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(use-modules (ice-9 format)
(ice-9 popen)
(ice-9 rdelim)
(srfi srfi-1))
;; Assuming a 64 bit intel machine here.
(define wordsize 8)
(define fixnum-mask 3)
(define fixnum-shift 2)
(define fixnum-tag 0)
(define char-mask 255)
(define char-shift 8)
(define char-tag 15)
(define boolean-mask 127)
(define boolean-shift 7)
(define boolean-tag 31)
(define empty-list 47) ;; #b00101111
(define (emit template-string . args)
(apply format #t template-string args)
(newline))
(define (immediate-rep x)
(cond
((integer? x)
(ash x fixnum-shift))
((char? x)
(logior (ash (char->integer x) char-shift) char-tag))
((boolean? x)
(logior (ash (if x 1 0) boolean-shift) boolean-tag))
((null? x)
empty-list)))
(define (immediate? x)
(or (integer? x)
(char? x)
(boolean? x)
(null? x)))
(define (primcall? x)
(and (pair? x)
(memq (first x)
'(add1
sub1
integer->char
char->integer
zero?
null?
integer?
char?
boolean?
+ - *
= < <= > >=
eq? char=?))))
(define (primcall-op x)
(first x))
(define (primcall-operand1 x)
(second x))
(define (primcall-operand2 x)
(third x))
(define (emit-tag-check x mask tag si)
(emit-expr x si)
(emit "andl $~a, %eax" mask)
(emit "cmpl $~a, %eax" tag)
(emit "movl $0, %eax")
(emit "sete %al")
(emit "sall $~a, %eax" boolean-shift)
(emit "orl $~a, %eax" boolean-tag))
(define (emit-comparison x y instruction si)
(emit-expr y si)
(emit "movl %eax, ~a(%rsp)" si)
(emit-expr x (- si wordsize))
(emit "cmpl ~a(%rsp), %eax" si)
(emit "movl $0, %eax")
(emit "~a %al" instruction)
(emit "sall $~a, %eax" boolean-shift)
(emit "orl $~a, %eax" boolean-tag))
(define (emit-primitive-call x si)
(case (primcall-op x)
((add1)
(emit-expr (primcall-operand1 x) si)
(emit "addl $~a, %eax" (immediate-rep 1)))
((sub1)
(emit-expr (primcall-operand1 x) si)
(emit "subl $~a, %eax" (immediate-rep 1)))
((integer->char)
(emit-expr (primcall-operand1 x) si)
(emit "sall $~a, %eax" (- char-shift fixnum-shift))
(emit "orl $~a, %eax" char-tag))
((char->integer)
(emit-expr (primcall-operand1 x) si)
(emit "shr $~a, %eax" (- char-shift fixnum-shift)))
((zero?)
(emit-expr (primcall-operand1 x) si)
;; Since the tag of fixnums is 0, we can skip an 'andl'
;; instruction that would apply the mask to the immediate
;; value.
(emit "cmpl $0, %eax")
(emit "movl $0, %eax")
(emit "sete %al")
(emit "sall $~a, %eax" boolean-shift)
(emit "orl $~a, %eax" boolean-tag))
((null?)
(emit-expr (primcall-operand1 x) si)
(emit "cmpl $~a, %eax" empty-list)
(emit "movl $0, %eax")
(emit "sete %al")
(emit "sall $~a, %eax" boolean-shift)
(emit "orl $~a, %eax" boolean-tag))
((integer?)
(emit-tag-check (primcall-operand1 x) fixnum-mask fixnum-tag si))
((char?)
(emit-tag-check (primcall-operand1 x) char-mask char-tag si))
((boolean?)
(emit-tag-check (primcall-operand1 x) boolean-mask boolean-tag si))
((+)
(emit-expr (primcall-operand2 x) si)
(emit "movl %eax, ~a(%rsp)" si)
(emit-expr (primcall-operand1 x) (- si wordsize))
(emit "addl ~a(%rsp), %eax" si))
((-)
(emit-expr (primcall-operand2 x) si)
(emit "movl %eax, ~a(%rsp)" si)
(emit-expr (primcall-operand1 x) (- si wordsize))
(emit "subl ~a(%rsp), %eax" si))
((*)
(emit-expr (primcall-operand2 x) si)
(emit "movl %eax, ~a(%rsp)" si)
(emit-expr (primcall-operand1 x) (- si wordsize))
(emit "imull ~a(%rsp), %eax" si)
;; When two fixnums (which have 2 tag bits) are multiplied, the
;; relevant bits for the result are now 4 bytes to the left, so
;; we have to shift back 2 bytes.
