[X86][SSE] LowerUINT_TO_FP_i64 - only use HADDPD for size/fast-hops

We were always generating a single source HADDPD, but really we should only do this if shouldUseHorizontalOp says its a good idea.

Differential Revision: https://reviews.llvm.org/D69175

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375341 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed