On Wed, May 06, 2009 at 02:29:46AM -0400, DJ Delorie wrote:
>
> Andrew Pinski <[email protected]> writes:
> > You could do what the rs6000 back-end does for the altivec builtins
> > and resolve them while the parser is run (the SPU back-end does the
> > same thing too). Yes there are opaque vector types, you just use
> > build_opaque_vector_type instead of build_vector_type.
>
> Thanks, I'll look at those. Any way to prototype such functions in C ?
As Andrew says the rs6000/spu have the notion of overloaded builtins. I've
been working in this area somewhat for the power7 port, and you might want to
look at my power7-branch.
In rs6000.h it uses REGISTER_TARGET_PRAGMAS to set the
resolve_overloaded_builtin target hook:
/* Target pragma. */
#define REGISTER_TARGET_PRAGMAS() do { \
c_register_pragma (0, "longcall", rs6000_pragma_longcall); \
targetm.resolve_overloaded_builtin = altivec_resolve_overloaded_builtin; \
} while (0)
In rs6000-c.c you have the function that tries to resolve the builtin given the
argument types:
tree
altivec_resolve_overloaded_builtin (tree fndecl, void *passed_arglist)
{
...
}
It returns a tree of the builtin function with the appropriate types. In the
code, there is a giant table (altivec_overloaded_builtins) that maps the
generic builtin functions to the specific ones based on the argument types.
For example, altivec has a builtin function that does absolute value for any
vector type, and internally it converts this to the appropriate builtin for
each type:
const struct altivec_builtin_types altivec_overloaded_builtins[] = {
/* Unary AltiVec/VSX builtins. */
{ ALTIVEC_BUILTIN_VEC_ABS, ALTIVEC_BUILTIN_ABS_V16QI,
RS6000_BTI_V16QI, RS6000_BTI_V16QI, 0, 0 },
{ ALTIVEC_BUILTIN_VEC_ABS, ALTIVEC_BUILTIN_ABS_V8HI,
RS6000_BTI_V8HI, RS6000_BTI_V8HI, 0, 0 },
{ ALTIVEC_BUILTIN_VEC_ABS, ALTIVEC_BUILTIN_ABS_V4SI,
RS6000_BTI_V4SI, RS6000_BTI_V4SI, 0, 0 },
{ ALTIVEC_BUILTIN_VEC_ABS, ALTIVEC_BUILTIN_ABS_V4SF,
RS6000_BTI_V4SF, RS6000_BTI_V4SF, 0, 0 },
...
};
--
Michael Meissner, IBM
4 Technology Place Drive, MS 2203A, Westford, MA, 01886, USA
[email protected]
