tree-vrp.c (simplify_stmt_for_jump_threading): Try to simplify assignments too.

	* tree-vrp.c (simplify_stmt_for_jump_threading): Try to
	simplify assignments too.  If the RHS collapses to a singleton
	range, then return the value for the range.

	* gcc.dg/tree-ssa/ssa-vrp-thread-1.c: New test.

From-SVN: r201898

gcc/ChangeLog

+2013-08-21  Jeff Law  <law@redhat.com>
+
+	* tree-vrp.c (simplify_stmt_for_jump_threading): Try to
+	simplify assignments too.  If the RHS collapses to a singleton
+	range, then return the value for the range.
+
 2013-08-21  Kirill Yukhin  <kirill.yukhin@intel.com>
 
         * config/i386/sse.md (V16): Rename to...

gcc/testsuite/ChangeLog

+2013-08-21  Jeff Law  <law@redhat.com>
+
+	* gcc.dg/tree-ssa/ssa-vrp-thread-1.c: New test.
+
 2013-08-21  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/56134

gcc/testsuite/gcc.dg/tree-ssa/ssa-vrp-thread-1.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-vrp1-details" } */
+
+
+struct basic_block_def;
+typedef struct basic_block_def *basic_block;
+enum gimple_code
+{
+  LAST_AND_UNUSED_GIMPLE_CODE
+};
+struct omp_region
+{
+  struct omp_region *outer;
+  basic_block cont;
+};
+void
+build_omp_regions_1 (basic_block bb, struct omp_region *parent,
+		     unsigned char single_tree, enum gimple_code code)
+{
+  if (code == 25)
+    parent = parent->outer;
+  else if (code == 42)
+    parent->cont = bb;
+  if (single_tree && !parent)
+    return;
+  oof ();
+}
+
+/* { dg-final { scan-tree-dump-times "Threaded" 1 "vrp1" }  } */
+/* { dg-final { cleanup-tree-dump "vrp1" } } */
+

gcc/tree-vrp.c

@@ -9273,15 +9273,27 @@ static vec<tree> equiv_stack;
 static tree
 simplify_stmt_for_jump_threading (gimple stmt, gimple within_stmt)
 {
-  /* We only use VRP information to simplify conditionals.  This is
-     overly conservative, but it's unclear if doing more would be
-     worth the compile time cost.  */
-  if (gimple_code (stmt) != GIMPLE_COND)
-    return NULL;
+  if (gimple_code (stmt) == GIMPLE_COND)
+    return vrp_evaluate_conditional (gimple_cond_code (stmt),
+				     gimple_cond_lhs (stmt),
+				     gimple_cond_rhs (stmt), within_stmt);
+
+  if (gimple_code (stmt) == GIMPLE_ASSIGN)
+    {
+      value_range_t new_vr = VR_INITIALIZER;
+      tree lhs = gimple_assign_lhs (stmt);
+
+      if (TREE_CODE (lhs) == SSA_NAME
+	  && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
+	      || POINTER_TYPE_P (TREE_TYPE (lhs))))
+	{
+	  extract_range_from_assignment (&new_vr, stmt);
+	  if (range_int_cst_singleton_p (&new_vr))
+	    return new_vr.min;
+	}
+    }
 
-  return vrp_evaluate_conditional (gimple_cond_code (stmt),
-				   gimple_cond_lhs (stmt),
-				   gimple_cond_rhs (stmt), within_stmt);
+  return NULL_TREE;
 }
 
 /* Blocks which have more than one predecessor and more than