Landing: 090baea02d76

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Project / Subsystem

gcc / gcc/rtl-optimization

Date

2026-08-14

Author

Jeff Law

Commit

090baea02d768ff884d1b326d6bf7d57cfcc1231

Source

github

Perf win

Yes

Breaking

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All attributes

project: gcc
subsystem: gcc/rtl-optimization
patch_id: —
commit_hash: 090baea02d768ff884d1b326d6bf7d57cfcc1231
source_type: github
headline: Ext-dce handles vector modes more conservatively
tldr: Extended dead code elimination now conservatively handles vector modes to prevent incorrect removal of code.
author: Jeff Law
outcome: committed
performance_win: true
breaking_change: false
series_id: —
series_parts: []
tags: • optimization
• rtl
• vectorization
• dead code elimination
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/090baea02d768ff884d1b326d6bf7d57cfcc1231
date: 2026-08-14T00:00:00.000Z

The extended dead code elimination (ext-dce) pass has been updated to handle vector modes more conservatively. A previous flaw in determining live bits for vector types led to the incorrect removal of code, specifically extensions, because the compiler wrongly assumed certain bits were never read. This change ensures more accurate liveness analysis for vector operations, preventing such optimizations from removing necessary code.