tree 60c24d88d0b5f509b4e70df6864299f7d77f57b9
parent 4981b193dea6d31249f9dfe64239ab9b07017cf1
author Peter Collingbourne <peter@pcc.me.uk> 1600992084 -0700
committer Copybara-Service <copybara-worker@google.com> 1603221928 -0700

scudo: Make it thread-safe to set some runtime configuration flags.

Move some of the flags previously in Options, as well as the
UseMemoryTagging flag previously in the primary allocator, into an
atomic variable so that it can be updated while other threads are
running. Relaxed accesses are used because we only have the requirement
that the other threads see the new value eventually.

The code is set up so that the variable is generally loaded once per
allocation function call with the exception of some rarely used code
such as error handlers. The flag bits can generally stay in a register
during the execution of the allocation function which means that they
can be branched on with minimal overhead (e.g. TBZ on aarch64).

Differential Revision: https://reviews.llvm.org/D88523

GitOrigin-RevId: 719ab7309eb7b7b5d802273b0f1871d6cdb965b1