[google] Propagate profile information to RTL level during switch expansion

[Xinliang David Li]

Ok for google branch with minor changes below.

thanks,

David

>> +static bool non_zero_profile_counts ( VEC(edge,gc) *edges) {

static bool
non_zero_profile_counts(...)

Please also provide function documentation.

>> +  edge e;
>> +  edge_iterator ei;
>> +  FOR_EACH_EDGE(e, ei, edges)
>> +    {
>> +      if (e->count > 0)
>> +        return true;
>> +    }
>> +  return false;
>> +}


>> +#define case_probability(x, y) ((y) ? ((x) * REG_BR_PROB_BASE  / (y))  : -1)
>> +

Using upper case for macro?


>> +  int default_count = 0;

int --> gcov_type

>> +          int count = bb->count;

int --> gcov_type

>> 	  table_label = gen_label_rtx ();
>> 	  if (! try_casesi (index_type, index_expr, minval, range,
>> 			    table_label, default_label, fallback_label))
>> 	    {
>> 	      bool ok;
>> +              int default_probability;
>>
>> +              if (has_gaps)
>> +                {
>> +                  /* There is at least one entry in the jump table that jumps
>> +                     to default label. The default label can either be reached
>> +                     through the indirect jump or the direct conditional jump
>> +                     before that. Split the probability of reaching the
>> +                     default label among these two jumps.  */
>> +                  default_probability = case_probability (default_count/2,
>> +                                                          bb->count);

Some heuristics can probably be developed to make better split of the
default probability and value range information can be used. For
instance, if the case values are from an enum and the gaps between two
enumerators are defined, then the preceding conditional jump should
have get 100% of the default probability. This can be enhanced later.

>> +                  count -= default_count;
>> +                  default_count = 0;

Why resetting it to 0?


>> +
>> +static void
>> +add_prob_note_to_last_insn(int probability)
>> +{

Missing document.