re PR tree-optimization/29738 (Missed constant propagation into loops)

	PR tree-optimization/29738
	* tree-ssa-ccp.c: Remove UNKNOWN_VAL from comments.
	(ccp_lattice_t): Remove UNKNOWN_VAL.
	(dump_lattice_value, ccp_lattice_meet, ccp_visit_phi_node):
	Do not handle UNKNOWN_VAL.
	(get_default_value): Set initial value of virtual operands to
	VARYING.
	(get_value): Always use get_default_value on uninitialized
	operands.
	(set_value_varying, surely_varying_stmt_p): New functions.
	(set_lattice_value): Do not pass argument to get_value.
	Do not handle UNKNOWN_VAL.
	(likely_value): Follow the semantics described in the comment.
	(ccp_initialize): Use surely_varying_stmt_p.  Do not mark
	phi nodes DONT_SIMULATE_AGAIN.
	(ccp_fold): Do not pass argument to get_value.
	(fold_const_aggregate_ref, visit_assignment): Ditto.  Do not
	handle UNKNOWN_VAL.

	* gcc.dg/tree-ssa/ssa-ccp-14.c: New test.
	* gcc.dg/tree-ssa/ssa-ccp-15.c: New test.

From-SVN: r118602

gcc/ChangeLog

+2006-11-08  Zdenek Dvorak <dvorakz@suse.cz>
+
+	PR tree-optimization/29738
+	* tree-ssa-ccp.c: Remove UNKNOWN_VAL from comments.
+	(ccp_lattice_t): Remove UNKNOWN_VAL.
+	(dump_lattice_value, ccp_lattice_meet, ccp_visit_phi_node):
+	Do not handle UNKNOWN_VAL.
+	(get_default_value): Set initial value of virtual operands to
+	VARYING.
+	(get_value): Always use get_default_value on uninitialized
+	operands.
+	(set_value_varying, surely_varying_stmt_p): New functions.
+	(set_lattice_value): Do not pass argument to get_value.
+	Do not handle UNKNOWN_VAL.
+	(likely_value): Follow the semantics described in the comment.
+	(ccp_initialize): Use surely_varying_stmt_p.  Do not mark
+	phi nodes DONT_SIMULATE_AGAIN.
+	(ccp_fold): Do not pass argument to get_value.
+	(fold_const_aggregate_ref, visit_assignment): Ditto.  Do not
+	handle UNKNOWN_VAL.
+
 2006-11-08  Andrew Pinski  <Andrew_Pinski@playstation.sony.com>
 
 	* tree-pretty-print.c (dump_generic_node) <INTEGER_CST>: Use 

gcc/testsuite/ChangeLog

+2006-11-08  Zdenek Dvorak <dvorakz@suse.cz>
+
+	* gcc.dg/tree-ssa/ssa-ccp-14.c: New test.
+	* gcc.dg/tree-ssa/ssa-ccp-15.c: New test.
+
 2006-11-08  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* gcc.dg/torture/builtin-math-3.c: Add more sincos tests.

gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-14.c

+/* PR tree-optimization/29738.  We used not to realize that "i" can never
+   become nonzero.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+int i;
+
+void foo (void);
+void bar (void)
+{
+  int j;
+  i = 0;
+  for (j = 0; j < 10000; j++)
+    if (i)
+      foo ();
+}
+
+/* Everything except for the "i = 0" assignment should get removed.  */
+/* { dg-final { scan-tree-dump-times "if" 0 "optimized"} } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-15.c

+/* { dg-do compile } */ 
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+/* Check that the initial values are honored when necessary.  */
+
+void link_error (void);
+
+/* The call to link_error cannot be eliminated in this case.  */
+
+void test1 (int param1, int param2, int x)
+{
+  if (param1)
+    x = 3;
+
+  if (param2)
+    if (x != 3)
+      link_error ();
+}
+
+/* The call to link_error cannot be eliminated in this case.  */
+
+int global;
+void test2 (int param1, int param2)
+{
+  if (param1)
+    global = 3;
+
+  if (param2)
+    if (global != 3)
+      link_error ();
+}
+
+/* In this case, we can eliminate the call, as unless "local" is set
+   to 3, its value is undefined.  */
+
+void test3 (int param1, int param2)
+{
+  int local;
+
+  if (param1)
+    local = 3;
+
+  if (param2)
+    if (local != 3)
+      link_error ();
+}
+
+/* { dg-final { scan-tree-dump-times "link_error" 2 "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */