(emit "notq %rax")
(emit "andq $1, %rax"))
+(define (codegen-eq a b si env)
+ (codegen-expr a si env)
+ (emit "movq %rax, ~a(%rsp)" si)
+ (codegen-expr b (- si wordsize) env)
+ (emit "subq ~a(%rsp), %rax" si)
+ (emit "not %rax")
+ (emit "andq $1, %rax"))
+
+(define (codegen-print x si env)
+ (codegen-expr x si env) ; x should be a static-string, producing a label
+
+ ; get the length of the null terminated string
+ (emit "mov %rax, %rdi")
+ (emit "xor %al, %al") ; set %al to 0
+ (emit "mov $-1, %rcx") ; max search length = max int = -1
+ (emit "cld") ; clear direction flag, search up in memory
+ (emit "repne scasb") ; scan string, %rcx = -strlen - 1 - 1
+
+ (emit "not %rcx") ; -%rcx = strlen + 1
+ (emit "dec %rcx")
+
+ (emit "mov %rcx, %rdx") ; number of bytes
+ (emit "mov %rax, %rsi") ; addr of string
+ (emit "mov $1, %rax") ; file handle 1 (stdout)
+ (emit "mov $1, %rdi") ; syscall 1 (write)
+ (emit "syscall"))
+
(define (range s n)
(if (= 0 n) '()
(append (range s (- n 1))
; for now we can only call closures
(define (codegen-call closure args si env)
+ (when (not (eq? (ast-type closure) 'closure))
+ (error #f (format "~a is not a closure" closure)))
(let* ((captured (caddr closure))
(label (cadr closure))
(argument-start (length captured)))
(codegen-expr body (* (- wordsize) (length vars)) env)
)))) ; move args and capture vars to stack
+(define cur-label 0)
+(define (fresh-label)
+ (set! cur-label (+ 1 cur-label))
+ (format "label~a" (- cur-label 1)))
+
+(define (codegen-if cond then else si env)
+ (codegen-expr cond si env)
+ (emit "cmpq $0, %rax")
+ (let ((exit-label (fresh-label))
+ (else-label (fresh-label)))
+ (emit "je ~a" else-label)
+ (codegen-expr then si env)
+ (emit "jmp ~a" exit-label)
+ (emit "~a:" else-label)
+ (codegen-expr else si env)
+ (emit "~a:" exit-label)))
+
(define (codegen-expr e si env)
(case (ast-type e)
('builtin e)
('- (codegen-sub (cadr e) (caddr e) si env))
('* (codegen-mul (cadr e) (caddr e) si env))
('! (codegen-not (cadr e) si env))
+ ('= (codegen-eq (cadr e) (caddr e) si env))
('bool->int (codegen-expr (cadr e) si env))
+ ('print (codegen-print (cadr e) si env))
(else (codegen-call callee (cdr e) si env)))))
('let (codegen-let (let-bindings e)
('var (codegen-var e si env))
- ('string-literal (emit "movq ~a, %rax" label))
+ ('if (codegen-if (cadr e) (caddr e) (cadddr e) si env))
+
('bool-literal (emit "movq $~a, %rax" (if e 1 0)))
('int-literal (emit "movq $~a, %rax" e))
+ ('static-string (emit "movq $~a, %rax" (cadr e))) ; move label
+
(else (error #f "don't know how to codegen this"))))
(define (extract e)
(case (ast-type e)
('lambda (add-lambda e))
- ('let `(let
- ,(map extract (let-bindings e))
+ ('let `(let ,(map extract (let-bindings e))
,@(map extract (let-body e))))
('app (append (list (extract (car e)))
(map extract (cdr e))))
- (else e)))
+ (else (ast-traverse extract e))))
(let ((transformed (extract program)))
(cons lambdas transformed)))
-;(define (extract-strings program))
+(define (extract-strings program)
+ (let ((cur-string 0)
+ (strings '())) ; assoc list of labels -> string
+ (define (fresh-string)
+ (set! cur-string (+ cur-string 1))
+ (format "string~a" (- cur-string 1)))
+ (define (extract e)
+ (case (ast-type e)
+ ('string-literal
+ (let ((label (fresh-string)))
+ (set! strings (cons (cons label e) strings))
+ `(static-string ,label)))
+ (else (ast-traverse extract e))))
+ (let ((transformed (extract program)))
+ (cons strings transformed))))
+
+(define (codegen-string-data s)
+ (emit "~a:" (car s))
+ (emit "\t.string \"~a\"" (cdr s)))
(define (amd64-abi f)
; preserve registers
(else (format "~a(%rsp)" (- n 6)))))
(define (codegen program)
- (let* ((extract-result (extract-lambdas program))
- (lambdas (car extract-result))
- (xform-prog (cdr extract-result)))
- (emit ".text")
- (emit ".p2align 4,,15")
+ (let* ((extract-res-0 (extract-strings program))
+ (strings (car extract-res-0))
+ (extract-res-1 (extract-lambdas (cdr extract-res-0)))
+ (lambdas (car extract-res-1))
+ (xform-prog (cdr extract-res-1)))
+
+ (emit "\t.globl _start")
+ (emit "\t.text")
+; (emit ".p2align 4,,15") is this needed?
(for-each codegen-lambda lambdas)
- (emit ".globl _scheme_entry")
- (emit "_scheme_entry:")
+ (emit "_start:")
+ (codegen-expr xform-prog 0 '())
- (amd64-abi
- (lambda () (codegen-expr xform-prog 0 '())))))
+ ; exit syscall
+ (emit "mov %rax, %rdi")
+ (emit "mov $60, %rax")
+ (emit "syscall")
+
+ (emit "\t.data")
+
+ (for-each codegen-string-data strings)))
(define (compile-to-binary program output)
(when (not (eq? (typecheck program) 'int)) (error #f "not an int"))
(when (file-exists? tmp-path) (delete-file tmp-path))
(with-output-to-file tmp-path
(lambda () (codegen program)))
- (system (format "clang -fomit-frame-pointer /tmp/a.s rts.c -o ~a" output))))
+ (system (format "clang -nostdlib /tmp/a.s -o ~a" output))))