the chaining methods on PartialOrd for slices too rust-lang/rust#138881
- not sure Option<bool> ever worked in Rust-GPU (the comments I found are confusing, I thought it had users and/or tests, but maybe not)
(the remaining ones have to do w/ rustc_codegen_ssa patching)
- (see also: Tracking issue: undo rustc_codegen_ssa patching (aka pqp_cg_ssa). #182)
rustc_codegen_spirv had to be switched to the Rust 2024 edition (as rustc_codegen_ssa had done the same upstream)
old-style #[repr(simd)] (using individual struct fields) has had even more support ripped out upstream
- hooking/patching that support back in was possible, but it's clearly not an intended feature and we should try to move off of it sooner than later
some dependencies of rustc_codegen_ssa::back (i.e. object) required more patching to remove their use sites
- only needed because nightlies have had two prebuilt versions of object, breaking extern crate object; (as it may load the wrong version)
- this was also the original blocker for rustup to nightly-2025-04-28 #246
  (before all the other issues were discovered through testing)
- @LegNeato has been separately working on removing that duplication upstream

While not necessary, this (just like #246) includes a full migration of the entire workspace to Rust 2024 (leading to lots of unsafe {...} in unsafe fns in spirv-std, mainly) - we can split that out if it seems better, but I at least tried to keep it in its own commit.

…essChain`s.

…allowing libcore to build.

Firestar99 · 2025-05-12T21:33:33Z

Thanks for getting us up to the newest versions! 🎉
I'm currently away from home, so I'll likely won't be able to review until next week.

LegNeato

Some minor comments. I liked how many of your changes are better than mine ha. Only rejecting so it doesn't merge and others can review.

LegNeato · 2025-05-12T22:08:52Z

crates/rustc_codegen_spirv/build.rs

@@ -276,6 +317,12 @@ mod maybe_pqp_cg_ssa;

    println!("cargo::rustc-check-cfg=cfg(rustc_codegen_spirv_disable_pqp_cg_ssa)");

+    // HACK(eddyb) `if cfg!(llvm_enzyme)` added upstream for autodiff support.
+    println!("cargo::rustc-check-cfg=cfg(llvm_enzyme)");


Oh cool, I didn't know you could put those here.

LegNeato · 2025-05-12T22:09:59Z

crates/rustc_codegen_spirv/src/abi.rs

+            ty::Bool => {
+                // HACK(eddyb) we can't bypass e.g. `Option<bool>` being a byte,
+                // due to `core` PR https://github.com/rust-lang/rust/pull/138881
+                // (which adds a new `transmute`, from `ControlFlow<bool>` to `u8`).


Should we fix / backout stuff upstream?

Nope, it's our absurd problem that we want bool to have a layout Option<bool> can't have (cue "qptr will fix this").

LegNeato · 2025-05-12T22:13:36Z

crates/rustc_codegen_spirv/src/builder/builder_methods.rs

        // --- Attempt GEP Merging Path ---

        // Check if the base pointer `ptr` itself was the result of a previous
        // AccessChain instruction. Merging is only attempted if the input type `ty`
        // matches the pointer's actual underlying pointee type `original_pointee_ty`.
        // If they differ, merging could be invalid.
+        // HACK(eddyb) always attempted now, because we `pointercast` first, which:


Just update the comment rather than having a new comment modify...we have git 😄

To be clear, when I do this it's because I'm already several steps deep and accurately rewording comments might not be the easiest/quickest thing at that moment (but I agree I could/should fix it before landing the PR).

Or just delete the comment!

