[PATCH] D28314: Change sqrt partial inlining to depend on sqrt argument rather than result.

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added a subscriber: spatel.
RKSimon added a comment.

As mentioned on PR31455, on X86 btver2, this changes goes from being slower to gcc (88cy vs 84cy) (which hoists the sqrtsd) to actually being slightly faster (82cy). This is for a tight loop of ::sqrt() calls across an array of 65535 pre-randomized doubles (~10% of which use the sqrt call and the rest use sqrtsd). This will be mainly due to reduced speculative usage of the FSQRT unit.


https://reviews.llvm.org/D28314