4 (define target 'darwin)
11 (define (codegen-add xs si env)
14 (emit "movq ~a(%rbp), %rax" si)
18 (emit "addq $~a, ~a(%rbp)" y si)
20 (codegen-expr y (- si wordsize) env)
21 (emit "addq %rax, ~a(%rbp)" si))))
24 ; use si(%rbp) as the accumulator
25 (emit "movq $0, ~a(%rbp)" si)
28 (define (codegen-binop opcode)
30 (codegen-expr b si env)
31 (emit "movq %rax, ~a(%rbp)" si)
32 (codegen-expr a (- si wordsize) env)
33 (emit "~a ~a(%rbp), %rax" opcode si)))
35 (define codegen-sub (codegen-binop "sub"))
37 (define codegen-mul (codegen-binop "imul"))
39 (define (codegen-not x si env)
40 (codegen-expr x si env)
42 (emit "andq $1, %rax"))
44 (define (codegen-eq a b si env)
45 (codegen-expr a si env)
46 (emit "movq %rax, ~a(%rbp)" si)
47 (codegen-expr b (- si wordsize) env)
48 (emit "subq ~a(%rbp), %rax" si)
50 (emit "andq $1, %rax"))
52 ; 'write file handle addr-string num-bytes
54 (define (codegen-print x si env)
55 (codegen-expr x si env) ; x should be a static-string, producing a label
57 ; make a copy of string address since %rax and %rdi are clobbered
58 (emit "mov %rax, %rbx")
60 ; get the length of the null terminated string
61 (emit "mov %rax, %rdi")
62 (emit "xor %al, %al") ; set %al to 0
63 (emit "mov $-1, %rcx") ; max search length = max int = -1
64 (emit "cld") ; clear direction flag, search up in memory
65 (emit "repne scasb") ; scan string, %rcx = -strlen - 1 - 1
67 (emit "not %rcx") ; -%rcx = strlen + 1
72 (emit "movq %rbx, %rsi") ; string addr
73 (emit "movq %rcx, %rdx") ; num bytes
74 (emit "movq $1, %rdi") ; file handle (stdout)
75 (emit "movq $0x2000004, %rax")) ; syscall 4 (write)
77 (emit "mov %rbx, %rsi") ; string addr
78 (emit "mov %rcx, %rdx") ; num bytes
79 (emit "mov $1, %rax") ; file handle (stdout)
80 (emit "mov $1, %rdi"))) ; syscall 1 (write)
85 (append (range s (- n 1))
86 (list (+ s (- n 1))))))
90 (define (codegen-let bindings body si env)
91 (let* ((stack-offsets (map (lambda (x) (- si (* x wordsize)))
92 (range 0 (length bindings))))
93 (inner-si (- si (* (length bindings) wordsize)))
94 (names (map car bindings))
95 (exprs (map cadr bindings))
97 ; recursive let bindings: build environment as we go
99 (lambda (env name expr offset)
100 (codegen-expr expr inner-si env)
101 (emit "movq %rax, ~a(%rbp)" offset)
102 (cons (cons name offset) env))
103 env names exprs stack-offsets)))
104 (for-each (lambda (form)
105 (codegen-expr form inner-si inner-env))
108 (define (codegen-var name si env)
109 (when (not (assoc name env))
110 (error #f (format "Variable ~a is not bound" name)))
111 (let ((offset (cdr (assoc name env))))
112 (emit "movq ~a(%rbp), %rax" offset)))
114 (define cur-lambda 0)
115 (define (fresh-lambda)
116 (set! cur-lambda (+ 1 cur-lambda))
117 (format "_lambda~a" (- cur-lambda 1)))
119 ; a closure on the heap looks like:
121 ; addr var1.... var2.... var3....
123 (define (codegen-closure label captured si env)
124 (let* ((heap-offsets (map (lambda (i) (+ 8 (* 8 i)))
125 (range 0 (length captured))))) ; 4, 12, 20, etc.
