[PATCH] Fix PR28776, ICE in build_polynomial_chrec

[Sebastian Pop]

> 2006-08-22  Richard Guenther  <rguenther@suse.de>
> 
> 	PR middle-end/28776
> 	* tree-scalar-evolution.c (fold_used_pointer): Convert
> 	arguments to arithmetic expression to the chrecs type.
> 
> 	* gcc.c-torture/compile/pr28776-1.c: New testcase.
> 	* gcc.c-torture/compile/pr28776-2.c: Likewise.
> 

Ok, with a small change.

:REVIEWMAIL:

> Index: tree-scalar-evolution.c
> ===================================================================
> *** tree-scalar-evolution.c	(revision 116318)
> --- tree-scalar-evolution.c	(working copy)
> *************** fold_used_pointer (tree expr)
> *** 1847,1852 ****
> --- 1847,1854 ----
>         if (new0 == op0 && new1 == op1)
>   	return expr;
>   
> +       new0 = chrec_convert (TREE_TYPE (expr), new0, NULL_TREE);
> +       new1 = chrec_convert (TREE_TYPE (expr), new1, NULL_TREE);

I'm seeing that fold_used_pointer is currently used only in a
MODIFY_EXPR case in analyze_scalar_evolution_1, that means that you
can add an extra "at_stmt" argument to fold_used_pointer and pass it
to chrec_convert instead of passing NULL_TREE.  The conversion will
just have more precise information.  Try something like the following
patch.

Thanks,
Sebastian

Index: tree-scalar-evolution.c
===================================================================
--- tree-scalar-evolution.c	(revision 116321)
+++ tree-scalar-evolution.c	(working copy)
@@ -1765,7 +1765,8 @@ pointer_offset_p (tree expr)
 /* EXPR is a scalar evolution of a pointer that is dereferenced or used in
    comparison.  This means that it must point to a part of some object in
    memory, which enables us to argue about overflows and possibly simplify
-   the EXPR.  Returns the simplified value.
+   the EXPR.  AT_STMT is the statement in which this conversion has to be
+   performed.  Returns the simplified value.
 
    Currently, for
 
@@ -1820,7 +1821,7 @@ pointer_offset_p (tree expr)
    bugs.  */
 
 static tree
-fold_used_pointer (tree expr)
+fold_used_pointer (tree expr, tree at_stmt)
 {
   tree op0, op1, new0, new1;
   enum tree_code code = TREE_CODE (expr);
@@ -1833,13 +1834,13 @@ fold_used_pointer (tree expr)
 
       if (pointer_offset_p (op1))
 	{
-	  new0 = fold_used_pointer (op0);
+	  new0 = fold_used_pointer (op0, at_stmt);
 	  new1 = fold_used_pointer_cast (op1);
 	}
       else if (code == PLUS_EXPR && pointer_offset_p (op0))
 	{
 	  new0 = fold_used_pointer_cast (op0);
-	  new1 = fold_used_pointer (op1);
+	  new1 = fold_used_pointer (op1, at_stmt);
 	}
       else
 	return expr;
@@ -1847,6 +1848,9 @@ fold_used_pointer (tree expr)
       if (new0 == op0 && new1 == op1)
 	return expr;
 
+      new0 = chrec_convert (TREE_TYPE (expr), new0, at_stmt);
+      new1 = chrec_convert (TREE_TYPE (expr), new1, at_stmt);
+
       if (code == PLUS_EXPR)
 	expr = chrec_fold_plus (TREE_TYPE (expr), new0, new1);
       else
@@ -1948,7 +1952,7 @@ analyze_scalar_evolution_1 (struct loop 
       if (POINTER_TYPE_P (type)
 	  && !automatically_generated_chrec_p (res)
 	  && pointer_used_p (var))
-	res = fold_used_pointer (res);
+	res = fold_used_pointer (res, def);
       break;
 
     case PHI_NODE: