[Bug tree-optimization/117997] [15 regression] libgo regressions on aarch64 after g:4d2b9202fe94c54e63fb07d48293a78da3d82532

[jakub at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117997

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Reduced testcase (again -O2 -fpie misbehaves, -O2 or -O2 -fpie
-fno-optimize-crc is fine) below.
While it is still quite large, most of it actually isn't executed at all, what
misbehaves is the
baz function (i.e. crc8 update) when filling the array, but strangely it
doesn't misbehave if I
just call it alone.

__attribute__((noipa)) unsigned char
foo (const unsigned char *data, unsigned int len)
{
  __builtin_abort ();
}

__attribute__((noipa)) unsigned short
bar (const unsigned char *data, unsigned int len)
{
  __builtin_abort ();
}

static unsigned char
baz (unsigned char byte, unsigned char crc)
{
  unsigned int i;
  crc ^= byte;
  for (i = 0; i < 8; i++)
    crc = (crc << 1) ^ ((crc >> 7) ? 0x07 : 0);
  return crc;
}

static unsigned short
qux (unsigned char byte, unsigned short crc)
{
  unsigned int i;
  crc ^= byte << 8;
  for (i = 0; i < 8; i++)
    crc = (crc << 1) ^ ((crc >> 15) ? 0x8005 : 0);
  return crc;
}

__attribute__((noipa)) int
corge (const unsigned char *data)
{
  const unsigned char expected[] = {
    0x00, 0x07, 0x1b, 0x48, 0xe3, 0xbc, 0x2f, 0xd8,
    0x3e, 0x85, 0xa4, 0x44, 0xff, 0xd0, 0x14, 0x41,
    0xb0, 0x6e, 0x73, 0x27, 0x99, 0xad, 0x28, 0xbd,
    0x72, 0x16, 0x24, 0xbd, 0x6e, 0x5e, 0xc7, 0x06
  };
  for (int i = 0; i < 32; ++i)
    if (data[i] != expected[i])
      __builtin_abort ();
  return 1;
}

static int
garply (const unsigned char *data, unsigned long size)
{
  unsigned int i;
  unsigned char crc0, crc1;
  crc0 = 0;
  crc1 = foo (data, 0);
  if (crc1 != crc0)
    return 0;
  for (i = 0; i < size; i++)
    {
      crc0 = baz (data[i], crc0);
      crc1 = foo (data, i + 1);
      if (crc1 != crc0)
        return 0;
    }
  return 1;
}

static int
freddy (const unsigned char *data, unsigned long size)
{
  unsigned int i;
  unsigned short crc0, crc1;
  crc0 = 0;
  crc1 = bar (data, 0);
  if (crc1 != crc0)
    return 0;
  for (i = 0; i < size; i++)
    {
      crc0 = qux (data[i], crc0);
      crc1 = bar (data, i + 1);
      if (crc1 != crc0)
        return 0;
    }
  return 1;
}

__attribute__((noipa)) int
blah (void)
{
  unsigned int i;
  unsigned char data[64] = { 0 };
  for (i = 1; i < 64; i++)
    data[i] = baz (i % 256, data[i - 1]);
  if (corge (data))
    return 0;
  if (!garply (data, 64))
    return 1;
  if (!freddy (data, 64))
    return 1;
   return 1;
}

int
main ()
{
  if (blah ())
    __builtin_abort ();
}