move a * (1 << b) -> a << b pattern from fold-const.c to match.pd

[Prathamesh Kulkarni]

Hi,
The attached patch moves pattern a * (1 << b) -> a << b.
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
OK for trunk if testing passes ?

Thank you,
Prathamesh

2015-07-06  Prathamesh Kulkarni  <prathamesh.kulka...@linaro.org>

        * fold-const.c (fold_binary_loc): Remove pattern a * 1 << b -> a << b.
        * match.pd (a * 1 << b -> a << b): New pattern.

testsuite/
        * gcc.dg/tree-ssa/fold-shiftmult.c: New test-case.

Index: fold-const.c
===================================================================
--- fold-const.c        (revision 225473)
+++ fold-const.c        (working copy)
@@ -10175,16 +10175,6 @@
                                                  negate_expr (arg0)),
                                tem);
 
-         /* (a * (1 << b)) is (a << b)  */
-         if (TREE_CODE (arg1) == LSHIFT_EXPR
-             && integer_onep (TREE_OPERAND (arg1, 0)))
-           return fold_build2_loc (loc, LSHIFT_EXPR, type, op0,
-                               TREE_OPERAND (arg1, 1));
-         if (TREE_CODE (arg0) == LSHIFT_EXPR
-             && integer_onep (TREE_OPERAND (arg0, 0)))
-           return fold_build2_loc (loc, LSHIFT_EXPR, type, op1,
-                               TREE_OPERAND (arg0, 1));
-
          /* (A + A) * C -> A * 2 * C  */
          if (TREE_CODE (arg0) == PLUS_EXPR
              && TREE_CODE (arg1) == INTEGER_CST
Index: match.pd
===================================================================
--- match.pd    (revision 225473)
+++ match.pd    (working copy)
@@ -854,6 +854,12 @@
       && tree_expr_nonnegative_p (@1))
   @0))
 
+/* a * (1 << b) -> a << b */
+(simplify
+  (mult:c @a (lshift integer_onep @b))
+  (if (!FLOAT_TYPE_P (type))
+    (lshift @a @b)))
+
 (for shiftrotate (lrotate rrotate lshift rshift)
  (simplify
   (shiftrotate @0 integer_zerop)
Index: testsuite/gcc.dg/tree-ssa/fold-shiftmult.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/fold-shiftmult.c  (revision 0)
+++ testsuite/gcc.dg/tree-ssa/fold-shiftmult.c  (working copy)
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-forwprop-details" } */
+
+int f1(int a, int b)
+{
+  int t1 = 1 << b;
+  int f1_val = a * t1;
+  return f1_val;
+}
+/* { dg-final { scan-tree-dump "gimple_simplified to f1_val_\\d\+ = 
a_\\d\+\\(D\\) << b_\\d\+\\(D\\)" "forwprop1" } } */
+
+int f2(int a, int b)
+{
+  int t1 = 1 << b;
+  int f2_val = t1 * a;
+  return f2_val;
+}
+
+/* { dg-final { scan-tree-dump "gimple_simplified to f2_val_\\d\+ = 
a_\\d\+\\(D\\) << b_\\d\+\\(D\\)" "forwprop1" } } */