Landing: d9d70a5fbbe2

← All landings

Project / Subsystem

gcc / gcc

Date

2026-07-13

Author

Vladimir N. Makarov

Commit

d9d70a5fbbe25ddbed66c05b9ec04fe97a23059f

Source

github

Perf win

Breaking

View on GitHub →

All attributes

project: gcc
subsystem: gcc
patch_id: —
commit_hash: d9d70a5fbbe25ddbed66c05b9ec04fe97a23059f
source_type: github
headline: Prevent equivalence substitution in LRA from causing incorrect reloads
tldr: LRA optimization pass now avoids a specific equivalence substitution that could lead to wrong memory reload offsets.
author: Vladimir N. Makarov
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • optimization
• compiler
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/d9d70a5fbbe25ddbed66c05b9ec04fe97a23059f
date: 2026-07-13T00:00:00.000Z

A bug in the GCC Link-Time Register Allocation (LRA) pass could cause incorrect memory addresses to be used for reloads when employing equivalence substitution. This occurred because the elimination offset was updated only once per instruction, leading to an incorrect offset in the output reload instruction. To fix this, equivalence substitution is now disabled in specific cases where it is not profitable and complex to fix, preventing the incorrect reloads.