[Diffusion] rL248439: set div/rem default values to 'expensive' in TargetTransformInfo's cost model

[Sanjay Patel via llvm-commits]

spatel added a comment.

I still think this is a safe change to take on its own. The behavior with this change is restoring what we had before:
http://reviews.llvm.org/rL228826

Ie, we only started speculating expensive ops (fdiv) after that r228826. And that's why we got bug reports about triggering FP exceptions recently.

FWIW, the full solution is still in progress. Recent related commits:
http://reviews.llvm.org/rL252625
http://reviews.llvm.org/rL252639
http://reviews.llvm.org/rL252755

Counting zeros became expensive by default recently, so I'm having to fix those too. A patch to despeculate counting zeros will be posted for review shortly.


Users:
  spatel (Author, Auditor)
  3.7-release (Auditor)
  llvm-commits (Auditor)
  tstellarAMD (Auditor)

http://reviews.llvm.org/rL248439