)]}'
{
  "commit": "1e376cd95506af60a27fd1b9cfa14e9f4f248389",
  "tree": "839ce477f8dd5dd805b5915701f9cfaa107fef54",
  "parents": [
    "d99b5ba1b633c8e2d05ee9b22ace14a37bc9626f"
  ],
  "author": {
    "name": "Clayton Knittel",
    "email": "cknittel@google.com",
    "time": "Tue Nov 03 16:17:57 2026 -0800"
  },
  "committer": {
    "name": "Copybara-Service",
    "email": "copybara-worker@google.com",
    "time": "Wed Nov 04 00:10:12 2026 -0800"
  },
  "message": "Cache the arena pointer in ParseContext.\n\nThis allows us to load the arena pointer from the parse context instead of the message being parsed. `MessageLite::GetArena` has a branch, while the new `ParseContext::arena` is a simple load.\n\nWe take special care to reload the arena pointer when descending to parse an already-allocated submessage of a field. It is possible for parent and child messages to live in different arenas due to `unsafe_arena_set_allocated` APIs and the like. This includes normal submessages, lazy submessages, and extensions, all of which have `UnsafeSetAllocated` methods or similar.\n\nCross-arena messages trees should be exceptionally rare. This is an anti-pattern, and is only possible if using the `unsafe_arena_*` APIs. In the submessage parsers in `TcParser`, we build-in the expectation that messages are on the same arena, and have a slow fallback if parsing a message on a different arena. This avoids 2 unnecessary exchanges of `ParseContext::arena_` every time we enter a submessage.\n\nPiperOrigin-RevId: 1013373359\n",
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