X-Git-Url: http://git.lukelau.me/?a=blobdiff_plain;f=codegen.scm;h=a1a0aa71280e66b510be50964d9c7c37893b1a91;hb=703d22df97baba39426f890c6badd8d272e0bf45;hp=d30adc54e61a144097c3b0bb541a5835af8c028a;hpb=e51b9e423665428c41cddac0642d1e34b18ca1da;p=scheme.git

diff --git a/codegen.scm b/codegen.scm
index d30adc5..a1a0aa7 100644
--- a/codegen.scm
+++ b/codegen.scm
@@ -38,6 +38,33 @@
   (emit "notq %rax")
   (emit "andq $1, %rax"))
 
+(define (codegen-eq a b si env)
+  (codegen-expr a si env)
+  (emit "movq %rax, ~a(%rsp)" si)
+  (codegen-expr b (- si wordsize) env)
+  (emit "subq ~a(%rsp), %rax" si)
+  (emit "not %rax")
+  (emit "andq $1, %rax"))
+
+(define (codegen-print x si env)
+  (codegen-expr x si env) ; x should be a static-string, producing a label
+
+					; get the length of the null terminated string
+  (emit "mov %rax, %rdi")
+  (emit "xor %al, %al")   ; set %al to 0
+  (emit "mov $-1, %rcx") ; max search length = max int = -1
+  (emit "cld")           ; clear direction flag, search up in memory
+  (emit "repne scasb")   ; scan string, %rcx = -strlen - 1 - 1
+  
+  (emit "not %rcx")      ; -%rcx = strlen + 1
+  (emit "dec %rcx")
+  
+  (emit "mov %rcx, %rdx") ; number of bytes
+  (emit "mov %rax, %rsi") ; addr of string
+  (emit "mov $1, %rax") ; file handle 1 (stdout)
+  (emit "mov $1, %rdi") ; syscall 1 (write)
+  (emit "syscall"))
+
 (define (range s n)
   (if (= 0 n) '()
       (append (range s (- n 1))
@@ -51,12 +78,17 @@
 	 (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))
@@ -71,6 +103,8 @@
 
 					; for now we can only call closures
 (define (codegen-call closure args 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)))
@@ -130,43 +164,70 @@
        (codegen-expr body (* (- wordsize) (length vars)) env)
        ))))			; move args and capture vars to stack
 
-(define (codegen-expr e si env)
-  (cond ((builtin? e) e)
-	((closure? e) e)
+(define cur-label 0)
+(define (fresh-label)
+  (set! cur-label (+ 1 cur-label))
+  (format "label~a" (- cur-label 1)))
+
+(define (codegen-if cond then else si env)
+  (codegen-expr cond si env)
+  (emit "cmpq $0, %rax")
+  (let ((exit-label (fresh-label))
+	(else-label (fresh-label)))
+    (emit "je ~a" else-label)
+    (codegen-expr then si env)
+    (emit "jmp ~a" exit-label)
+    (emit "~a:" else-label)
+    (codegen-expr else si env)
+    (emit "~a:" exit-label)))
 
-	((app? e)
+(define (codegen-expr e si env)
+  (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))
+	 ('= (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)))))
 
-	((let? e) (codegen-let
-		   (let-bindings e)
+    ('let (codegen-let (let-bindings e)
 		       (let-body e)
 		       si
 		       env))
-	((var? e) (codegen-var e si env))
-	((boolean? e) (emit "movq $~a, %rax" (if e 1 0)))
-	(else (emit "movq $~a, %rax" e))))
+
+    ('var (codegen-var e si env))
+
+    ('if (codegen-if (cadr e) (caddr e) (cadddr e) si env))
+    
+    ('bool-literal (emit "movq $~a, %rax" (if e 1 0)))
+    ('int-literal (emit "movq $~a, %rax" e))
+    
+    ('static-string (emit "movq $~a, %rax" (cadr e))) ; move label
+
+    (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)
-    (cond
-     ((builtin? e) '()) ; do nothing
-     ((var? e) (if (memq e bound) '() (list e)))
-     ((lambda? 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? e) (fold-map collect e))
-     ((let? e)
+      ('app (fold-map collect e))
+      ('let
 	  (let ((bind-fvs (fold-map (lambda (a)
 				      ((set! bound (cons (car a) bound))
 				       (collect (cdr a))))
@@ -176,9 +237,6 @@
       (else '())))
   (collect prog))
 
