re PR middle-end/52134 (Does not fold (x * 4) & -4)

2012-03-13  Richard Guenther  <rguenther@suse.de>

	PR middle-end/52134
	* fold-const.c (fold_binary_loc): Fold (X * Y) & -(1 << CST) to X * Y
	if Y is a constant multiple of 1 << CST.

	* gcc.dg/pr52134.c: New testcase.

From-SVN: r185334

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 34d49a2705a65e6a15391daa0fff684d2382241d..d5c679cf479fafcde585dd259d769190efdca109 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2012-03-13  Richard Guenther  <rguenther@suse.de>
+
+       PR middle-end/52134
+       * fold-const.c (fold_binary_loc): Fold (X * Y) & -(1 << CST) to X * Y
+       if Y is a constant multiple of 1 << CST.
+
 2012-03-13  Georg-Johann Lay  <avr@gjlay.de>
 
        PR target/52488

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 0f806752dd36a80d67d7bb47f36b38df83301e6f..ab653ea074bb30384bbeaefba50b5c883b0423ee 100644 (file)
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -11398,6 +11398,20 @@ fold_binary_loc (location_t loc,
                              fold_convert_loc (loc, type, arg0));
        }
 
+      /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
+         multiple of 1 << CST.  */
+      if (TREE_CODE (arg1) == INTEGER_CST)
+       {
+         double_int cst1 = tree_to_double_int (arg1);
+         double_int ncst1 = double_int_ext (double_int_neg (cst1),
+                                            TYPE_PRECISION (TREE_TYPE (arg1)),
+                                            TYPE_UNSIGNED (TREE_TYPE (arg1)));
+         if (double_int_equal_p (double_int_and (cst1, ncst1), ncst1)
+             && multiple_of_p (type, arg0,
+                               double_int_to_tree (TREE_TYPE (arg1), ncst1)))
+           return fold_convert_loc (loc, type, arg0);
+       }
+
       /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
         ((A & N) + B) & M -> (A + B) & M
         Similarly if (N & M) == 0,

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e2f1b876ae7f24c08443395e5879e81bc7c2990a..1e6c43facdc8845c48d2bb7fab2b77d8d568e4e7 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2012-03-13  Richard Guenther  <rguenther@suse.de>
+
+       PR middle-end/52134
+       * gcc.dg/pr52134.c: New testcase.
+
 2012-03-13  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
        * ada/acats/tests/cd/cdd1001.a (CDD1001): Fix typo.

diff --git a/gcc/testsuite/gcc.dg/pr52134.c b/gcc/testsuite/gcc.dg/pr52134.c
new file mode 100644 (file)
index 0000000..44cb4a6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr52134.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-original" } */
+
+unsigned f(unsigned t)
+{
+    return (t*4)&-4;
+}
+int f1(int t)
+{
+    return (t*4)&-4;
+}
+
+/* { dg-final { scan-tree-dump-not "\\\&" "original" } } */
+/* { dg-final { cleanup-tree-dump "original" } } */