tree 5babb6ff1c8c55072a31fb8c811cf6527aa4cc4a
parent 261353e78a8360c30411ad40cc8c267dae314ceb
author Sterling Augustine <saugustine@google.com> 1583867004 -0700
committer Copybara-Service <copybara-worker@google.com> 1598638574 -0700

Cache uwnind frame headers as they are found.

Summary:
This improves unwind performance quite substantially, and follows
a somewhat similar approach used in libgcc_s as described in the
thread here:

https://gcc.gnu.org/ml/gcc/2005-02/msg00625.html

On certain extremely exception heavy internal tests, the time
drops from about 80 minutes to about five minutes.

Subscribers: libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D75954

GitOrigin-RevId: c53c2058ffb8ff877702bb2dded31c85c1dfe66d