Landing: b81218009e09

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Project / Subsystem

gcc / x86_cse

Date

2026-04-29

Author

H.J. Lu

Commit

b81218009e091e92145a3fc54971fbbdb82d7298

Source

github

Perf win

Yes

Breaking

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All attributes

project: gcc
subsystem: x86_cse
patch_id: —
commit_hash: b81218009e091e92145a3fc54971fbbdb82d7298
source_type: github
headline: x86_cse: Convert CONST_VECTOR load to constant integer load
tldr: The x86 compiler can now convert constant vector loads into constant integer loads, improving code generation for certain operations.
author: H.J. Lu
outcome: committed
performance_win: true
breaking_change: false
series_id: —
series_parts: []
tags: • x86
• optimization
• cse
• vectorization
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/b81218009e091e92145a3fc54971fbbdb82d7298
date: 2026-04-29T00:00:00.000Z

The x86 common subexpression elimination (CSE) pass can now convert CONST_VECTOR loads that are no larger than an integer register into constant integer loads. This optimization applies when loading a constant vector into an MMX or XMM register. Redundant constant integer loads are now kept, and the code generates zero CONST_VECTOR loads. This change can improve code generation for vector operations on x86 architectures.