Landing: 435ff0c5dff1

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Project / Subsystem

gcc / tree-optimization

Date

2026-06-05

Author

Richard Biener

Commit

435ff0c5dff136eef427872991398ee09739fa3b

Source

github

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Breaking

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project: gcc
subsystem: tree-optimization
patch_id: —
commit_hash: 435ff0c5dff136eef427872991398ee09739fa3b
source_type: github
headline: Tree optimization: Avoid negating the most negative signed value during loop analysis
tldr: GCC's tree-ssa-loop-niter pass now avoids incorrect negation of the most negative signed integer, preventing potential compiler misbehavior with loop iteration…
author: Richard Biener
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • optimization
• loops
• bugfix
• integer-overflow
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/435ff0c5dff136eef427872991398ee09739fa3b
date: 2026-06-05T00:00:00.000Z

GCC’s number_of_iterations_until_wrap function, part of the tree-ssa-loop-niter optimization pass, has been improved to prevent the problematic negation of the most negative signed integer value. This issue, identified by PR125602, could lead to incorrect INTEGER_CST results during loop analysis. The fix restructures the negation and type conversion logic to avoid this overflow, ensuring accurate calculation of loop bounds and preventing potential miscompilations.