On 6 January 2012 12:16, a <a@a.com> wrote:

Walter Bright Wrote:

> which provides two functions:
>
> __v128 simdop(operator, __v128 op1);
> __v128 simdop(operator, __v128 op1, __v128 op2);

You would also need functions that take an immediate too to support instructions such as shufps.

> One caveat is it is typeless; a __v128 could be used as 4 packed ints or 2
> packed doubles. One problem with making it typed is it'll add 10 more types to
> the base compiler, instead of one. Maybe we should just bite the bullet and do
> the types:
>
> __vdouble2
> __vfloat4
> __vlong2
> __vulong2
> __vint4
> __vuint4
> __vshort8
> __vushort8
> __vbyte16
> __vubyte16

I don't see it being typeless as a problem. The purpose of this is to expose hardware capabilities to D code and the vector registers are typeless, so why shouldn't vector type be "typeless" too? Types such as vfloat4 can be implemented in a library (which could also be made portable and have a nice API).

Hooray! I think we're on exactly the same page. That's refreshing :)

I think this __simdop( op, v1, v2, etc ) api is a bit of a bad idea... there are too many permutations of arguments.

I know some PPC functions that receive FIVE arguments (2-3 regs, and 2-3 literals)..

Why not just expose the opcodes as intrinsic functions directly, for instance (maybe in std.simd.sse)?

__v128 __sse_mul_ss( __v128 v1, __v128 v2 );

__v128 __sse_mul_ps( __v128 v1, __v128 v2 );

__v128 __sse_madd_epi16( __v128 v1, __v128 v2, __v128 v3 ); // <- some have more args

__v128 __sse_shuffle_ps( __v128 v1, __v128 v2, immutable int i ); // <- some need literal ints

etc...

This works best for other architectures too I think, they expose their own set of intrinsics, and some have rather different parameter layouts.

VMX for instance (perhaps in std.simd.vmx?):

__v128 __vmx_vmsum4fp( __v128 v1, __v128 v2, __v128 v3 );

__v128 __vmx_vpermwi( __v128 v1, immutable int i ); // <-- needs a literal

__v128 __vmx_vrlimi( __v128 v1, __v128 v2, immutable int mask, immutable int rot ); // <-- you really don't want to add your enum style function for all these prototypes?

etc...

I have seen at least these argument lists:

( v1 )

( v1, v2 )

( v1, v2, v3 )

( v1, immutable int )

( v1, v2, immutable int )

( v1, v2, immutable int, immutable int )