Landing: b407be9e4bdc

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Project / Subsystem

gcc / m68k

Date

2026-07-09

Author

Andreas Schwab

Commit

b407be9e4bdc117a59d232a4db9672544c14a40a

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: m68k
patch_id: —
commit_hash: b407be9e4bdc117a59d232a4db9672544c14a40a
source_type: github
headline: M68k bit operations on memory now use correct bit number
tldr: M68k bitset and bitclear instructions operating on memory now correctly use only the lower 3 bits of the bit number.
author: Andreas Schwab
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • m68k
• codegen
• bugfix
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/b407be9e4bdc117a59d232a4db9672544c14a40a
date: 2026-07-09T00:00:00.000Z

GCC’s m68k backend now correctly models the behavior of bset and bclr instructions when operating on memory. These instructions only use the lower 3 bits of the bit number to determine which bit to set or clear. A new test case is added to verify this fix.