MATCH: [PR111432] Simplify `a & (x | CST)` to a when we know that (a & ~CST) == 0

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.

diff --git a/gcc/match.pd b/gcc/match.pd
index dbd554e2e7c1cfa72dafc5965ee41ac18a90bad8..067328a2a16b43c14a38de92f915b01905bd6f84 100644 (file)
--- 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 (file)
index 0000000..7fb18db
--- /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" } } */