This adds the simplification `a & (x | CST)` to a when we know that
`(a & ~CST) == 0`. In a similar fashion as `a & CST` is handle.
I looked into handling `a | (x & CST)` but that I don't see any decent
simplifications happening.
OK? Bootstrapped and tested on x86_linux-gnu with no regressions.
PR tree-optimization/111432
gcc/ChangeLog:
* match.pd (`a & (x | CST)`): New pattern.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/bitops-7.c: New test.
---
gcc/match.pd | 8 ++++++++
gcc/testsuite/gcc.dg/tree-ssa/bitops-7.c | 24 ++++++++++++++++++++++++
2 files changed, 32 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/bitops-7.c
diff --git a/gcc/match.pd b/gcc/match.pd
index 51e5065d086..45624f3dcb4 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1550,6 +1550,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(if (INTEGRAL_TYPE_P (TREE_TYPE (@0))
&& wi::bit_and_not (get_nonzero_bits (@0), wi::to_wide (@1)) == 0)
@0))
+
+/* `a & (x | CST)` -> a if we know that (a & ~CST) == 0 */
+(simplify
+ (bit_and:c SSA_NAME@0 (bit_ior @1 INTEGER_CST@2))
+ (if (INTEGRAL_TYPE_P (TREE_TYPE (@0))
+ && wi::bit_and_not (get_nonzero_bits (@0), wi::to_wide (@2)) == 0)
+ @0))
+
/* x | C -> C if we know that x & ~C == 0. */
(simplify
(bit_ior SSA_NAME@0 INTEGER_CST@1)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bitops-7.c
b/gcc/testsuite/gcc.dg/tree-ssa/bitops-7.c
new file mode 100644
index 00000000000..7fb18db3a11
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/bitops-7.c
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized-raw" } */
+/* PR tree-optimization/111432 */
+
+int
+foo3(int c, int bb)
+{
+ if ((bb & ~3)!=0) __builtin_unreachable();
+ return (bb & (c|3));
+}
+
+int
+foo_bool(int c, _Bool bb)
+{
+ return (bb & (c|7));
+}
+
+/* Both of these functions should be able to remove the `IOR` and `AND`
+ as the only bits that are non-zero for bb is set on the other side
+ of the `AND`.
+ */
+
+/* { dg-final { scan-tree-dump-not "bit_ior_expr, " "optimized" } } */
+/* { dg-final { scan-tree-dump-not "bit_and_expr, " "optimized" } } */
--
2.39.3
