Constants tracking issue

[VonTum]

Constants are SUS's way of building compile-time functions.

// Basic builtin constants
__builtin__ const bool false {}
__builtin__ const bool true {}
const int HUNDRED_PI {HUNDRED_PI = 314}

// But also, compiletime functions, and builtins like
__builtin__ const int sizeof #(T) {}
const int factorial #(int num) {
  factorial = 1
  for i in 1..num {
    factorial = factorial * i
  }
}

Basic:

• Parser
• Initialization
• Flattened
• Typecheck
• Get constant value in execute
• Built-in Constants taking parameters (int sizeof #(T), int clog2 #(int V))

Custom compile-time functions

• Updating flattening such that the instructions within const are all generative
• Updating abstract typecheck to pass over const (not a big deal, since everything's shared in LinkInfo)
• Updating Execute, such that it can call other execute instances recursively to evaluate constants
• Updating tree-walk to show the content of const (and maybe struct too, if we're editing that anyhow, most code would be shared)

[VonTum]

Add Verilog's $clog2