(format "_lambda~a" (- cur-lambda 1)))
; a closure on the heap looks like:
-; 0-x x+0 x+4 x+12 x+20
-; label #vars var1.... var2.... var3....
+ ; 0 8 16 24
+ ; addr var1.... var2.... var3....
(define (codegen-closure label captured si env)
- (let* ((heap-offsets (range 4 (length captured))) ; 4, 12, 20, etc.
- (inner-si (- si (* (length captured) wordsize))))
- (emit "movl $~a, (heap_start)")
- (emit "add $4, (heap_start)")
- (for-each (lambda (var-name new-offset)
- (emit "movq ~a(%rbp), ~a(heap_start)" ; todo: do we need to copy this?
+ (let* ((heap-offsets (map (lambda (i) (+ 8 (* 8 i)))
+ (range 0 (length captured))))) ; 4, 12, 20, etc.
+
+ (emit "movq heap_start@GOTPCREL(%rip), %rbx")
+
+ (emit "movq (%rbx), %rax") ; %rax = heap addr of closure
+
+
+ ; point heap_start to next space
+ (emit "addq $~a, (%rbx)" (+ 8 (* 8 (length captured))))
+
+ ; store the address to the lambda code
+ (emit "movq ~a@GOTPCREL(%rip), %rbx" label)
+ (emit "movq %rbx, 0(%rax)")
+
+ ; store the captured vars
+ (for-each
+ (lambda (var-name new-offset)
+ (emit "movq ~a(%rbp), ~a(rax)"
(cdr (assoc var-name env))
- new-offset)
- (emit "add $8, (heap_start)")
+ new-offset))
captured
- stack-offsets)
-)))
+ heap-offsets)))
+
; for now we can only call closures
-(define (codegen-call closure args si env)
-; (codegen-expr closure 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)))
-
- ; first move the captured variables into param registers
- (for-each
- (lambda (e i)
- (emit "movq ~a(%rbp), ~a"
- (cdr (assoc e env)) ; offset of the var
- (param-register i)))
- captured (range 0 (length captured)))
+(define (codegen-call f args si env)
+ (codegen-expr f si env)
+
+ (emit "## starting call")
- ; then codegen the arguments and move them into the next param registers
+ (emit "movq %rax, ~a(%rbp)" si) ; store address of closure first on stack
+
+ ; codegen the arguments, store them intermediately
(for-each
(lambda (e i)
(begin
- (codegen-expr e si env)
- ; move result to correct param register
- (emit "movq %rax, ~a" (param-register i))))
- args (range argument-start (length args)))
+ (emit "## arg no. ~a" (- i 1))
+ (codegen-expr e (- si (* wordsize i)) env)
+ ; store intermediate result on stack
+ (emit "movq %rax, ~a(%rbp)" (- si (* wordsize i)))))
+
+ args (range 1 (length args)))
+
+ ; now that we have everything we need on the stack,
+ ; move them into the param registers
+
+ (emit "## moving args into place")
+ (for-each
+ (lambda (i) (emit "movq ~a(%rbp), ~a"
+ (- si (* wordsize i))
+ (param-register i)))
+ (range 1 (length args)))
+
+ ; todo: can this be made more efficient
+ (emit "movq ~a(%rbp), %rax" si) ; load back pointer to closure
+
+ (emit "## moving captives into place")
+
+ ; move captives into first argument
+ (emit "movq %rax, %rbx")
+ (emit "addq $8, %rbx")
+ (emit "movq %rbx, ~a" (param-register 0))
+
+ (emit "## performing call")
(emit "addq $~a, %rsp" si) ; adjust the stack pointer to account all the stuff we put in the env
- (emit "callq ~a" label)
- (emit "subq $~a, %rsp" si)))
+ (emit "callq *(%rax)") ; call closure function
+ (emit "subq $~a, %rsp" si))
+
+ ; LAMBDAS:
+ ; 1st param: pointer to captured args
+ ; 2nd param: 1st arg
+ ; 3rd param: 2nd arg, etc.
