[patch tree-optimization]: 0 of 6 Improve reassoc for bitwise operations

[Kai Tietz]

Hello,

This patch does rename break_up_subtract_bb to break_up_expr_bb, and it
modifies build_and_add_sum so that unary expression can be created by it, too.
The patch is a prerequisit of the following 6 additional patches.

ChangeLog

2011-10-07  Kai Tietz  <ktietz@redhat.com>

	* tree-ssa-reassoc.c (break_up_subtract_bb): Rename to
	(break_up_expr_bb): as function name.
	(build_and_add_sum): Add support for unary statement creation.
	

Index: gcc/gcc/tree-ssa-reassoc.c
===================================================================
--- gcc.orig/gcc/tree-ssa-reassoc.c
+++ gcc/gcc/tree-ssa-reassoc.c
@@ -44,6 +44,9 @@ along with GCC; see the file COPYING3.
 #include "params.h"
 #include "diagnostic-core.h"

+/* Forwarders.  */
+static gimple build_and_add_sum (tree, tree, tree, enum tree_code);
+
 /*  This is a simple global reassociation pass.  It is, in part, based
     on the LLVM pass of the same name (They do some things more/less
     than we do, in different orders, etc).
@@ -1018,8 +1021,8 @@ zero_one_operation (tree *def, enum tree
   while (1);
 }

-/* Builds one statement performing OP1 OPCODE OP2 using TMPVAR for
-   the result.  Places the statement after the definition of either
+/* Builds one statement performing OP1 OPCODE OP2, or OPCODE OP1 using
+   TMPVAR for the result.  Places the statement after the definition of either
    OP1 or OP2.  Returns the new statement.  */

 static gimple
@@ -1038,7 +1041,7 @@ build_and_add_sum (tree tmpvar, tree op1
   /* Find an insertion place and insert.  */
   if (TREE_CODE (op1) == SSA_NAME)
     op1def = SSA_NAME_DEF_STMT (op1);
-  if (TREE_CODE (op2) == SSA_NAME)
+  if (op2 && TREE_CODE (op2) == SSA_NAME)
     op2def = SSA_NAME_DEF_STMT (op2);
   if ((!op1def || gimple_nop_p (op1def))
       && (!op2def || gimple_nop_p (op2def)))
@@ -2777,7 +2780,7 @@ can_reassociate_p (tree op)
    En passant, clear the GIMPLE visited flag on every statement.  */

 static void
-break_up_subtract_bb (basic_block bb)
+break_up_expr_bb (basic_block bb)
 {
   gimple_stmt_iterator gsi;
   basic_block son;
@@ -2812,7 +2815,7 @@ break_up_subtract_bb (basic_block bb)
   for (son = first_dom_son (CDI_DOMINATORS, bb);
        son;
        son = next_dom_son (CDI_DOMINATORS, son))
-    break_up_subtract_bb (son);
+    break_up_expr_bb (son);
 }

 /* Reassociate expressions in basic block BB and its post-dominator as
@@ -2981,7 +2984,7 @@ debug_ops_vector (VEC (operand_entry_t,
 static void
 do_reassoc (void)
 {
-  break_up_subtract_bb (ENTRY_BLOCK_PTR);
+  break_up_expr_bb (ENTRY_BLOCK_PTR);
   reassociate_bb (EXIT_BLOCK_PTR);
 }