Ahmed Bougacha 9e9bde9b54 [CodeGen] Don't blindly combine (fp_round (fp_round x)) to (fp_round x).
We used to do this DAG combine, but it's not always correct:
If the first fp_round isn't a value preserving truncation, it might
introduce a tie in the second fp_round, that wouldn't occur in the
single-step fp_round we want to fold to.
In other words, double rounding isn't the same as rounding.

Differential Revision: http://reviews.llvm.org/D7571


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228911 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-12 06:15:29 +00:00
..
2015-01-10 23:41:24 +00:00