This is the following patch of D68686. It adds strict node support for instructions fadd/fsub/fmul/fdiv
I don't think it will break X87 types, but it does seems to be weird that legalize X87 strict nodes at the same time before X87 patches.
Adding testcase for scalar_math_patterns and AVX512_scalar_math_fp_patterns.
Moving setOperationAction(ISD::STRICT_FADD/STRICT_FSUB/STRICT_FDIV/STRICT_FMUL, MVT::v2f64, Legal) into SSE2 judgment statement.