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:
120 ; 0-x x+0 x+4 x+12 x+20
121 ; label #vars var1.... var2.... var3....
123 (define (codegen-closure label captured si env)
124 (let* ((heap-offsets (range 4 (length captured))) ; 4, 12, 20, etc.
125 (inner-si (- si (* (length captured) wordsize))))
126 (emit "movl $~a, (heap_start)")
127 (emit "add $4, (heap_start)")
128 (for-each (lambda (var-name new-offset)
129 (emit "movq ~a(%rbp), ~a(heap_start)" ; todo: do we need to copy this?
130 (cdr (assoc var-name env))
132 (emit "add $8, (heap_start)")
136 ; for now we can only call closures
137 (define (codegen-call closure args si env)
138 ; (codegen-expr closure si env)
139 (when (not (eq? (ast-type closure) 'closure))
140 (error #f (format "~a is not a closure" closure)))
141 (let* ((captured (caddr closure))
142 (label (cadr closure))
143 (argument-start (length captured)))
145 ; first move the captured variables into param registers
148 (emit "movq ~a(%rbp), ~a"
149 (cdr (assoc e env)) ; offset of the var
151 captured (range 0 (length captured)))
153 ; then codegen the arguments and move them into the next param registers
157 (codegen-expr e si env)
158 ; move result to correct param register
159 (emit "movq %rax, ~a" (param-register i))))
160 args (range argument-start (length args)))
162 (emit "addq $~a, %rsp" si) ; adjust the stack pointer to account all the stuff we put in the env
163 (emit "callq ~a" label)
164 (emit "subq $~a, %rsp" si)))
166 (define (codegen-lambda l)
167 (let* ((label (car l))
171 ; params = what actually gets passed
172 (params (append captured args))
174 (param-registers (map param-register
175 (range 0 (length params))))
176 (stack-offsets (map (lambda (i)
178 (range 1 (length params))))
180 (copy-insts (map (lambda (r o)
181 (format "movq ~a, ~a(%rbp)" r o))
182 param-registers stack-offsets))
184 (env (map cons params stack-offsets)))
186 (display "## lambda body: ")
189 (display "## environment: ")
193 (emit "push %rbp") ; preserve caller's base pointer
194 (emit "movq %rsp, %rbp") ; set up our own base pointer
196 (for-each emit copy-insts)
197 (codegen-expr body (* (- wordsize) (+ 1 (length params))) env)
199 (emit "pop %rbp") ; restore caller's base pointer
202 (define (codegen-string label)
204 ('darwin (emit "movq ~a@GOTPCREL(%rip), %rax" label))
205 ('linux (emit "lea $~a, %rax" label))))
208 (define (fresh-label)
209 (set! cur-label (+ 1 cur-label))
210 (format "label~a" (- cur-label 1)))
212 (define (codegen-if cond then else si env)
213 (codegen-expr cond si env)
214 (emit "cmpq $0, %rax")
215 (let ((exit-label (fresh-label))
216 (else-label (fresh-label)))
217 (emit "je ~a" else-label)
218 (codegen-expr then si env)
219 (emit "jmp ~a" exit-label)
220 (emit "~a:" else-label)
221 (codegen-expr else si env)
222 (emit "~a:" exit-label)))
224 (define (codegen-expr e si env)
227 ('closure (codegen-closure (cadr e) (caddr e) si env))
229 (let ((callee (codegen-expr (car e) si env)))
231 ('+ (codegen-add (cdr e) si env))
232 ('- (codegen-sub (cadr e) (caddr e) si env))
233 ('* (codegen-mul (cadr e) (caddr e) si env))
234 ('! (codegen-not (cadr e) si env))
235 ('= (codegen-eq (cadr e) (caddr e) si env))
236 ('bool->int (codegen-expr (cadr e) si env))
237 ('print (codegen-print (cadr e) si env))
238 (else (codegen-call callee (cdr e) si env)))))
240 ('let (codegen-let (let-bindings e)
245 ('var (codegen-var e si env))
247 ('if (codegen-if (cadr e) (caddr e) (cadddr e) si env))
249 ('bool-literal (emit "movq $~a, %rax" (if e 1 0)))
250 ('int-literal (emit "movq $~a, %rax" e))
252 ('static-string (codegen-string (cadr e)))
254 (else (error #f "don't know how to codegen this"))))
257 (define (fold-map f x) (fold-left append '() (map f x)))
259 (define (free-vars prog)
263 ('builtin '()) ; do nothing
264 ('var (if (memq e bound) '() (list e)))
266 (set! bound (append (lambda-args e) bound))
267 (collect (lambda-body e)))
269 ('app (fold-map collect e))
271 (let ((bind-fvs (fold-map (lambda (a)
272 ((set! bound (cons (car a) bound))
274 (let-bindings cadr)))
275 (body-fvs (fold-map collect (let-body e))))
276 (append bind-fvs body-fvs)))
280 ; ((lambda (x) (+ x 1)) 42) => {lambda0: (x) (+ x 1)}, (@lambda0 42)
281 (define (extract-lambdas program)
283 (define (add-lambda e)
284 (let* ((label (fresh-lambda))
285 (args (lambda-args e))
286 (captured (free-vars e))
287 (body (extract (lambda-body e)))
288 (new-lambda (list label args captured body)))
289 (set! lambdas (cons new-lambda lambdas))
290 `(closure ,label ,captured))) ; todo: should we string->symbol?