(emit "shr $~a, %eax" fixnum-shift))
((=)
(emit-comparison (primcall-operand1 x) (primcall-operand2 x) "sete" si))
((<)
(emit-comparison (primcall-operand1 x) (primcall-operand2 x) "setl" si))
((<=)
(emit-comparison (primcall-operand1 x) (primcall-operand2 x) "setle" si))
((>)
(emit-comparison (primcall-operand1 x) (primcall-operand2 x) "setg" si))
((>=)
(emit-comparison (primcall-operand1 x) (primcall-operand2 x) "setge" si))
((eq?)
(emit-comparison (primcall-operand1 x) (primcall-operand2 x) "sete" si))
((char=?)
(emit-comparison (primcall-operand1 x) (primcall-operand2 x) "sete" si))
(else
(error "unknown primcall op" (primcall-op x)))))
(define (emit-expr x si)
(cond
((immediate? x)
(emit "movl $~a, %eax" (immediate-rep x)))
((primcall? x)
(emit-primitive-call x si))
(else
(error "unknown expression" x))))
(define (compile-program x)
(emit-expr x (- wordsize))
(emit "ret"))
(define (compile-and-run x)
(with-output-to-file "scheme_entry.S"
(lambda ()
(display ".text
.p2align 4
.globl scheme_entry
.type scheme_entry, @function
scheme_entry:
")
(compile-program x)))
(and (zero? (system* "gcc" "-c" "scheme_entry.S"))
(zero? (system* "gcc" "-c" "test.c"))
(zero? (system* "gcc" "-o" "test" "scheme_entry.o" "test.o"))
(let* ((pipe (open-pipe* OPEN_READ "./test"))
(output (read-line pipe)))
(close pipe)
output)))
(define (test-case x expected-output)
(let ((result (compile-and-run x)))
(if (string=? result expected-output)
#t
(begin
(display "expected: ")
(display expected-output)
(display ", got: ")
(display result)
(newline)
#f))))
(begin
(test-case 1 "1")
(test-case #\b "b")
(test-case #t "#t")
(test-case #f "#f")
(test-case '(add1 3) "4")
(test-case '(sub1 3) "2")
(test-case '(integer->char 98) "b")
(test-case '(char->integer #\b) "98")
(test-case '(zero? 1) "#f")
(test-case '(zero? 0) "#t")
(test-case '(null? 1) "#f")
(test-case '(null? #\b) "#f")
(test-case '(null? #t) "#f")
(test-case '(null? #f) "#f")
(test-case '(null? ()) "#t")
(test-case '(integer? #\b) "#f")
(test-case '(integer? #f) "#f")
(test-case '(integer? 1) "#t")
(test-case '(char? 1) "#f")
(test-case '(char? #f) "#f")
(test-case '(char? #\b) "#t")
(test-case '(boolean? 1) "#f")
(test-case '(boolean? #\b) "#f")
(test-case '(boolean? #f) "#t")
(test-case '(boolean? #t) "#t")
(test-case '(+ 1 2) "3")
(test-case '(- 3 1) "2")
(test-case '(* 2 3) "6")
(test-case '(= 1 2) "#f")
(test-case '(= 1 1) "#t")
(test-case '(< 2 1) "#f")
(test-case '(< 1 2) "#t")
(test-case '(<= 2 1) "#f")
(test-case '(<= 1 2) "#t")
(test-case '(<= 2 2) "#t")
(test-case '(> 1 2) "#f")
(test-case '(> 2 1) "#t")
(test-case '(>= 1 2) "#f")
(test-case '(>= 2 1) "#t")
(test-case '(>= 2 2) "#t")
(test-case '(char=? #\a #\b) "#f")
(test-case '(char=? #\b #\b) "#t"))
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