Re: [PATCH] Fix result for conditional reductions matching at index 0

[Kilian Verhetsel <kilian dot verhetsel at uclouvain dot be>]

Jakub Jelinek <jakub@redhat.com> writes:
> Of course it can be done efficiently, what we care most is that the body of
> the vectorized loop is efficient.

That's fair, I was looking at the x86 assembly being generated when a single
vectorized iteration was enough (because that is the context in which I
first encountered this bug):

    int f(unsigned int *x, unsigned int k) {
      unsigned int result = 8;
      for (unsigned int i = 0; i < 8; i++) {
        if (x[i] == k) result = i;
      }
      return result;
    }

where the vpand instruction this generates would have to be replaced
with a variable blend if the default value weren't 0 — although I had
not realized even SSE4.1 on x86 includes such an instruction, making
this point less relevant.

> Thanks, it applies cleanly now
> > +  else if ((STMT_VINFO_VEC_REDUCTION_TYPE (stmt_info) == COND_REDUCTION
> > +	    || (STMT_VINFO_VEC_REDUCTION_TYPE (stmt_info)
> > +		== INTEGER_INDUC_COND_REDUCTION))
> > +	   && reduc_fn == IFN_LAST)»
>
> contains a character at the end of line that makes it not to compile.

My bad, I must have added this when I opened the patch file itself to
inspect it...

> Another thing is, as your patch is quite large, we need a copyright
> assignment for the changes before we can accept it, see
> https://gcc.gnu.org/contribute.html for details.
>
> If you are already covered by an assignment of some company, please tell
> us which one it is, otherwise contact us and we'll get you the needed
> forms.

I am not covered by any copyright assignment yet. Do I need to send you
any additional information?