I was looking at PR 19893 (gcc.dg/vect/vect-76 fails on ia64-hpux) and I
think it is caused by a non-platform specific bug, though it may not
cause vect-76 to fail on other platforms. I was hoping someone might be
able to help me understand what is going on.
Here is a cut down test case (with no vector stuff in it):
typedef int aint __attribute__ ((__aligned__(16)));
aint ib[12];
int ic[12], *x, *y;
int main (void)
{
x = &ib[4];
y = &ic[4];
}
If you look at the assembly language generated on IA64 (HP-UX or Linux)
or probably on any platform, you will see that 'y' gets correctly set to
the address of ic[4]. But 'x' gets set to ib[0], instead of ib[4].
Things look good in all the tree dumps but the first rtl dump looks bad
so I believe things are going wrong during expansion. Looking in
tree.def I see:
/* Array indexing.
Operand 0 is the array; operand 1 is a (single) array index.
Operand 2, if present, is a copy of TYPE_MIN_VALUE of the index.
Operand 3, if present, is the element size, measured in units of
the alignment of the element type. */
DEFTREECODE (ARRAY_REF, "array_ref", tcc_reference, 4)
Now I think this the problem is with operand 3. What value should it
have if the alignment is greater than the element size? That is what I
have in the test case above and when I dump the array_ref for ib[4] I
see that I have an operand 3 and it is zero and I think this is causing
the test failure. What value should operand 3 have in this situation?
Or should it have been left out?
Steve Ellcey
[EMAIL PROTECTED]
