Landing: d5044b85d3bd

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Project / Subsystem

gcc / match.pd

Date

2026-05-08

Author

Philipp Tomsich

Commit

d5044b85d3bd3ed0b8ddae3ea186eef747b1ef2d

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: match.pd
patch_id: —
commit_hash: d5044b85d3bd3ed0b8ddae3ea186eef747b1ef2d
source_type: github
headline: match.pd: factor MSB OR-cascade out of clz_table_index
tldr: MSB OR-cascade logic refactored into reusable match patterns for clarity and future use.
author: Philipp Tomsich
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • refactoring
• match.pd
• optimization
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/d5044b85d3bd3ed0b8ddae3ea186eef747b1ef2d
date: 2026-05-08T00:00:00.000Z

The logic for generating the MSB OR-cascade, which sets all bits from 0 up to the most significant bit, has been refactored into two new match patterns: msb_or_cascade_32 and msb_or_cascade_64. The existing clz_table_index patterns for 32-bit and 64-bit integers are rewritten to use these new helpers. This change is a non-functional refactoring that improves code organization and prepares for a subsequent optimization.