Landing: a8b044785b09

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Project / Subsystem

gcc / forwprop

Date

2026-01-20

Author

Artemiy Volkov

Commit

a8b044785b091c96202b8228b4944be238879319

Source

github

Perf win

Yes

Breaking

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All attributes

project: gcc
subsystem: forwprop
patch_id: —
commit_hash: a8b044785b091c96202b8228b4944be238879319
source_type: github
headline: Forward Prop Allow More Vector Permutations
tldr: The forward propagation pass now creates more vector permutation expressions, relying on a later pass to legalize them, improving optimization.
author: Artemiy Volkov
outcome: committed
performance_win: true
breaking_change: false
series_id: —
series_parts: []
tags: • optimization
• vectorization
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/a8b044785b091c96202b8228b4944be238879319
date: 2026-01-20T00:00:00.000Z

The forward propagation pass (forwprop) now creates more VEC_PERM_EXPR (vector permutation expressions) during vector constructor simplification. Previously, the pass avoided creating unsupported permutations. Now, it creates them if a later vector lowering pass can legalize them. This change can improve optimization by allowing more opportunities for vectorization.