Landing: 771f488a90f7

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Project / Subsystem

gcc / gcc/match.pd

Date

2026-09-13

Author

Dominic P

Commit

771f488a90f748613940a62de40b57d1131b2fcd

Source

github

Perf win

Yes

Breaking

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All attributes

project: gcc
subsystem: gcc/match.pd
patch_id: —
commit_hash: 771f488a90f748613940a62de40b57d1131b2fcd
source_type: github
headline: Fold A - MIN (B, C) to A + MAX (-B, -C) in match.pd.
tldr: GCC's pattern matching now optimizes subtraction with min/max, improving code generation.
author: Dominic P
outcome: committed
performance_win: true
breaking_change: false
series_id: gcc:match.pd: fold a - min (b, c) to a + max (-b, -c)
series_parts: []
tags: • optimization
• gcc
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/771f488a90f748613940a62de40b57d1131b2fcd
date: 2026-09-13T00:00:00.000Z

This commit introduces new patterns to GCC’s match.pd that optimize expressions of the form A - MIN (B, C) and A - MAX (B, C) into additions with negated max/min respectively. This transformation, A - MIN(B, C) -> A + MAX(-B, -C), requires that B and C are negatable and accounts for potential overflow in wrapping types, leading to more efficient code generation.