Patchwork [tree-optimization] : Try to sink type-casts for binary and/or/xor operations

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Submitter Kai Tietz
Date June 27, 2011, 3:37 p.m.
Message ID <1382815177.792937.1309189041108.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com>
Download mbox | patch
Permalink /patch/102202/
State New
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Comments

Kai Tietz - June 27, 2011, 3:37 p.m.
----- Original Message -----
From: "Richard Guenther" <richard.guenther@gmail.com>
To: "Kai Tietz" <ktietz@redhat.com>
Cc: gcc-patches@gcc.gnu.org
Sent: Monday, June 27, 2011 4:08:41 PM
Subject: Re: [patch tree-optimization]: Try to sink type-casts for binary and/or/xor operations

On Mon, Jun 27, 2011 at 3:46 PM, Kai Tietz <ktietz@redhat.com> wrote:
> Hello,
>
> this patch sink type conversions in forward-propagate for the following patterns:
> - ((type) X) op ((type) Y): If X and Y have compatible types.
> - ((type) X) op CST: If the conversion of (type) ((type-x) CST) == CST and X has integral type.
> - CST op ((type) X): If the conversion of (type) ((type-x) CST) == CST and X has integral type.

See IRC comments.

> Additionally it fixes another issue shown by this type-sinking in bswap detection. The bswap pattern matching algorithm goes for the first hit, and not tries to seek for best hit.  So we search here two times. First for di case (if present) and then for si mode case.

Please split this piece out.  I suppose either walking over stmts backwards
or simply handling __builtin_bswap in find_bswap_1 would be a better
fix than yours.

Richard.

> ChangeLog
>
> 2011-06-27  Kai Tietz  <ktietz@redhat.com>
>
>        * tree-ssa-forwprop.c (simplify_bitwise_binary): Improve
>        type sinking.
>        * tree-ssa-math-opts.c (execute_optimize_bswap): Separate
>        search for di/si mode patterns for finding widest match.
>
> Bootstrapped and regression tested for x86_64-pc-linux-gnu.  Ok for apply?


Revised patch without the bswap part.

Regards,
Kai

Patch

Index: gcc-head/gcc/tree-ssa-forwprop.c
===================================================================
--- gcc-head.orig/gcc/tree-ssa-forwprop.c
+++ gcc-head/gcc/tree-ssa-forwprop.c
@@ -1624,30 +1624,56 @@  simplify_bitwise_binary (gimple_stmt_ite
   /* If the first argument is an SSA name that is itself a result of a
      typecast of an ADDR_EXPR to an integer, feed the ADDR_EXPR to the
      folder rather than the ssa name.  */
-  if (code == BIT_AND_EXPR
-      && TREE_CODE (arg2) == INTEGER_CST
+  if (TREE_CODE (arg2) == INTEGER_CST
       && TREE_CODE (arg1) == SSA_NAME)
     {
       gimple def = SSA_NAME_DEF_STMT (arg1);
       tree op = arg1;
+      tree opp = NULL_TREE;
+      tree folded_int = NULL_TREE;
 
-      /* ???  This looks bogus - the conversion could be truncating.  */
       if (is_gimple_assign (def)
 	  && CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def))
 	  && INTEGRAL_TYPE_P (TREE_TYPE (arg1)))
 	{
-	  tree opp = gimple_assign_rhs1 (def);
-	  if (TREE_CODE (opp) == ADDR_EXPR)
+	  opp = gimple_assign_rhs1 (def);
+	  folded_int = fold_convert_loc (gimple_location (stmt),
+					 TREE_TYPE (opp), arg2);
+	  /* Check if integer value remains the same on cast back
+	     to original type.  */
+	  if (!operand_equal_p (arg2, fold_convert (TREE_TYPE (arg1),
+						    folded_int), 0))
+	    folded_int = NULL_TREE;
+	  if (TREE_CODE (opp) == ADDR_EXPR && folded_int)
 	    op = opp;
 	}
+      if (code == BIT_AND_EXPR)
+        {
+	  res = fold_binary_loc (gimple_location (stmt),
+				 BIT_AND_EXPR,
+				 TREE_TYPE (gimple_assign_lhs (stmt)),
+				 op, arg2);
+	  if (res && is_gimple_min_invariant (res))
+	    {
+	      gimple_assign_set_rhs_from_tree (gsi, res);
+	      update_stmt (stmt);
+	      return true;
+	    }
+	}
 
-      res = fold_binary_loc (gimple_location (stmt),
-			     BIT_AND_EXPR, TREE_TYPE (gimple_assign_lhs (stmt)),
-			     op, arg2);
-      if (res && is_gimple_min_invariant (res))
-	{
-	  gimple_assign_set_rhs_from_tree (gsi, res);
-	  update_stmt (stmt);
+      /* Convert (type) X & CST -> (type) (X & (typeof-X) CST),
+         if conversion of CST is reversible.  */
+      if (opp != NULL_TREE && folded_int != NULL_TREE)
+        {
+	  gimple newop;
+	  tree tem = create_tmp_reg (TREE_TYPE (opp), NULL);
+	  newop = gimple_build_assign_with_ops (code, tem, opp, folded_int);
+	  tem = make_ssa_name (tem, newop);
+	  gimple_assign_set_lhs (newop, tem);
+	  gsi_insert_before (gsi, newop, GSI_SAME_STMT);
+	  gimple_assign_set_rhs_with_ops_1 (gsi, NOP_EXPR,
+					    tem, NULL_TREE, NULL_TREE);
+	  update_stmt (gsi_stmt (*gsi));
 	  return true;
 	}
     }
@@ -1682,10 +1708,11 @@  simplify_bitwise_binary (gimple_stmt_ite
   if (CONVERT_EXPR_CODE_P (def1_code)
       && CONVERT_EXPR_CODE_P (def2_code)
       && types_compatible_p (TREE_TYPE (def1_arg1), TREE_TYPE (def2_arg1))
-      /* Make sure that the conversion widens the operands or that it
-	 changes the operation to a bitfield precision.  */
+      /* Make sure that the conversion widens the operands, or has same
+	 precision,  or that it changes the operation to a bitfield
+	 precision.  */
       && ((TYPE_PRECISION (TREE_TYPE (def1_arg1))
-	   < TYPE_PRECISION (TREE_TYPE (arg1)))
+	   <= TYPE_PRECISION (TREE_TYPE (arg1)))
 	  || (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (arg1)))
 	      != MODE_INT)
 	  || (TYPE_PRECISION (TREE_TYPE (arg1))