Landing: 91663770f795

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Project / Subsystem

gcc / avoid-store-forwarding

Date

2026-07-28

Author

Konstantinos Eleftheriou

Commit

91663770f795fd02688c1da004337a1e7c94e810

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: avoid-store-forwarding
patch_id: —
commit_hash: 91663770f795fd02688c1da004337a1e7c94e810
source_type: github
headline: Unshare load destination when re-applying store-forwarding extension.
tldr: Fixes a resource sharing issue in the store-forwarding avoidance pass that could lead to compiler internal errors.
author: Konstantinos Eleftheriou
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • optimization
• rtl
• bugfix
• ice
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/91663770f795fd02688c1da004337a1e7c94e810
date: 2026-07-28T00:00:00.000Z

The avoid-store-forwarding pass in GCC could incorrectly share a destination register (rtx) between two instructions when a load was preserved after a partial store-forwarding avoidance. This was particularly problematic when the destination was a SUBREG, leading to an verify_rtx_sharing ICE. The fix ensures the destination is unshared using copy_rtx when rebuilding the affected move instruction, resolving the ICE and passing new test cases.