Fix PR 110666: `(a != 2) == a` produces wrong code

I had messed up the case where the outer operator is `==`.
The check for the resulting should have been `==` and not `!=`.
This patch fixes that and adds a full runtime testcase now for
all cases to make sure it works.

OK? Bootstrapped and tested on x86-64-linux-gnu with no regressions.

gcc/ChangeLog:

	PR tree-optimization/110666
	* match.pd (A NEEQ (A NEEQ CST)): Fix Outer EQ case.

gcc/testsuite/ChangeLog:

	PR tree-optimization/110666
	* gcc.c-torture/execute/pr110666-1.c: New test.

2 files changed, 71 insertions, 14 deletions

diff --git a/gcc/match.pd b/gcc/match.pd
index 351d928..88061fa 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -6431,8 +6431,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 
 /* x != (typeof x)(x == CST) -> CST == 0 ? 1 : (CST == 1 ? (x!=0&&x!=1) : x != 0) */
 /* x != (typeof x)(x != CST) -> CST == 1 ? 1 : (CST == 0 ? (x!=0&&x!=1) : x != 1) */
-/* x == (typeof x)(x == CST) -> CST == 0 ? 0 : (CST == 1 ? (x==0||x==1) : x != 0) */
-/* x == (typeof x)(x != CST) -> CST == 1 ? 0 : (CST == 0 ? (x==0||x==1) : x != 1) */
+/* x == (typeof x)(x == CST) -> CST == 0 ? 0 : (CST == 1 ? (x==0||x==1) : x == 0) */
+/* x == (typeof x)(x != CST) -> CST == 1 ? 0 : (CST == 0 ? (x==0||x==1) : x == 1) */
 (for outer (ne eq)
  (for inner (ne eq)
   (simplify
@@ -6443,23 +6443,29 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
      bool innereq = inner == EQ_EXPR;
      bool outereq = outer == EQ_EXPR;
     }
-   (switch
-    (if (innereq ? cst0 : cst1)
-     { constant_boolean_node (!outereq, type); })
-    (if (innereq ? cst1 : cst0)
+    (switch
+     (if (innereq ? cst0 : cst1)
+      { constant_boolean_node (!outereq, type); })
+     (if (innereq ? cst1 : cst0)
+      (with {
+        tree utype = unsigned_type_for (TREE_TYPE (@0));
+        tree ucst1 = build_one_cst (utype);
+       }
+       (if (!outereq)
+        (gt (convert:utype @0) { ucst1; })
+        (le (convert:utype @0) { ucst1; })
+       )
+      )
+     )
      (with {
-       tree utype = unsigned_type_for (TREE_TYPE (@0));
-       tree ucst1 = build_one_cst (utype);
+       tree value = build_int_cst (TREE_TYPE (@0), !innereq);
       }
-      (if (!outereq)
-       (gt (convert:utype @0) { ucst1; })
-       (le (convert:utype @0) { ucst1; })
+      (if (outereq)
+       (eq @0 { value; })
+       (ne @0 { value; })
       )
      )
     )
-    (if (innereq)
-     (ne @0 { build_zero_cst (TREE_TYPE (@0)); }))
-    (ne @0 { build_one_cst (TREE_TYPE (@0)); }))
    )
   )
  )
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr110666-1.c b/gcc/testsuite/gcc.c-torture/execute/pr110666-1.c
new file mode 100644
index 0000000..b22eb77
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr110666-1.c
@@ -0,0 +1,51 @@
+
+#define func_name(outer,inner,cst) outer##inner##_##cst
+#define func_name_v(outer,inner,cst) outer##inner##_##cst##_v
+
+#define func_decl(outer,inner,cst) \
+int outer##inner##_##cst (int) __attribute__((noipa)); \
+int outer##inner##_##cst (int a) { \
+  return (a op_##inner cst) op_##outer a; \
+} \
+int outer##inner##_##cst##_v (int) __attribute__((noipa)); \
+int outer##inner##_##cst##_v (volatile int a) { \
+  return (a op_##inner cst) op_##outer a; \
+}
+
+#define functions_n(outer, inner) \
+func_decl(outer,inner,0) \
+func_decl(outer,inner,1) \
+func_decl(outer,inner,2)
+
+#define functions() \
+functions_n(eq,eq) \
+functions_n(eq,ne) \
+functions_n(ne,eq) \
+functions_n(ne,ne)
+
+#define op_ne !=
+#define op_eq ==
+
+#define test(inner,outer,cst,arg) \
+func_name_v (inner,outer,cst)(arg) != func_name(inner,outer,cst)(arg)
+
+functions()
+
+#define tests_n(inner,outer,arg) \
+if (test(inner,outer,0,arg)) __builtin_abort(); \
+if (test(inner,outer,1,arg)) __builtin_abort(); \
+if (test(inner,outer,2,arg)) __builtin_abort();
+
+#define tests(arg) \
+tests_n(eq,eq,arg) \
+tests_n(eq,ne,arg) \
+tests_n(ne,eq,arg) \
+tests_n(ne,ne,arg)
+
+
+int main()
+{
+  for(int n = -1; n <= 2; n++) {
+    tests(n)
+  }
+}