[tsan] Add Mutex annotation flag for constant-initialized __tsan_mutex_linker_init behavior
Add a new flag, __tsan_mutex_not_static, which has the opposite sense
of __tsan_mutex_linker_init. When the new __tsan_mutex_not_static flag
is passed to __tsan_mutex_destroy, tsan ignores the destruction unless
the mutex was also created with the __tsan_mutex_not_static flag.
This is useful for constructors that otherwise woud set
__tsan_mutex_linker_init but cannot, because they are declared constexpr.
Google has a custom mutex with two constructors, a "linker initialized"
constructor that relies on zero-initialization and sets
__tsan_mutex_linker_init, and a normal one which sets no tsan flags.
The "linker initialized" constructor is morally constexpr, but we can't
declare it constexpr because of the need to call into tsan as a side effect.
With this new flag, the normal c'tor can set __tsan_mutex_not_static,
the "linker initialized" constructor can rely on tsan's lazy initialization,
and __tsan_mutex_destroy can still handle both cases correctly.
Author: Greg Falcon (gfalcon)
Reviewed in: https://reviews.llvm.org/D39095
llvm-svn: 316209