[PATCH] D15541: [PGO] generate different version for FE instrumentation and IR level instrumentation profiles

[Xinliang David Li via llvm-commits]

Yes -- I like this suggestion (I have done that in an abandoned patch
before :) ).

David

On Fri, Jan 8, 2016 at 11:30 AM, Justin Bogner <mail at justinbogner.com> wrote:
> Rong Xu <xur at google.com> writes:
>> xur updated this revision to Diff 43190.
>> xur added a comment.
>>
>> Integrated David's comments.
>>
>>
>> http://reviews.llvm.org/D15541
>>
>> Files:
>>   lib/profile/InstrProfData.inc
>>   lib/profile/InstrProfiling.c
>>
>>
>> Index: lib/profile/InstrProfiling.c
>> ===================================================================
>> --- lib/profile/InstrProfiling.c
>> +++ lib/profile/InstrProfiling.c
>> @@ -18,6 +18,9 @@
>>
>>  char *(*GetEnvHook)(const char *) = 0;
>>
>> +/* IR level instrumentation declares a strong symbol and sets the value to 1. */
>> +COMPILER_RT_WEAK int IR_LEVEL_PROF_VARNAME = 0;
>> +
>>  COMPILER_RT_VISIBILITY uint64_t __llvm_profile_get_magic(void) {
>>    return sizeof(void *) == sizeof(uint64_t) ? (INSTR_PROF_RAW_MAGIC_64)
>>                                              : (INSTR_PROF_RAW_MAGIC_32);
>> @@ -32,6 +35,8 @@
>>  }
>>
>>  COMPILER_RT_VISIBILITY uint64_t __llvm_profile_get_version(void) {
>> +  if (IR_LEVEL_PROF_VARNAME)
>> +    return INSTR_PROF_RAW_VERSION | VARIANT_MASK_IR_PROF;
>>    return INSTR_PROF_RAW_VERSION;
>>  }
>>
>> Index: lib/profile/InstrProfData.inc
>> ===================================================================
>> --- lib/profile/InstrProfData.inc
>> +++ lib/profile/InstrProfData.inc
>> @@ -678,6 +678,18 @@
>>  /* Raw profile format version. */
>>  #define INSTR_PROF_RAW_VERSION 2
>>
>> +/* Profile version is always of type uint_64_t. Reserve the upper 8 bits in the
>> + * version for other variants of profile. We set the lowest bit of the upper 8
>> + * bits (i.e. bit 56) to 1 to indicate if this is an IR-level instrumentaiton
>> + * generated profile, and 0 if this is a Clang FE generated profile.
>> + */
>> +#define VARIANT_MASKS_ALL 0xff00000000000000ULL
>> +#define VARIANT_MASK_IR_PROF (0x1ULL << 56)
>> +#define GET_VERSION(V) ((V)&~VARIANT_MASKS_ALL)
>> +#define IR_LEVEL_PROF_VARNAME __llvm_profile_ir_level
>> +#define IR_LEVEL_PROF_STRINGFY(s) #s
>> +#define IR_LEVEL_PROF_STRING(s) IR_LEVEL_PROF_STRINGFY(s)
>
> It would be simpler to just have the instrumentation logic in llvm emit
> the fully processed version number, then the compiler-rt code doesn't
> need to know anything about the version variant flags.
>
> David: WDYT?
>
>> +
>>  /* Runtime section names and name strings.  */
>>  #define INSTR_PROF_DATA_SECT_NAME __llvm_prf_data
>>  #define INSTR_PROF_NAME_SECT_NAME __llvm_prf_names
>>
>>