127 (emit "movq heap_start@GOTPCREL(%rip), %rbx")
129 (emit "movq (%rbx), %rax") ; %rax = heap addr of closure
132 ; point heap_start to next space
133 (emit "addq $~a, (%rbx)" (+ 8 (* 8 (length captured))))
135 ; store the address to the lambda code
136 (emit "movq ~a@GOTPCREL(%rip), %rbx" label)
137 (emit "movq %rbx, 0(%rax)")
139 ; store the captured vars
141 (lambda (var-name new-offset)
142 (emit "movq ~a(%rbp), ~a(rax)"
143 (cdr (assoc var-name env))
148 ; for now we can only call closures
149 (define (codegen-call f args si env)
150 (codegen-expr f si env)
152 (emit "## starting call")
154 (emit "movq %rax, ~a(%rbp)" si) ; store address of closure first on stack
156 ; codegen the arguments, store them intermediately
160 (emit "## arg no. ~a" (- i 1))
161 (codegen-expr e (- si (* wordsize i)) env)
162 ; store intermediate result on stack
163 (emit "movq %rax, ~a(%rbp)" (- si (* wordsize i)))))
165 args (range 1 (length args)))
167 ; now that we have everything we need on the stack,
168 ; move them into the param registers
170 (emit "## moving args into place")
172 (lambda (i) (emit "movq ~a(%rbp), ~a"
173 (- si (* wordsize i))
175 (range 1 (length args)))
177 ; todo: can this be made more efficient
178 (emit "movq ~a(%rbp), %rax" si) ; load back pointer to closure
180 (emit "## moving captives into place")
182 ; move captives into first argument
183 (emit "movq %rax, %rbx")
184 (emit "addq $8, %rbx")
185 (emit "movq %rbx, ~a" (param-register 0))
187 (emit "## performing call")
189 (emit "addq $~a, %rsp" si) ; adjust the stack pointer to account all the stuff we put in the env
190 (emit "callq *(%rax)") ; call closure function
191 (emit "subq $~a, %rsp" si))
194 ; 1st param: pointer to captured args
196 ; 3rd param: 2nd arg, etc.
198 (define (codegen-lambda l)
199 (let* ((label (car l))
201 (captured (car stuff))
204 ; params = what actually gets passed
205 (params (append captured args))
207 (stack-offsets (map (lambda (i)
209 (range 1 (length params))))
211 (env (map cons params stack-offsets)))
214 (display "## lambda captives: ")
217 (display "## lambda args: ")
220 (display "## lambda body: ")
224 (emit "push %rbp") ; preserve caller's base pointer
225 (emit "movq %rsp, %rbp") ; set up our own base pointer
227 ; load the captured vars onto the stack
230 (emit "movq ~a(~a), ~a(%rbp)"
231 i (param-register 0) (* (- wordsize) i)))
232 (range 0 (length captured)))
234 ; load the args onto the stack
237 (emit "movq ~a, ~a(%rbp)"
238 (param-register i) (* (- wordsize) i)))
239 (range 1 (length args)))
241 (codegen-expr body (* (- wordsize) (+ 1 (length params))) env)
243 (emit "pop %rbp") ; restore caller's base pointer
246 (define (codegen-string label)
248 ('darwin (emit "movq ~a@GOTPCREL(%rip), %rax" label))
249 ('linux (emit "lea $~a, %rax" label))))
252 (define (fresh-label)
253 (set! cur-label (+ 1 cur-label))
254 (format "label~a" (- cur-label 1)))
256 (define (codegen-if cond then else si env)
257 (codegen-expr cond si env)
258 (emit "cmpq $0, %rax")
259 (let ((exit-label (fresh-label))
260 (else-label (fresh-label)))
261 (emit "je ~a" else-label)
262 (codegen-expr then si env)
263 (emit "jmp ~a" exit-label)
264 (emit "~a:" else-label)
