re PR rtl-optimization/47299 (Widening multiply optimization generates bad code)

	PR rtl-optimization/47299
	* expr.c (expand_expr_real_2) <case WIDEN_MULT_EXPR>: Don't use
	subtarget.  Use normal multiplication if both operands are
	constants.
	* expmed.c (expand_widening_mult): Don't try to optimize constant
	multiplication if op0 has VOIDmode.  Convert op1 constant to mode
	before using it.

	* gcc.c-torture/execute/pr47299.c: New test.

From-SVN: r168944

gcc/ChangeLog

+2011-01-18  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/47299
+	* expr.c (expand_expr_real_2) <case WIDEN_MULT_EXPR>: Don't use
+	subtarget.  Use normal multiplication if both operands are
+	constants.
+	* expmed.c (expand_widening_mult): Don't try to optimize constant
+	multiplication if op0 has VOIDmode.  Convert op1 constant to mode
+	before using it.
+
 2011-01-17  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
 
 	* doc/lto.texi (LTO): Ensure two spaces after period.  Fix

gcc/expmed.c

 /* Medium-level subroutines: convert bit-field store and extract
    and shifts, multiplies and divides to rtl instructions.
    Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
+   2011
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -3188,12 +3189,17 @@ expand_widening_mult (enum machine_mode mode, rtx op0, rtx op1, rtx target,
 		      int unsignedp, optab this_optab)
 {
   bool speed = optimize_insn_for_speed_p ();
+  rtx cop1;
 
   if (CONST_INT_P (op1)
-      && (INTVAL (op1) >= 0
+      && GET_MODE (op0) != VOIDmode
+      && (cop1 = convert_modes (mode, GET_MODE (op0), op1,
+				this_optab == umul_widen_optab))
+      && CONST_INT_P (cop1)
+      && (INTVAL (cop1) >= 0
 	  || GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT))
     {
-      HOST_WIDE_INT coeff = INTVAL (op1);
+      HOST_WIDE_INT coeff = INTVAL (cop1);
       int max_cost;
       enum mult_variant variant;
       struct algorithm algorithm;

gcc/expr.c

 /* Convert tree expression to rtl instructions, for GNU compiler.
    Copyright (C) 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-   2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+   2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -7631,10 +7631,10 @@ expand_expr_real_2 (sepops ops, rtx target, enum machine_mode tmode,
 	      if (optab_handler (this_optab, mode) != CODE_FOR_nothing)
 		{
 		  if (TYPE_UNSIGNED (TREE_TYPE (treeop0)))
-		    expand_operands (treeop0, treeop1, subtarget, &op0, &op1,
+		    expand_operands (treeop0, treeop1, NULL_RTX, &op0, &op1,
 				     EXPAND_NORMAL);
 		  else
-		    expand_operands (treeop0, treeop1, subtarget, &op1, &op0,
+		    expand_operands (treeop0, treeop1, NULL_RTX, &op1, &op0,
 				     EXPAND_NORMAL);
 		  goto binop3;
 		}
@@ -7652,7 +7652,8 @@ expand_expr_real_2 (sepops ops, rtx target, enum machine_mode tmode,
 	  optab other_optab = zextend_p ? smul_widen_optab : umul_widen_optab;
 	  this_optab = zextend_p ? umul_widen_optab : smul_widen_optab;
 
-	  if (mode == GET_MODE_2XWIDER_MODE (innermode))
+	  if (mode == GET_MODE_2XWIDER_MODE (innermode)
+	      && TREE_CODE (treeop0) != INTEGER_CST)
 	    {
 	      if (optab_handler (this_optab, mode) != CODE_FOR_nothing)
 		{

gcc/testsuite/ChangeLog

+2011-01-18  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/47299
+	* gcc.c-torture/execute/pr47299.c: New test.
+
 2011-01-17  Jason Merrill  <jason@redhat.com>
 
 	* g++.dg/cpp0x/constexpr-virtual.C: New.

gcc/testsuite/gcc.c-torture/execute/pr47299.c

+/* PR rtl-optimization/47299 */
+
+extern void abort (void);
+
+__attribute__ ((noinline, noclone)) unsigned short
+foo (unsigned char x)
+{
+  return x * 255;
+}
+
+int
+main ()
+{
+  if (foo (0x40) != 0x3fc0)
+    abort ();
+  return 0;
+}