(define (codegen-lambda l)
(let* ((label (car l))
- (args (cadr l))
- (captured (caddr l))
- (body (cadddr l))
+ (stuff (cdr l))
+ (captured (car stuff))
+ (args (cadr stuff))
+ (body (caddr stuff))
; params = what actually gets passed
(params (append captured args))
- (param-registers (map param-register
- (range 0 (length params))))
(stack-offsets (map (lambda (i)
(* (- wordsize) i))
(range 1 (length params))))
- (copy-insts (map (lambda (r o)
- (format "movq ~a, ~a(%rbp)" r o))
- param-registers stack-offsets))
-
(env (map cons params stack-offsets)))
(emit "~a:" label)
+
+ (display "## lambda captives: ")
+ (display captured)
+ (newline)
+ (display "## lambda args: ")
+ (display args)
+ (newline)
(display "## lambda body: ")
(display body)
(newline)
- (display "## environment: ")
- (display env)
- (newline)
(emit "push %rbp") ; preserve caller's base pointer
(emit "movq %rsp, %rbp") ; set up our own base pointer
- (for-each emit copy-insts)
+ ; load the captured vars onto the stack
+ (for-each
+ (lambda (i)
+ (emit "movq ~a(~a), ~a(%rbp)"
+ i (param-register 0) (* (- wordsize) i)))
+ (range 0 (length captured)))
+
+ ; load the args onto the stack
+ (for-each
+ (lambda (i)
+ (emit "movq ~a, ~a(%rbp)"
+ (param-register i) (* (- wordsize) i)))
+ (range 1 (length args)))
+
(codegen-expr body (* (- wordsize) (+ 1 (length params))) env)
(emit "pop %rbp") ; restore caller's base pointer
(define (codegen-expr e si env)
(case (ast-type e)
- ('builtin e)
('closure (codegen-closure (cadr e) (caddr e) si env))
('app
- (let ((callee (codegen-expr (car e) si env)))
- (case callee
+ (case (car e)
('+ (codegen-add (cdr e) si env))
('- (codegen-sub (cadr e) (caddr e) si env))
('* (codegen-mul (cadr e) (caddr 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)))))
+ (else (codegen-call (car e) (cdr e) si env))))
+
+ ; this is a builtin being passed around as a variable
+ ('builtin (emit "movq $~a, %rax" (builtin-id e)))
('let (codegen-let (let-bindings e)
(let-body e)
(else '())))
(collect prog))
- ; ((lambda (x) (+ x 1)) 42) => {lambda0: (x) (+ x 1)}, (@lambda0 42)
+ ; ((lambda (x) (+ x y)) 42) => ((closure lambda1 (y)) 42)
+ ; [(lambda1 . ((y), (x), (+ x y))]
+ ; for builtins, this generates a closure if it is used
+ ; outside of an immediate app
+ ; but only one closure for each builtin
+
(define (extract-lambdas program)
(define lambdas '())
(define (add-lambda e)
(args (lambda-args e))
(captured (free-vars e))
(body (extract (lambda-body e)))
- (new-lambda (list label args captured body)))
+ (new-lambda (cons label (list captured args body))))
(set! lambdas (cons new-lambda lambdas))
`(closure ,label ,captured))) ; todo: should we string->symbol?
