Landing: 5e45cc08f3bb

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Project / Subsystem

gcc / gcc

Date

2026-07-29

Author

Richard Biener

Commit

5e45cc08f3bbbfa77b6e6524127f7acbec1d2c83

Source

github

Perf win

Yes

Breaking

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All attributes

project: gcc
subsystem: gcc
patch_id: —
commit_hash: 5e45cc08f3bbbfa77b6e6524127f7acbec1d2c83
source_type: github
headline: Avoid SSA copies from vect_add_slp_permutation.
tldr: Vectorizer no longer creates unnecessary SSA copies when vector permutations are readily available.
author: Richard Biener
outcome: committed
performance_win: true
breaking_change: false
series_id: —
series_parts: []
tags: • vectorization
• compiler optimization
• SSA
• SLP
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/5e45cc08f3bbbfa77b6e6524127f7acbec1d2c83
date: 2026-07-29T00:00:00.000Z

This commit refactors the GCC vectorizer’s SLP (Sliding-window Pattern) pass to eliminate unnecessary SSA copies. Previously, a stmt_vec_info was required for all vector definitions, leading to extra copies even when the vector extraction was directly available. The changes in tree-vect-slp.cc remove this requirement and improve handling of default definitions and constants within vector definitions.