[Bug tree-optimization/21548] [4.0 regression] Wrong warning about uninitialized variable

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-13 
22:23 -------
thinking again out loud:
The function could be changed to (which we seem to be missing on the mainline):
static int blocksize = 4096; 
 
int bar (int); 
 
void foo (void) 
{ 
  int toread; 
  int bytes; 
  static char eof_reached = 0;
 
  toread = blocksize; 
  while (1) 
    { 
      bytes = bar (toread); 
      if (bytes <= 0) 
        { 
          if (bytes < 0) 
            continue; 
          goto temp; 
        } 
      toread -= bytes; 
     if (toread == 0)
       goto temp1;
    } 
   
 
  if (bytes == 0) 
temp:
    eof_reached = 1; 
temp1:
} 

So comming out of the loop bytes will be zero if we break out of it but 
otherwise cannot, so we can skip 
if statement.  This is a missing optimization on the mainline (someone should 
look into it) but now my 
comment #10 becomes true and we see that it is always used as uninitized.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21548