Add DSL methods for representing operand decorators

[postmodern]

Some assembly instructions permit decorations on certain operands.

Examples

Write mask of k1 onto the memory operand [rax] which results in operand type (ex: m64{k}).

vmovss [rax]{k1}, xmm0

Write mask of k1 with z mode enabled on the destination register zmm0 resulting in an operand type zmm{k}{z}.

vpsubb zmm0{k1}{z}, zmm0, zmm1

Broadcast decorator on one of the source 64bit memory operands resulting into the operand type m256/m64bcst; the instruction operates on packed double-word integers (32bit), the memory operand is 64bit and the source operands are 256bit, so 256 / 64 == {1to8} == m256/m64bcst.

vpaddd ymm0, ymm0, [rdi] {1to8}

[postmodern]

Some ideas of how the Ruby syntax might look like:

Faux Array access methods:

vpsubb zmm0[k1][z], zmm0, zmm1

Downside: we will have to define a z method to represent the zero-mode flag.

Yielding blocks

vpsubb zmm0 { k1 }, zmm0, zmm1

Upside: easy to implement!
Downside: cannot chain together { } methods (ex: zmm0{k1}{z}). No possible way to use this technique on memory operands that are defined as Arrays (ex: [rdi]).

Operand Methods

vpsubb zmm0.k1.z, zmm0, zmm1

Downside: readability is not great and have to define k0 - k5 methods.

Override The Register Methods

vpsubb zmm0(k1, z), zmm0, zmm1

Downside: still requires defining a z method.

Override The Register Methods With Keyword Arguments

vpsubb zmm0(k: k1, z: true), zmm0, zmm1

Downside: k: k1 seems a bit redundant and z: true feels too explicit?