PATCH - [mainline] AltiVec power-pc-darwin fix for vec_ld

[Fariborz Jahanian <fjahanian at apple dot com>]

Following test case shows a bug in selection of overloaded c++ version
of altivec intrinsic functions with 'const' qualifier in their 
parameter type:


typedef vector unsigned char vuc_t;
const vuc_t* p;
int main()
{
            vec_ld(0,p);
}

g++ issues bogus error, because, it does not add 'const'  qualifier in 
building the
parameter type when matching the overloaded function: 'vec_ld'

mygcct5 -x c++ -faltivec bad.c
bad.c: In function `int main()':
bad.c:7: error: invalid conversion from `const unsigned char 
__vector__*' to `unsigned char __vector__*'
bad.c:7: error:   initializing argument 2 of `unsigned char __vector__ 
vec_ld(int, unsigned char __vector__*)'

Following patch, bootstrapped, dejagnu tested on ppc-darwin fixes the 
problem.

OK for mainline?

- Thanks, fariborz


ChangeLog:

2004-05-10  Fariborz Jahanian  <fjahanian@apple.com>

        * config/rs6000/rs6000.c (rs6000_handle_altivec_attribute):
        Add const qualifier to altivec vector type if one is needed.


Index: rs6000.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/rs6000/rs6000.c,v
retrieving revision 1.635
diff -c -p -r1.635 rs6000.c
*** rs6000.c    7 May 2004 23:00:39 -0000       1.635
--- rs6000.c    10 May 2004 22:13:56 -0000
*************** rs6000_handle_altivec_attribute (tree *n
*** 15040,15045 ****
--- 15040,15048 ----
      default: break;
      }

+   if (result && result != type && TYPE_READONLY(type))
+     result = build_qualified_type (result, TYPE_QUAL_CONST);
+
    *no_add_attrs = true;  /* No need to hang on to the attribute.  */

    if (!result)