[all-commits] [llvm/llvm-project] d67cf7: Rework findUnwindSectionsByPhdr to be more optimal.

[Sterling-Augustine via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: d67cf7a0a970df6e69db437514bf61a2ab283e67
      https://github.com/llvm/llvm-project/commit/d67cf7a0a970df6e69db437514bf61a2ab283e67
  Author: Sterling Augustine <saugustine at google.com>
  Date:   2020-03-10 (Tue, 10 Mar 2020)

  Changed paths:
    M libunwind/src/AddressSpace.hpp

  Log Message:
  -----------
  Rework findUnwindSectionsByPhdr to be more optimal.

Summary:
- Executable segment is usually segment 3. Look there for the address first.
- GNU_EH_FRAME_HEADER segment is usually near the end. Iterate from the end.
- Exit early if both phdrs have been found.

This is the last cl before a patch to cache the information this function
finds.

Subscribers: libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D75781