[(9/7)] Widening multiplies with constant inputs

2011-08-19  Andrew Stubbs  <ams@codesourcery.com>

	gcc/
	* tree-ssa-math-opts.c (is_widening_mult_rhs_p): Handle constants
	beyond conversions.
	(convert_mult_to_widen): Convert constant inputs to the right type.
	(convert_plusminus_to_widen): Don't automatically reject inputs that
	are not an SSA_NAME.
	Convert constant inputs to the right type.

	gcc/testsuite/
	* gcc.target/arm/wmul-11.c: New file.
	* gcc.target/arm/wmul-12.c: New file.
	* gcc.target/arm/wmul-13.c: New file.

--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/wmul-11.c
@@ -0,0 +1,11 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-require-effective-target arm_dsp } */
+
+long long
+foo (int *b)
+{
+  return 10 * (long long)*b;
+}
+
+/* { dg-final { scan-assembler "smull" } } */
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/wmul-12.c
@@ -0,0 +1,12 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-require-effective-target arm_dsp } */
+
+long long
+foo (int *b, int *c)
+{
+  int tmp = *b * *c;
+  return 10 + (long long)tmp;
+}
+
+/* { dg-final { scan-assembler "smlal" } } */
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/wmul-13.c
@@ -0,0 +1,11 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-require-effective-target arm_dsp } */
+
+long long
+foo (int *a, int *b)
+{
+  return *a + (long long)*b * 10;
+}
+
+/* { dg-final { scan-assembler "smlal" } } */
--- a/gcc/tree-ssa-math-opts.c
+++ b/gcc/tree-ssa-math-opts.c
@@ -1995,7 +1995,16 @@  is_widening_mult_rhs_p (tree type, tree rhs, tree *type_out,
 	      : rhs_code != FIXED_CONVERT_EXPR)
 	    rhs1 = rhs;
 	  else
-	    rhs1 = gimple_assign_rhs1 (stmt);
+	    {
+	      rhs1 = gimple_assign_rhs1 (stmt);
+
+	      if (TREE_CODE (rhs1) == INTEGER_CST)
+		{
+		  *new_rhs_out = rhs1;
+		  *type_out = NULL;
+		  return true;
+		}
+	    }
 	}
       else
 	rhs1 = rhs;
@@ -2164,6 +2173,12 @@  convert_mult_to_widen (gimple stmt, gimple_stmt_iterator *gsi)
       rhs2 = build_and_insert_cast (gsi, loc, tmp, rhs2);
     }
 
+  /* Handle constants.  */
+  if (TREE_CODE (rhs1) == INTEGER_CST)
+    rhs1 = fold_convert (type1, rhs1);
+  if (TREE_CODE (rhs2) == INTEGER_CST)
+    rhs2 = fold_convert (type2, rhs2);
+
   gimple_assign_set_rhs1 (stmt, rhs1);
   gimple_assign_set_rhs2 (stmt, rhs2);
   gimple_assign_set_rhs_code (stmt, WIDEN_MULT_EXPR);
@@ -2215,8 +2230,6 @@  convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple stmt,
       if (is_gimple_assign (rhs1_stmt))
 	rhs1_code = gimple_assign_rhs_code (rhs1_stmt);
     }
-  else
-    return false;
 
   if (TREE_CODE (rhs2) == SSA_NAME)
     {
@@ -2224,8 +2237,6 @@  convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple stmt,
       if (is_gimple_assign (rhs2_stmt))
 	rhs2_code = gimple_assign_rhs_code (rhs2_stmt);
     }
-  else
-    return false;
 
   /* Allow for one conversion statement between the multiply
      and addition/subtraction statement.  If there are more than
@@ -2373,6 +2384,12 @@  convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple stmt,
     add_rhs = build_and_insert_cast (gsi, loc, create_tmp_var (type, NULL),
 				     add_rhs);
 
+  /* Handle constants.  */
+  if (TREE_CODE (mult_rhs1) == INTEGER_CST)
+    rhs1 = fold_convert (type1, mult_rhs1);
+  if (TREE_CODE (mult_rhs2) == INTEGER_CST)
+    rhs2 = fold_convert (type2, mult_rhs2);
+
   gimple_assign_set_rhs_with_ops_1 (gsi, wmult_code, mult_rhs1, mult_rhs2,
 				    add_rhs);
   update_stmt (gsi_stmt (*gsi));