Landing: 4e45547e66cc

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Project / Subsystem

gcc / x86

Date

2026-05-02

Author

H.J. Lu

Commit

4e45547e66cc7bc144ccfeffabe4856175a8a699

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: x86
patch_id: —
commit_hash: 4e45547e66cc7bc144ccfeffabe4856175a8a699
source_type: github
headline: X86: Avoid AVX-512 instruction generation on non-AVX512 CPUs.
tldr: Fixes a SIGILL error that occurred when AVX512 instructions were generated on CPUs lacking AVX512 support by adding a runtime CPU feature check.
author: H.J. Lu
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • x86
• avx512
• sigill
• optimization
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/4e45547e66cc7bc144ccfeffabe4856175a8a699
date: 2026-05-02T00:00:00.000Z

The compiler was generating AVX512 instructions even when the target CPU lacked AVX512 support, leading to SIGILL errors. This commit extracts the test code into a separate function, do_test, and calls it only if __builtin_cpu_supports ("gfni") returns true, ensuring that AVX512 instructions are only executed on capable CPUs. This prevents the test from failing on CPUs without AVX512 support.