Reg alloc (?) bug in gcc-3.0.1, i586-linux

["Bradley G. Kaiser" <bkaiser at acelink dot net>]

The following code fragment (taken from the mutt email program by
Michael Elkins, v1.2.5) generates invalid code with gcc-3.0.1
(i586-linux) with either "-O -fgcse -frerun-cse-after-loop 
-fomit-frame-pointer" or "-O2 -fomit-frame-pointer".  ("-O3
-fomit-frame-pointer" obviously triggers the problem as well).

The resulting assembly code uses the ebp register as a ptr
into the stack frame without initializing it.

(I believe this problem also causes a gcc bootstrap with "-O3
-fomit-frame-pointer -fno-inline-functions" to segfault in stage2.)

The problem seems to be in global register allocation or
reload, but I haven't been successful in narrowing it down further
than that.  

Regards,

Brad Kaiser
(bkaiser@acelink.net) 

---------------8<----------------8<-----------------

#define FILE struct iobuf_
#define NULL  ((void *)0)
#define LONG_STRING 1024


extern int COLS;


void format_line (FILE *f, int ismacro,
			 const char *t1, const char *t2, const char *t3)
{
  int col;
  int col_a, col_b;
  int split;

  fputs (t1, f);

  if ((split = COLS < 40))
  {
    col_a = col = 0;
    col_b = LONG_STRING;
    fputc ('\n', f);
  }
  else
  {
    col_a = COLS > 83 ? (COLS - 32) >> 2 : 12;
    col_b = COLS > 49 ? (COLS - 10) >> 1 : 19;
    col = pad (f, mutt_strlen(t1), col_a);
  }

  if (ismacro > 0)
  {
    if (!split)
    {
      col += print_macro (f, col_b - col - 4, &t2);
    }
  }

  col += print_macro (f, col_b - col - 1, &t2);
  if (split)
    fputc ('\n', f);
  else
    col = pad (f, col, col_b);

}


--------------->8---------------->8-----------------