2008-03-18 Richard Guenther <rguenther@suse.de>

	* tree-ssa-sccvn.c (visit_reference_op_load): If the lookup
	found an expression with constants, note that in the VN for the lhs.
	* tree-ssa-pre.c (eliminate): Visit COND_EXPR statements and
	fold them to constants if possible.  Run cleanup_cfg if done so.
	(execute_pre): Return todo.
	(do_pre): Likewise.
	(execute_fre): Likewise.
	* tree-ssa-forwprop.c (can_propagate_from): Allow propagation
	of constants.
	(get_prop_source_stmt): Look through pointer conversions.

	* gcc.dg/tree-ssa/forwprop-4.c: New testcase.
	* gcc.dg/tree-ssa/ssa-fre-16.c: Likewise.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@133315 138bc75d-0d04-0410-961f-82ee72b054a4

7 files changed, 130 insertions, 12 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 82374258411..add3e25ad86 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,16 @@
+2008-03-18  Richard Guenther  <rguenther@suse.de>
+
+	* tree-ssa-sccvn.c (visit_reference_op_load): If the lookup
+	found an expression with constants, note that in the VN for the lhs.
+	* tree-ssa-pre.c (eliminate): Visit COND_EXPR statements and
+	fold them to constants if possible.  Run cleanup_cfg if done so.
+	(execute_pre): Return todo.
+	(do_pre): Likewise.
+	(execute_fre): Likewise.
+	* tree-ssa-forwprop.c (can_propagate_from): Allow propagation
+	of constants.
+	(get_prop_source_stmt): Look through pointer conversions.
+
 2008-03-18  Jan Hubicka  <jh@suse.cz>
 
 	* tree-pretty-print.c: Include predict.h.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index d5543830532..d9bca3944e0 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2008-03-18  Richard Guenther  <rguenther@suse.de>
 
+	* gcc.dg/tree-ssa/forwprop-4.c: New testcase.
+	* gcc.dg/tree-ssa/ssa-fre-16.c: Likewise.
+
+2008-03-18  Richard Guenther  <rguenther@suse.de>
+
 	* gcc.dg/tree-ssa/loop-19.c: Revert previous change.
 
 2008-03-17  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/forwprop-4.c b/gcc/testsuite/gcc.dg/tree-ssa/forwprop-4.c
new file mode 100644
index 00000000000..7eabd1a7bd8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/forwprop-4.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-forwprop1" } */
+
+/* We should be able to fold the comparison at least with the
+   first forwprop pass, if not a ccp pass before.  */
+
+extern void link_error (void);
+void foo()
+{
+  int i;
+  char *p = (char *)&i;
+  long *q = (long *)p;
+  if (q == 0)
+    link_error ();
+}
+
+/* { dg-final { scan-tree-dump-not "link_error" "forwprop1" } } */
+/* { dg-final { cleanup-tree-dump "forwprop1" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-16.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-16.c
new file mode 100644
index 00000000000..56d85e58e7f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-16.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-fre" } */
+
+/* FRE should be able to combine i and j and perform simplification
+   on the condition.  */
+
+extern void link_error (void);
+int i;
+int foo(int b, int c)
+{
+  i = b + 1;
+  int j = i - 1;
+  if (b != j)
+    link_error ();
+}
+
+/* { dg-final { scan-tree-dump-not "link_error" "fre" } } */
+/* { dg-final { cleanup-tree-dump "fre" } } */
diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index 5108cfcd6f2..1766869d0c4 100644
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -218,14 +218,28 @@ get_prop_source_stmt (tree name, bool single_use_only, bool *single_use_p)
     /* If name is not a simple copy destination, we found it.  */
     if (TREE_CODE (GIMPLE_STMT_OPERAND (def_stmt, 1)) != SSA_NAME)
       {
+	tree rhs;
+
 	if (!single_use_only && single_use_p)
 	  *single_use_p = single_use;
 
-	return def_stmt;
+	/* We can look through pointer conversions in the search
+	   for a useful stmt for the comparison folding.  */
+	rhs = GIMPLE_STMT_OPERAND (def_stmt, 1);
+	if ((TREE_CODE (rhs) == NOP_EXPR
+	     || TREE_CODE (rhs) == CONVERT_EXPR)
+	    && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
+	    && POINTER_TYPE_P (TREE_TYPE (rhs))
+	    && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))))
+	  name = TREE_OPERAND (rhs, 0);
+	else
+	  return def_stmt;
+      }
+    else
+      {
+	/* Continue searching the def of the copy source name.  */
+	name = GIMPLE_STMT_OPERAND (def_stmt, 1);
       }
-
-    /* Continue searching the def of the copy source name.  */
-    name = GIMPLE_STMT_OPERAND (def_stmt, 1);
   } while (1);
 }
 
