Re: recent troubles with float vectors & bitwise ops

[Paolo Bonzini <paolo dot bonzini at lu dot unisi dot ch>]

> # cat regressionorbugfix.cc
> typedef float v4sf_t __attribute__ ((__vector_size__ (16)));
> typedef int v4si_t __attribute__ ((__vector_size__ (16)));
> v4sf_t foo(v4sf_t a, v4sf_t b, v4sf_t c) {
>     return a + (b | c);
> }
> v4sf_t bar(v4sf_t a, v4sf_t b, v4sf_t c) {
>     return a + (v4sf_t) ((v4si_t) b | (v4si_t) c);
> }
> int main() { return 0; }
>
> 0000000000400a30 <foo(float __vector, float __vector, float __vector)>:
>   400a30:       orps   %xmm2,%xmm1
>   400a33:       addps  %xmm1,%xmm0
>   400a36:       retq
>
> 0000000000400a40 <bar(float __vector, float __vector, float __vector)>:
>   400a40:       por    %xmm2,%xmm1
>   400a44:       addps  %xmm1,%xmm0
>   400a47:       retq
>
> I'm surely not qualified to argue about typing, but you'd need a rather 
> strong distortion field to not characterize that as a regression.

I've added 5 minutes ago an XFAILed test for exactly this code.  OTOH, I 
have also committed a fix that will avoid producing tons of shuffle and 
unpacking instructions when function "bar" is compiled with "-msse" but 
without "-msse2".

I'm also going to file a missed optimization bug soon.

I'm curious, does ICC support vector arithmetic like this? Do both 
functions compile? What code does it produce for bar?

Paolo