Landing: 6efd09212a59

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Project / Subsystem

gcc / gcc

Date

2026-04-08

Author

Heiko Eißfeldt

Commit

6efd09212a591001a7e631f780a5ca85f39389f3

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: gcc
patch_id: —
commit_hash: 6efd09212a591001a7e631f780a5ca85f39389f3
source_type: github
headline: Avoid stack overflow in verify_vssa for large functions
tldr: Reduces stack usage in `verify_vssa` by replacing recursion with iteration.
author: Heiko Eißfeldt
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • gcc
• ssa
• verification
• stack overflow
• bugfix
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/6efd09212a591001a7e631f780a5ca85f39389f3
date: 2026-04-08T00:00:00.000Z

The verify_vssa function in GCC, which performs verification of the Value State SSA form, could exhaust stack space when processing very large functions, leading to an internal compiler error (ICE). This commit replaces the recursive implementation of verify_vssa with an iterative one using a worklist. This reduces stack usage and prevents stack overflows when compiling functions with an extreme number of basic blocks.