This patch removes patterns for a few operations which allows mathToLLVM
conversion to convert the operations into LLVM intrinsics instead since
they are supported directly by the AMDGPU backend.
Support fastMath and other non-supported mathOp which only require float
operands and call libdevice function directly to nvvm.
1. lowering mathOp with fastMath attribute to correct libdevice
intrinsic.
2. some mathOp in math dialect has been lowered to libdevice now, but it
doesn't cover all mathOp. so this mr lowers all the remaining mathOp
which only require float operands.
This patch refactors the conversion of math operations to ROCDL library
calls. This pass will also be used in flang to lower Fortran
intrinsics/math functions for OpenMP target offloading codgen.
