Re: No source code for static library (compiled with -g -ggdb)

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Thu, Apr 28, 2016 at 01:44:16PM -0400, Mark Davis escreveu:
> Hello, I'm using perf record and perf report to profile an application
> which is made from a static (.a) library file that I made as well as a
> handful of C++ files that are not in the static library. They are all
> compiled with "-g -ggdb -fno-inline -O2 -fno-omit-frame-pointer" and
> all linked together to create the application.
> 
> When I use perf report (in interactive/tui mode), when I annotate the
> symbols that are in the C++ files (not the static library), I see the
> source code intermingled with the assembly (this is what I want). I
> can do this at any layer of the call stack. However, when I drill into
> the symbols that are from the static library, I just see the assembly
> of the leaf symbol. I don't expect to see the source in this case, as
> the leaf symbol is a low-level library from libc; but, perf report
> won't let me drill into (i.e., annotate) any non-leaf symbols.
> 
> Example:
> execute_native_thread_routine
> std::_Bind_simple<int (*(int, char**, Thread*))(int, char**,
> Thread*)>::operator()()
> main(int, char**)
> my_func_A
> my_func_B
> malloc

What happens when you press 'V'? Here, say for this callchain:

-    0.73%  gnome-shell      libgobject-2.0.so.0.4600.2          [.] handlers_find
   - handlers_find
      - 0.68% signal_handlers_foreach_matched_R
           g_signal_handlers_disconnect_matched
           0x7f71fe809a80
           g_object_unref
         - st_widget_get_theme_node
              0.58% 0x7f71fe813429 

And I press V, I get:

-    0.73%  gnome-shell      libgobject-2.0.so.0.4600.2          [.] handlers_find
   -→handlers_find libgobject-2.0.so.0.4600.2
      - 0.68% signal_handlers_foreach_matched_R libgobject-2.0.so.0.4600.2
           g_signal_handlers_disconnect_matched libgobject-2.0.so.0.4600.2
           0x7f71fe809a80 libgnome-shell.so
          →g_object_unref libgobject-2.0.so.0.4600.2
         -→st_widget_get_theme_node libgnome-shell.so
              0.58% 0x7f71fe813429 libgnome-shell.so 

See those arrows? They point to the places where you can annotate, the others
can't because they had no samples or were unresolved.

With some changes I think we can show the ones without samples, but that remains to be done.

Also, this is with:

[root@jouet ~]# perf --version
perf version 4.6.rc4.ga453697

This feature was introduced in:

commit 70e972788888315851a5c1b4982efbcafcd03b5b
Author: Arnaldo Carvalho de Melo <acme@redhat.com>
Date:   Thu Mar 19 16:07:21 2015 -0300

    perf hists browser: Indicate which callchain entries are annotated
    
    Now that we can annotate entries in a callchain, show which ones have an
    associated symbol and samples, by adding a right arrow just before the
    symbol name when in verbose mode.
    
    To toggle verbose mode press 'V'.

---------------------------------

Which is:

[acme@jouet linux]$ git tag --contains 70e972788888315851a5c1b4982efbcafcd03b5b | grep ^v4 | head -1
v4.1
[acme@jouet linux]$

Thanks,

- Arnaldo
 
> When I annotate my_func_A and my_func_B, it just jumps to the
> annotation of malloc (I see this listed at the top of the annotation
> view). Note that my_func_A and my_func_B are both defined in the
> static library that I'm linking in. However, when I do a similar thing
> with a different stack where I'm annotating a function that's not from
> the static library (but in the regular C++ files), it works fine.
> 
> Here's what I'm doing to create my static lib:
> ar -cvrs $@ $(OBJS)
> 
> 
> I did confirm with nm --debug-syms that my static lib has debugging
> symbols in it:
> 
> U __assert_fail
> 0000000000000000 b .bss
> 0000000000000000 n .comment
> U __cxa_atexit
> 0000000000000000 d .data
> 0000000000000000 N .debug_abbrev
> 0000000000000000 N .debug_aranges
> 0000000000000000 N .debug_info
> 0000000000000000 N .debug_line
> 0000000000000000 N .debug_loc
> 0000000000000000 N .debug_ranges
> 0000000000000000 N .debug_str
> U __dso_handle
> 0000000000000000 r .eh_frame
> U exit
> 
> 
> How can I compile and link my application and configure perf report so
> I can drill in like this on functions defined in a static library with
> debug symbols?
> 
> Thank you,
> Mark
> --
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