[llvm-dev] Working on FP SCEV Analysis

Andrew Trick via llvm-dev llvm-dev at lists.llvm.org
Mon May 16 20:34:03 PDT 2016

> On May 16, 2016, at 6:31 PM, Hal Finkel via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> To be honest, I don't think that loops with a floating-point reduction variable, written as the loop counter, is common or worth much dedicated effort. I have seen this in real code, but it normally comes from people trying (perhaps too hard) to work around integer register pressure problems. The case that Elena presented, however:
> > float fp_inc;
> > 
> > float x = init;
> > for (int i=0;i<N;i++){
> > A[i] = x;
> > x += fp_inc; // Loop invariant variable or constant
> > }
> is not uncommon. Being able to do something intelligent with this is worthwhile.

Yes, we should handle floating-point reductions, not induction variables. Sorry if I misunderstood the intent. I thought that Tyler already solved the problem of vectorizing FP reductions though.

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