Landing: 46ee9bbc9a7d
Project / Subsystem
gcc / gcc/tree-optimization
Date
2026-09-18
Author
Kael Andrew Alonzo Franco
Commit
46ee9bbc9a7d92eb3435999b59c3d8b42254f88a
Source
github
Perf win
No
Breaking
No
All attributes
- project
- gcc
- subsystem
- gcc/tree-optimization
- patch_id
- —
- commit_hash
- 46ee9bbc9a7d92eb3435999b59c3d8b42254f88a
- source_type
- github
- headline
- Restrict (X {+,-} M*N) / N optimization to avoid overflow
- tldr
- Compiler avoids integer overflow by restricting an optimization for division by -1.
- author
- Kael Andrew Alonzo Franco
- outcome
- committed
- performance_win
- false
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • optimization
- • integer overflow
- • compiler bug
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-09-18T00:00:00.000Z
The compiler’s tree optimizer previously performed an optimization on expressions of the form ((X {+,-} M*N) / N), simplifying it to ((X / N) {+,-} M). However, this transformation can cause integer overflow when X is INT_MIN and N is -1, because INT_MIN / -1 overflows while the original expression may not. This commit adds checks for X > INT_MIN and N != -1 to prevent this overflow.