[llvm-dev] [LLVM] (RFC) Addition/Support of new Vectorization Pragmas in LLVM

[Doerfert, Johannes via llvm-dev]

Hi Terry,

I'm curious.

>    * Primarily ivdep allows ambiguous dependencies to be ignored, examples:
>        *  p[i] = q[j]
>        *  a[ix[i]] = b[iy[i]]
>        *  a[ix[i]] += 1.0
> 
>    * ivdep still requires automatic detection of reductions, including
>      multiple homogeneous reductions on a single variable, examples:
>        *  x = x + a[i]
>        *  x = x + a[i]; if ( c[i] > 0.0 ) { x = x + b[i] }

How do you define the difference between
  a[ix[i]] += 1.0
and
  x += 1.0
as you require reduction detection for the latter but seem to ignore the
(histogram) reduction dependences for the former.

Thanks,
  Johannes
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