265 (codegen-expr else si env)
266 (emit "~a:" exit-label)))
268 (define (codegen-expr e si env)
270 ('closure (codegen-closure (cadr e) (caddr e) si env))
273 ('+ (codegen-add (cdr e) si env))
274 ('- (codegen-sub (cadr e) (caddr e) si env))
275 ('* (codegen-mul (cadr e) (caddr e) si env))
276 ('! (codegen-not (cadr e) si env))
277 ('= (codegen-eq (cadr e) (caddr e) si env))
278 ('bool->int (codegen-expr (cadr e) si env))
279 ('print (codegen-print (cadr e) si env))
280 (else (codegen-call (car e) (cdr e) si env))))
282 ; this is a builtin being passed around as a variable
283 ('builtin (emit "movq $~a, %rax" (builtin-id e)))
285 ('let (codegen-let (let-bindings e)
290 ('var (codegen-var e si env))
292 ('if (codegen-if (cadr e) (caddr e) (cadddr e) si env))
294 ('bool-literal (emit "movq $~a, %rax" (if e 1 0)))
295 ('int-literal (emit "movq $~a, %rax" e))
297 ('static-string (codegen-string (cadr e)))
299 (else (error #f "don't know how to codegen this"))))
302 (define (fold-map f x) (fold-left append '() (map f x)))
304 (define (free-vars prog)
308 ('builtin '()) ; do nothing
309 ('var (if (memq e bound) '() (list e)))
311 (set! bound (append (lambda-args e) bound))
312 (collect (lambda-body e)))
314 ('app (fold-map collect e))
316 (let ((bind-fvs (fold-map (lambda (a)
317 ((set! bound (cons (car a) bound))
319 (let-bindings cadr)))
320 (body-fvs (fold-map collect (let-body e))))
321 (append bind-fvs body-fvs)))
325 ; ((lambda (x) (+ x y)) 42) => ((closure lambda1 (y)) 42)
326 ; [(lambda1 . ((y), (x), (+ x y))]
327 ; for builtins, this generates a closure if it is used
328 ; outside of an immediate app
329 ; but only one closure for each builtin
331 (define (extract-lambdas program)
333 (define (add-lambda e)
334 (let* ((label (fresh-lambda))
335 (args (lambda-args e))
336 (captured (free-vars e))
337 (body (extract (lambda-body e)))
338 (new-lambda (cons label (list captured args body))))
339 (set! lambdas (cons new-lambda lambdas))
340 `(closure ,label ,captured))) ; todo: should we string->symbol?
342 (define (find-builtin-lambda e)
343 (let [(l (assq (builtin-name e) lambdas))]
344 (if l `(closure ,(car l) ,(caadr l)) #f)))
346 (define (builtin-name e)
351 ('bool->int "_bool2int")
352 (else (error #f "fill this out"))))
353 (define (builtin-args e)
359 (else (error #f "fill this out"))))
361 (define (add-builtin-lambda e)
362 (let* [(label (builtin-name e))
364 (args (builtin-args e))
366 (new-lambda (cons label (list captured args body)))]
367 (set! lambdas (cons new-lambda lambdas))
368 `(closure ,label ,captured)))
372 ('lambda (add-lambda e))
373 ('let `(let ,(map extract (let-bindings e))
374 ,@(map extract (let-body e))))
376 ; if a builtin is used as a function, don't generate lambda
377 (if (eqv? 'builtin (ast-type (car e)))
379 (list (extract (car e))))
380 (map extract (cdr e))))
383 (if (find-builtin-lambda e)
384 (find-builtin-lambda e)
385 (add-builtin-lambda e)))
388 (else (ast-traverse extract e))))
389 (let ((transformed (extract program)))
390 (cons lambdas transformed)))
392 (define (extract-strings program)
394 (strings '())) ; assoc list of labels -> string
395 (define (fresh-string)
396 (set! cur-string (+ cur-string 1))
