[gcjx] Definite Assignment Fix

[Ranjit Mathew <rmathew at gmail dot com>]

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Hi,

  This patch corrects a minor error in variable_state::check_loop()
that was exposed by a couple of Jacks tests. As explained in the
beginning of Chapter 16 of the JLS (page 531 in the JLS3 PDF), we
can conclusively state that an assignment to a variable has occurred
only if it is both definitely assigned and not definitely unassigned.
The method was only checking for the latter.

I found the print() method handy for debugging but it had a couple
of minor problems - it used to print all variables without information
on whether a variable is definitely [un]assigned and it was not a
const method (using const iterators) and was thus ununsable with a
"const variable_state& other". The attached patch also includes a
fix for these.

The net effect of this patch on my Jacks run is:

  @@ -48,2 +47,0 @@
  -RESULT 16.2.10-definite-unassign-pass-3 FAILED
  -RESULT 16.2.11-definite-unassign-pass-3 FAILED
  @@ -62 +59,0 @@
  -RESULT 16.2.9-definite-unassign-pass-3 FAILED
  @@ -252,3 +249,6 @@
  -RESULT non-jls-jsr41.4-loop-1 FAILED
  -RESULT non-jls-jsr41.4-loop-2 FAILED
  -RESULT non-jls-jsr41.4-loop-3 FAILED
  +RESULT non-jls-jsr41.4-loop-16 FAILED
  +RESULT non-jls-jsr41.4-loop-17 FAILED
  +RESULT non-jls-jsr41.4-loop-18 FAILED
  +RESULT non-jls-jsr41.4-loop-4 FAILED
  +RESULT non-jls-jsr41.4-loop-5 FAILED
  +RESULT non-jls-jsr41.4-loop-6 FAILED

The new FAILs are the exposure of a problem with boolean expressions
like "foo && false", which I plan to tackle next.

OK?

Thanks,
Ranjit

- --
Ranjit Mathew       Email: rmathew AT gmail DOT com

Bangalore, INDIA.     Web: http://ranjitmathew.hostingzero.com/




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Index: ChangeLog
from  Ranjit Mathew  <rmathew@gcc.gnu.org>

	* defassign.cc (variable_state::check_loop): Complain about possible
	multiple assignments only if the variable in question is definitely
	assigned and not definitely unassigned.
	(variable_state::print): Make const method and use const iterators.
	Print out only definitely [un]assigned variables.

Index: defassign.cc
===================================================================
--- defassign.cc	2005-09-17 10:06:59.000000000 +0530
+++ defassign.cc	2005-09-17 13:32:44.000000000 +0530
@@ -170,8 +170,9 @@ public:
 
   // Perform checking after a loop completes.  THIS is the state
   // before the loop.  OTHER is the state after the loop.  Look for
-  // final variables which are not definitely unassigned in OTHER but
-  // are definitely unassigned here and issue errors for them.
+  // final variables which are definitely assigned and not definitely
+  // unassigned in OTHER but are definitely unassigned here and issue
+  // errors for them.
   void check_loop (model_element *request, const variable_state &other)
   {
     for (map_type::const_iterator i = other.unassign.begin ();
@@ -180,9 +181,9 @@ public:
       {
 	if ((*i).first->final_p () && ! (*i).second)
 	  {
-	    if (unassigned_p ((*i).first))
+	    if (other.assigned_p ((*i).first) && unassigned_p ((*i).first))
 	      {
-		std::cerr << request->error ("variable %1 may be assigned "
+		std::cerr << request->error ("variable %1 might be assigned "
 					     "multiple times")
 		  // FIXME: need operator% for this.
 		  % (*i).first->get_name ();
@@ -191,18 +192,23 @@ public:
       }
   }
 
-  /// For debugging convenience.
-  void print ()
+  /// For debugging convenience.  Prints the definitely [un]assigned
+  /// variables in this state.
+  void print (void) const
   {
     std::cout << "================" << std::endl;
-    for (map_type::iterator i = assign.begin ();
+
+    for (map_type::const_iterator i = assign.begin ();
 	 i != assign.end ();
 	 ++i)
-      std::cout << "assigned: " << (*i).first->get_name () << std::endl;
-    for (map_type::iterator i = unassign.begin ();
+      if ((*i).second)
+        std::cout << "assigned: " << (*i).first->get_name () << std::endl;
+
+    for (map_type::const_iterator i = unassign.begin ();
 	 i != unassign.end ();
 	 ++i)
-      std::cout << "unassigned: " << (*i).first->get_name () << std::endl;
+      if ((*i).second)
+        std::cout << "unassigned: " << (*i).first->get_name () << std::endl;
   }
 };