(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))
(inner-si (- si (* (length bindings) wordsize)))
(names (map car bindings))
(exprs (map cadr bindings))
- (inner-env (append (map cons names stack-offsets) env)))
- (for-each (lambda (expr offset)
+
+ ; recursive let bindings: build environment as we go
+ (inner-env (fold-left
+ (lambda (env name expr offset)
(codegen-expr expr inner-si env)
- (emit "movq %rax, ~a(%rsp)" offset))
- exprs stack-offsets)
- (for-each (lambda (form) (codegen-expr form inner-si inner-env)) body)))
+ (emit "movq %rax, ~a(%rsp)" offset)
+ (cons (cons name offset) env))
+ env names exprs stack-offsets)))
+ (for-each (lambda (form)
+ (codegen-expr form inner-si inner-env))
+ body)))
(define (codegen-var name si env)
+ (when (not (assoc name env))
+ (error #f (format "Variable ~a is not bound" name)))
(let ((offset (cdr (assoc name env))))
(emit "movq ~a(%rsp), %rax" offset)))
; 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 (codegen-expr e si env)
- (cond ((builtin? e) e)
- ((closure? e) e)
+(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)))
- ((app? e)
+(define (codegen-expr e si env)
+ (case (ast-type e)
+ ('builtin e)
+ ('closure e)
+ ('app
(let ((callee (codegen-expr (car e) si env)))
(case callee
('+ (codegen-add (cdr e) si env))
('- (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? e) (codegen-let
- (let-bindings e)
+ ('let (codegen-let (let-bindings e)
(let-body e)
si
env))
- ((var? e) (codegen-var e si env))
- ((boolean? e) (emit "movq $~a, %rax" (if e 1 0)))
- (else (emit "movq $~a, %rax" e))))
+
+ ('var (codegen-var e si env))
+
+ ('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 (fold-map f x) (fold-left append '() (map f x)))
(define (free-vars prog)
(define bound '())
(define (collect e)
- (cond
- ((builtin? e) '()) ; do nothing
- ((var? e) (if (memq e bound) '() (list e)))
- ((lambda? e)
+ (case (ast-type e)
+ ('builtin '()) ; do nothing
+ ('var (if (memq e bound) '() (list e)))
+ ('lambda
(set! bound (append (lambda-args e) bound))
(collect (lambda-body e)))
- ((app? e) (fold-map collect e))
- ((let? e)
+ ('app (fold-map collect e))
+ ('let
(let ((bind-fvs (fold-map (lambda (a)
((set! bound (cons (car a) bound))
(collect (cdr a))))
(else '())))
(collect prog))
-(define (closure? e)
- (and (list? e) (eqv? (car e) 'closure)))
-
; ((lambda (x) (+ x 1)) 42) => {lambda0: (x) (+ x 1)}, (@lambda0 42)
(define (extract-lambdas program)
(define lambdas '())
(set! lambdas (cons new-lambda lambdas))
`(closure ,label ,captured))) ; todo: should we string->symbol?
(define (extract e)
- (cond
- ((lambda? e) (add-lambda e))
- ((let? e) `(let
- ,(map extract (let-bindings e))
+ (case (ast-type e)
+ ('lambda (add-lambda e))
+ ('let `(let ,(map extract (let-bindings e))
,@(map extract (let-body e))))
- ((app? e) (append (list (extract (car 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)
+ (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
(emit "push %rbp")
(else (error #f "need to test out the below"))
(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)
+(define (compile-to-binary program output)
(when (not (eq? (typecheck program) 'int)) (error #f "not an int"))
(let ([tmp-path "/tmp/a.s"])
(when (file-exists? tmp-path) (delete-file tmp-path))
(with-output-to-file tmp-path
(lambda () (codegen program)))
- (system "clang -fomit-frame-pointer /tmp/a.s rts.c")))
+ (system (format "clang -nostdlib /tmp/a.s -o ~a" output))))
projects / scheme.git / blobdiff