[x86] add tests for phaddd/phaddw; NFC
[x86] add tests for phaddd/phaddw; NFC

More tests related to PR39195:
https://bugs.llvm.org/show_bug.cgi?id=39195

If we limit the horizontal codegen, it may require different
constraints for FP and integer.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@343994 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm