[Mingw-users] Inline ASM "x" constraint question

[Rodrigo H. <kw...@ae...>]

Hi,
I am having trouble getting my inline asm SSE code right (everything
seems in order, but runtime
results are skewed), so I took a look at the GCC manual here:

http://gcc.gnu.org/onlinedocs/gcc-3.4.4/gcc/Machine-Constraints.html#Machine-Constraints

seems like I should be able to use the "x" constraint to specify a xmm
register and turn this:
asm
(
       "movups %0,%%xmm0\n\t"
       "movups %1,%%xmm1\n\t"
       "addps %%xmm1,%%xmm0\n\t"
         "movups %%xmm0,%2\n\t"
         :
         : "m" (var1[0]), "m" (var2[0]),"m"(result[0])
         : "%xmm0", "%xmm1"
);

into this:

asm
(
         "addps %2,%1\n\t"
         "movups %1,%0\n\t"
         : "=x"(result[0])
         : "x" (var1[0]), "x" (var2[0])
);

but I get an "impossible constraint in `asm'" error, now the variables
here are 16 bit aligned float[4] arrays, my guess is that "x" is
expecting a 128 bit type, I dont know what this type is.

I looked for examples and found none, perhaps the constraint is too new,
so does anyone actually know how to use it?

Thanks.