[Bug middle-end/37316] [4.4 Regression] Small structs are not passed correctly on hppa64-*-*

["dave at hiauly1 dot hia dot nrc dot ca" <gcc-bugzilla@gcc.gnu.org>]

------- Comment #16 from dave at hiauly1 dot hia dot nrc dot ca  2008-10-25 01:11 -------
Subject: Re:  [4.4 Regression] Small structs are not passed correctly on
hppa64-*-*

> Can you please look at the testcases why they fail (what is passed differently)
> and try to minimize them as much as possible?  Finding a bug in RTL or assembly
> without knowing what you are looking for is certainly harder than when you have
> a debugger and can see what is passed differently...

The following is a simplification of the first failure in
gcc.dg/compat/scalar-by-value-4.

_Complex char g01cc;

void
initcc (_Complex char *p, _Complex char v)
{
  *p = v + (0 + 1 * __extension__ 1i);
}

void
checkcc (_Complex char x, _Complex char v)
{
  if (x != v + (0 + 1 * __extension__ 1i)) abort ();
}

void
checkgcc (void)
{
  checkcc (g01cc, 1);
}

int
main ()
{
  initcc (&g01cc, 1);
  checkgcc ();
  return 0;
}

The first argument passed to checkcc is wrong.  The value passed in
r26 (the first argument register) is 1.  4.3.2 passed 0x101.  The value
passed for v is 0x100 in both versions.

Now, as I understand the 64-bit runtime specification for hppa64-hpux,
neither GCC version is correct.  However, I don't believe HP cc or aCC
supports integer complex values, so I can't check for consistency.
My understanding is that small structs and aggregates should be left
justified.  This unfortunately differs from the right justification
used on most big endian targets.  I believe tha correct value for
x and v should be 0x0101000000000000 and 0x010000000000000, respectively.

I have checked that the struct { byte x; byte y } is correctly left
justified.

Dave


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37316