Re: [RISCV] redundant return-only BB not eliminated

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Project / Subsystem

gcc / gcc

Date

2026-09-19

Proposer

Robert Guthrie <forkbombidable@gmail.com>

Source type

public_inbox

Consensus

Proposed

Sentiment

—/10

Technical tradeoffs

• Potential for introducing regressions in specific edge cases (e.g., verbatim asm diffs) while optimizing CFG.
• Ensuring correct handling of CFG RTL modes is complex.

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All attributes

project: gcc
subsystem: gcc
patch_id: —
discussion_id: aq7cmLNnJVp9Bzy9@bertguix
source_type: public_inbox
title: Re: [RISCV] redundant return-only BB not eliminated
headline: Redundant return-only BB elimination
tldr: Proposes a patch to eliminate redundant return-only basic blocks in CFG cleanup.
proposer: Robert Guthrie <forkbombidable@gmail.com>
consensus: Proposed
outcome: proposed
sentiment_score: —
technical_tradeoffs: • Potential for introducing regressions in specific edge cases (e.g., verbatim asm diffs) while optimizing CFG.
• Ensuring correct handling of CFG RTL modes is complex.
series_id: —
series_role: standalone
series_parts: []
tags: • optimization
• cfg
• riscv
url: https://inbox.sourceware.org/gcc/aq7cmLNnJVp9Bzy9@bertguix
bugzilla_url: —
date: 2026-09-19T00:00:00.000Z

Re: [RISCV] redundant return-only BB not eliminated

Robert Guthrie proposes a new patch to address the elimination of redundant return-only basic blocks. This change aims to simplify the control flow graph by merging consecutive blocks that only contain a return instruction. The patch passes most tests, with a minor noted issue on a verbatim asm diff.