Landing: ec79b0779b6e

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Project / Subsystem

gcc / tree-cfgcleanup

Date

2026-05-20

Author

Andrew Pinski

Commit

ec79b0779b6eeb9ef3b8a45f46a596cbb75a7844

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: tree-cfgcleanup
patch_id: —
commit_hash: ec79b0779b6eeb9ef3b8a45f46a596cbb75a7844
source_type: github
headline: Tree-CFGCleanup Retains Forwarder Blocks with PHIs and Abnormal Uses
tldr: The compiler now avoids incorrectly removing forwarder blocks that contain PHI nodes with abnormal uses, preventing potential code generation issues.
author: Andrew Pinski
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • tree-cfgcleanup
• optimization
• bugfix
• phi
• ssa
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/ec79b0779b6eeb9ef3b8a45f46a596cbb75a7844
date: 2026-05-20T00:00:00.000Z

The tree-cfgcleanup pass in GCC could incorrectly remove forwarder blocks containing PHI nodes if the PHI arguments had abnormal uses. This commit fixes this issue by adding a check to ensure that forwarder blocks with PHIs referencing SSA names with abnormal uses are not removed. This prevents potential issues with live range overlap and incorrect code generation during optimization.