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Remove code for ThinLTO from cg_gcc#152566

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bjorn3:cg_gcc_no_thin_lto
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Remove code for ThinLTO from cg_gcc#152566
bjorn3 wants to merge 1 commit intorust-lang:mainfrom
bjorn3:cg_gcc_no_thin_lto

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@bjorn3 bjorn3 commented Feb 13, 2026 •
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It was just a dummy implementation to workarround the fact that thin local lto is the default in rustc. By adding a thin_lto_supported thin local lto can be automatically disabled for cg_gcc, removing the need for this dummy implementation. This makes improvements to the LTO handling on the cg_ssa side a lot easier.

cc #rustc-codegen-gcc > thin LTO implementation
This should make the work on rust-lang/compiler-team#908 easier.

r? rust-lang/wg-gcc-backend

@bjorn3 bjorn3 added C-cleanup Category: PRs that clean code up or issues documenting cleanup. A-LTO Area: Link-time optimization (LTO) A-gcc Things relevant to the [future] GCC backend labels Feb 13, 2026
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rustbot commented Feb 13, 2026

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo, @GuillaumeGomez

rustc_macros::diagnostics was changed

cc @davidtwco, @TaKO8Ki, @JonathanBrouwer

@rustbot rustbot added A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. A-translation Area: Translation infrastructure, and migrating existing diagnostics to SessionDiagnostic 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 Feb 13, 2026
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@bjorn3 bjorn3 force-pushed the cg_gcc_no_thin_lto branch from 391291e to f5d451d Compare February 13, 2026 10:14
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@bjorn3 bjorn3 force-pushed the cg_gcc_no_thin_lto branch from f5d451d to a7dc3b0 Compare February 13, 2026 10:40
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@bjorn3 bjorn3 force-pushed the cg_gcc_no_thin_lto branch 2 times, most recently from 9801a76 to 2c4a301 Compare February 13, 2026 11:30
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@bjorn3 bjorn3 force-pushed the cg_gcc_no_thin_lto branch from 2c4a301 to fe75297 Compare February 13, 2026 12:29
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@bjorn3 bjorn3 force-pushed the cg_gcc_no_thin_lto branch from d73f5d4 to 810a137 Compare February 13, 2026 14:16
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@bjorn3 bjorn3 force-pushed the cg_gcc_no_thin_lto branch 3 times, most recently from 445a2d7 to 1d32b5d Compare February 13, 2026 15:30
@bjorn3
Remove code for ThinLTO from cg_gcc
fa753a4 
It was just a dummy implementation to workarround the fact that thin
local lto is the default in rustc. By adding a thin_lto_supported thin
local lto can be automatically disabled for cg_gcc, removing the need
for this dummy implementation. This makes improvements to the LTO
handling on the cg_ssa side a lot easier.
@bjorn3 bjorn3 force-pushed the cg_gcc_no_thin_lto branch from 1d32b5d to fa753a4 Compare February 15, 2026 10:06
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rustbot commented Feb 15, 2026

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.

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Looks good to me.
Please remove the ThinBuffer struct if it's not needed.

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compiler/rustc_codegen_gcc/src/lib.rs
// FIXME(antoyo): that shouldn't be Sync. Parallel compilation is currently disabled with "CodegenBackend::supports_parallel()".
unsafe impl Sync for SyncContext {}

pub struct ThinBuffer;
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Is this struct still needed?
Could we juste use

type ThinBuffer = ();

below?

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It needs to be a type implementing ThinBufferMethods. It will go away in future PR by merging the ModuleBuffer and ThinBuffer associated types.

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bjorn3 commented Feb 15, 2026

@bors r=antoyo

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rust-bors bot commented Feb 15, 2026

📌 Commit fa753a4 has been approved by antoyo

It is now in the queue for this repository.

@rust-bors rust-bors bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Feb 15, 2026
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JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request Feb 15, 2026
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Rollup merge of rust-lang#152566 - bjorn3:cg_gcc_no_thin_lto, r=antoyo
4a4ea14 
Remove code for ThinLTO from cg_gcc

It was just a dummy implementation to workarround the fact that thin local lto is the default in rustc. By adding a thin_lto_supported thin local lto can be automatically disabled for cg_gcc, removing the need for this dummy implementation. This makes improvements to the LTO handling on the cg_ssa side a lot easier.

cc [#rustc-codegen-gcc > thin LTO implementation](https://rust-lang.zulipchat.com/#narrow/channel/386786-rustc-codegen-gcc/topic/thin.20LTO.20implementation/with/573625132)
This should make the work on rust-lang/compiler-team#908 easier.

r? rust-lang/wg-gcc-backend
@JonathanBrouwer JonathanBrouwer mentioned this pull request Feb 15, 2026
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rust-bors bot pushed a commit that referenced this pull request Feb 15, 2026
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Auto merge of #152671 - JonathanBrouwer:rollup-4Ov19Nw, r=JonathanBro…
873b4be 
…uwer

Rollup of 4 pull requests

Successful merges:

 - #152566 (Remove code for ThinLTO from cg_gcc)
 - #152278 (Fix const normalization for generic const items with trait assoc consts)
 - #152604 (Relocate some tests)
 - #152625 (Provide all lint group names to Clippy)
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A-gcc Things relevant to the [future] GCC backend A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. A-LTO Area: Link-time optimization (LTO) A-translation Area: Translation infrastructure, and migrating existing diagnostics to SessionDiagnostic C-cleanup Category: PRs that clean code up or issues documenting cleanup. S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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