src/wam/constants.lisp @ ce87039ad178
Make L2 work properly This changes a lot of things. First, we split apart all the register-using opcodes into local and stack variants, and tear out the register designator stuff. This is ugly, but will be way faster because the check doesn't need to happen at runtime any more. It's made slightly less ugly with a real nasty macro. We also change how the head and first body term in clauses interact. It turns out the head needs to respect the arity of the first body clause (if it's larger), and the two clauses need to share local variable register assignments. Apparently when HAK says "compiled as one unit" in the book he means this. Would have been nice if he could have explained that, or at least showed an example that makes use of it so I have a chance of noticing it. Still to do before we move on to L3: * Add a few comments to document the stuff added in this commit. * Rework the query code store to fall at the beginning of the `CODE` section so we can just have one program counter and interpreter function to rule them all. * Consider figuring out the answer extraction process (we basically need to modify the query compiler to treat all variables as permanent, and keep that mapping so we can extract them from the stack at the very end).
| author | Steve Losh <steve@stevelosh.com> |
|---|---|
| date | Sun, 17 Apr 2016 21:36:15 +0000 |
| parents | 2f0b5c92febe |
| children | 902d171a1a85 |
(in-package #:bones.wam) (define-constant +cell-width+ 16 :documentation "Number of bits in each heap cell.") (define-constant +cell-tag-width+ 2 :documentation "Number of bits reserved for cell type tags.") (define-constant +cell-value-width+ (- +cell-width+ +cell-tag-width+) :documentation "Number of bits reserved for cell values.") (define-constant +cell-tag-bitmask+ #b11 :documentation "Bitmask for masking the cell type tags.") (define-constant +heap-limit+ (expt 2 +cell-value-width+) ;; We can only address 2^value-bits cells. :documentation "Maximum size of the WAM heap.") (define-constant +code-word-size+ 16 :documentation "Size (in bits) of each word in the code store.") (define-constant +code-limit+ (expt 2 +code-word-size+) :documentation "Maximum size of the WAM code store.") (define-constant +code-sentinal+ (1- +code-limit+) :documentation "Sentinal value used in the PC and CP.") (define-constant +tag-null+ #b00 :documentation "An empty cell.") (define-constant +tag-structure+ #b01 :documentation "A structure cell.") (define-constant +tag-reference+ #b10 :documentation "A pointer to a cell.") (define-constant +tag-functor+ #b11 :documentation "A functor.") (define-constant +functor-arity-width+ 4 :documentation "Number of bits dedicated to functor arity.") (define-constant +functor-arity-bitmask+ #b1111 :documentation "Bitmask for the functor arity bits.") (define-constant +register-count+ 16 :documentation "The number of registers the WAM has available.") (define-constant +maximum-arity+ (1- (expt 2 +functor-arity-width+)) :documentation "The maximum allowed arity of functors.") (define-constant +maximum-query-size+ 256 :documentation "The maximum size (in bytes of bytecode) a query may compile to.") (define-constant +tag-local-register+ #b0 :documentation "A local register (X_n or A_n).") (define-constant +tag-stack-register+ #b1 :documentation "A stack register (Y_n).") (define-constant +stack-word-size+ 16 :documentation "Size (in bits) of each word in WAM stack.") (define-constant +stack-limit+ (expt 2 +stack-word-size+) ;; We can only address 2^value-bits cells, and since stack address are ;; themselves stored on the stack (the environment continuation pointer) they ;; can only reference so much memory. ;; ;; todo: we might want to limit this further to prevent the stack from growing ;; too large. :documentation "Maximum size of the WAM stack.") (define-constant +stack-frame-size-limit+ (+ 3 +register-count+) :documentation "The maximum size, in stack frame words, that a stack frame could be.") ;;;; Opcodes ;;; Program (define-constant +opcode-get-structure-local+ 0) (define-constant +opcode-get-structure-stack+ 1) (define-constant +opcode-unify-variable-local+ 2) (define-constant +opcode-unify-variable-stack+ 3) (define-constant +opcode-unify-value-local+ 4) (define-constant +opcode-unify-value-stack+ 5) (define-constant +opcode-get-variable-local+ 6) (define-constant +opcode-get-variable-stack+ 7) (define-constant +opcode-get-value-local+ 8) (define-constant +opcode-get-value-stack+ 9) ;;; Query (define-constant +opcode-put-structure-local+ 10) (define-constant +opcode-put-structure-stack+ 11) (define-constant +opcode-set-variable-local+ 12) (define-constant +opcode-set-variable-stack+ 13) (define-constant +opcode-set-value-local+ 14) (define-constant +opcode-set-value-stack+ 15) (define-constant +opcode-put-variable-local+ 16) (define-constant +opcode-put-variable-stack+ 17) (define-constant +opcode-put-value-local+ 18) (define-constant +opcode-put-value-stack+ 19) ;;; Control (define-constant +opcode-call+ 20) (define-constant +opcode-proceed+ 21) (define-constant +opcode-allocate+ 22) (define-constant +opcode-deallocate+ 23) ;;;; Debug Config (defparameter *off-by-one* nil)