On Tue, Dec 16, 2014 at 03:08:23PM +0100, Richard Biener wrote:
> You can use
>
> (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)); })))
>
> to combine both patterns. Btw, shoudln't it be (bit_and (...)
Ah, we can have multiple operators to iterate (and yes, it's
documented, my bad).
> integer_each_onep)? I'm always unsure about the complex integer case
> (maybe try a runtime testcase and see what happens - eventually we
> just don't support bit operations on them...)
Correct - we don't allow complex operands for neither shift, nor bit and.
So I left the integer_onep in there. Thanks.
2014-12-16 Marek Polacek <pola...@redhat.com>
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.
diff --git gcc/match.pd gcc/match.pd
index 083d65f..dbca99e 100644
--- gcc/match.pd
+++ 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 gcc/testsuite/gcc.dg/pr64309.c gcc/testsuite/gcc.dg/pr64309.c
index e69de29..710a762 100644
--- gcc/testsuite/gcc.dg/pr64309.c
+++ 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" } } */
Marek
