Update to LLVM 23 by nikic · Pull Request #158734 · rust-lang/rust

nikic · 2026-07-03T14:03:29Z

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Changes in this PR (apart from the LLVM update):

Updated cov-map tests due to minor ordering changes introduced in llvm/llvm-project@5931034. The affected tests are limited to LLVM >= 23 now.
Set LLVM_VERSIONED_DYLIB_NAME_ON_DARWIN=OFF, which restores the previous unversioned naming of the LLVM dylib on Darwin. I expect we'll want to change this for consistency with Linux, but given the amount of trouble Darwin dylibs have caused in the past, I'm not trying to do it in this PR.
Distribute the llvm-project/libc subproject, which is now a build dependency of LLVM.
Pull in f128 Windows ABI changes from adjust f128 windows abi for LLVM 23 #158778. These need to land in sync with the LLVM update (as ABI of libcalls is controlled by LLVM, not our ABI lowering).
Disable RISCV backend on dist-i686-mingw, because the build OOMs on a large generated file. This is a temporary measure until host tools are removed by Drop tier 2 i686-pc-windows-gnu host tools compiler-team#1020.
The llvm-project fork includes a new downstream patch for mingw: rust-lang/llvm-project@b89cd8e It works around mingw having broken TLS prior to GCC 16. (We're currently on GCC 14.)

Issues:

nikic · 2026-07-03T14:06:12Z

@bors try @rust-timer queue

Update to LLVM 23

rust-bors · 2026-07-03T14:45:45Z

💔 Test for b003a3f failed: CI. Failed job:

try - dist-x86_64-linux-quick (web logs, enhanced plaintext logs)

nikic · 2026-07-13T14:40:28Z

@bors try

Update to LLVM 23

rust-bors · 2026-07-13T15:21:10Z

💔 Test for 0259978 failed: CI. Failed job:

try - dist-x86_64-linux-quick (web logs, enhanced plaintext logs)

nikic · 2026-07-14T07:28:00Z

@bors try

Update to LLVM 23

rust-bors · 2026-07-14T08:36:48Z

💔 Test for 4973bfc failed: CI. Failed job:

try - dist-x86_64-linux-quick (web logs, enhanced plaintext logs)

Update to LLVM 23 try-job: dist-i686-mingw

nikic · 2026-07-20T14:42:04Z

The include-blob regression is due to escape_string_symbol(), where that particular benchmark spends basically all the time. Having trouble creating a reproducer for that though, the LTO/PGO really doesn't make it easy to independently reproduce optimization issues.

Maybe it would be easier to just reimplement that function in rustc, the way this currently happens via escape_default() and layers of iterators and formatters is horrible.

rust-bors · 2026-07-20T16:02:14Z

☀️ Try build successful (CI)
Build commit: af3dce7 (af3dce70e26ccb50ebf15fe1f2a3d83cea5764b7)
Base parent: 14ead7d (14ead7d3d509f50efe9afb84673e65885dfd4d07)

nikic · 2026-07-20T18:41:25Z

Tried that in #159609, it does seem like even a naive implementation is better than using the std iterator with to_string()...

rustbot · 2026-07-22T08:42:24Z

Some changes occurred in coverage tests.

cc @Zalathar

This PR changes how LLVM is built. Consider updating src/bootstrap/download-ci-llvm-stamp.

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

cc @bjorn3

Warning

If you are changing how CI LLVM is built or linked, make sure to bump
src/bootstrap/download-ci-llvm-stamp.

cc @jieyouxu

rustbot · 2026-07-22T08:42:27Z

r? @davidtwco

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rustbot · 2026-07-22T08:42:29Z

⚠️ Warning ⚠️

Some commits in this PR modify submodules.

If this was not intentional, see I changed a submodule on accident in the rustc dev guide.

There is a minor change in sorted order due to: llvm/llvm-project@5931034

We probably want to change this to align with Linux, but for now keep the old behavior.

It's a dependency of LLVM now.

We can start matching the codegen introduced by LLVM at [1]. This alone isn't enough to make f128 functional on the platform because libcalls use the LLVM ABI. Current behavior originally introduced in RUST-128388. [1]: llvm/llvm-project@aa47e59

rustbot · 2026-07-22T20:13:08Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

nikic · 2026-07-22T20:23:41Z

r? @cuviper

bjorn3

cg_clif changes LGTM

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 3, 2026

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rust-bors Bot pushed a commit that referenced this pull request Jul 3, 2026

Auto merge of #158734 - nikic:llvm23, r=<try>

b003a3f

Update to LLVM 23

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nikic force-pushed the llvm23 branch from 5ae3f12 to 26b9e8a Compare July 13, 2026 14:39

rustbot added A-CI Area: Our Github Actions CI A-testsuite Area: The testsuite used to check the correctness of rustc T-infra Relevant to the infrastructure team, which will review and decide on the PR/issue. labels Jul 13, 2026

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rust-bors Bot pushed a commit that referenced this pull request Jul 13, 2026

Auto merge of #158734 - nikic:llvm23, r=<try>

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Update to LLVM 23

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nikic force-pushed the llvm23 branch from 26b9e8a to cbbd380 Compare July 14, 2026 07:12

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rust-bors Bot pushed a commit that referenced this pull request Jul 14, 2026

Auto merge of #158734 - nikic:llvm23, r=<try>

4973bfc

Update to LLVM 23

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nikic force-pushed the llvm23 branch from cbbd380 to b052a0d Compare July 14, 2026 08:55

rust-bors Bot pushed a commit that referenced this pull request Jul 20, 2026

Auto merge of #158734 - nikic:llvm23, r=<try>

af3dce7

Update to LLVM 23 try-job: dist-i686-mingw

nikic force-pushed the llvm23 branch from efcff8e to 54f145e Compare July 22, 2026 08:29

nikic marked this pull request as ready for review July 22, 2026 08:42

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 22, 2026

rustbot assigned davidtwco Jul 22, 2026

bjorn3 reviewed Jul 22, 2026

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Comment thread compiler/rustc_codegen_cranelift/src/abi/mod.rs

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nikic and others added 6 commits July 22, 2026 21:57

Update to LLVM 23

38262aa

Update host toolchain

7c1a8ca

Update cov-map tests for LLVM 23

39c595d

There is a minor change in sorted order due to: llvm/llvm-project@5931034

Set LLVM_VERSIONED_DYLIB_NAME_ON_DARWIN=OFF

809e1a2

We probably want to change this to align with Linux, but for now keep the old behavior.

Distribute llvm-project/libc

533ccb4

It's a dependency of LLVM now.

nikic force-pushed the llvm23 branch from 54f145e to 102902f Compare July 22, 2026 20:13

rustbot assigned cuviper and unassigned davidtwco Jul 22, 2026

bjorn3 reviewed Jul 22, 2026

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Comment thread compiler/rustc_codegen_cranelift/src/abi/mod.rs Outdated

folkertdev and others added 2 commits July 22, 2026 23:24

fix f128 libcall abi in the cranelift backend

e75aa57

Disable RISCV on dist-i686-mingw

81cd9a0

nikic force-pushed the llvm23 branch from 102902f to 81cd9a0 Compare July 22, 2026 21:24

bjorn3 approved these changes Jul 22, 2026

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