[Bug tree-optimization/80520] [7/8 Regression] Performance regression from missing if-conversion

[krister.walfridsson at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80520

--- Comment #5 from krister.walfridsson at gmail dot com ---
I have extracted a smaller test case.  The loops are generated from

  typedef mersenne_twister_engine<
      uint_fast32_t,
      32, 624, 397, 31,
      0x9908b0dfUL, 11,
      0xffffffffUL, 7,
      0x9d2c5680UL, 15,
      0xefc60000UL, 18, 1812433253UL> mt19937;

and the expansion of the template end up with loops like

void foo(unsigned long *M)
{
  for (unsigned long k = 0; k < 227; ++k)
    {
      unsigned long y =
        ((M[k] & 0xffffffff80000000) | (M[k + 1] & 0x7fffffff));
      M[k] = (M[k + 397] ^ (y >> 1) ^ ((y & 1) ? 2567483615 : 0));
    }
}

which generates the dump described in the bug report.

--- Comment #6 from krister.walfridsson at gmail dot com ---
I have extracted a smaller test case.  The loops are generated from

  typedef mersenne_twister_engine<
      uint_fast32_t,
      32, 624, 397, 31,
      0x9908b0dfUL, 11,
      0xffffffffUL, 7,
      0x9d2c5680UL, 15,
      0xefc60000UL, 18, 1812433253UL> mt19937;

and the expansion of the template end up with loops like

void foo(unsigned long *M)
{
  for (unsigned long k = 0; k < 227; ++k)
    {
      unsigned long y =
        ((M[k] & 0xffffffff80000000) | (M[k + 1] & 0x7fffffff));
      M[k] = (M[k + 397] ^ (y >> 1) ^ ((y & 1) ? 2567483615 : 0));
    }
}

which generates the dump described in the bug report.