Landing: 6e33c9be872c

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Project / Subsystem

gcc / tree-optimization

Date

2026-09-15

Author

Richard Biener

Commit

6e33c9be872cc7d2474b4224d1a16515e1b0d2b8

Source

github

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All attributes

project: gcc
subsystem: tree-optimization
patch_id: —
commit_hash: 6e33c9be872cc7d2474b4224d1a16515e1b0d2b8
source_type: github
headline: tree-optimization/126760 - Fix vectorization of switches
tldr: Corrects CFG shape check for switch statement vectorization after if-conversion.
author: Richard Biener
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • vectorization
• optimization
• switch statement
• bugfix
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/6e33c9be872cc7d2474b4224d1a16515e1b0d2b8
date: 2026-09-15T00:00:00.000Z

This commit fixes a bug in GCC’s vectorization of switch statements that are converted using if-conversion. The check if_convertible_switch_p was incorrectly elided for blocks dominating loop latches, leading to faulty conversion. The fix delays the switch validation until the loop iterating over PHIs, ensuring correct CFG shape analysis and enabling reliable vectorization for such constructs, addressing PRs tree-optimization/126760 and tree-optimization/127391.