re PR middle-end/64309 (if (1 & (1 << n)) not simplified to if (n == 0))

	PR middle-end/64309
	* match.pd: Add ((1 << A) & 1) != 0 -> A == 0 and
	((1 << A) & 1) == 0 -> A != 0.

	* gcc.dg/pr64309.c: New test.

From-SVN: r218787

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 609b8d1..b399b6e 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2014-12-16  Marek Polacek  <polacek@redhat.com>
+
+       PR middle-end/64309
+       * match.pd: Add ((1 << A) & 1) != 0 -> A == 0 and
+       ((1 << A) & 1) == 0 -> A != 0.
+
 2014-12-16  Richard Biener  <rguenther@suse.de>
 
        * genmatch.c (parser::parser): Initialize capture_ids.

diff --git a/gcc/match.pd b/gcc/match.pd
index 083d65f..dbca99e 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -599,6 +599,13 @@ along with GCC; see the file COPYING3.  If not see
                            build_int_cst (TREE_TYPE (@1),
                                           element_precision (type)), @1); }))
 
+/* ((1 << A) & 1) != 0 -> A == 0
+   ((1 << A) & 1) == 0 -> A != 0 */
+(for cmp (ne eq)
+     icmp (eq ne)
+ (simplify
+  (cmp (bit_and (lshift integer_onep @0) integer_onep) integer_zerop)
+  (icmp @0 { build_zero_cst (TREE_TYPE (@0)); })))
 
 /* Simplifications of conversions.  */
 

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 47565a2..a211462 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2014-12-16  Marek Polacek  <polacek@redhat.com>
+
+       PR middle-end/64309
+       * gcc.dg/pr64309.c: New test.
+
 2014-12-16  Felix Yang  <felix.yang@huawei.com>
 
        PR rtl-optimization/64240

diff --git a/gcc/testsuite/gcc.dg/pr64309.c b/gcc/testsuite/gcc.dg/pr64309.c
new file mode 100644 (file)
index 0000000..710a762
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr64309.c
@@ -0,0 +1,66 @@
+/* PR middle-end/64309 */
+/* { dg-do run } */
+/* { dg-options "-fdump-tree-original" } */
+
+int
+fn1 (int n)
+{
+  return ((1 << n) & 1) != 0;
+}
+
+int
+fn2 (int n)
+{
+  return (1 & (1 << n)) != 0;
+}
+
+int
+fn3 (int n)
+{
+  return ((1 << n) & 1) == 0;
+}
+
+int
+fn4 (int n)
+{
+  return (1 & (1 << n)) == 0;
+}
+
+int
+main (void)
+{
+  if (fn1 (0) != 1
+      || fn1 (1) != 0
+      || fn1 (2) != 0
+      || fn1 (3) != 0
+      || fn1 (4) != 0
+      || fn1 (5) != 0)
+    __builtin_abort ();
+
+  if (fn2 (0) != 1
+      || fn2 (1) != 0
+      || fn2 (2) != 0
+      || fn2 (3) != 0
+      || fn2 (4) != 0
+      || fn2 (5) != 0)
+    __builtin_abort ();
+
+  if (fn3 (0) != 0
+      || fn3 (1) != 1
+      || fn3 (2) != 1
+      || fn3 (3) != 1
+      || fn3 (4) != 1
+      || fn3 (5) != 1)
+    __builtin_abort ();
+
+  if (fn4 (0) != 0
+      || fn4 (1) != 1
+      || fn4 (2) != 1
+      || fn4 (3) != 1
+      || fn4 (4) != 1
+      || fn4 (5) != 1)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump-not "(<<|>>)" "original" } } */
+/* { dg-final { cleanup-tree-dump "original" } } */