397 (format "string~a" (- cur-string 1)))
401 (let ((label (fresh-string)))
402 (set! strings (cons (cons label e) strings))
403 `(static-string ,label)))
404 (else (ast-traverse extract e))))
405 (let ((transformed (extract program)))
406 (cons strings transformed))))
408 (define (emit-string-data s)
410 (emit "\t.string \"~a\"" (cdr s)))
412 ;; (define (amd64-abi f)
413 ;; ; preserve registers
414 ;; (emit "push %rbp")
415 ;; ;; (emit "push %rbx")
416 ;; ;; (for-each (lambda (i)
417 ;; ;; (emit (string-append
419 ;; ;; (number->string i))))
420 ;; ;; '(12 13 14 15))
422 ;; (emit "movq %rsp, %rbp") ; set up the base pointer
425 ;; ; restore preserved registers
426 ;; ;; (for-each (lambda (i)
427 ;; ;; (emit (string-append
429 ;; ;; (number->string i))))
430 ;; ;; '(15 14 13 12))
431 ;; ;; (emit "pop %rbx")
436 ; 16(%rbp) mem arg 0 prev frame
437 ; -----------------------
438 ; 8(%rbp) return address cur frame
440 ; -8(%rbp) do what you want
441 ; ... do what you want
442 ; 0(%rsp) do what you want
444 (define (param-register n)
452 (else (error #f "need to test out the below"))
453 (else (format "~a(%rsp)" (- n 6)))))
455 (define (initialize-heap)
458 ('darwin "0x20000c5")
460 ; allocate some heap memory
461 (emit "mov $~a, %rax" mmap) ; mmap
462 (emit "xor %rdi, %rdi") ; addr = null
463 (emit "movq $1024, %rsi") ; length = 1kb
464 (emit "movq $0x3, %rdx") ; prot = read | write = 0x2 | 0x1
465 ; flags = anonymous | private
467 ('darwin (emit "movq $0x1002, %r10")) ; anon = 0x1000, priv = 0x02
468 ('linux (emit "movq $0x22, %r10"))) ; anon = 0x20, priv = 0x02
469 (emit "movq $-1, %r8") ; fd = -1
470 (emit "xor %r9, %r9") ; offset = 0
472 ; %rax now contains pointer to the start of the heap
475 (emit "movq heap_start@GOTPCREL(%rip), %rsi")
476 (emit "movq %rax, (%rsi)")))
478 (define (codegen program)
479 (let* ((extract-res-0 (extract-strings program))
480 (strings (car extract-res-0))
481 (extract-res-1 (extract-lambdas (cdr extract-res-0)))
482 (lambdas (car extract-res-1))
483 (xform-prog (cdr extract-res-1)))
485 (emit "\t.global _start")
487 ; (emit ".p2align 4,,15") is this needed?
489 (for-each codegen-lambda lambdas)
495 (emit "movq %rsp, %rbp") ; set up the base pointer
496 (codegen-expr xform-prog 0 '())
499 (emit "mov %rax, %rdi")
501 ('darwin (emit "movq $0x2000001, %rax"))
502 ('linux (emit "mov $60, %rax")))
510 (for-each emit-string-data strings)))
512 (define (compile-to-binary program output t)
514 (when (not (eq? (typecheck program) 'int)) (error #f "not an int"))
515 (let ([tmp-path "/tmp/a.s"])
516 (when (file-exists? tmp-path) (delete-file tmp-path))
517 (with-output-to-file tmp-path
518 (lambda () (codegen program)))
522 (system "as /tmp/a.s -o /tmp/a.o")
523 (system (format "ld /tmp/a.o -e _start -macosx_version_min 10.14 -static -o ~a" output)))
525 (system "as /tmp/a.s -o /tmp/a.o")
526 (system (format "ld /tmp/a.o -o ~a" output))))))
529 ; syscalls in linux and darwin use the following arguments for syscall instruction:
538 ; on darwin, the syscall is offset by 0x2000000
539 ; https://opensource.apple.com/source/xnu/xnu-2782.20.48/bsd/kern/syscalls.master
540 ; documentation for most syscalls: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/sys