X-Git-Url: http://git.lukelau.me/?a=blobdiff_plain;f=codegen.scm;h=9b3878a2e947f3d3314c8c9c4bc96bca38a83a7f;hb=6f699d1ddbb1cd33ec3095a0e6e9a6eee157d708;hp=25d99a199da43889ef289b1e6af1292595aa4af0;hpb=2d16419b1556917b7c73d5dffe546124bb8ed534;p=scheme.git

diff --git a/codegen.scm b/codegen.scm
index 25d99a1..9b3878a 100644
--- 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"))
@@ -118,7 +121,6 @@
 	     (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)
@@ -213,7 +215,7 @@
     ('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"))))
 
@@ -340,6 +342,21 @@
     (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 '())
 
@@ -348,7 +365,10 @@
     (emit "mov $60, %rax")
     (emit "syscall")
 
-    (emit "\t.data")
+    (emit ".data")
+
+    (emit "heap_start:")
+    (emit "\t.quad 0")
 
     (for-each emit-string-data strings)))
 
@@ -359,3 +379,13 @@
     (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