match: Improve the `x ==/!= ~x` pattern [PR118483]

This improves this pattern by 2 ways:
* Allow for an optional convert, similar to how the few other
  `a OP ~a` patterns also allow for an optional convert.
* Use bitwise_inverted_equal_p/maybe_bit_not instead of directly
  matching bit_not. Just like the other patterns do too.

Note pr118483-2.c used to optimized for aarch64-linux-gnu with GCC 4.9.4
on the RTL level even though the gimple level was missing it.

	PR tree-optimization/118483

gcc/ChangeLog:

	* match.pd (`x ==/!= ~x`): Allow for an optional convert
	and use itwise_inverted_equal_p/maybe_bit_not instead of
	directly matching bit_not.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/pr118483-1.c: New test.
	* gcc.dg/tree-ssa/pr118483-2.c: New test.
	* gcc.dg/tree-ssa/pr118483-3.c: New test.
	* gcc.dg/tree-ssa/pr118483-4.c: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

diff --git a/gcc/match.pd b/gcc/match.pd
index f4359d3a005a80a23a8f537c835c8ba1bc810d99..1cdc7e94f1feed429994ae7805567ec2ea83bb43 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -6959,8 +6959,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 /* x != ~x -> true */
 (for cmp (eq ne)
  (simplify
-  (cmp:c @0 (bit_not @0))
-  { constant_boolean_node (cmp == NE_EXPR, type); }))
+  (cmp:c (convert? @0) (convert? (maybe_bit_not @1)))
+  (with { bool wascmp; }
+   (if (types_match (TREE_TYPE (@0), TREE_TYPE (@1))
+        && bitwise_inverted_equal_p (@0, @1, wascmp))
+    { constant_boolean_node (cmp == NE_EXPR, type); }))))
 
 /* Fold ~X op ~Y as Y op X.  */
 (for cmp (simple_comparison)

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr118483-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr118483-1.c
new file mode 100644 (file)
index 0000000..e31876c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr118483-1.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* PR tree-optimization/118483 */
+/* { dg-final { scan-tree-dump-not "abort " "optimized" } } */
+
+
+/* The value of `l == e` is always false as it is
+   `(b == 0) == (b != 0)`. */
+
+int d;
+int f(int b)
+{
+  int e = b == 0;
+  d = e;
+  int l = b != 0;
+  if (l == e)
+    __builtin_abort ();
+}

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr118483-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr118483-2.c
new file mode 100644 (file)
index 0000000..8486771
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr118483-2.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* PR tree-optimization/118483 */
+/* { dg-final { scan-tree-dump-not "abort " "optimized" } } */
+
+
+/* The value of `l == e` is always false as it is
+   `(b == 0) == (b != 0)`. */
+
+int d;
+int f(int b)
+{
+  int e = b == 0;
+  d = e;
+  int l = !e;
+  if (l == e)
+    __builtin_abort ();
+}

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr118483-3.c b/gcc/testsuite/gcc.dg/tree-ssa/pr118483-3.c
new file mode 100644 (file)
index 0000000..65efaf5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr118483-3.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* PR tree-optimization/118483 */
+/* { dg-final { scan-tree-dump "return 0;" "optimized" } } */
+
+/* This should optimize down to just `return 0;` */
+/* as `(short)a == ~(short)a` is always false. */
+int f(int a)
+{
+  short b = a;
+  int e = ~a;
+  short c = e;
+  return b == c;
+}

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr118483-4.c b/gcc/testsuite/gcc.dg/tree-ssa/pr118483-4.c
new file mode 100644 (file)
index 0000000..c6e389c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr118483-4.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* PR tree-optimization/118483 */
+/* { dg-final { scan-tree-dump "return 0;" "optimized" } } */
+
+/* This should optimize down to just `return 0;` */
+/* as `a == 0` and `a != 0` are opposites. */
+int f(int a)
+{
+  return (a == 0) == (a != 0);
+}