Landing: 684d385720cd

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Project / Subsystem

gcc / gcc

Date

2026-05-11

Author

Shreya Munnangi

Commit

684d385720cd5d25df8dc69c5281fc0fb9c3bebe

Source

github

Perf win

Yes

Breaking

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project: gcc
subsystem: gcc
patch_id: —
commit_hash: 684d385720cd5d25df8dc69c5281fc0fb9c3bebe
source_type: github
headline: Simplify RTL bit-flipping operations to use XOR
tldr: The compiler can now simplify certain bit-flipping RTL patterns into XOR operations, improving code generation for RISC-V and potentially other architectures.
author: Shreya Munnangi
outcome: committed
performance_win: true
breaking_change: false
series_id: —
series_parts: []
tags: • optimization
• RISC-V
• code generation
• RTL
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/684d385720cd5d25df8dc69c5281fc0fb9c3bebe
date: 2026-05-11T00:00:00.000Z

The compiler can now recognize and simplify RTL patterns that flip specific bits in a register. The optimization applies when the RTL code uses IOR, AND, and NOT operations with constants to isolate and flip a bit. This change improves code generation on RISC-V and may benefit other targets, especially those with sub-word arithmetic. The simplification rewrites the code to use a single XOR operation.