Re: [GOOGLE] Fix gcda build info support

[Teresa Johnson <tejohnson at google dot com>]

On Wed, Sep 10, 2014 at 3:31 PM, Xinliang David Li <davidxl@google.com> wrote:
> Can you share the buildinfo reader code with the merger by defininig
> some hooks for different callbacks?

Do you mean the two blobs of code guarded by 'if (tag ==
GCOV_TAG_BUILD_INFO)' that I added here and the existing one in
gcov_exit_merge_gcda further down in the same file? Sure, I could
outline that and pass in the gi_ptr for the merger case. Let me know
if you meant something else.

Teresa

>
> David
>
> On Wed, Sep 10, 2014 at 10:24 AM, Teresa Johnson <tejohnson@google.com> wrote:
>> While porting recent support for a build info section in the gcda from
>> google/4_8 to 4_9 and doing manual testing, I discovered that it does
>> not interact well with the COMDAT fixup handling. This patch fixes the
>> issue, and adds a test case that exposes the problem without the fix.
>>
>> Here is the google/4_8 patch - I plan to commit there first then port
>> it along with the original build info patch to 4_9.
>>
>> Passes regression tests - ok for google branches?
>>
>> Thanks,
>> Teresa
>>
>> 2014-09-10  Teresa Johnson  <tejohnson@google.com>
>>
>> libgcc:
>>         * libgcov-driver.c (gcov_scan_to_function_data): Rename from
>>         gcov_scan_summary_end, scan past BUILD_INFO section.
>>         (gcov_dump_module_info): Rename gcov_scan_summary_end to
>>         gcov_scan_to_function_data.
>>
>> gcc/testsuite:
>>         * g++.dg/tree-prof/lipo/buildinfo.txt: Input for
>>         -fprofile-generate-buildinfo option.
>>         * g++.dg/tree-prof/lipo/comdat_fixup_0.C: New test.
>>         * g++.dg/tree-prof/lipo/comdat_fixup_1.C: Ditto.
>>         * g++.dg/tree-prof/lipo/comdat_fixup_2.C: Ditto.
>>         * g++.dg/tree-prof/lipo/comdat_fixup.h: Ditto.
>>         * lib/profopt.exp: Declare srcdir for use in test options.
>>
>> Index: libgcc/libgcov-driver.c
>> ===================================================================
>> --- libgcc/libgcov-driver.c     (revision 214976)
>> +++ libgcc/libgcov-driver.c     (working copy)
>> @@ -428,13 +428,15 @@ struct gcov_filename_aux{
>>  #include "libgcov-driver-system.c"
>>
>>  /* Scan through the current open gcda file corresponding to GI_PTR
>> -   to locate the end position of the last summary, returned in
>> -   SUMMARY_END_POS_P.  Return 0 on success, -1 on error.  */
>> +   to locate the end position just before function data should be rewritten,
>> +   returned in SUMMARY_END_POS_P. E.g. scan past the last summary and other
>> +   sections that won't be rewritten, like the build info.  Return 0 on success,
>> +   -1 on error.  */
>>  static int
>> -gcov_scan_summary_end (struct gcov_info *gi_ptr,
>> -                       gcov_position_t *summary_end_pos_p)
>> +gcov_scan_to_function_data (struct gcov_info *gi_ptr,
>> +                            gcov_position_t *summary_end_pos_p)
>>  {
>> -  gcov_unsigned_t tag, version, stamp;
>> +  gcov_unsigned_t tag, version, stamp, i, length;
>>    tag = gcov_read_unsigned ();
>>    if (tag != GCOV_DATA_MAGIC)
>>      {
>> @@ -467,6 +469,28 @@ static int
>>          return -1;
>>      }
>>
>> +  /* If there is a build info section, scan past it as well.  */
>> +  if (tag == GCOV_TAG_BUILD_INFO)
>> +    {
>> +      length = gcov_read_unsigned ();
>> +      gcov_unsigned_t num_strings = 0;
>> +      char **build_info_strings = gcov_read_build_info (length, &num_strings);
>> +      if (!build_info_strings)
>> +        {
>> +          gcov_error ("profiling:%s:Error reading build info\n", gi_filename);
>> +          return -1;
>> +        }
>> +
>> +      for (i = 0; i < num_strings; i++)
>> +        free (build_info_strings[i]);
>> +      free (build_info_strings);
>> +
>> +      *summary_end_pos_p = gcov_position ();
