mirror of
https://github.com/Zenithsiz/ftmemsim-valgrind.git
synced 2026-02-14 14:58:07 +00:00
85a86af96d
e.g. perf/memrw is improved by 2% to 3% with this patch. The unwinding code on x86 is trying to unwind using either the %ebp-chain or CFI unwinding. If these 2 techniques fail, then it tries to unwind using FPO (PDB) debug info. However, unless running wine or similar, there will never be such FPO/PDB info. The function VG_(use_FPO_info) is thus called for nothing for each 'end of stack'. This function scans all the loaded di to find a debug info that has some FP, to not find anything. With this patch, the unwind code on x86 will only call VG_(use_FPO_info) if some FPO/PDB info was loaded. The fact that FPO/PDB info was loaded is cached and updated similarly to cfi cache : each time new debug info is loaded, the cache value is refreshed using the debuginfo generation. The patch also changes the name of VG_(CF_info_generation) to VG_(debuginfo_generation), as this generation is changed for any kind of load or unload of debug info, not only for CFI based debug info git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15293
On 4 Apr 06, the debuginfo reader (m_debuginfo) was majorly cleaned up
and restructured. It has been a bit of a tangle for a while. On 18 Sep 14
the STABS support was completely removed. The new structure looks like this:
debuginfo.c
readelf.c
readdwarf.c
storage.c
Each .c can only call those below it on the page.
storage.c contains the SegInfo structure and stuff for
maintaining/searching arrays of symbols, line-numbers, and Dwarf CF
info records.
readdwarf.c parses the relevant kind of info and call storage.c to
store the results.
readelf.c reads ELF format, hands syms directly to storage.c,
then delegates to readdwarf.c for debug info. All straightforward.
debuginfo.c is the top-level file, and is quite small.
There are 2 goals to this:
(1) Generally tidy up something which needs tidying up
(2) Introduce more modularity, so as to make it easier to add
readers for other formats, if needed
Rationale for (1) and (2) are obvious.
Originally there was also goal (3) Simplify the stabs reader.
But stabs support was broken since 3.9.0 and completely removed in 3.10.0.
The worst thing is that it is the stabs type reader that was crashing,
not the stabs line-number reader.
Old versions of the stabs type reader can be found in the subversion repository
as m_debuginfo/UNUSED_STABS.txt, the stabs line-number reader was in
m_debuginfo/readstabs.c. The old version of this file explained more
about the setup.