tree-ssa-forwprop.c (simplify_vce): New function.

2013-11-21  Richard Biener  <rguenther@suse.de>

	* tree-ssa-forwprop.c (simplify_vce): New function.
	(ssa_forward_propagate_and_combine): Call it.

From-SVN: r205211

gcc/ChangeLog

@@ -1,3 +1,8 @@
+2013-11-21  Richard Biener  <rguenther@suse.de>
+
+	* tree-ssa-forwprop.c (simplify_vce): New function.
+	(ssa_forward_propagate_and_combine): Call it.
+
 2013-11-21  Richard Biener  <rguenther@suse.de>
 
 	* tree-vect-loop-manip.c (vect_build_loop_niters,

gcc/tree-ssa-forwprop.c

@@ -2994,6 +2994,69 @@ combine_conversions (gimple_stmt_iterator *gsi)
   return 0;
 }
 
+/* Combine VIEW_CONVERT_EXPRs with their defining statement.  */
+
+static bool
+simplify_vce (gimple_stmt_iterator *gsi)
+{
+  gimple stmt = gsi_stmt (*gsi);
+  tree type = TREE_TYPE (gimple_assign_lhs (stmt));
+
+  /* Drop useless VIEW_CONVERT_EXPRs.  */
+  tree op = TREE_OPERAND (gimple_assign_rhs1 (stmt), 0);
+  if (useless_type_conversion_p (type, TREE_TYPE (op)))
+    {
+      gimple_assign_set_rhs1 (stmt, op);
+      update_stmt (stmt);
+      return true;
+    }
+
+  if (TREE_CODE (op) != SSA_NAME)
+    return false;
+
+  gimple def_stmt = SSA_NAME_DEF_STMT (op);
+  if (!is_gimple_assign (def_stmt))
+    return false;
+
+  tree def_op = gimple_assign_rhs1 (def_stmt);
+  switch (gimple_assign_rhs_code (def_stmt))
+    {
+    CASE_CONVERT:
+      /* Strip integral conversions that do not change the precision.  */
+      if ((INTEGRAL_TYPE_P (TREE_TYPE (op))
+	   || POINTER_TYPE_P (TREE_TYPE (op)))
+	  && (INTEGRAL_TYPE_P (TREE_TYPE (def_op))
+	      || POINTER_TYPE_P (TREE_TYPE (def_op)))
+	  && (TYPE_PRECISION (TREE_TYPE (op))
+	      == TYPE_PRECISION (TREE_TYPE (def_op))))
+	{
+	  TREE_OPERAND (gimple_assign_rhs1 (stmt), 0) = def_op;
+	  update_stmt (stmt);
+	  return true;
+	}
+      break;
+
+    case VIEW_CONVERT_EXPR:
+      /* Series of VIEW_CONVERT_EXPRs on register operands can
+	 be contracted.  */
+      if (TREE_CODE (TREE_OPERAND (def_op, 0)) == SSA_NAME)
+	{
+	  if (useless_type_conversion_p (type,
+					 TREE_TYPE (TREE_OPERAND (def_op, 0))))
+	    gimple_assign_set_rhs1 (stmt, TREE_OPERAND (def_op, 0));
+	  else
+	    TREE_OPERAND (gimple_assign_rhs1 (stmt), 0)
+		= TREE_OPERAND (def_op, 0);
+	  update_stmt (stmt);
+	  return true;
+	}
+
+    default:;
+    }
+
+  return false;
+}
+
 /* Combine an element access with a shuffle.  Returns true if there were
    any changes made, else it returns false.  */
  
@@ -3491,6 +3554,8 @@ ssa_forward_propagate_and_combine (void)
 		      
 		    changed = did_something != 0;
 		  }
+		else if (code == VIEW_CONVERT_EXPR)
+		  changed = simplify_vce (&gsi);
 		else if (code == VEC_PERM_EXPR)
 		  {
 		    int did_something = simplify_permutation (&gsi);