tree c8ccc638caee2f009c6d9a81e15363bfb1c0ffe8
parent a1d9f1b49db06b604565d0f328e213a19d7969c3
author Kostya Kortchinsky <kostyak@google.com> 1604963689 -0800
committer Copybara-Service <copybara-worker@google.com> 1605561516 -0800

[scudo][standalone] Correct min/max region indices

The original code to keep track of the minimum and maximum indices
of allocated 32-bit primary regions was sketchy at best.

`MinRegionIndex` & `MaxRegionIndex` were shared between all size
classes, and could (theoretically) have been updated concurrently. This
didn't materialize anywhere I could see, but still it's not proper.

This changes those min/max indices by making them class specific rather
than global: classes are locked when growing, so there is no
concurrency there. This also allows to simplify some of the 32-bit
release code, that now doesn't have to go through all the regions to
get the proper min/max. Iterate and unmap will no longer have access to
the global min/max, but they aren't used as much so this is fine.

Differential Revision: https://reviews.llvm.org/D91106

GitOrigin-RevId: f0703cb1b24be4f915257f91a290a3d92ac6cd4f