(define-module (backend tacky traverse)
  #:use-module (backend ast ir)
  #:export (func-ir
            stmt-ir
            ))


(define (func-ir name instrs)
  (list 'srout-ir name instrs))

(define (stmt-ir val)
  (list 'instrs-ir
        (cons 'list (append (cdr val)
                            `((instr-ir ret-ir ,(car val)))))))

(define (expr-ir op . args)
  ;; args is an alist--key: last reg, value: instrs
  (make-instruction (apply append (map cdr args))
                    op (map car args)))

(define (const-ir val)
  (cons (imm-ir val) '()))

(define (make-instruction instrs op srcs)
  (let ((dst (make-temporary)))
    (cons dst
          (append instrs
                  `((instr-ir ,op ,@srcs dst))))))

(define make-temporary
  (let ((count 100))
    (lambda ()
      (set! count (1+ count))
      (list 'tmp-ir count))))