5 (define target host-os)
12 (define (codegen-add xs si env)
15 (emit "movq ~a(%rbp), %rax" si)
19 (emit "addq $~a, ~a(%rbp)" y si)
21 (codegen-expr y (- si wordsize) env)
22 (emit "addq %rax, ~a(%rbp)" si))))
25 ; use si(%rbp) as the accumulator
26 (emit "movq $0, ~a(%rbp)" si)
29 (define (codegen-binop opcode)
31 (codegen-expr b si env)
32 (emit "movq %rax, ~a(%rbp)" si)
33 (codegen-expr a (- si wordsize) env)
34 (emit "~a ~a(%rbp), %rax" opcode si)))
36 (define codegen-sub (codegen-binop "sub"))
38 (define codegen-mul (codegen-binop "imul"))
40 (define (codegen-not x si env)
41 (codegen-expr x si env)
43 (emit "andq $1, %rax"))
45 (define (codegen-eq a b si env)
46 (codegen-expr a si env)
47 (emit "movq %rax, ~a(%rbp)" si)
48 (codegen-expr b (- si wordsize) env)
49 (emit "## ~a = ~b" a b)
50 (emit "cmpq ~a(%rbp), %rax" si)
53 ; 'write file handle addr-string num-bytes
55 (define (codegen-print x si env)
56 (codegen-expr x si env) ; x should be a static-string, producing a label
58 ; make a copy of string address since %rax and %rdi are clobbered
59 (emit "mov %rax, %rbx")
61 ; get the length of the null terminated string
62 (emit "mov %rax, %rdi")
63 (emit "xor %al, %al") ; set %al to 0
64 (emit "mov $-1, %rcx") ; max search length = max int = -1
65 (emit "cld") ; clear direction flag, search up in memory
66 (emit "repne scasb") ; scan string, %rcx = -strlen - 1 - 1
68 (emit "not %rcx") ; -%rcx = strlen + 1
71 (emit "movq %rbx, %rsi") ; string addr
72 (emit "movq %rcx, %rdx") ; num bytes
73 (emit "movq $1, %rdi") ; file handle (stdout)
75 ('darwin (emit "mov $0x2000004, %rax")) ; syscall 4 (write)
76 ('linux (emit "mov $1, %rax"))) ; syscall 1 (write)
81 (append (range s (- n 1))
82 (list (+ s (- n 1))))))
86 (define (codegen-let bindings body si env)
87 (let* ((stack-offsets (map (lambda (x) (- si (* x wordsize)))
88 (range 0 (length bindings))))
89 (inner-si (- si (* (length bindings) wordsize)))
90 (names (map car bindings))
91 (exprs (map cadr bindings))
93 ; recursive let bindings: build environment as we go
95 (lambda (env name expr offset)
96 (codegen-expr expr inner-si env)
97 (emit "movq %rax, ~a(%rbp)" offset)
98 (cons (cons name offset) env))
99 env names exprs stack-offsets)))
100 (for-each (lambda (form)
101 (codegen-expr form inner-si inner-env))
104 (define (codegen-var name si env)
105 (when (not (assoc name env))
106 (error #f (format "Variable ~a is not bound" name)))
107 (let ((offset (cdr (assoc name env))))
108 (emit "movq ~a(%rbp), %rax" offset)))
110 (define cur-lambda 0)
111 (define (fresh-lambda)
112 (set! cur-lambda (+ 1 cur-lambda))
113 (format "_lambda~a" (- cur-lambda 1)))
115 ; a closure on the heap looks like:
117 ; addr var1.... var2.... var3....
119 (define (codegen-closure label captured si env)
120 (let* ((heap-offsets (map (lambda (i) (+ 8 (* 8 i)))
121 (range 0 (length captured))))) ; 4, 12, 20, etc.