@@ -245,6 +259,10 @@ can_propagate_from (tree def_stmt)
   if (REFERENCE_CLASS_P (rhs))
     return false;
 
+  /* Constants can be always propagated.  */
+  if (is_gimple_min_invariant (rhs))
+    return true;
+
   /* We cannot propagate ssa names that occur in abnormal phi nodes.  */
   switch (TREE_CODE_LENGTH (TREE_CODE (rhs)))
     {
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index 616627ccb1b..ad628a31916 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -3605,10 +3605,11 @@ do_SCCVN_insertion (tree stmt, tree ssa_vn)
 
 /* Eliminate fully redundant computations.  */
 
-static void
+static unsigned int
 eliminate (void)
 {
   basic_block b;
+  unsigned int todo = 0;
 
   FOR_EACH_BB (b)
     {
@@ -3689,8 +3690,46 @@ eliminate (void)
 		    }
 		}
 	    }
+	  /* Visit COND_EXPRs and fold the comparison with the
+	     available value-numbers.  */
+	  else if (TREE_CODE (stmt) == COND_EXPR
+		   && COMPARISON_CLASS_P (COND_EXPR_COND (stmt)))
+	    {
+	      tree cond = COND_EXPR_COND (stmt);
+	      tree op0 = TREE_OPERAND (cond, 0);
+	      tree op1 = TREE_OPERAND (cond, 1);
+	      tree result;
+
+	      if (TREE_CODE (op0) == SSA_NAME)
+		op0 = VN_INFO (op0)->valnum;
+	      if (TREE_CODE (op1) == SSA_NAME)
+		op1 = VN_INFO (op1)->valnum;
+	      result = fold_binary (TREE_CODE (cond), TREE_TYPE (cond),
+				    op0, op1);
+	      if (result && TREE_CODE (result) == INTEGER_CST)
+		{
+		  COND_EXPR_COND (stmt) = result;
+		  update_stmt (stmt);
+		  todo = TODO_cleanup_cfg;
+		}
+	    }
+	  else if (TREE_CODE (stmt) == COND_EXPR
+		   && TREE_CODE (COND_EXPR_COND (stmt)) == SSA_NAME)
+	    {
+	      tree op = COND_EXPR_COND (stmt);
+	      op = VN_INFO (op)->valnum;
+	      if (TREE_CODE (op) == INTEGER_CST)
+		{
+		  COND_EXPR_COND (stmt) = integer_zerop (op)
+		    ? boolean_false_node : boolean_true_node;
+		  update_stmt (stmt);
+		  todo = TODO_cleanup_cfg;
+		}
+	    }
 	}
     }
+
+  return todo;
 }
 
 /* Borrow a bit of tree-ssa-dce.c for the moment.
@@ -3931,9 +3970,10 @@ fini_pre (void)
 /* Main entry point to the SSA-PRE pass.  DO_FRE is true if the caller
    only wants to do full redundancy elimination.  */
 
-static void
+static unsigned int
 execute_pre (bool do_fre)
 {
+  unsigned int todo = 0;
 
   do_partial_partial = optimize > 2;
   init_pre (do_fre);
@@ -3947,7 +3987,7 @@ execute_pre (bool do_fre)
       if (!do_fre)
 	remove_dead_inserted_code ();
       fini_pre ();
-      return;
+      return 0;
     }
   switch_to_PRE_table ();
   compute_avail ();
@@ -3978,7 +4018,7 @@ execute_pre (bool do_fre)
     }
 
   /* Remove all the redundant expressions.  */
-  eliminate ();
+  todo |= eliminate ();
 
   if (dump_file && (dump_flags & TDF_STATS))
     {
@@ -3999,6 +4039,8 @@ execute_pre (bool do_fre)
     }
 
   fini_pre ();
+
+  return todo;
 }
 
 /* Gate and execute functions for PRE.  */
@@ -4006,8 +4048,7 @@ execute_pre (bool do_fre)
 static unsigned int
 do_pre (void)
 {
-  execute_pre (false);
-  return TODO_rebuild_alias;
+  return TODO_rebuild_alias | execute_pre (false);
 }
 
 static bool
@@ -4041,8 +4082,7 @@ struct tree_opt_pass pass_pre =
 static unsigned int
 execute_fre (void)
 {
-  execute_pre (true);
-  return 0;
+  return execute_pre (true);
 }
 
 static bool
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index b10d3e31a85..b613b2ba21f 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -1251,6 +1251,12 @@ visit_reference_op_load (tree lhs, tree op, tree stmt)
   if (result)
     {
       changed = set_ssa_val_to (lhs, result);
+      if (TREE_CODE (result) == SSA_NAME
+	  && VN_INFO (result)->has_constants)
+	{
+	  VN_INFO (lhs)->expr = VN_INFO (result)->expr;
+	  VN_INFO (lhs)->has_constants = true;
+	}
     }
   else
     {