[Valgrind-developers] precise stack traces in presence of inlining

[Konstantin S. <kon...@gm...>]

Hello, Valgrind developers.

Currently, if memcheck is run on a program which is compiled with
inlining enabled, the stack traces are not precise.
Example:

% cat inl_test.c
#include <stdio.h>

inline void foo(int *p) {
  if (*p == 777) printf("777\n");
}

 __attribute__ ((noinline))
void bar (int *p) {
  foo(p);
}

int main() {
  int uninitialized_stack[10];
  bar(&uninitialized_stack[1]);
  return 0;
}

% gcc -g -O0   inl_test.c && ~/valgrind/trunk/inst/bin/valgrind -q ./a.out
==27322== Conditional jump or move depends on uninitialised value(s)
==27322==    at 0x400523: foo (inl_test.c:4)
==27322==    by 0x400545: bar (inl_test.c:9)
==27322==    by 0x40055C: main (inl_test.c:14)

% gcc -g -O2   inl_test.c && ~/valgrind/trunk/inst/bin/valgrind -q ./a.out
==27380== Conditional jump or move depends on uninitialised value(s)
==27380==    at 0x400536: bar (inl_test.c:4)
==27380==    by 0x40055D: main (inl_test.c:14)


You can see that with -O0 the stack trace contains foo and with -O2 it
doers not.

But the DWARF info contains the information about inlining:

% readelf -w a.out
 <1><421>: Abbrev Number: 14 (DW_TAG_subprogram)
  <422>     DW_AT_external    : 1
  <423>     DW_AT_name        : foo
...
 <1><465>: Abbrev Number: 18 (DW_TAG_subprogram)
  <466>     DW_AT_external    : 1
  <467>     DW_AT_name        : bar
...
 <2><492>: Abbrev Number: 20 (DW_TAG_inlined_subroutine)
  <493>     DW_AT_abstract_origin: <421>
  <497>     DW_AT_low_pc      : 0x400530
  <49f>     DW_AT_high_pc     : 0x40054a
  <4a7>     DW_AT_call_file   : 1
  <4a8>     DW_AT_call_line   : 9


So, it is theoreticlally possible to produce a precise stack trace
even in presence of inlining.
Or I miss something?
Shall I file a bug (feature request)?

Thanks,

--kcc