Fixing constant propogation test

The variable_sensitivity_domaint::ai_simplify was retuning true if it
simplied, but it should have been returning true if no simplification
was performed (as specified in ai.h).

The test also had the wrong number of goto statements, there are two in
the original program, both of which are removed

Author: thk123

regression/goto-analyzer/constant_propagation_01/main.c

@@ -1,13 +1,14 @@
+#include <assert.h>
 
 int main()
 {
   int i, j=20;
-  
+
   if (j==20)
   {
     int x=1,y=2,z;
     z=x+y;
     assert(z==3);
   }
-    
+
 }

regression/goto-analyzer/constant_propagation_01/test.desc

@@ -3,7 +3,7 @@ main.c
 --variable --simplify out.gb
 ^EXIT=0$
 ^SIGNAL=0$
-^Simplified:  assert: 1, assume: 0, goto: 1, assigns: 5, function calls: 0$
+^Simplified:  assert: 1, assume: 0, goto: 2, assigns: 5, function calls: 0$
 ^Unmodified:  assert: 0, assume: 0, goto: 0, assigns: 12, function calls: 2$
 --
 ^warning: ignoring

src/analyses/variable-sensitivity/variable_sensitivity_domain.cpp

@@ -261,8 +261,7 @@ Function: variable_sensitivity_domaint::ai_simplify
    ns - the namespace
    lhs - is the expression on the left hand side
 
- Outputs: True if simplified the condition. False otherwise. condition
-          will be updated with the simplified condition if it has worked
+ Outputs: True if no simplification was made
 
  Purpose: Use the information in the domain to simplify the expression
           with respect to the current location.  This may be able to
@@ -282,13 +281,13 @@ bool variable_sensitivity_domaint::ai_simplify(
     sharing_ptrt<abstract_objectt> res = abstract_state.eval(condition, ns);
     exprt c = res->to_constant();
 
-    if (c.id() == ID_nil)  // TODO : simplification within an expression
-      return false;
+    if(c.id() == ID_nil)  // TODO : simplification within an expression
+      return true;
     else
     {
-      bool b = (condition!=c);
+      bool condition_changed = (condition!=c);
       condition = c;
-      return b;
+      return !condition_changed;
     }
   }
   assert(0); // All conditions should be handled
@@ -335,7 +334,7 @@ Function: variable_sensitivity_domaint::ai_simplify_lhs
    condition - the expression to simplify
    ns - the namespace
 
- Outputs: True if simplified the condition. False otherwise. condition
+ Outputs: True if condition did not change. False otherwise. condition
           will be updated with the simplified condition if it has worked
 
  Purpose: Use the information in the domain to simplify the expression
@@ -360,7 +359,7 @@ bool variable_sensitivity_domaint::ai_simplify_lhs(
       condition = simplify_expr(ie, ns);
     }
 
-    return changed;
+    return !changed;
   }
   else if (condition.id()==ID_dereference)
   {
@@ -373,7 +372,7 @@ bool variable_sensitivity_domaint::ai_simplify_lhs(
       condition = simplify_expr(de, ns);  // So *(&x) -> x
     }
 
-    return changed;
+    return !changed;
   }
   else if (condition.id()==ID_member)
   {
@@ -386,8 +385,8 @@ bool variable_sensitivity_domaint::ai_simplify_lhs(
       condition = simplify_expr(me, ns);
     }
 
-    return changed;
+    return !changed;
   }
   else
-    return false;
+    return true;
 }