[Bug tree-optimization/89475] New: Teach ccp about __builtin_bswap{16,32,64}

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89475

            Bug ID: 89475
           Summary: Teach ccp about __builtin_bswap{16,32,64}
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

When looking at PR89435, I've noticed ccp should be able, but doesn't, optimize
__builtin_bswap{16,32,64}.

Those builtins should preserve both the mask and INTEGER_CST from the argument,
just bswapped.

Short testcase:

void link_error (void);

unsigned short
f0 (unsigned short x)
{
  x &= 0xaa55;
  x = __builtin_bswap16 (x);
  if (x & 0xaa55)
    link_error ();
  return x;
}

unsigned short
f1 (unsigned short x)
{
  x &= 0x55aa;
  x = __builtin_bswap16 (x);
  if (x & 0x55aa)
    link_error ();
  return x;
}

unsigned int
f2 (unsigned int x)
{
  x &= 0x55aa5aa5U;
  x = __builtin_bswap32 (x);
  if (x & 0x5aa555aaU)
    link_error ();
  return x;
}

unsigned long long int
f3 (unsigned long long int x)
{
  x &= 0x55aa5aa544cc2211ULL;
  x = __builtin_bswap64 (x);
  if (x & 0xeedd33bb5aa555aaULL)
    link_error ();
  return x;
}

unsigned short
f4 (unsigned short x)
{
  x = __builtin_bswap32 (x);
  if (x != 0)
    link_error ();
  return x;
}

unsigned int
f5 (unsigned int x)
{
  x = __builtin_bswap64 (x);
  if (x != 0)
    link_error ();
  return x;
}

unsigned short
f6 (unsigned short x)
{
  x |= 0xaa55;
  x = __builtin_bswap16 (x);
  if ((x | 0xaa55) != 0xffff)
    link_error ();
  return x;
}

unsigned short
f7 (unsigned short x)
{
  x |= 0x55aa;
  x = __builtin_bswap16 (x);
  if ((x | 0x55aa) != 0xffff)
    link_error ();
  return x;
}

unsigned int
f8 (unsigned int x)
{
  x |= 0x55aa5aa5U;
  x = __builtin_bswap32 (x);
  if ((x | 0x5aa555aaU) != 0xffffffffU)
    link_error ();
  return x;
}

unsigned long long int
f9 (unsigned long long int x)
{
  x |= 0x55aa5aa544cc2211ULL;
  x = __builtin_bswap64 (x);
  if ((x | 0xeedd33bb5aa555aaULL) != 0xffffffffffffffffULL)
    link_error ();
  return x;
}

Perhaps somewhat related to PR55177.