>> +      tag = gcov_read_unsigned ();
>> +    }
>> +  /* The next section should be the function counters.  */
>> +  gcc_assert (tag == GCOV_TAG_FUNCTION);
>> +
>>    return 0;
>>  }
>>
>> @@ -1031,10 +1055,10 @@ gcov_dump_module_info (struct gcov_filename_aux *g
>>
>>        if (changed)
>>          {
>> -          /* Scan file to find the end of the summary section, which is
>> +          /* Scan file to find the start of the function section, which is
>>               where we will start re-writing the counters.  */
>>            gcov_position_t summary_end_pos;
>> -          if (gcov_scan_summary_end (gi_ptr, &summary_end_pos) == -1)
>> +          if (gcov_scan_to_function_data (gi_ptr, &summary_end_pos) == -1)
>>              gcov_error ("profiling:%s:Error scanning summaries\n",
>>                          gi_filename);
>>            else
>> Index: gcc/testsuite/g++.dg/tree-prof/lipo/buildinfo.txt
>> ===================================================================
>> --- gcc/testsuite/g++.dg/tree-prof/lipo/buildinfo.txt   (revision 0)
>> +++ gcc/testsuite/g++.dg/tree-prof/lipo/buildinfo.txt   (revision 0)
>> @@ -0,0 +1 @@
>> +Test -fprofile-generate-buildinfo option
>> Index: gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup_0.C
>> ===================================================================
>> --- gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup_0.C        (revision 0)
>> +++ gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup_0.C        (revision 0)
>> @@ -0,0 +1,9 @@
>> +/* { dg-options "-O2 -fno-inline
>> -fprofile-generate-buildinfo=$srcdir/g++.dg/tree-prof/lipo/buildinfo.txt"
>> } */
>> +#include <stdio.h>
>> +
>> +extern int foo1(int x);
>> +extern int foo2(int x);
>> +int main()
>> +{
>> +  printf ("Result = %d\n", foo1(1) + foo2(1));
>> +}
>> Index: gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup_1.C
>> ===================================================================
>> --- gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup_1.C        (revision 0)
>> +++ gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup_1.C        (revision 0)
>> @@ -0,0 +1,7 @@
>> +/* { dg-options "-O2 -fno-inline" } */
>> +#include "comdat_fixup.h"
>> +int foo1(int x)
>> +{
>> +  Foo f;
>> +  return f.foo(x);
>> +}
>> Index: gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup_2.C
>> ===================================================================
>> --- gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup_2.C        (revision 0)
>> +++ gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup_2.C        (revision 0)
>> @@ -0,0 +1,7 @@
>> +/* { dg-options "-O2 -fno-inline" } */
>> +#include "comdat_fixup.h"
>> +int foo2(int x)
>> +{
>> +  Foo f;
>> +  return f.foo(x);
>> +}
>> Index: gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup.h
>> ===================================================================
>> --- gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup.h  (revision 0)
>> +++ gcc/testsuite/g++.dg/tree-prof/lipo/comdat_fixup.h  (revision 0)
>> @@ -0,0 +1,5 @@
>> +class Foo
>> +{
>> + public:
>> +  int foo(int x) { return x; }
>> +};
>> Index: gcc/testsuite/lib/profopt.exp
>> ===================================================================
>> --- gcc/testsuite/lib/profopt.exp       (revision 214976)
>> +++ gcc/testsuite/lib/profopt.exp       (working copy)
>> @@ -169,6 +169,8 @@ proc profopt-final-code { which final_code name }
>>  # SRC is the full pathname of the testcase.
>>  #
>>  proc profopt-get-options { src } {
>> +    global srcdir
>> +
>>      # dg-options sets a variable called dg-extra-tool-flags.
>>      set dg-extra-tool-flags ""
>>
>>
>>
>> --
>> Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413



-- 
Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413