SSE asm with functions

[Timon Gehr]

Byron wrote:
> In the attached file xmm.d I have a function xnormal that takes a vector ( alias
float[4] )  an computes the
> unit vector.  The SSE code seems to work fine, but it keeps returning [nan, nan,
nan, nan ] and the
> writeln prints the same. But if I change the return from r ( output vector ) to
v ( input vector ) it prints
> the correct normal vector, and returns the input vector.  Is this my bug or a
compiler bug?
> DMD32 v2.053  OS X
>
> const(vector) xnormal( ref const(vector) v )
> {
>     vector r;
>     asm
>     {
>         mov EAX, v;
>         movups XMM0, [EAX]; //load vector
>         movaps XMM2, XMM0; // copy original data
>
>         // find x^2 + y^2 + z^2 + w^2
>         mulps XMM0, XMM0; // xx, yy, zz, ww
>         movaps XMM1, XMM0; // copy, cause we will write into X0
>         shufps XMM0, XMM1, 0x4e; // 0100 1110 zwxy
>         addps XMM0, XMM1; // xyzw + zwxy
>
>         movaps XMM1, XMM0; // copy, cause we will write into X0
>         shufps XMM0, XMM1, 0x11; // 0001 0001 (y+w)(x+z)(y+w)(x+z)
>         addps XMM0, XMM1; // (x+z)(y+w)(z+x)(w+y) + (y+w)(x+z)(y+w)(x+z)
>                           // (x+z+y+w)(y+w+x+z)(z+x+y+w)(w+y+x+z)
>
>         rsqrtps XMM0, XMM0; // 1/sqrt(XMM0)
>         mulps XMM2, XMM0; // x/sqrt(x^2+y^2+z^2+w^2) , ...
>         movups r, XMM2;
>     }
>     writeln( "Result: ", r, "\t", v );
>     return r;
> }
>
> I would like to use D for a thesis projects, but wont be able to if its still
this buggy.
>
> -Byron
> << xmm.d >>

It seems it is a backend bug in DMD as the same code works just fine with GDC.
(frontend version 2.052 though, this might need some further investigation).

Timon