Landing: ef7d69b3a91c

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Project / Subsystem

gcc / gcc/i386

Date

2026-09-29

Author

Uros Bizjak

Commit

ef7d69b3a91c3b12a647ffca92e2553229f324dd

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: gcc/i386
patch_id: —
commit_hash: ef7d69b3a91c3b12a647ffca92e2553229f324dd
source_type: github
headline: i386: Fix va_arg access alignment for over-aligned stack arguments
tldr: Prevents misaligned memory accesses when using va_arg with over-aligned stack arguments on i386.
author: Uros Bizjak
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • i386
• alignment
• va_arg
• optimization
• ABI
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/ef7d69b3a91c3b12a647ffca92e2553229f324dd
date: 2026-09-29T00:00:00.000Z

On i386 architectures, this commit corrects how va_arg accesses arguments on the stack when those arguments are over-aligned. Previously, GCC could generate code that read from misaligned addresses, leading to incorrect behavior or crashes, especially with optimizations. The fix ensures that the alignment claimed for accesses does not exceed the actual alignment of the stack slot.