Add strings and print primitive

[scheme.git] / codegen.scm

diff --git a/codegen.scm b/codegen.scm
index 70a8ca4aa0df75518989d386502765e90e535137..a1a0aa71280e66b510be50964d9c7c37893b1a91 100644 (file)
--- 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))
@@ -76,6 +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)))
@@ -135,6 +164,23 @@
        (codegen-expr body (* (- wordsize) (length vars)) env)
        ))))                    ; move args and capture vars to stack
 
+(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)))
+
 (define (codegen-expr e si env)
   (case (ast-type e)
     ('builtin e)
@@ -146,7 +192,9 @@
         ('- (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 (codegen-let (let-bindings e)
@@ -156,10 +204,13 @@
 
     ('var (codegen-var e si env))
 
-    ('string-literal (emit "movq ~a, %rax" label))
+    ('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"))))
 
 
@@ -200,16 +251,33 @@
   (define (extract e)
     (case (ast-type e)
       ('lambda (add-lambda e))
-     ('let `(let
-                   ,(map extract (let-bindings 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)))
+      (else (ast-traverse extract e))))
   (let ((transformed (extract program)))
     (cons lambdas transformed)))
 
-;(define (extract-strings program))
+(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
@@ -253,20 +321,30 @@
     (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"))
@@ -274,4 +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))))