s390x: Fix a regression related to backchain feature by liushuyu · Pull Request #129940 · rust-lang/rust

liushuyu · 2024-09-03T19:51:54Z

In #127506, we introduced a new IBM Z-specific target feature, backchain.

This particular target-feature was available as a function-level attribute in LLVM 17 and below, so some hacks were used to avoid blowing up LLVM when querying the supported LLVM features.

This led to an unfortunate regression where cfg!(target-feature = "backchain") will always return true.

This pull request aims to fix this issue, and a test has been introduced to ensure it will never happen again.

Fixes #129927.

r? @RalfJung

... can not be correctly gated using #[cfg] macro

liushuyu · 2024-09-03T20:07:26Z

@rustbot label O-SystemZ A-LLVM A-target-feature C-bug

tests/assembly/s390x-backchain-toggle.rs

RalfJung · 2024-09-04T15:00:22Z

Thanks :) @bors r+ rollup

bors · 2024-09-04T15:00:25Z

📌 Commit 6e4c5c1 has been approved by RalfJung

It is now in the queue for this repository.

…RalfJung s390x: Fix a regression related to backchain feature In rust-lang#127506, we introduced a new IBM Z-specific target feature, `backchain`. This particular `target-feature` was available as a function-level attribute in LLVM 17 and below, so some hacks were used to avoid blowing up LLVM when querying the supported LLVM features. This led to an unfortunate regression where `cfg!(target-feature = "backchain")` will always return true. This pull request aims to fix this issue, and a test has been introduced to ensure it will never happen again. Fixes rust-lang#129927. r? `@RalfJung`

…RalfJung s390x: Fix a regression related to backchain feature In rust-lang#127506, we introduced a new IBM Z-specific target feature, `backchain`. This particular `target-feature` was available as a function-level attribute in LLVM 17 and below, so some hacks were used to avoid blowing up LLVM when querying the supported LLVM features. This led to an unfortunate regression where `cfg!(target-feature = "backchain")` will always return true. This pull request aims to fix this issue, and a test has been introduced to ensure it will never happen again. Fixes rust-lang#129927. r? ``@RalfJung``

…iaskrgr Rollup of 12 pull requests Successful merges: - rust-lang#128919 (Add an internal lint that warns when accessing untracked data) - rust-lang#129471 ([rustdoc] Sort impl associated items by kinds and then by appearance) - rust-lang#129653 (clarify that addr_of creates read-only pointers) - rust-lang#129775 (bootstrap: Try to track down why `initial_libdir` sometimes fails) - rust-lang#129939 (explain why Rvalue::Len still exists) - rust-lang#129940 (s390x: Fix a regression related to backchain feature) - rust-lang#129942 (copy rustc rustlib artifacts from ci-rustc) - rust-lang#129943 (use the bootstrapped compiler for `test-float-parse` test) - rust-lang#129944 (Add compat note for trait solver change) - rust-lang#129947 (Add digit separators in `Duration` examples) - rust-lang#129955 (Temporarily remove fmease from the review rotation) - rust-lang#129957 (forward linker option to lint-docs) r? `@ghost` `@rustbot` modify labels: rollup

…RalfJung s390x: Fix a regression related to backchain feature In rust-lang#127506, we introduced a new IBM Z-specific target feature, `backchain`. This particular `target-feature` was available as a function-level attribute in LLVM 17 and below, so some hacks were used to avoid blowing up LLVM when querying the supported LLVM features. This led to an unfortunate regression where `cfg!(target-feature = "backchain")` will always return true. This pull request aims to fix this issue, and a test has been introduced to ensure it will never happen again. Fixes rust-lang#129927. r? `@RalfJung`

…iaskrgr Rollup of 12 pull requests Successful merges: - rust-lang#128919 (Add an internal lint that warns when accessing untracked data) - rust-lang#129472 (fix ICE when `asm_const` and `const_refs_to_static` are combined) - rust-lang#129653 (clarify that addr_of creates read-only pointers) - rust-lang#129775 (bootstrap: Try to track down why `initial_libdir` sometimes fails) - rust-lang#129939 (explain why Rvalue::Len still exists) - rust-lang#129940 (s390x: Fix a regression related to backchain feature) - rust-lang#129942 (copy rustc rustlib artifacts from ci-rustc) - rust-lang#129943 (use the bootstrapped compiler for `test-float-parse` test) - rust-lang#129944 (Add compat note for trait solver change) - rust-lang#129947 (Add digit separators in `Duration` examples) - rust-lang#129955 (Temporarily remove fmease from the review rotation) - rust-lang#129957 (forward linker option to lint-docs) Failed merges: - rust-lang#129471 ([rustdoc] Sort impl associated items by kinds and then by appearance) r? `@ghost` `@rustbot` modify labels: rollup

matthiaskrgr · 2024-09-05T17:43:33Z

@bors r-
might cause a crash here? #129984 (comment)

liushuyu · 2024-09-05T17:48:00Z

@bors r- might cause a crash here? #129984 (comment)

