X-Git-Url: http://git.lukelau.me/?p=scheme.git;a=blobdiff_plain;f=codegen.scm;h=70a8ca4aa0df75518989d386502765e90e535137;hp=76fa6717c46d9d1ae69a4dd28d9fcbb135739d05;hb=21a9f0aaa56d6dd767cefb30c606f4c62eecff48;hpb=05e0f42eb4a44694b96297ce50b5a27eb6bb9f71

diff --git a/codegen.scm b/codegen.scm
index 76fa671..70a8ca4 100644
--- a/codegen.scm
+++ b/codegen.scm
@@ -9,19 +9,35 @@
 (define (codegen-add xs si env)
   (define (go ys)
     (if (null? ys)
-      (emit "movq %rbx, %rax")
+      (emit "movq ~a(%rsp), %rax" si)
       (begin
 	(let ((y (car ys)))
 	     (if (integer? y)
-		 (emit "addq $~a, %rbx" y)
+		 (emit "addq $~a, ~a(%rsp)" y si)
 		 (begin
-		   (codegen-expr y si env)
-		   (emit "addq %rax, %rbx"))))
+		   (codegen-expr y (- si wordsize) env)
+		   (emit "addq %rax, ~a(%rsp)" si))))
 	(go (cdr ys)))))
   (begin
-    (emit "movq $0, %rbx")
+					; use si(%rsp) as the accumulator
+    (emit "movq $0, ~a(%rsp)" si)
     (go xs)))
 
+(define (codegen-binop opcode)
+  (lambda (a b si env)
+    (codegen-expr b si env)
+    (emit "movq %rax, ~a(%rsp)" si)
+    (codegen-expr a (- si wordsize) env)
+    (emit "~a ~a(%rsp), %rax" opcode si)))
+
+(define codegen-sub (codegen-binop "sub"))
+(define codegen-mul (codegen-binop "imul"))
+
+(define (codegen-not x si env)
+  (codegen-expr x si env)
+  (emit "notq %rax")
+  (emit "andq $1, %rax"))
+
 (define (range s n)
   (if (= 0 n) '()
       (append (range s (- n 1))
@@ -35,35 +51,168 @@
 	 (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)))
 
+(define cur-lambda 0)
+(define (fresh-lambda)
+  (set! cur-lambda (+ 1 cur-lambda))
+  (format "_lambda~a" (- cur-lambda 1)))
+
+					; for now we can only call closures
+(define (codegen-call closure args si env)
+  (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(%rsp), ~a"
+	     (cdr (assoc e env)) ; offset of the var
+	     (param-register i)))
+     captured (range 0 (length captured)))
+
+
+					; then codegen the arguments and move them into the next param registers
+    (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)))
+
+			    		; now call
+    (emit "callq ~a" label)))
+
+
+(define (codegen-lambda l)
+  (let* ((label (car l))
+	 (args (cadr l))
+	 (captured (caddr l))
+	 (body (cadddr l))
+	 ; captured, then args
+	 (vars (append captured args))
+
+	 (param-registers (map param-register
+			     (range 0 (length vars))))
+	 (stack-offsets (map (lambda (i)
+			       (* (- wordsize) i))
+			     (range 0 (length vars))))
+
+	 (copy-insts (map (lambda (r o)
+			    (format "movq ~a, ~a(%rsp)"
+				    r o))
+			  param-registers stack-offsets))
+
+	 (env (map cons vars stack-offsets)))
+    (emit "~a:" label)
+    (display "## lambda body: ")
+    (display body)
+    (newline)
+    (display "## environment: ")
+    (display env)
+    (newline)
+    (amd64-abi
+     (lambda ()
+       (for-each emit copy-insts)
+       (codegen-expr body (* (- wordsize) (length vars)) env)
+       ))))			; move args and capture vars to stack
+
 (define (codegen-expr e si env)
-  (cond ((and (list? e) (eq? (car e) '+))
-	 (codegen-add (cdr e) si env))
-	((let? e) (codegen-let
-		   (let-bindings e)
+  (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))
+	 ('bool->int (codegen-expr (cadr e) si env))
+	 (else (codegen-call callee (cdr e) si env)))))
+
+    ('let (codegen-let (let-bindings e)
 		       (let-body e)
 		       si
 		       env))
-	((var? e) (codegen-var e si env))
-	(else (emit "movq $~a, %rax" e))))
 
-(define (codegen program)
-  (emit ".text")
-  (emit ".p2align 4,,15")
-  (emit ".globl _scheme_entry")
-  (emit "_scheme_entry:")
+    ('var (codegen-var e si env))
 
-  ; handle incoming call from C
+    ('string-literal (emit "movq ~a, %rax" label))
+    ('bool-literal (emit "movq $~a, %rax" (if e 1 0)))
+    ('int-literal (emit "movq $~a, %rax" e))
+
+    (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)
+    (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 (fold-map collect e))
+      ('let
+	  (let ((bind-fvs (fold-map (lambda (a)
+				      ((set! bound (cons (car a) bound))
+				       (collect (cdr a))))
+				    (let-bindings cadr)))
+		(body-fvs (fold-map collect (let-body e))))
+	    (append bind-fvs body-fvs)))
+      (else '())))
+  (collect prog))
+
+					; ((lambda (x) (+ x 1)) 42) => {lambda0: (x) (+ x 1)}, (@lambda0 42)
+(define (extract-lambdas program)
+  (define lambdas '())
+  (define (add-lambda e)
+    (let* ((label (fresh-lambda))
+	   (args (lambda-args e))
+	   (captured (free-vars e))
+	   (body (extract (lambda-body e)))
+	   (new-lambda (list label args captured body)))
+      (set! lambdas (cons new-lambda lambdas))
+      `(closure ,label ,captured))) ; todo: should we string->symbol?
+  (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)))
+		       (map extract (cdr e))))
+     (else e)))
+  (let ((transformed (extract program)))
+    (cons lambdas transformed)))
+
+;(define (extract-strings program))
+
+(define (amd64-abi f)
+					; preserve registers
   (emit "push %rbp")
   (emit "push %rbx")
   (for-each (lambda (i)
@@ -72,9 +221,7 @@
 		     (number->string i))))
 	    '(12 13 14 15))
 
-  ; our code goes here
-  (codegen-expr program 0 '())
-
+  (f) ; call stuff
 					; restore preserved registers
   (for-each (lambda (i)
 	      (emit (string-append
@@ -83,13 +230,48 @@
 	    '(15 14 13 12))
   (emit "pop %rbx")
   (emit "pop %rbp")
-
   (emit "ret"))
 
-(define (compile-to-binary program)
+					; 24(%rbp) mem arg 1
+					; 16(%rbp) mem arg 0          prev frame
+					; -----------------------
+					;  8(%rbp) return address     cur frame
+					;  0(%rbp) prev %rbp
+					; -8(%rbp) do what you want
+					;  ...     do what you want
+					;  0(%rsp) do what you want
+
+(define (param-register n)
+  (case n
+    (0 "%rdi")
+    (1 "%rsi")
+    (2 "%rdx")
+    (3 "%rcx")
+    (4 "%r8")
+    (5 "%r9")
+    (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")
+
+    (for-each codegen-lambda lambdas)
+
+    (emit ".globl _scheme_entry")
+    (emit "_scheme_entry:")
+
+
+    (amd64-abi
+     (lambda () (codegen-expr xform-prog 0 '())))))
+
+(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 -fomit-frame-pointer /tmp/a.s rts.c -o ~a" output))))