R600/SI: don't try min3/max3/med3 with f64

There are no opcodes for this. This also adds a test case.

v2: make test more robust

Patch by: Grigori Goronzy

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232386 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed