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[asan] Reduce stack usage of DescribeThread() (#176540)

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Manually eliminate tail calls, because the compiler didn't.

This fixes some rare crashes (stack overflows) that can occur during
ASan's error reporting, if there is a deep nesting structure to thread
creation. Besides that, it has no change to ASan's output.
This commit is contained in:
Thurston Dang 2026-01-20 15:49:08 -08:00 committed by GitHub
parent ade2435ca5
commit 05f5ce5c69
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1 changed files with 31 additions and 25 deletions
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56
compiler-rt/lib/asan/asan_descriptions.cpp
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@ -36,37 +36,43 @@ AsanThreadIdAndName::AsanThreadIdAndName(u32 tid)
asanThreadRegistry().CheckLocked();
}
// Prints this thread and, if flags()->print_full_thread_history, its ancestors
void DescribeThread(AsanThreadContext *context) {
CHECK(context);
asanThreadRegistry().CheckLocked();
// No need to announce the main thread.
if (context->tid == kMainTid || context->announced) {
return;
}
context->announced = true;
while (true) {
CHECK(context);
asanThreadRegistry().CheckLocked();
// No need to announce the main thread.
if (context->tid == kMainTid || context->announced) {
return;
}
context->announced = true;
InternalScopedString str;
str.AppendF("Thread %s", AsanThreadIdAndName(context).c_str());
InternalScopedString str;
str.AppendF("Thread %s", AsanThreadIdAndName(context).c_str());
AsanThreadContext *parent_context =
context->parent_tid == kInvalidTid
? nullptr
: GetThreadContextByTidLocked(context->parent_tid);
AsanThreadContext* parent_context =
context->parent_tid == kInvalidTid
? nullptr
: GetThreadContextByTidLocked(context->parent_tid);
// `context->parent_tid` may point to reused slot. Check `unique_id` which
// is always smaller for the parent, always greater for a new user.
if (!parent_context || context->unique_id <= parent_context->unique_id) {
str.Append(" created by unknown thread\n");
// `context->parent_tid` may point to reused slot. Check `unique_id` which
// is always smaller for the parent, always greater for a new user.
if (!parent_context || context->unique_id <= parent_context->unique_id) {
str.Append(" created by unknown thread\n");
Printf("%s", str.data());
return;
}
str.AppendF(" created by %s here:\n",
AsanThreadIdAndName(context->parent_tid).c_str());
Printf("%s", str.data());
return;
StackDepotGet(context->stack_id).Print();
// Describe parent thread if requested
if (flags()->print_full_thread_history)
context = parent_context;
else
return;
}
str.AppendF(" created by %s here:\n",
AsanThreadIdAndName(context->parent_tid).c_str());
Printf("%s", str.data());
StackDepotGet(context->stack_id).Print();
// Recursively described parent thread if needed.
if (flags()->print_full_thread_history)
DescribeThread(parent_context);
}
// Shadow descriptions