[Bug tree-optimization/72866] New: [7 Regression] Compile time hog w/ -O3 (-Ofast)

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72866

            Bug ID: 72866
           Summary: [7 Regression] Compile time hog w/ -O3 (-Ofast)
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: compile-time-hog
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

gcc-7.0.0-alpha20160807 takes large (or infinite?) time when compiling the
following reduced testcase w/ -O3 or -Ofast:

unsigned int dl;
int rx, lb;

void
fo (int jv, int be)
{
  const unsigned int xw = 16;
  unsigned int ya, wo;

  for (ya = 0; ya < 2; ++ya)
    for (wo = 0; wo < xw; ++wo)
      {
        dl += (jv ? be : rx);
        rx += ((lb == 0) + 1);
      }
}

Compilation time appears to be dependent on the value stored in `xw'.