From 061bd3c48dce7104c848eb6d5028f90d6d98dfb8 Mon Sep 17 00:00:00 2001
From: Dmitry Boulytchev <dboulytchev@gmail.com>
Date: Thu, 11 Apr 2019 17:31:45 +0300
Subject: [PATCH] Better support for assignment

---
 src/SM.ml  | 13 +++++++++----
 src/X86.ml | 11 ++++++++++-
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/SM.ml b/src/SM.ml
index 4e9a68b3c..6ce19894b 100644
--- a/src/SM.ml
+++ b/src/SM.ml
@@ -12,7 +12,8 @@ open Language
 (* create an S-expression                    *) | SEXP    of string * int
 (* load a variable to the stack              *) | LD      of string
 (* load a variable address to the stack      *) | LDA     of string
-(* store a value into a reference            *) | ST
+(* store a value into a variable             *) | ST      of string
+(* store a value into a reference            *) | STI
 (* store a value into array/sexp/string      *) | STA                                  
 (* a label                                   *) | LABEL   of string
 (* unconditional jump                        *) | JMP     of string
@@ -67,7 +68,8 @@ let rec eval env ((cstack, stack, ((st, i, o) as c)) as conf) = function
                                  eval env (cstack, (Value.sexp s @@ List.rev vs)::stack', c) prg'
     | LD x                    -> eval env (cstack, State.eval st x :: stack, c) prg'
     | LDA x                   -> eval env (cstack, (Value.Var x) :: stack, c) prg'
-    | ST                      -> let z::r::stack' = stack in eval env (cstack, z::stack', (Expr.update st r z, i, o)) prg'
+    | ST  x                   -> let z::stack' = stack in eval env (cstack, z::stack', (State.update x z st, i, o)) prg'
+    | STI                     -> let z::r::stack' = stack in eval env (cstack, z::stack', (Expr.update st r z, i, o)) prg'
     | STA                     -> let v::j::x::stack' = stack in eval env (cstack, v::stack', (Expr.update st (Value.Elem (x, Value.to_int j)) v, i, o)) prg'
     | LABEL  _                -> eval env conf prg'
     | JMP    l                -> eval env conf (env#labeled l)
@@ -259,9 +261,12 @@ let compile (defs, p) =
                                
   | Expr.StringVal e        -> let lsv, env = env#get_label in
                                add_code (compile_expr lsv env e) lsv false [CALL (".stringval", 1)]
-      
+
   | Expr.Assign (x, e)      -> let lassn, env = env#get_label in
-                               add_code (compile_list lassn env [x; e]) lassn false [match x with Expr.ElemRef _ -> STA | _ -> ST]
+                               (match x with
+                               | Expr.Ref x -> add_code (compile_expr lassn env e) lassn false [ST x]
+                               | _          -> add_code (compile_list lassn env [x; e]) lassn false [match x with Expr.ElemRef _ -> STA | _ -> STI]
+                               )
                              
   | Expr.Skip               -> env, false, []
 
diff --git a/src/X86.ml b/src/X86.ml
index e4ff62b83..b69c360c0 100644
--- a/src/X86.ml
+++ b/src/X86.ml
@@ -180,11 +180,20 @@ let compile env code =
 	      | S _ | M _ -> [Mov (env'#loc x, eax); Mov (eax, s)]
 	      | _         -> [Mov (env'#loc x, s)]
 	     )
+
+          | ST x ->              
+	     let env' = env#variable x in
+             let s    = env'#peek      in
+             env',
+             (match s with
+              | S _ | M _ -> [Mov (s, eax); Mov (eax, env'#loc x)]
+              | _         -> [Mov (s, env'#loc x)]
+	     )
              
           | STA ->
              call env ".sta" 3
                            
-	  | ST ->
+	  | STI ->
              let v, x, env' = env#pop2 in
              env'#push x,
              (match x with