Landing: cd15f0e55944

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Project / Subsystem

gcc / xtensa

Date

2026-09-28

Author

Alexey Lapshin

Commit

cd15f0e559442c9b387d3cb7c6ce07d7109b825e

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: xtensa
patch_id: —
commit_hash: cd15f0e559442c9b387d3cb7c6ce07d7109b825e
source_type: github
headline: xtensa: Prevent out-of-bounds access in xt_true_regnum
tldr: Fixes a bug in Xtensa's register renumbering to prevent crashes during local register allocation.
author: Alexey Lapshin
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • xtensa
• bugfix
• register allocation
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/cd15f0e559442c9b387d3cb7c6ce07d7109b825e
date: 2026-09-28T00:00:00.000Z

A bug in the Xtensa backend’s xt_true_regnum function has been fixed to prevent out-of-bounds reads from the reg_renumber array. This function is used during instruction emission for moves. The fix ensures that reg_renumber is only accessed after the Local Register Allocation (LRA) pass has resized it to accommodate new pseudos, or after reload has completed, thus avoiding crashes.