gcc/testsuite/gcc.dg/tree-ssa/pr59597.c

/* { dg-do compile } */
/* { dg-options "-Ofast -fdump-tree-vrp-thread1-details" } */

typedef unsigned short u16;
typedef unsigned char u8;
typedef unsigned int u32;
__extension__ typedef __INT32_TYPE__ i32;

long int random(int);
#define NNN 10

u32 f[NNN], t[NNN];

static u16
Calc_crc8 (u8 data, u16 crc)
{
  u8 i=0,x16=0,carry=0;
  for (i = 0; i < 8; i++)
    {
      x16 = (u8)((data & 1) ^ ((u8)crc & 1));
      data >>= 1;
 
      if (x16 == 1)
	{
	  crc ^= 0x4002;
	  carry = 1;
	}
      else
	carry = 0;
      crc >>= 1;
      if (carry)
	crc |= 0x8000;
      else
	crc &= 0x7fff;
    }
  return crc;
}

int
main (int argc, char argv[])
{
  int i; i32 j; u16 crc;
  for (j = 0; j < 10000000; j++)
    {
      for (i = 0; i < NNN; i++)
	{
	  f[i] = random(i);
	  t[i] = random(NNN - i - 1);
	}
      for (i=0; i<NNN; i++) 
	{
	  crc=Calc_crc8(f[i],(u16)argc);
	  crc=Calc_crc8(t[i],crc);
	}
    }
  return crc;
}

/* Previously we had 3 jump threads, but one of them crossed loops.
   The reason the old threader was allowing it, was because there was
   an ASSERT_EXPR getting in the way.  Without the ASSERT_EXPR, we
   have an empty pre-header block as the final block in the thread,
   which the threader will simply join with the next block which *is*
   in a different loop.  */
/* { dg-final { scan-tree-dump-times "Registering jump thread" 2 "vrp-thread1" } } */
/* { dg-final { scan-tree-dump-not "joiner" "vrp-thread1" } } */