Re: [GOOGLE] Define libgcov interface for distinguishing -ftest-coverage from -fprofile-generate

[Teresa Johnson <tejohnson at google dot com>]

On Wed, Jul 2, 2014 at 1:15 PM, Xinliang David Li <davidxl@google.com> wrote:
> Should the interface be something like:
>
> int __gcov_profiling_for_test_coverage(void)?

I was equating the term "profiling" with -fprofile-generate, as
opposed to -ftest-coverage instrumentation. But I can change it to
this if you think that is clearer.

Teresa

>
> David
>
>
> On Wed, Jul 2, 2014 at 12:55 PM, Teresa Johnson <tejohnson@google.com> wrote:
>> The following patch adds support for a new libgcov interface,
>> __gcov_profiling_enabled, that can be used by applications to
>> determine whether a binary has been instrumented for test coverage or
>> profile optimization.
>>
>> Passes regression tests and manual testing with different options. Ok
>> for google branches?
>>
>> Thanks,
>> Teresa
>>
>> 2014-07-02  Teresa Johnson  <tejohnson@google.com>
>>
>>         Google ref b/15378201.
>>         * gcc/tree-profile.c (gcov_test_coverage_decl): Declare.
>>         (tree_init_instrumentation): Initialize gcov_test_coverage_decl.
>>         * libgcc/libgcov-driver.c (__gcov_dummy_ref7): Define.
>>         * libgcc/libgcov-interface.c (__gcov_profiling_enabled): New function.
>>
>> Index: gcc/tree-profile.c
>> ===================================================================
>> --- gcc/tree-profile.c  (revision 212044)
>> +++ gcc/tree-profile.c  (working copy)
>> @@ -164,6 +164,9 @@ static GTY(()) tree gcov_sample_counter_decl = NUL
>>  /* extern gcov_unsigned_t __gcov_profile_prefix  */
>>  static tree GTY(()) gcov_profile_prefix_decl = NULL_TREE;
>>
>> +/* extern gcov_unsigned_t __gcov_test_coverage  */
>> +static tree GTY(()) gcov_test_coverage_decl = NULL_TREE;
>> +
>>  /* extern gcov_unsigned_t __gcov_sampling_period  */
>>  static GTY(()) tree gcov_sampling_period_decl = NULL_TREE;
>>
>> @@ -498,6 +501,27 @@ tree_init_instrumentation (void)
>>        DECL_INITIAL (gcov_profile_prefix_decl) = prefix_ptr;
>>        varpool_finalize_decl (gcov_profile_prefix_decl);
>>      }
>> +
>> +  if (!gcov_test_coverage_decl)
>> +    {
>> +      /* Initialize __gcov_test_coverage to 1 if -ftest-coverage
>> +         specified, 0 otherwise. Used by libgcov to determine whether
>> +         a binary was instrumented for coverage or profile optimization.  */
>> +      gcov_test_coverage_decl = build_decl (
>> +          UNKNOWN_LOCATION,
>> +          VAR_DECL,
>> +          get_identifier ("__gcov_test_coverage"),
>> +          get_gcov_unsigned_t ());
>> +      TREE_PUBLIC (gcov_test_coverage_decl) = 1;
>> +      DECL_ARTIFICIAL (gcov_test_coverage_decl) = 1;
>> +      DECL_COMDAT_GROUP (gcov_test_coverage_decl)
>> +          = DECL_ASSEMBLER_NAME (gcov_test_coverage_decl);
>> +      TREE_STATIC (gcov_test_coverage_decl) = 1;
>> +      DECL_INITIAL (gcov_test_coverage_decl) = build_int_cst (
>> +          get_gcov_unsigned_t (),
>> +          flag_test_coverage ? 1 : 0);
>> +      varpool_finalize_decl (gcov_test_coverage_decl);
>> +    }
>>  }
>>
>>  /* Initialization function for FDO sampling.  */
>> Index: libgcc/libgcov-driver.c
>> ===================================================================
>> --- libgcc/libgcov-driver.c     (revision 212044)
>> +++ libgcc/libgcov-driver.c     (working copy)
>> @@ -79,6 +79,8 @@ extern unsigned int __gcov_sampling_enabled (void)
>>  char *(*__gcov_dummy_ref5)(void) = &__gcov_sampling_enabled;
>>  extern void __gcov_flush (void);
>>  char *(*__gcov_dummy_ref6)(void) = &__gcov_flush;
>> +extern unsigned int __gcov_profiling_enabled (void);
>> +char *(*__gcov_dummy_ref7)(void) = &__gcov_profiling_enabled;
>>
>>  /* Default callback function for profile instrumentation callback.  */
>>  extern void __coverage_callback (gcov_type, int);
>> Index: libgcc/libgcov-interface.c
>> ===================================================================
>> --- libgcc/libgcov-interface.c  (revision 212044)
>> +++ libgcc/libgcov-interface.c  (working copy)
>> @@ -116,6 +116,20 @@ __gcov_dump (void)
>>    set_gcov_dump_complete ();
>>  }
>>
>> +/* Emitted in coverage.c.  */
>> +extern gcov_unsigned_t __gcov_test_coverage;
>> +
>> +unsigned int __gcov_profiling_enabled (void);
>> +
>> +/* Function that can be called from application to distinguish binaries
>> +   instrumented from coverage fro those instrumented for profiling
>> +   (e.g. -fprofile-generate).  */
>> +
>> +unsigned int __gcov_profiling_enabled (void)
>> +{
>> +  return !__gcov_test_coverage;
>> +}
>> +
>>  #endif /* L_gcov_dump */
>>
>>  #ifdef L_gcov_sampling
>>
>>
>> --
>> Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413



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