libcxx: accept both GNU and ELF Tool Chain readelf format

[emaste]

Summary

In libcxx ABI list tooling. ELF Tool Chain provides alternatives to most GNU binutils tools, currently used in FreeBSD.

Sponsored by: The FreeBSD Foundation

[emaste]

We will want to update ELF Tool Chain readelf to match GNU readelf's output, but have existing FreeBSD releases that will produce the current style.

[emaste]

libcxx/utils/libcxx/sym_check/extract.py

186–187

ELF Tool Chain readelf does not (currently) emit a blank line before the heading.

[philnik]

Please make sure to have the repo set. Otherwise we don't get notifications on the patches.

LGTM assuming you checked locally that this actually fixes the problem.

libcxx/utils/libcxx/sym_check/extract.py

186–187

Could you add this as a comment in the code?

[emaste]

Comment moved into code block. With this change generate-cxx-abilist functions:

$ ninja generate-cxx-abilist
[1/1] Generating the ABI list file for configuration x86_64-unknown-freebsd.libcxxrt.v1.stable.exceptions.new

and the output looks broadly reasonable.

libcxx/utils/libcxx/sym_check/extract.py

def process_syms(self, sym_list):
             new_syms += [new_sym]
         return new_syms
 
     def get_dynsym_table(self, out):
         lines = out.splitlines()
         start = -1
         end = -1
         for i in range(len(lines)):
-            if lines[i].startswith("Symbol table '.dynsym'"):
+            # Accept both GNU and ELF Tool Chain readelf format.  Some versions
+            # of ELF Tool Chain readelf use ( ) around the symbol table name
+            # instead of ' ', and omit the blank line before the heading.
+            if re.match(r"Symbol table ['(].dynsym[')]", lines[i]):
                 start = i + 2
-            if start != -1 and end == -1 and not lines[i].strip():
+            elif start != -1 and end == -1:
+                if not lines[i].strip():
                     end = i + 1
+                if lines[i].startswith("Symbol table ("):
+                    end = i
         assert start != -1
         if end == -1:
             end = len(lines)
         return lines[start:end]
 
 class AIXDumpExtractor(object):
      """
      AIXDumpExtractor - Extract symbol lists from libraries using AIX dump.