simplify_abs now has new interface

This improves memory safety.

Author: Daniel Kroening

src/util/simplify_expr.cpp

@@ -63,21 +63,17 @@ struct simplify_expr_cachet
 simplify_expr_cachet simplify_expr_cache;
 #endif
 
-bool simplify_exprt::simplify_abs(exprt &expr)
+simplify_exprt::resultt<> simplify_exprt::simplify_abs(const abs_exprt &expr)
 {
-  if(expr.operands().size()!=1)
-    return true;
-
-  if(to_unary_expr(expr).op().is_constant())
+  if(expr.op().is_constant())
   {
     const typet &type = to_unary_expr(expr).op().type();
 
     if(type.id()==ID_floatbv)
     {
       ieee_floatt value(to_constant_expr(to_unary_expr(expr).op()));
       value.set_sign(false);
-      expr=value.to_expr();
-      return false;
+      return value.to_expr();
     }
     else if(type.id()==ID_signedbv ||
             type.id()==ID_unsignedbv)
@@ -87,20 +83,18 @@ bool simplify_exprt::simplify_abs(exprt &expr)
       {
         if(*value >= 0)
         {
-          expr = to_unary_expr(expr).op();
-          return false;
+          return to_unary_expr(expr).op();
         }
         else
         {
           value->negate();
-          expr = from_integer(*value, type);
-          return false;
+          return from_integer(*value, type);
         }
       }
     }
   }
 
-  return true;
+  return unchanged(expr);
 }
 
 bool simplify_exprt::simplify_sign(exprt &expr)
@@ -2528,7 +2522,14 @@ bool simplify_exprt::simplify_node(exprt &expr)
   else if(expr.id()==ID_isnormal)
     no_change = simplify_isnormal(expr) && no_change;
   else if(expr.id()==ID_abs)
-    no_change = simplify_abs(expr) && no_change;
+  {
+    auto r = simplify_abs(to_abs_expr(expr));
+    if(r.has_changed())
+    {
+      no_change = false;
+      expr = r.expr;
+    }
+  }
   else if(expr.id()==ID_sign)
     no_change = simplify_sign(expr) && no_change;
   else if(expr.id() == ID_popcount)

src/util/simplify_expr_class.h

@@ -25,6 +25,7 @@ Author: Daniel Kroening, [email protected]
 #include "replace_expr.h"
 #endif
 
+class abs_exprt;
 class array_exprt;
 class bswap_exprt;
 class byte_extract_exprt;
@@ -159,7 +160,7 @@ class simplify_exprt
   bool simplify_isinf(exprt &expr);
   bool simplify_isnan(exprt &expr);
   bool simplify_isnormal(exprt &expr);
-  bool simplify_abs(exprt &expr);
+  resultt<> simplify_abs(const abs_exprt &);
   bool simplify_sign(exprt &expr);
   bool simplify_popcount(popcount_exprt &expr);
   bool simplify_complex(exprt &expr);