+
+ (define (find-builtin-lambda e)
+ (let [(l (assq (builtin-name e) lambdas))]
+ (if l `(closure ,(car l) ,(caadr l)) #f)))
+
+ (define (builtin-name e)
+ (case e
+ ('+ "_add")
+ ('- "_sub")
+ ('* "_mul")
+ ('bool->int "_bool2int")
+ (else (error #f "fill this out"))))
+ (define (builtin-args e)
+ (case e
+ ('+ '(x y))
+ ('- '(x y))
+ ('* '(x y))
+ ('bool->int '(x))
+ (else (error #f "fill this out"))))
+
+ (define (add-builtin-lambda e)
+ (let* [(label (builtin-name e))
+ (captured '())
+ (args (builtin-args e))
+ (body `(,e ,@args))
+ (new-lambda (cons label (list captured args body)))]
+ (set! lambdas (cons new-lambda lambdas))
+ `(closure ,label ,captured)))
+
(define (extract e)
(case (ast-type e)
('lambda (add-lambda e))
('let `(let ,(map extract (let-bindings e))
,@(map extract (let-body e))))
- ('app (append (list (extract (car e)))
+ ('app (append
+ ; if a builtin is used as a function, don't generate lambda
+ (if (eqv? 'builtin (ast-type (car e)))
+ '()
+ (list (extract (car e))))
(map extract (cdr e))))
+
+ ('builtin
+ (if (find-builtin-lambda e)
+ (find-builtin-lambda e)
+ (add-builtin-lambda e)))
+
+
(else (ast-traverse extract e))))
(let ((transformed (extract program)))
(cons lambdas transformed)))
(else (error #f "need to test out the below"))
(else (format "~a(%rsp)" (- n 6)))))
+(define (initialize-heap)
+ (let ((mmap
+ (case target
+ ('darwin "0x20000c5")
+ ('linux "9"))))
+ ; allocate some heap memory
+ (emit "mov $~a, %rax" mmap) ; mmap
+ (emit "xor %rdi, %rdi") ; addr = null
+ (emit "movq $1024, %rsi") ; length = 1kb
+ (emit "movq $0x3, %rdx") ; prot = read | write = 0x2 | 0x1
+ ; flags = anonymous | private
+ (case target
+ ('darwin (emit "movq $0x1002, %r10")) ; anon = 0x1000, priv = 0x02
+ ('linux (emit "movq $0x22, %r10"))) ; anon = 0x20, priv = 0x02
+ (emit "movq $-1, %r8") ; fd = -1
+ (emit "xor %r9, %r9") ; offset = 0
+ (emit "syscall")
+ ; %rax now contains pointer to the start of the heap
+ ; keep track of it
+
+ (emit "movq heap_start@GOTPCREL(%rip), %rsi")
+ (emit "movq %rax, (%rsi)")))
+
(define (codegen program)
(let* ((extract-res-0 (extract-strings program))
(strings (car extract-res-0))
(emit "_start:")
- ; allocate some heap memory
- (emit "mov $9, %rax") ; mmap
- (emit "xor %rdi, %rdi") ; addr = null
- (emit "movq $1024, %rsi") ; length = 1kb
- (emit "movq $0x3, %rdx") ; prot = read | write = 0x2 | 0x1
- (emit "movq $0x22, %r10") ; flags = anonymous | private = 0x20 | 0x02
- (emit "movq $-1, %r8") ; fd = -1
- (emit "xor %r9, %r9") ; offset = 0
- (emit "syscall")
-
- ; %rax now contains pointer to the start of the heap
- ; keep track of it
- (emit "movq %rax, (heap_start)")
+ (initialize-heap)
(emit "movq %rsp, %rbp") ; set up the base pointer
(codegen-expr xform-prog 0 '())
(system (format "ld /tmp/a.o -o ~a" output))))))
; NOTES
-; syscalls in linux use the following arguments for syscall instruction:
+; syscalls in linux and darwin use the following arguments for syscall instruction:
; %rax = syscall #
; %rdi = 1st arg
; %rsi = 2nd arg
; %r10 = 4th arg
; %r8 = 5th arg
; %r9 = 6th arg
+
+; on darwin, the syscall is offset by 0x2000000
+; https://opensource.apple.com/source/xnu/xnu-2782.20.48/bsd/kern/syscalls.master
+; documentation for most syscalls: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/sys
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