Help with rich_location and GIMPLE stmts

[Martin Liška]

Hi.

I sent this email to David some time ago, but it should be probably answered
on gcc mailing list.

I have idea one to improve gcov tool and I'm interested in more precise 
locations for gimple
statements. For gcov purpose, we dump location in ipa-profile pass, which is an 
early IPA
pass and this data is used by gcov tool to map statements (blocks) to lines of 
code.

I did a small experiment on the place we emit the location data:
                  inform (gimple_location (stmt), "output_location");

and it shows for:
$ cat m2.c
unsigned int
UuT (void)
{ unsigned int true_var = 1; unsigned int false_var = 0; unsigned int ret = 0; 
if (true_var) /* count(1) */ { if (false_var) /* count(1) */ ret = 111; /* 
count(#####) */ } else ret = 999; /* count(#####) */ return ret; }

int
main (int argc, char **argv)
{
  UuT ();
  return 0;
}

$ gcc --coverage m2.c
m2.c: In function ‘main’:
m2.c:8:3: note: output_location
   UuT ();
   ^~~~~~
# .MEM_2 = VDEF <.MEM_1(D)>
UuT ();
m2.c:9:10: note: output_location
   return 0;
          ^
_3 = 0;
m2.c: In function ‘UuT’:
m2.c:3:16: note: output_location
 { unsigned int true_var = 1; unsigned int false_var = 0; unsigned int ret = 0; 
if (true_var) /* count(1) */ { if (false_var) /* count(1) */ ret = 111; /* 
count(#####) */ } else ret = 999; /* count(#####) */ return ret; }
                ^~~~~~~~
true_var_3 = 1;
m2.c:3:43: note: output_location
 { unsigned int true_var = 1; unsigned int false_var = 0; unsigned int ret = 0; 
if (true_var) /* count(1) */ { if (false_var) /* count(1) */ ret = 111; /* 
count(#####) */ } else ret = 999; /* count(#####) */ return ret; }
                                           ^~~~~~~~~
false_var_4 = 0;
m2.c:3:71: note: output_location
 { unsigned int true_var = 1; unsigned int false_var = 0; unsigned int ret = 0; 
if (true_var) /* count(1) */ { if (false_var) /* count(1) */ ret = 111; /* 
count(#####) */ } else ret = 999; /* count(#####) */ return ret; }
                                                                       ^~~
ret_5 = 0;
m2.c:3:83: note: output_location
 { unsigned int true_var = 1; unsigned int false_var = 0; unsigned int ret = 0; 
if (true_var) /* count(1) */ { if (false_var) /* count(1) */ ret = 111; /* 
count(#####) */ } else ret = 999; /* count(#####) */ return ret; }
                                                                                
   ^
if (true_var_3 != 0)
m2.c:3:114: note: output_location
 { unsigned int true_var = 1; unsigned int false_var = 0; unsigned int ret = 0; 
if (true_var) /* count(1) */ { if (false_var) /* count(1) */ ret = 111; /* 
count(#####) */ } else ret = 999; /* count(#####) */ return ret; }
                                                                                
                                  ^
if (false_var_4 != 0)
m2.c:3:145: note: output_location
 { unsigned int true_var = 1; unsigned int false_var = 0; unsigned int ret = 0; 
if (true_var) /* count(1) */ { if (false_var) /* count(1) */ ret = 111; /* 
count(#####) */ } else ret = 999; /* count(#####) */ return ret; }
                                                                                
                                                             ~~~~^~~~~
ret_7 = 111;
m2.c:3:182: note: output_location
 { unsigned int true_var = 1; unsigned int false_var = 0; unsigned int ret = 0; 
if (true_var) /* count(1) */ { if (false_var) /* count(1) */ ret = 111; /* 
count(#####) */ } else ret = 999; /* count(#####) */ return ret; }
                                                                                
                                                                                
                  ~~~~^~~~~
ret_6 = 999;
m2.c:3:215: note: output_location
 { unsigned int true_var = 1; unsigned int false_var = 0; unsigned int ret = 0; 
if (true_var) /* count(1) */ { if (false_var) /* count(1) */ ret = 111; /* 
count(#####) */ } else ret = 999; /* count(#####) */ return ret; }
                                                                                
                                                                                
                                                       ^~~
_8 = ret_2;
m2.c:3:215: note: output_location
# VUSE <.MEM_9(D)>
return _8;

Which is not optimal, for some assignments I see just LHS (false_var_4 = 0), 
for return statements only a returned value is displayed. For conditions, only 
condition beginning is showed.
Is this known behavior or do I miss something?

Thanks,
Martin