293 ('lambda (add-lambda e))
294 ('let `(let ,(map extract (let-bindings e))
295 ,@(map extract (let-body e))))
296 ('app (append (list (extract (car e)))
297 (map extract (cdr e))))
298 (else (ast-traverse extract e))))
299 (let ((transformed (extract program)))
300 (cons lambdas transformed)))
302 (define (extract-strings program)
304 (strings '())) ; assoc list of labels -> string
305 (define (fresh-string)
306 (set! cur-string (+ cur-string 1))
307 (format "string~a" (- cur-string 1)))
311 (let ((label (fresh-string)))
312 (set! strings (cons (cons label e) strings))
313 `(static-string ,label)))
314 (else (ast-traverse extract e))))
315 (let ((transformed (extract program)))
316 (cons strings transformed))))
318 (define (emit-string-data s)
320 (emit "\t.string \"~a\"" (cdr s)))
322 ;; (define (amd64-abi f)
323 ;; ; preserve registers
324 ;; (emit "push %rbp")
325 ;; ;; (emit "push %rbx")
326 ;; ;; (for-each (lambda (i)
327 ;; ;; (emit (string-append
329 ;; ;; (number->string i))))
330 ;; ;; '(12 13 14 15))
332 ;; (emit "movq %rsp, %rbp") ; set up the base pointer
335 ;; ; restore preserved registers
336 ;; ;; (for-each (lambda (i)
337 ;; ;; (emit (string-append
339 ;; ;; (number->string i))))
340 ;; ;; '(15 14 13 12))
341 ;; ;; (emit "pop %rbx")
346 ; 16(%rbp) mem arg 0 prev frame
347 ; -----------------------
348 ; 8(%rbp) return address cur frame
350 ; -8(%rbp) do what you want
351 ; ... do what you want
352 ; 0(%rsp) do what you want
354 (define (param-register n)
362 (else (error #f "need to test out the below"))
363 (else (format "~a(%rsp)" (- n 6)))))
365 (define (codegen program)
366 (let* ((extract-res-0 (extract-strings program))
367 (strings (car extract-res-0))
368 (extract-res-1 (extract-lambdas (cdr extract-res-0)))
369 (lambdas (car extract-res-1))
370 (xform-prog (cdr extract-res-1)))
372 (emit "\t.global _start")
374 ; (emit ".p2align 4,,15") is this needed?
376 (for-each codegen-lambda lambdas)
380 ; allocate some heap memory
381 (emit "mov $9, %rax") ; mmap
382 (emit "xor %rdi, %rdi") ; addr = null
383 (emit "movq $1024, %rsi") ; length = 1kb
384 (emit "movq $0x3, %rdx") ; prot = read | write = 0x2 | 0x1
385 (emit "movq $0x22, %r10") ; flags = anonymous | private = 0x20 | 0x02
386 (emit "movq $-1, %r8") ; fd = -1
387 (emit "xor %r9, %r9") ; offset = 0
390 ; %rax now contains pointer to the start of the heap
392 (emit "movq %rax, (heap_start)")
394 (emit "movq %rsp, %rbp") ; set up the base pointer
395 (codegen-expr xform-prog 0 '())
398 (emit "mov %rax, %rdi")
400 ('darwin (emit "movq $0x2000001, %rax"))
401 ('linux (emit "mov $60, %rax")))
409 (for-each emit-string-data strings)))
411 (define (compile-to-binary program output t)
413 (when (not (eq? (typecheck program) 'int)) (error #f "not an int"))
414 (let ([tmp-path "/tmp/a.s"])
415 (when (file-exists? tmp-path) (delete-file tmp-path))
416 (with-output-to-file tmp-path
417 (lambda () (codegen program)))
421 (system "as /tmp/a.s -o /tmp/a.o")
422 (system (format "ld /tmp/a.o -e _start -macosx_version_min 10.14 -static -o ~a" output)))
424 (system "as /tmp/a.s -o /tmp/a.o")
425 (system (format "ld /tmp/a.o -o ~a" output))))))
428 ; syscalls in linux use the following arguments for syscall instruction: