Refactor to pass the stack index around

scm/inc/compiler.scm

@@ -38,49 +38,50 @@
  (emit "sall $~a,  %eax" boolean-shift) ; construct correctly tagged boolean value
  (emit "xorl $~a, %eax" #b0011111))
(define (emit-expr x)
(define (emit-expr x si)
  (cond
    ((immediate? x)
     (emit "movl $~a, %eax" (immediate-rep x)))
    ((primcall? x)
     (case (primcall-op x)
       ((add1)
        (emit-expr (primcall-operand1 x))
        (emit "addl $~a, %eax" (immediate-rep 1)))
       ((integer->char)
        (emit-expr (primcall-operand1 x))
        (emit "shl $6, %eax")
        (emit "xorl $15, %eax"))
       ((char->integer)
        (emit-expr (primcall-operand1 x))
        (emit "shrl $6, %eax"))
       ((zero?)
        (emit-expr (primcall-operand1 x))
        (emit "cmpl $0,  %eax") ; x == 0
        (emit-compare))
       ((null?)
        (emit-expr (primcall-operand1 x))
        (emit "cmpl $~a, %eax" #b00101111)
        (emit-compare))
       ((integer?)
        (emit-expr (primcall-operand1 x))
        (emit "andl $~a, %eax" #b11)
        (emit-compare))
       ((char?)
        (emit-expr (primcall-operand1 x))
        (emit "andl $~a, %eax" #b11111111)
        (emit "cmpl $~a, %eax" #b00001111)
        (emit-compare))
       ((boolean?)
        (emit-expr (primcall-operand1 x))
        (emit "andl $~a, %eax" #b1111111)
        (emit "cmpl $~a, %eax" #b0011111)
        (emit-compare))
       ))))
    ((primcall? x) (emit-primitive-call x si))))
(define (emit-primitive-call x si)
  (case (primcall-op x)
    ((add1)
     (emit-expr (primcall-operand1 x) si)
     (emit "addl $~a, %eax" (immediate-rep 1)))
    ((integer->char)
     (emit-expr (primcall-operand1 x) si)
     (emit "shl $6, %eax")
     (emit "xorl $15, %eax"))
    ((char->integer)
     (emit-expr (primcall-operand1 x) si)
     (emit "shrl $6, %eax"))
    ((zero?)
     (emit-expr (primcall-operand1 x) si)
     (emit "cmpl $0,  %eax") ; x == 0
     (emit-compare))
    ((null?)
     (emit-expr (primcall-operand1 x) si)
     (emit "cmpl $~a, %eax" #b00101111)
     (emit-compare))
    ((integer?)
     (emit-expr (primcall-operand1 x) si)
     (emit "andl $~a, %eax" #b11)
     (emit-compare))
    ((char?)
     (emit-expr (primcall-operand1 x) si)
     (emit "andl $~a, %eax" #b11111111)
     (emit "cmpl $~a, %eax" #b00001111)
     (emit-compare))
    ((boolean?)
     (emit-expr (primcall-operand1 x) si)
     (emit "andl $~a, %eax" #b1111111)
     (emit "cmpl $~a, %eax" #b0011111)
     (emit-compare))))
(define (compile-program x)
  (display ".globl scheme_entry\n\n")
  (display "scheme_entry:\n")
  (emit-expr x)
  (emit-expr x 0)
  (emit "ret"))