-(define (closure? e)
-  (and (list? e) (eqv? (car e) 'closure)))
-
 					; ((lambda (x) (+ x 1)) 42) => {lambda0: (x) (+ x 1)}, (@lambda0 42)
 (define (extract-lambdas program)
   (define lambdas '())
@@ -191,17 +249,36 @@
       (set! lambdas (cons new-lambda lambdas))
       `(closure ,label ,captured))) ; todo: should we string->symbol?
   (define (extract e)
-    (cond
-     ((lambda? e) (add-lambda e))
-     ((let? e) `(let
-		    ,(map extract (let-bindings e))
+    (case (ast-type e)
+      ('lambda (add-lambda e))
+      ('let `(let ,(map extract (let-bindings e))
 	       ,@(map extract (let-body e))))
-     ((app? e) (append (list (extract (car e)))
+      ('app (append (list (extract (car e)))
 		    (map extract (cdr e))))
-     (else e)))
+      (else (ast-traverse extract e))))
   (let ((transformed (extract program)))
     (cons lambdas transformed)))
 
+(define (extract-strings program)
+  (let ((cur-string 0)
+	(strings '())) ; assoc list of labels -> string
+    (define (fresh-string)
+      (set! cur-string (+ cur-string 1))
+      (format "string~a" (- cur-string 1)))
+    (define (extract e)
+      (case (ast-type e)
+	('string-literal
+	 (let ((label (fresh-string)))
+	   (set! strings (cons (cons label e) strings))
+	   `(static-string ,label)))
+	(else (ast-traverse extract e))))
+    (let ((transformed (extract program)))
+      (cons strings transformed))))
+
+(define (codegen-string-data s)
+  (emit "~a:" (car s))
+  (emit "\t.string \"~a\"" (cdr s)))
+
 (define (amd64-abi f)
 					; preserve registers
   (emit "push %rbp")
@@ -243,23 +320,31 @@
     (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")
+  (let* ((extract-res-0 (extract-strings program))
+	 (strings (car extract-res-0))
+	 (extract-res-1 (extract-lambdas (cdr extract-res-0)))
+	 (lambdas (car extract-res-1))
+	 (xform-prog (cdr extract-res-1)))
+
+    (emit "\t.globl _start")
+    (emit "\t.text")
+;    (emit ".p2align 4,,15") is this needed?
 
     (for-each codegen-lambda lambdas)
 
-    (emit ".globl _scheme_entry")
-    (emit "_scheme_entry:")
 
+    (emit "_start:")
+    (codegen-expr xform-prog 0 '())
 
-    (amd64-abi
-     (lambda () (codegen-expr xform-prog 0 '())))))
+					; exit syscall
+    (emit "mov %rax, %rdi")
+    (emit "mov $60, %rax")
+    (emit "syscall")
+
+    (emit "\t.data")
+
+    (for-each codegen-string-data strings)))
 
 (define (compile-to-binary program output)
   (when (not (eq? (typecheck program) 'int)) (error #f "not an int"))
@@ -267,4 +352,4 @@
     (when (file-exists? tmp-path) (delete-file tmp-path))
     (with-output-to-file tmp-path
       (lambda () (codegen program)))
-    (system (format "clang -fomit-frame-pointer /tmp/a.s rts.c -o ~a" output))))
+    (system (format "clang -nostdlib /tmp/a.s -o ~a" output))))