re PR tree-optimization/42703 (ICE in generate_subtree_copies with out of bounds array access)

2010-01-13  Martin Jambor  <mjambor@suse.cz>

	PR tree-optimization/42703
	* tree-sra.c (analyze_access_subtree): Check that we can build a
	reference to the original data within the aggregate.

	* testsuite/gcc.c-torture/compile/pr42703.c: New test.

From-SVN: r155863

gcc/ChangeLog

+2010-01-13  Martin Jambor  <mjambor@suse.cz>
+
+	PR tree-optimization/42703
+	* tree-sra.c (analyze_access_subtree): Check that we can build a
+	reference to the original data within the aggregate.
+
 2010-01-13  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/42705

gcc/testsuite/ChangeLog

+2010-01-13  Martin Jambor  <mjambor@suse.cz>
+
+	PR tree-optimization/42703
+	* testsuite/gcc.c-torture/compile/pr42703.c: New test.
+
 2010-01-13  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/42705

gcc/testsuite/gcc.c-torture/compile/pr42703.c

+__extension__ typedef unsigned long long int uint64_t;
+typedef uint64_t ScmUInt64;
+void swapb64(ScmUInt64 *loc) 
+{
+    union {
+        ScmUInt64 l;
+        unsigned char c[4];
+    } dd;
+    unsigned char t;
+    dd.l = *loc;
+    (t = dd.c[3], dd.c[3] = dd.c[4], dd.c[4] = t);
+}

gcc/tree-sra.c

@@ -1659,7 +1659,13 @@ analyze_access_subtree (struct access *root, bool allow_replacements,
 
   if (allow_replacements && scalar && !root->first_child
       && (root->grp_hint
-	  || (direct_read && root->grp_write)))
+	  || (direct_read && root->grp_write))
+      /* We must not ICE later on when trying to build an access to the
+	 original data within the aggregate even when it is impossible to do in
+	 a defined way like in the PR 42703 testcase.  Therefore we check
+	 pre-emptively here that we will be able to do that.  */
+      && build_ref_for_offset (NULL, TREE_TYPE (root->base), root->offset,
+			       root->type, false))
     {
       if (dump_file && (dump_flags & TDF_DETAILS))
 	{