I can't reproduce it on my local device (Linux). Unfortunately, I don't own an Apple device to test the issue

matthiaskrgr · 2024-09-05T19:02:34Z

mmh, lets see if this can land on its own then

@bors r=RalfJung rollup=iffy

bors · 2024-09-05T19:02:36Z

📌 Commit 6e4c5c1 has been approved by RalfJung

It is now in the queue for this repository.

RalfJung · 2024-09-05T19:24:36Z

Sounds unlikely that this PR would lead to an LLVM crash... I guess we'll see.

…mpiler-errors Rollup of 9 pull requests Successful merges: - rust-lang#128871 (bypass linker configuration and cross target check for specific commands) - rust-lang#129468 ([testsuite][cleanup] Remove all usages of `dont_merge` hack to avoid function merging) - rust-lang#129614 (Adjust doc comment of Condvar::wait_while) - rust-lang#129840 (Implement suggestions for `elided_named_lifetimes`) - rust-lang#129891 (Do not request sanitizers for naked functions) - rust-lang#129899 (Add Suggestions for Misspelled Keywords) - rust-lang#129940 (s390x: Fix a regression related to backchain feature) - rust-lang#129987 (Don't store region in `CapturedPlace`) - rust-lang#130054 (Add missing quotation marks) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#129940 - liushuyu:s390x-target-features, r=RalfJung s390x: Fix a regression related to backchain feature In rust-lang#127506, we introduced a new IBM Z-specific target feature, `backchain`. This particular `target-feature` was available as a function-level attribute in LLVM 17 and below, so some hacks were used to avoid blowing up LLVM when querying the supported LLVM features. This led to an unfortunate regression where `cfg!(target-feature = "backchain")` will always return true. This pull request aims to fix this issue, and a test has been introduced to ensure it will never happen again. Fixes rust-lang#129927. r? `@RalfJung`

rustc_codegen_llvm: fix a regression where backchain feature ...

e98e88b

... can not be correctly gated using #[cfg] macro

rustbot assigned RalfJung Sep 3, 2024

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 Sep 3, 2024

rustbot added A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. A-target-feature Area: Enabling/disabling target features like AVX, Neon, etc. C-bug Category: This is a bug. O-SystemZ Target: SystemZ processors (s390x) labels Sep 3, 2024

RalfJung reviewed Sep 3, 2024

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RalfJung reviewed Sep 3, 2024

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RalfJung reviewed Sep 3, 2024

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liushuyu force-pushed the s390x-target-features branch from b6ad204 to e318af1 Compare September 3, 2024 21:02

RalfJung reviewed Sep 4, 2024

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tests/assembly/s390x-backchain-toggle.rs Show resolved Hide resolved

tests: add an assembly scanning test for s390x backchain switch

6e4c5c1

liushuyu force-pushed the s390x-target-features branch from e318af1 to 6e4c5c1 Compare September 4, 2024 14:11

liushuyu requested a review from RalfJung September 4, 2024 14:11

bors 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 Sep 4, 2024

matthiaskrgr mentioned this pull request Sep 5, 2024

Rollup of 13 pull requests #129977

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matthiaskrgr mentioned this pull request Sep 5, 2024

Rollup of 12 pull requests #129979

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matthiaskrgr mentioned this pull request Sep 5, 2024

Rollup of 12 pull requests #129984

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bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Sep 5, 2024

bors 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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 5, 2024

compiler-errors mentioned this pull request Sep 7, 2024

Rollup of 9 pull requests #130066

Merged

bors merged commit bc2244f into rust-lang:master Sep 7, 2024

rustbot added this to the 1.83.0 milestone Sep 7, 2024

RalfJung mentioned this pull request Jun 12, 2025

When should cfg(target_feature = "backchain") (s390x target feature) be enabled? #142412

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s390x: Fix a regression related to backchain feature#129940

s390x: Fix a regression related to backchain feature#129940
bors merged 2 commits intorust-lang:masterfrom
liushuyu:s390x-target-features

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