[Bug rtl-optimization/40761] New: IRA memory hog for insanely nested loops

[bonzini at gnu dot org]

#define ONE     while (b())
#define TEN     ONE ONE ONE ONE ONE ONE ONE ONE ONE ONE
#define HUN     TEN TEN TEN TEN TEN TEN TEN TEN TEN TEN
#define THOU    HUN HUN HUN HUN HUN HUN HUN HUN HUN HUN

void foo()
{
  /* 11,000 nested whiles.  */
  THOU THOU THOU THOU THOU THOU THOU THOU THOU THOU THOU
  a();
}

shows IRA taking 82% of compile-time wall time (25 seconds here at -O0) and
needing 1 GB of memory.  The reason why I'm reporting this, is that it seems to
be quadratic or at least well superlinear.  Changing it to 5500 loops requires
only 300 MB.

Not that it's the most important bug.


-- 
           Summary: IRA memory hog for insanely nested loops
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Keywords: memory-hog
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bonzini at gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40761