[InstCombine] canonicalize fdiv after fmul if reassociation is allowed

  (X / Y) * Z --> (X * Z) / Y

This can allow other optimizations/reassociations as shown in the test diffs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358404 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed