On Thu, Jun 18, 2015 at 05:41:18PM +0200, Marek Polacek wrote:
> > Again for symmetry, it seems like this comes with
> > x + y - (x | y) -> x & y
> > x + y - (x & y) -> x | y
> > which seem fine when overflow is undefined or wraps, but not if for instance
> > it saturates.
>
> I'll leave this as a follow-up.
...here.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2015-06-19 Marek Polacek <pola...@redhat.com>
* match.pd (x + y - (x | y) -> x & y,
(x + y) - (x & y) -> x | y): New patterns.
* gcc.dg/fold-minus-4.c: New test.
* gcc.dg/fold-minus-5.c: New test.
diff --git gcc/match.pd gcc/match.pd
index badb80a..61ff710 100644
--- gcc/match.pd
+++ gcc/match.pd
@@ -343,6 +343,18 @@ along with GCC; see the file COPYING3. If not see
(plus:c (bit_and @0 @1) (bit_ior @0 @1))
(plus @0 @1))
+/* x + y - (x | y) -> x & y */
+(simplify
+ (minus (plus @0 @1) (bit_ior @0 @1))
+ (if (!TYPE_OVERFLOW_SANITIZED (type) && !TYPE_SATURATING (type))
+ (bit_and @0 @1)))
+
+/* (x + y) - (x & y) -> x | y */
+(simplify
+ (minus (plus @0 @1) (bit_and @0 @1))
+ (if (!TYPE_OVERFLOW_SANITIZED (type) && !TYPE_SATURATING (type))
+ (bit_ior @0 @1)))
+
/* (x | y) - (x ^ y) -> x & y */
(simplify
(minus (bit_ior @0 @1) (bit_xor @0 @1))
diff --git gcc/testsuite/gcc.dg/fold-minus-4.c
gcc/testsuite/gcc.dg/fold-minus-4.c
index e69de29..2d76b4f 100644
--- gcc/testsuite/gcc.dg/fold-minus-4.c
+++ gcc/testsuite/gcc.dg/fold-minus-4.c
@@ -0,0 +1,37 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-cddce1" } */
+
+int
+fn1 (int a, int b)
+{
+ int tem1 = a + b;
+ int tem2 = a & b;
+ return tem1 - tem2;
+}
+
+int
+fn2 (int a, int b)
+{
+ int tem1 = b + a;
+ int tem2 = a & b;
+ return tem1 - tem2;
+}
+
+int
+fn3 (int a, int b)
+{
+ int tem1 = a + b;
+ int tem2 = b & a;
+ return tem1 - tem2;
+}
+
+int
+fn4 (int a, int b)
+{
+ int tem1 = b + a;
+ int tem2 = b & a;
+ return tem1 - tem2;
+}
+
+/* { dg-final { scan-tree-dump-not " & " "cddce1" } } */
+/* { dg-final { scan-tree-dump-not " \\+ " "cddce1" } } */
diff --git gcc/testsuite/gcc.dg/fold-minus-5.c
gcc/testsuite/gcc.dg/fold-minus-5.c
index e69de29..a31e1cc 100644
--- gcc/testsuite/gcc.dg/fold-minus-5.c
+++ gcc/testsuite/gcc.dg/fold-minus-5.c
@@ -0,0 +1,37 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-cddce1" } */
+
+int
+fn1 (int a, int b)
+{
+ int tem1 = a + b;
+ int tem2 = a | b;
+ return tem1 - tem2;
+}
+
+int
+fn2 (int a, int b)
+{
+ int tem1 = b + a;
+ int tem2 = a | b;
+ return tem1 - tem2;
+}
+
+int
+fn3 (int a, int b)
+{
+ int tem1 = a + b;
+ int tem2 = b | a;
+ return tem1 - tem2;
+}
+
+int
+fn4 (int a, int b)
+{
+ int tem1 = b + a;
+ int tem2 = b | a;
+ return tem1 - tem2;
+}
+
+/* { dg-final { scan-tree-dump-not " \\+ " "cddce1" } } */
+/* { dg-final { scan-tree-dump-not " \\| " "cddce1" } } */
Marek
