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ba2ece03b8
stack unwind mechanism (the function VG_(record_ExeContext) et al), clears up some associated kludges, and makes suppression matching work more reliably. Prior to this commit, a stack snapshot contained, at [0], the IP of the relevant thread, and at all positions [1] and above, the return addresses for the open calls. When showing a snapshot to the user (in VG_(apply_StackTrace)), and searching the stack for stack blocks (in VG_(get_data_description)), 1 is subtracted from positions [1] and above, so as to move these return addresses back to the last byte of the calling instruction. This subtraction is also done even in VG_(get_StackTrace_wrk) itself, in order to make the stack unwinding work at all. It turns out that suppression-vs-function-name matching requires the same hack, and sometimes failed to match suppressions that should match, because of this self-same problem. So the commit changes the stack unwinder itself, so that entries [1] and above point to the last byte of the call instruction, rather than the return address. The associated kludges in VG_(apply_StackTrace) and VG_(get_StackTrace_wrk) are removed, and suppression matching is observed to work in a case where it failed before. git-svn-id: svn://svn.valgrind.org/valgrind/trunk@8818
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. The new
structure looks like this:
debuginfo.c
readelf.c
readdwarf.c readstabs.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 and readstabs.c parse 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/readstabs.c for debug info. All
straightforward.
debuginfo.c is the top-level file, and is quite small.
There are 3 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
(3) Simplify the stabs reader.
Rationale for (1) and (2) are obvious.
Re (3), the stabs reader has for a good year contained a sophisticated
and impressive parser for stabs strings, with the aim of recording in
detail the types of variables (I think) (Jeremy's work). Unfortunately
that has caused various segfaults reading stabs info in the past few months
(#77869, #117936, #119914, #120345 and another to do with deeply nested
template types).
The worst thing is that it is the stabs type reader that is crashing,
not the stabs line-number reader, but the type info is only used by
Helgrind, which is looking pretty dead at the moment. So I have lifed
out the type-reader code and put it in UNUSED_STABS.txt for safe
storage, just leaving the line-number reader in place.
If Helgrind ever does come back to life we will need to reinstate the
type storage/reader stuff but with DWARF as its primary target.
Placing the existing stabs type-reader in hibernation improves
stability whilst retaining the development effort/expertise that went
into it for possible future reinstatement.