[cfe-dev] "vector" type, PS3 targets

[Douglas Gregor]

On Nov 18, 2009, at 3:41 PM, John Thompson wrote:

> Hi,
>
> I thought I'd to some preliminary work to see what issues I'd run  
> into trying to compile some sources intented for the PS3 PPU  
> target.  The PS3 devkit includes a gcc-based compiler, so I'm  
> thinking that would make it a bit easier.
>
> Although there is a -faltivec option, it appears that there is no  
> support yet for the "vector" type (or is it really "__vector", or  
> perhaps a built-in alias?).

There's a little bit of information about a "__vector" in the "PowerPC  
Type Attributes" section of the GCC manual, here:

	http://gcc.gnu.org/onlinedocs/gcc-4.4.2/gcc/Type-Attributes.html#Type-Attributes

> I don't know much about this, so I was wondering if someone out  
> there could say something about it with respect to plans for it in  
> clang.

Clang currently supports two kinds of vector types, the GNU vector  
attribute (e.g., "int __attribute__((vector_size(number-of-bytes)))")  
and Clang's own OpenCL-inspired extended vector attribute (e.g., "int  
__attribute__((ext_vector_type(number-of-elements)))"). The Altivec  
vector/__vector probably matches one of those.

> I suppose that in addition to the vector type, this would also  
> involve all the "__builtin_vec-*" functions, but not having the  
> vector type used in the altivec.h include file was the first thing I  
> ran into.
> I've enclosed some initial work for the targets, in  
> ps3targets.patch.  This depends on changes to the Triple class in  
> ps3triple.patch, which I've submitted seperately to the llvmdev  
> list.  The gcc-based compiler in the PS3 devkit uses the the "ppu- 
> uknown-lv2" and "spu-unknown-lv2" triples, so these changes do the  
> same.  I don't know why there isn't a "ps3" in there somewhere, but  
> it probably should be the same in both compilers.

+    // FIXME:  Does this belong in PPCTargetInfo?
+    if (Opts.AltiVec) {
+      Define(Defs, "__VEC__", "1");
+      Define(Defs, "__ALTIVEC__", "1");
+    }

GCC defines both of these when compiling for PPC, so they should go  
into PPCTargetInfo. I'm seeing the following definitions:

#define __VEC__ 10206
#define __ALTIVEC__ 1

Otherwise, the triple and target changes look good!

   - Doug