From 5b58b39b0a7d1c79b0d57e51199864f9a3685bb4 Mon Sep 17 00:00:00 2001
From: Bernd Schmidt <bernds@codesourcery.com>
Date: Thu, 22 Apr 2010 09:30:27 +0000
Subject: re PR middle-end/29274 (not using mulsidi3)

gcc/
	PR middle-end/29274
	* optabs.h (expand_widening_mult): Declare.
	* tree-pass.h (pass_optimize_widening_mul): Declare.
	* tree-ssa-math-opts.c (execute_optimize_widening_mul,
	gate_optimize_widening_mul): New static functions.
	(pass_optimize_widening_mul): New.
	* expr.c (expand_expr_real_2) <case WIDEN_MULT_EXPR>: New
	case.
	<case MULT_EXPR>: Remove support for widening multiplies.
	* tree.def (WIDEN_MULT_EXPR): Tweak comment.
	* cfgexpand.c (expand_debug_expr) <case WIDEN_MULT_EXPR>: Use
	simplify_gen_unary rather than directly building extensions.
	* tree-cfg.c (verify_gimple_assign_binary): Add tests for
	WIDEN_MULT_EXPR.
	* expmed.c (expand_widening_mult): New function.
	* passes.c (init_optimization_passes): Add pass_optimize_widening_mul.

gcc/testsuite/
	PR middle-end/29274
	* gcc.target/i386/wmul-1.c: New test.
	* gcc.target/i386/wmul-2.c: New test.
	* gcc.target/bfin/wmul-1.c: New test.
	* gcc.target/bfin/wmul-2.c: New test.

From-SVN: r158633
---
 gcc/expmed.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

(limited to 'gcc/expmed.c')

diff --git a/gcc/expmed.c b/gcc/expmed.c
index d4b0583..07b1dc6 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -3217,6 +3217,55 @@ expand_mult (enum machine_mode mode, rtx op0, rtx op1, rtx target,
   gcc_assert (op0);
   return op0;
 }
+
+/* Perform a widening multiplication and return an rtx for the result.
+   MODE is mode of value; OP0 and OP1 are what to multiply (rtx's);
+   TARGET is a suggestion for where to store the result (an rtx).
+   THIS_OPTAB is the optab we should use, it must be either umul_widen_optab
+   or smul_widen_optab.
+
+   We check specially for a constant integer as OP1, comparing the
+   cost of a widening multiply against the cost of a sequence of shifts
+   and adds.  */
+
+rtx
+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 ();
+
+  if (CONST_INT_P (op1)
+      && (INTVAL (op1) >= 0
+	  || GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT))
+    {
+      HOST_WIDE_INT coeff = INTVAL (op1);
+      int max_cost;
+      enum mult_variant variant;
+      struct algorithm algorithm;
+
+      /* Special case powers of two.  */
+      if (EXACT_POWER_OF_2_OR_ZERO_P (coeff))
+	{
+	  op0 = convert_to_mode (mode, op0, this_optab == umul_widen_optab);
+	  return expand_shift (LSHIFT_EXPR, mode, op0,
+			       build_int_cst (NULL_TREE, floor_log2 (coeff)),
+			       target, unsignedp);
+	}
+
+      /* Exclude cost of op0 from max_cost to match the cost
+	 calculation of the synth_mult.  */
+      max_cost = mul_widen_cost[speed][mode];
+      if (choose_mult_variant (mode, coeff, &algorithm, &variant,
+			       max_cost))
+	{
+	  op0 = convert_to_mode (mode, op0, this_optab == umul_widen_optab);
+	  return expand_mult_const (mode, op0, coeff, target,
+				    &algorithm, variant);
+	}
+    }
+  return expand_binop (mode, this_optab, op0, op1, target,
+		       unsignedp, OPTAB_LIB_WIDEN);
+}
 
 /* Return the smallest n such that 2**n >= X.  */
 
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