MATCH: [PR111679] Add alternative simplification of `a | ((~a) ^ b)`

So currently we have a simplification for `a | ~(a ^ b)` but
that does not match the case where we had originally `(~a) | (a ^ b)`
so we need to add a new pattern that matches that and uses bitwise_inverted_equal_p
that also catches comparisons too.

OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.

	PR tree-optimization/111679

gcc/ChangeLog:

	* match.pd (`a | ((~a) ^ b)`): New pattern.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/bitops-5.c: New test.

diff --git a/gcc/match.pd b/gcc/match.pd
index 31bfd8b6b6897f79bef6677200d399d2c31e849b..49740d189a7daf95d9e711be1ddaf5b2c034eb7e 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1350,6 +1350,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
       && TYPE_PRECISION (TREE_TYPE (@0)) == 1)
   (bit_ior @0 (bit_xor @1 { build_one_cst (type); }))))
 
+/* a | ((~a) ^ b)  -->  a | (~b) (alt version of the above 2) */
+(simplify
+ (bit_ior:c @0 (bit_xor:cs @1 @2))
+ (with { bool wascmp; }
+ (if (bitwise_inverted_equal_p (@0, @1, wascmp)
+      && (!wascmp || element_precision (type) == 1))
+  (bit_ior @0 (bit_not @2)))))
+
 /* (a | b) | (a &^ b)  -->  a | b  */
 (for op (bit_and bit_xor)
  (simplify

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bitops-5.c b/gcc/testsuite/gcc.dg/tree-ssa/bitops-5.c
new file mode 100644 (file)
index 0000000..990610e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/bitops-5.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized-raw" } */
+/* PR tree-optimization/111679 */
+
+int f1(int a, int b)
+{
+        return (~a) | (a ^ b); // ~(a & b) or (~a) | (~b)
+}
+
+_Bool fb(_Bool c, _Bool d)
+{
+        return (!c) | (c ^ d); // ~(c & d) or (~c) | (~d)
+}
+
+_Bool fb1(int x, int y)
+{
+        _Bool a = x == 10,  b = y > 100;
+        return (!a) | (a ^ b); // ~(a & b) or (~a) | (~b)
+        // or (x != 10) | (y <= 100)
+}
+
+/* { dg-final { scan-tree-dump-not   "bit_xor_expr, "   "optimized" } } */
+/* { dg-final { scan-tree-dump-times "bit_not_expr, " 2 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "bit_and_expr, " 2 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "bit_ior_expr, " 1 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "ne_expr, _\[0-9\]+, x_\[0-9\]+"      1 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "le_expr, _\[0-9\]+, y_\[0-9\]+"      1 "optimized" } } */