[all-commits] [llvm/llvm-project] 33c13c: Default to disabling the libunwind frameheader cache.

[Sterling-Augustine via All-commits]

  Branch: refs/heads/release/11.x
  Home:   https://github.com/llvm/llvm-project
  Commit: 33c13cd8c5772871ec79f0b061e7f7a2fb287383
      https://github.com/llvm/llvm-project/commit/33c13cd8c5772871ec79f0b061e7f7a2fb287383
  Author: Sterling Augustine <saugustine at google.com>
  Date:   2020-08-19 (Wed, 19 Aug 2020)

  Changed paths:
    M libunwind/CMakeLists.txt
    M libunwind/src/AddressSpace.hpp
    M libunwind/test/frameheadercache_test.pass.cpp

  Log Message:
  -----------
  Default to disabling the libunwind frameheader cache.

Although it works fine with glibc, as currently implemented the
frameheader cache is incompatible with certain platforms with
slightly different locking semantics inside dl_iterate_phdr.

Therefore only enable it when it is turned on explicitly with
a configure-time option.

Differential Revision: https://reviews.llvm.org/D86163

(cherry picked from commit a20f5fe70810e0a768c1814d69d10862965c21e4)