Landing: 6d218b0ffbd5

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Project / Subsystem

gcc / tree-optimization

Date

2026-04-27

Author

Richard Biener

Commit

6d218b0ffbd54ca438e904fccad86d226f26bb91

Source

github

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Breaking

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All attributes

project: gcc
subsystem: tree-optimization
patch_id: —
commit_hash: 6d218b0ffbd54ca438e904fccad86d226f26bb91
source_type: github
headline: Tree-optimization: Avoids ICE with niter Analysis and UBSAN.
tldr: The compiler now avoids an internal compiler error (ICE) when using niter analysis with UBSAN by preventing negation of the most negative signed integer.
author: Richard Biener
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • tree-optimization
• niter analysis
• ubsan
• ice
• loop optimization
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/6d218b0ffbd54ca438e904fccad86d226f26bb91
date: 2026-04-27T00:00:00.000Z

This commit fixes an internal compiler error (ICE) that occurred when using the niter analysis (loop iteration analysis) in conjunction with UBSAN (Undefined Behavior Sanitizer). The issue arose when computing the absolute step of a loop by negating a signed step, which could result in negating the most negative signed integer. The fix converts the signed step to an unsigned value before negating it, thus avoiding the undefined behavior. A new testcase was added to verify the fix.