123 (emit "## creating closure")
125 (emit "movq heap_start@GOTPCREL(%rip), %rbx")
127 (emit "movq (%rbx), %rax") ; %rax = heap addr of closure
130 ; point heap_start to next space
131 (emit "addq $~a, (%rbx)" (+ 8 (* 8 (length captured))))
133 (emit "## storing address to lambda")
134 ; store the address to the lambda code
135 (emit "movq ~a@GOTPCREL(%rip), %rbx" label)
136 (emit "movq %rbx, 0(%rax)")
138 (emit "## storing captives")
139 ; store the captured vars
141 (lambda (var-name new-offset)
143 (emit "movq ~a(%rbp), %rbx" (cdr (assoc var-name env)))
144 (emit "movq %rbx, ~a(%rax)" new-offset)))
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 0 (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
226 (emit "movq %rsp, %rbp") ; set up our own base pointer
227 (emit "subq $8, %rbp")
229 ; load the captured vars onto the stack
233 (emit "movq ~a(~a), %rbx" i (param-register 0))
234 (emit "movq %rbx, ~a(%rbp)" (* (- wordsize) i))))
235 (range 0 (length captured)))
237 ; load the args onto the stack
241 (emit "movq ~a, %rbx" (param-register (+ 1 i)))
242 (emit "movq %rbx, ~a(%rbp)"
244 (+ (length captured) i)))))
245 (range 0 (length args)))
247 (codegen-expr body (* (- wordsize) (+ 1 (length params))) env)
249 (emit "pop %rbp") ; restore caller's base pointer
253 (define (fresh-label)
254 (set! cur-label (+ 1 cur-label))
255 (format "label~a" (- cur-label 1)))
257 (define (codegen-if cond then else si env)
258 (codegen-expr cond si env)
259 (emit "cmpq $0, %rax")
260 (let ((exit-label (fresh-label))
261 (else-label (fresh-label)))
262 (emit "je ~a" else-label)
263 (codegen-expr then si env)
264 (emit "jmp ~a" exit-label)
265 (emit "~a:" else-label)
266 (codegen-expr else si env)
267 (emit "~a:" exit-label)))
269 (define (codegen-expr e si env)
272 ('closure (codegen-closure (cadr e) (caddr e) si env))
275 ('+ (codegen-add (cdr e) si env))
276 ('- (codegen-sub (cadr e) (caddr e) si env))
277 ('* (codegen-mul (cadr e) (caddr e) si env))
278 ('! (codegen-not (cadr e) si env))
279 ('= (codegen-eq (cadr e) (caddr e) si env))
280 ('bool->int (codegen-expr (cadr e) si env))
281 ('print (codegen-print (cadr e) si env))
282 (else (codegen-call (car e) (cdr e) si env))))
284 ; this is a builtin being passed around as a variable
285 ('builtin (emit "movq $~a, %rax" (builtin-id e)))
287 ('let (codegen-let (let-bindings e)
292 ('var (codegen-var e si env))
294 ('if (codegen-if (cadr e) (caddr e) (cadddr e) si env))
296 ('bool-literal (emit "movq $~a, %rax" (if e 1 0)))
297 ('int-literal (emit "movq $~a, %rax" e))
299 ('static-string (emit "movq ~a@GOTPCREL(%rip), %rax"
302 (else (error #f "don't know how to codegen this"))))
306 (define (free-vars prog)
310 ('builtin '()) ; do nothing
311 ('var (if (memq e bound) '() (list e)))
313 (set! bound (append (lambda-args e) bound))
314 (collect (lambda-body e)))
316 ('app (fold-map collect e))
318 (let ((bind-fvs (fold-map (lambda (a)
319 ((set! bound (cons (car a) bound))
321 (let-bindings cadr)))
322 (body-fvs (fold-map collect (let-body e))))
323 (append bind-fvs body-fvs)))
327 ; ((lambda (x) (+ x y)) 42) => ((closure lambda1 (y)) 42)
328 ; [(lambda1 . ((y), (x), (+ x y))]
329 ; for builtins, this generates a closure if it is used
330 ; outside of an immediate app
331 ; but only one closure for each builtin
333 (define (extract-lambdas program)
335 (define (add-lambda e)
336 (let* ((label (fresh-lambda))
337 (args (lambda-args e))
338 (captured (free-vars e))
339 (body (extract (lambda-body e)))
340 (new-lambda (cons label (list captured args body))))
341 (set! lambdas (cons new-lambda lambdas))
342 `(closure ,label ,captured))) ; todo: should we string->symbol?
