Revise handling of square bracket printing for labels

Previous implementations manually added the `rip` address under certain
conditions, but these did not always work properly in the presence of labels.
This change dynamically tracks whether a label occurs within the bounds of
square-bracket notation and only injects `rip` under these circumstances.

Author: pdarragh

a86/printer.rkt

@@ -14,6 +14,19 @@
 (define (asm-string a)
   (with-output-to-string (lambda () (asm-display a))))
 
+(define label-occurred? (make-parameter #f))
+(define-syntax (sqbracket stx)
+  (syntax-case stx ()
+    [(_ e)
+     #'(parameterize ([label-occurred? #f])
+         (let ([v e])
+           (string-append "["
+                          v
+                          (if (label-occurred?)
+                              " + rip"
+                              "")
+                          "]")))]))
+
 (define tab (make-string 8 #\space))
 
 (define (comment->string c)
@@ -28,8 +41,14 @@
 ;; prefix with _ for Mac
 (define label-symbol->string
   (match (system-type 'os)
-    ['macosx (λ (s) (string-append "_" (symbol->string s)))]
-    [_ (λ (s) (symbol->string s))]))
+    ['macosx
+     (λ (s)
+       (label-occurred? #t)
+       (string-append "_" (symbol->string s)))]
+    [_
+     (λ (s)
+       (label-occurred? #t)
+       (symbol->string s))]))
 
        ;(if (and (current-shared?) (memq s (current-extern-labels)))
            ; hack for ELF64 shared libraries in service of
@@ -39,9 +58,15 @@
 
 (define extern-label-decl-symbol->string
   (match (system-type 'os)
-    ['macosx  (λ (s) (string-append "_" (symbol->string s)))]
-    [_     (λ (s) (symbol->string s))]))
-  
+    ['macosx
+     (λ (s)
+       (label-occurred? #t)
+       (string-append "_" (symbol->string s)))]
+    [_
+     (λ (s)
+       (label-occurred? #t)
+       (symbol->string s))]))
+
 ;; Instruction -> String
 (define (common-instruction->string i)
   (let ((as (instruction-args i)))
@@ -66,7 +91,7 @@
     (match x
       [(? integer?) (number->string x)]
       [(? symbol?) (symbol->string x)]
-      [($ x) (string-append (label-symbol->string x)  " + rip ")]))
+      [($ x) (label-symbol->string x)]))
   (match m
     [(Mem l b i o s)
      (string-append
@@ -80,11 +105,14 @@
 (define (arg->string e)
   (match e
     [(? register?) (symbol->string e)]
-    [(? Mem?) (string-append "[" (mem->string e) "]")]
-    [(Offset (? register? r)) (string-append "[" (symbol->string r) "]")]
-    [(Offset ($ (? label? r))) (string-append "[" (label-symbol->string r) " + rip]")]
-    [(Offset e)
-     (string-append "[" (exp->string e) "]")]
+    #;[(? Mem?) (string-append "[" (mem->string e) "]")]
+    #;[(Offset (? register? r)) (string-append "[" (symbol->string r) "]")]
+    #;[(Offset ($ (? label? r))) (string-append "[" (label-symbol->string r) " + rip]")]
+    #;[(Offset e) (string-append "[" (exp->string e) "]")]
+    [(? Mem?)                  (sqbracket (mem->string e))]
+    [(Offset (? register? r))  (sqbracket (symbol->string r))]
+    [(Offset ($ (? label? r))) (sqbracket (label-symbol->string r))]
+    [(Offset e)                (sqbracket (exp->string e))]
     [_ (exp->string e)]))
 
 ;; Exp -> String
@@ -93,6 +121,7 @@
     [(? register?) (symbol->string e)]
     [(? integer?) (number->string e)]
     [($ x) (label-symbol->string x)]
+    ;; [($ x) (string-append (label-symbol->string x) " + rip")]
     [(list '? e1 e2 e3)
      (string-append "(" (exp->string e1) " ? " (exp->string e2) " : " (exp->string e3) ")")]
     [(list (? exp-unop? o) e1)
@@ -118,17 +147,17 @@
     [(Data)         (string-append tab ".data\n\t .p2align 3")] ; 8-byte aligned data
     [(Data n)       (string-append tab (data-section n))]
     [(Extern ($ l)) (string-append tab ".extern " (extern-label-decl-symbol->string l))]
-    [(Global ($ l))       (string-append tab ".global " (label-symbol->string l))]
+    [(Global ($ l)) (string-append tab ".global " (label-symbol->string l))]
     ;;[(Label ($ l))  (string-append "_" (symbol->string l) ":")]
     [(Label ($ l))  (string-append (label-symbol->string l) ":")]
     [(Lea d (? Mem? m))
      (string-append tab "lea "
-                    (arg->string d) ", [rip + "  
-                    (mem->string m) "]")]
+                    (arg->string d) ", "
+                    (sqbracket (mem->string m)))]
     [(Lea d e)
      (string-append tab "lea "
-                    (arg->string d) ", [rip + "
-                    (arg->string e) "]")]
+                    (arg->string d) ", "
+                    (sqbracket (arg->string e)))]
     [(Equ x c)
      (string-append tab
                     (symbol->string x)