Add WIP on passing about closures

[scheme.git] / codegen.scm

diff --git a/codegen.scm b/codegen.scm
index 5303b4975854be55bfc5d36aedcf5e607ebe8db9..b403939bc2122c2a4c9b5e24980955a2e329402e 100644 (file)
--- a/codegen.scm
+++ b/codegen.scm
@@ -50,6 +50,9 @@
 (define (codegen-print x si env)
   (codegen-expr x si env) ; x should be a static-string, producing a label
 
+                     ; make a copy of string address since %rax and %rdi are clobbered
+  (emit "mov %rax, %rbx")
+  
                      ; get the length of the null terminated string
   (emit "mov %rax, %rdi")
   (emit "xor %al, %al")   ; set %al to 0
@@ -61,7 +64,7 @@
   (emit "dec %rcx")
   
   (emit "mov %rcx, %rdx") ; number of bytes
-  (emit "mov %rax, %rsi") ; addr of string
+  (emit "mov %rbx, %rsi") ; addr of string
   (emit "mov $1, %rax") ; file handle 1 (stdout)
   (emit "mov $1, %rdi") ; syscall 1 (write)
   (emit "syscall"))
@@ -102,8 +105,21 @@
   (set! cur-lambda (+ 1 cur-lambda))
   (format "_lambda~a" (- cur-lambda 1)))
 
+(define (codegen-closure label captured si env)
+;; (define (codegen-closure label captured si env)
+;;   (let* ((stack-offsets (map (lambda (x) (- si (* x wordsize))))
+;;                     (range 0 (length captured)))
+;;      (inner-si (- si (* (length captured) wordsize))))
+;;     (for-each (lambda (var-name new-offset)
+;;             (emit "movq ~a(%rbp), ~a(%rbp)" ; todo: do we need to copy this?
+;;                   (cdr (assoc var-name env))
+;;                   new-offset))
+;;           captured
+;;           stack-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))
@@ -118,7 +134,6 @@
             (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)
@@ -188,7 +203,7 @@
 (define (codegen-expr e si env)
   (case (ast-type e)
     ('builtin e)
-    ('closure e)
+    ('closure (codegen-closure (cadr e) (caddr e) si env))
     ('app
      (let ((callee (codegen-expr (car e) si env)))
        (case callee
@@ -213,7 +228,7 @@
     ('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
+    ('static-string (emit "lea ~a, %rax" (cadr e))) ; move label
 
     (else (error #f "don't know how to codegen this"))))
 
@@ -279,7 +294,7 @@
     (let ((transformed (extract program)))
       (cons strings transformed))))
 
-(define (codegen-string-data s)
+(define (emit-string-data s)
   (emit "~a:" (car s))
   (emit "\t.string \"~a\"" (cdr s)))
 
@@ -340,6 +355,21 @@
     (for-each codegen-lambda lambdas)
 
     (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)")
+    
     (emit "movq %rsp, %rbp")            ; set up the base pointer
     (codegen-expr xform-prog 0 '())
 
@@ -348,9 +378,12 @@
     (emit "mov $60, %rax")
     (emit "syscall")
 
-    (emit "\t.data")
+    (emit ".data")
 
-    (for-each codegen-string-data strings)))
+    (emit "heap_start:")
+    (emit "\t.quad 0")
+
+    (for-each emit-string-data strings)))
 
 (define (compile-to-binary program output)
   (when (not (eq? (typecheck program) 'int)) (error #f "not an int"))
@@ -359,3 +392,13 @@
     (with-output-to-file tmp-path
       (lambda () (codegen program)))
     (system (format "clang -nostdlib /tmp/a.s -o ~a" output))))
+
+; NOTES
+; syscalls in linux use the following arguments for syscall instruction:
+; %rax = syscall #
+; %rdi = 1st arg
+; %rsi = 2nd arg
+; %rdx = 3rd arg
+; %r10 = 4th arg
+; %r8  = 5th arg
+; %r9  = 6th arg