344 (define (find-builtin-lambda e)
345 (let [(l (assq (builtin-name e) lambdas))]
346 (if l `(closure ,(car l) ,(caadr l)) #f)))
348 (define (builtin-name e)
355 ('bool->int "_bool2int")
357 (else (error #f "don't know this builtin"))))
358 (define (builtin-args e)
367 (else (error #f "don't know this builtin"))))
369 (define (add-builtin-lambda e)
370 (let* [(label (builtin-name e))
372 (args (builtin-args e))
374 (new-lambda (cons label (list captured args body)))]
375 (set! lambdas (cons new-lambda lambdas))
376 `(closure ,label ,captured)))
380 ('lambda (add-lambda e))
381 ('let `(let ,(map extract (let-bindings e))
382 ,@(map extract (let-body e))))
384 ; if a builtin is used as a function, don't generate lambda
385 (if (eqv? 'builtin (ast-type (car e)))
387 (list (extract (car e))))
388 (map extract (cdr e))))
391 (if (find-builtin-lambda e)
392 (find-builtin-lambda e)
393 (add-builtin-lambda e)))
396 (else (ast-traverse extract e))))
397 (let ((transformed (extract program)))
398 (cons lambdas transformed)))
400 (define (extract-strings program)
402 (strings '())) ; assoc list of labels -> string
403 (define (fresh-string)
404 (set! cur-string (+ cur-string 1))
405 (format "string~a" (- cur-string 1)))
409 (let ((label (fresh-string)))
410 (set! strings (cons (cons label e) strings))
411 `(static-string ,label)))
412 (else (ast-traverse extract e))))
413 (let ((transformed (extract program)))
414 (cons strings transformed))))
416 (define (emit-string-data s)
418 (emit "\t.string \"~a\"" (cdr s)))
420 ;; (define (amd64-abi f)
421 ;; ; preserve registers
422 ;; (emit "push %rbp")
423 ;; ;; (emit "push %rbx")
424 ;; ;; (for-each (lambda (i)
425 ;; ;; (emit (string-append
427 ;; ;; (number->string i))))
428 ;; ;; '(12 13 14 15))
430 ;; (emit "movq %rsp, %rbp") ; set up the base pointer
433 ;; ; restore preserved registers
434 ;; ;; (for-each (lambda (i)
435 ;; ;; (emit (string-append
437 ;; ;; (number->string i))))
438 ;; ;; '(15 14 13 12))
439 ;; ;; (emit "pop %rbx")
444 ; 16(%rbp) mem arg 0 prev frame
445 ; -----------------------
446 ; 8(%rbp) return address cur frame
448 ; -8(%rbp) do what you want
449 ; ... do what you want
450 ; 0(%rsp) do what you want
452 (define (param-register n)
460 (else (error #f "need to test out the below"))
461 (else (format "~a(%rsp)" (- n 6)))))
463 (define (initialize-heap)
466 ('darwin "0x20000c5")
468 ; allocate some heap memory
469 (emit "mov $~a, %rax" mmap) ; mmap
470 (emit "xor %rdi, %rdi") ; addr = null
471 (emit "movq $1024, %rsi") ; length = 1kb
472 (emit "movq $0x3, %rdx") ; prot = read | write = 0x2 | 0x1
473 ; flags = anonymous | private
475 ('darwin (emit "movq $0x1002, %r10")) ; anon = 0x1000, priv = 0x02
476 ('linux (emit "movq $0x22, %r10"))) ; anon = 0x20, priv = 0x02
477 (emit "movq $-1, %r8") ; fd = -1
478 (emit "xor %r9, %r9") ; offset = 0
480 ; %rax now contains pointer to the start of the heap
483 (emit "movq heap_start@GOTPCREL(%rip), %rsi")
484 (emit "movq %rax, (%rsi)")))
486 (define (codegen program)
489 (let* ((extract-res-0 (extract-strings program))
490 (strings (car extract-res-0))
491 (extract-res-1 (extract-lambdas (cdr extract-res-0)))
492 (lambdas (car extract-res-1))
493 (xform-prog (cdr extract-res-1)))
495 (emit "\t.global _start")
497 ; (emit ".p2align 4,,15") is this needed?
499 (for-each codegen-lambda lambdas)
505 (emit "movq %rsp, %rbp") ; set up the base pointer
506 (codegen-expr xform-prog 0 '())
509 (emit "mov %rax, %rdi")
511 ('darwin (emit "movq $0x2000001, %rax"))
512 ('linux (emit "mov $60, %rax")))
520 (for-each emit-string-data strings)))
522 (define (compile-to-binary program output t)
524 (when (not (eq? (typecheck program) 'int)) (error #f "not an int"))
525 (let ([tmp-path "/tmp/a.s"])
526 (when (file-exists? tmp-path) (delete-file tmp-path))
527 (with-output-to-file tmp-path
528 (lambda () (codegen program)))
532 (system "as /tmp/a.s -o /tmp/a.o")
533 (system (format "ld /tmp/a.o -e _start -macosx_version_min 10.14 -static -o ~a" output)))
535 (system "as /tmp/a.s -o /tmp/a.o")
536 (system (format "ld /tmp/a.o -o ~a" output))))))
539 ; syscalls in linux and darwin use the following arguments for syscall instruction:
548 ; on darwin, the syscall is offset by 0x2000000
549 ; https://opensource.apple.com/source/xnu/xnu-2782.20.48/bsd/kern/syscalls.master
550 ; documentation for most syscalls: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/sys