Landing: 2026474385dc

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Project / Subsystem

gcc / tree-optimization

Date

2026-08-14

Author

Richard Biener

Commit

2026474385dc23e9896577db08d963bc3a96f256

Source

github

Perf win

No

Breaking

No

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All attributes

project: gcc
subsystem: tree-optimization
patch_id: —
commit_hash: 2026474385dc23e9896577db08d963bc3a96f256
source_type: github
headline: Live lane check: Fix dominance for PHI nodes
tldr: Corrects dominance checks in live lane extraction for PHI nodes, improving vectorization reliability.
author: Richard Biener
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • optimization
• vectorization
• PHI node
• tree-optimization
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/2026474385dc23e9896577db08d963bc3a96f256
date: 2026-08-14T00:00:00.000Z

This commit fixes a bug in the live lane extraction dominance check within the vectorization pass, specifically when dealing with PHI (Промежуточная Инструкция) nodes. Previously, the compiler did not correctly verify the dominance of the vector definition with the scalar use in cases involving PHI uses. The fix ensures that the respective PHI edge source can reach the definition, thereby correctly establishing dominance. This resolves PR tree-optimization/126862 and improves the accuracy of vectorization by ensuring scalar uses of PHI nodes are properly dominated by their vector definitions.