Landing: 52ceb1698c9f
Project / Subsystem
gcc / gcc/tree-optimization
Date
2026-09-12
Author
Shivam Gupta
Commit
52ceb1698c9f46be900fe3719c2967fe74bcd1f7
Source
github
Perf win
No
Breaking
No
All attributes
- project
- gcc
- subsystem
- gcc/tree-optimization
- patch_id
- —
- commit_hash
- 52ceb1698c9f46be900fe3719c2967fe74bcd1f7
- source_type
- github
- headline
- Handle undefined ranges in CLZ loop optimization.
- tldr
- Fixes loop optimization for CLZ by correctly handling undefined ranges.
- author
- Shivam Gupta
- outcome
- committed
- performance_win
- false
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • tree-optimization
- • CLZ
- • loop optimization
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-09-12T00:00:00.000Z
The optimization that converts signed right-shift loops into Count Leading Zeros (CLZ) operations previously mishandled undefined ranges. When determining the number of loop iterations, the Ranger analysis could return an undefined range, which was then incorrectly treated as a valid non-negative range. This change adds explicit checks for undefined ranges, preventing incorrect optimization.