LegNeato · 2025-05-12T22:13:58Z

crates/rustc_codegen_spirv/src/builder/builder_methods.rs

@@ -908,12 +910,21 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
            // 2. The *last* index of the original AccessChain is a constant.
            // 3. The *first* index (`ptr_base_index`) of the *current* GEP is a constant.
            // Merging usually involves adding these two constant indices.
+            //
+            // FIXME(eddyb) the above comment seems inaccurate, there is no reason


Again, just fix or delete the comment.

crates/rustc_codegen_spirv/src/builder/intrinsics.rs

eddyb requested review from LegNeato, Firestar99 and schell as code owners May 12, 2025 18:40

eddyb enabled auto-merge May 12, 2025 18:40

eddyb force-pushed the rustup-1.88 branch 2 times, most recently from 88fd99e to 554d850 Compare May 12, 2025 19:24

eddyb added 9 commits May 12, 2025 22:32

intrinsics: use GLOp::RoundEven for round_ties_even.

9282a64

rustup: update to nightly-2024-12-01.

b737a46

Update target specs (remove os=unknown, add crt-static-respected).

8dff45e

Fix new clippy::unnecessary_map_or warnings.

9f5dcf9

rustup: update to nightly-2024-12-10.

8e21493

rustup: update to nightly-2024-12-15.

fcfa371

rustup: update to nightly-2024-12-16.

680e6be

builder: always pointercast first before attempting to merge `OpAcc…

020fde2

…essChain`s.

rustup: update to nightly-2024-12-17.

e0f3be2

eddyb force-pushed the rustup-1.88 branch from 554d850 to ae69015 Compare May 12, 2025 19:41

eddyb added 8 commits May 12, 2025 22:59

rustup: update to nightly-2024-12-20.

5ed558e

rustup: update to nightly-2024-12-25.

179571f

rustup: update to nightly-2025-01-03 (~1.85).

e4a9099

Fix new clippy::precedence warnings.

bf7c2e6

rustfmt using nightly-2025-02-16.

ff54cd7

rustup: update to nightly-2025-02-16 (~1.86).

1e6d631

Fix new clippy warnings.

7a0f1a2

rustc_codegen_spirv: switch to Rust 2024 edition.

f9c818d

eddyb force-pushed the rustup-1.88 branch from ae69015 to 78dce65 Compare May 12, 2025 20:03

eddyb added 5 commits May 12, 2025 23:05

rustup: update to nightly-2025-03-29 (~1.87).

3930056

abi: more workarounds for old-style #[repr(simd)] structs.

8ab84c7

Fix new clippy warnings.

e88f042

rustup: update to nightly-2025-04-13.

0517dff

rustup: update to nightly-2025-04-14.

4fcac6a

eddyb and others added 6 commits May 12, 2025 23:05

abi: unhide bool's niche, breaking Option<bool> for Rust-GPU but …

ed6e575

…allowing libcore to build.

Switch all crates to Rust 2024 edition.

3104930

rustup: update to nightly-2025-04-27.

2961102

Fix new clippy::uninlined_format_args warnings.

c78aae9

rustup to nightly-2025-04-28

4bd5f2d

rustup: update to nightly-2025-05-09 (~1.88).

45c42ca

eddyb force-pushed the rustup-1.88 branch from 78dce65 to 45c42ca Compare May 12, 2025 20:06

LegNeato requested changes May 13, 2025

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rustup: update to `nightly-2025-05-09` (~1.88) and Rust 2024 edition. #249

rustup: update to `nightly-2025-05-09` (~1.88) and Rust 2024 edition. #249

eddyb commented May 12, 2025

Firestar99 commented May 12, 2025

LegNeato left a comment

LegNeato May 12, 2025

LegNeato May 12, 2025

eddyb May 13, 2025

LegNeato May 12, 2025

eddyb May 13, 2025

LegNeato May 13, 2025

LegNeato May 12, 2025

rustup: update to nightly-2025-05-09 (~1.88) and Rust 2024 edition. #249

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rustup: update to nightly-2025-05-09 (~1.88) and Rust 2024 edition. #249

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rustup: update to `nightly-2025-05-09` (~1.88) and Rust 2024 edition. #249

rustup: update to `nightly-2025-05-09` (~1.88) and Rust 2024 edition. #249