tree addd0fb671a61a52a452bcf870d8d538b649b225
parent 76095175ff0efdc939f39d1b608c23d011d1d9d3
author Ryan Prichard <rprichard@google.com> 1600896313 -0700
committer Copybara-Service <copybara-worker@google.com> 1604019959 -0700

[libunwind] Combine dl_iterate_phdr codepaths for DWARF and EHABI

dl_iterate_phdr is used to search for unwind info provided by either
PT_GNU_EH_FRAME or PT_ARM_EXIDX. Most of the code between the two is
the same, so combine them, and factor out what's different into
checkForUnwindInfoSegment.

Details:
 - The FrameHeaderCache can now be enabled for ARM EHABI.
 - findUnwindSectionsByPhdr now finds the last PT_ARM_EXIDX rather than
   the first. There should only be one segment.
 - The dso_base and text_segment_length fields of UnwindInfoSections
   are now needed for dl_iterate_phdr when using EHABI, to hold the
   low and high PC values for a cache entry.

Reviewed By: compnerd, danielkiss, #libunwind, saugustine

Differential Revision: https://reviews.llvm.org/D87880

GitOrigin-RevId: b16d6653c01cee37f51a98dd4092c4ef302c47a5