HLSAutoDSL Frontend

[stefanpie]

We want to create a frontend to support the HLS_AUTO pragma parameterization syntax / DSL @ChengyueWang is using. I am informally calling this the "HLS Auto" DSL.

This syntax looks like this:

#pragma HLS_AUTO <directive> <token>*

token ::= fixed_token
        | [prefix]auto{option (, option)*}

option ::= identifier | "NULL"
prefix ::= "" | identifier "="     // e.g. "unit=", "target_ti="

Here are some examples:

Template	Concrete outputs (order preserved)
inline auto{NULL, off}	"" (remove) #pragma HLS inline #pragma HLS inline off
performance target_ti=auto{1,2} unit=auto{NULL,cycle}	"" #pragma HLS performance target_ti=1 #pragma HLS performance target_ti=1 unit=cycle #pragma HLS performance target_ti=2 `#pragma HLS performance target_ti=2 unit=cycle

The goal of this feature is to write a frontend that can auto find these HLS_AUTO pragma in the source code of a design and randomly sample pragma settings to generate a new randomly sampled design. This works like the OptDSL frontends.

This should be almost trivial, assuming a pragma is always on its own line with no comments, or It's never inside a comment. Even so, it seems like regex is the easiest and most valid solution to use for now.