We want to extend our macro-based KLV list definitions with new
information about the version from which given KLV is supported.
Add utility IF_ARGS macro that can be used in code generators to
emit different code based on the presence of additional arguments.

Introduce macro itself and extend our kunit tests to cover it.
We will use this macro in next patch.

Signed-off-by: Michal Wajdeczko <[email protected]>
Reviewed-by: Daniele Ceraolo Spurio <[email protected]>
---
 drivers/gpu/drm/xe/tests/xe_args_test.c | 53 +++++++++++++++++++++++++
 drivers/gpu/drm/xe/xe_args.h            | 18 +++++++++
 2 files changed, 71 insertions(+)

diff --git a/drivers/gpu/drm/xe/tests/xe_args_test.c 
b/drivers/gpu/drm/xe/tests/xe_args_test.c
index f3fb23aa5d2e..d11ea610f67a 100644
--- a/drivers/gpu/drm/xe/tests/xe_args_test.c
+++ b/drivers/gpu/drm/xe/tests/xe_args_test.c
@@ -78,6 +78,24 @@ static void pick_arg_example(struct kunit *test)
 #undef buz
 }
 
+static void if_args_example(struct kunit *test)
+{
+       enum { Z = 1, Q };
+
+#define foo    X, Y
+#define bar    IF_ARGS(Z, Q, foo)
+#define buz    IF_ARGS(Z, Q, DROP_FIRST_ARG(FIRST_ARG(foo)))
+
+       KUNIT_EXPECT_EQ(test, bar, Z);
+       KUNIT_EXPECT_EQ(test, buz, Q);
+       KUNIT_EXPECT_STREQ(test, __stringify(bar), "Z");
+       KUNIT_EXPECT_STREQ(test, __stringify(buz), "Q");
+
+#undef foo
+#undef bar
+#undef buz
+}
+
 static void sep_comma_example(struct kunit *test)
 {
 #define foo(f) f(X) f(Y) f(Z) f(Q)
@@ -198,6 +216,39 @@ static void last_arg_test(struct kunit *test)
        KUNIT_EXPECT_STREQ(test, __stringify(LAST_ARG(MAX_ARGS)), "-12");
 }
 
+static void if_args_test(struct kunit *test)
+{
+       bool with_args = true;
+       bool no_args = false;
+       enum { X = 100 };
+
+       KUNIT_EXPECT_TRUE(test, IF_ARGS(true, false, FOO_ARGS));
+       KUNIT_EXPECT_FALSE(test, IF_ARGS(true, false, NO_ARGS));
+
+       KUNIT_EXPECT_TRUE(test, CONCATENATE(IF_ARGS(with, no, FOO_ARGS), 
_args));
+       KUNIT_EXPECT_FALSE(test, CONCATENATE(IF_ARGS(with, no, NO_ARGS), 
_args));
+
+       KUNIT_EXPECT_STREQ(test, __stringify(IF_ARGS(yes, no, FOO_ARGS)), 
"yes");
+       KUNIT_EXPECT_STREQ(test, __stringify(IF_ARGS(no, no, NO_ARGS)), "no");
+
+       KUNIT_EXPECT_EQ(test, IF_ARGS(CALL_ARGS(COUNT_ARGS, FOO_ARGS), -1, 
FOO_ARGS), 4);
+       KUNIT_EXPECT_EQ(test, IF_ARGS(CALL_ARGS(COUNT_ARGS, FOO_ARGS), -1, 
NO_ARGS), -1);
+       KUNIT_EXPECT_EQ(test, IF_ARGS(CALL_ARGS(COUNT_ARGS, NO_ARGS), -1, 
FOO_ARGS), 0);
+       KUNIT_EXPECT_EQ(test, IF_ARGS(CALL_ARGS(COUNT_ARGS, NO_ARGS), -1, 
NO_ARGS), -1);
+
+       KUNIT_EXPECT_EQ(test,
+                       FIRST_ARG(CONCATENATE(CALL_ARGS(IF_ARGS, FOO, MAX, 
FOO_ARGS), _ARGS)), X);
+       KUNIT_EXPECT_EQ(test,
+                       FIRST_ARG(CONCATENATE(CALL_ARGS(IF_ARGS, FOO, MAX, 
NO_ARGS), _ARGS)), -1);
+
+       KUNIT_EXPECT_EQ(test,
+                       CALL_ARGS(COUNT_ARGS,
+                                 CONCATENATE(CALL_ARGS(IF_ARGS, FOO, MAX, 
FOO_ARGS), _ARGS)), 4);
+       KUNIT_EXPECT_EQ(test,
+                       CALL_ARGS(COUNT_ARGS,
+                                 CONCATENATE(CALL_ARGS(IF_ARGS, FOO, MAX, 
NO_ARGS), _ARGS)), 12);
+}
+
 static struct kunit_case args_tests[] = {
        KUNIT_CASE(count_args_test),
        KUNIT_CASE(call_args_example),
@@ -209,6 +260,8 @@ static struct kunit_case args_tests[] = {
        KUNIT_CASE(last_arg_example),
        KUNIT_CASE(last_arg_test),
        KUNIT_CASE(pick_arg_example),
+       KUNIT_CASE(if_args_example),
+       KUNIT_CASE(if_args_test),
        KUNIT_CASE(sep_comma_example),
        {}
 };
diff --git a/drivers/gpu/drm/xe/xe_args.h b/drivers/gpu/drm/xe/xe_args.h
index 4dbc7e53c624..657203852036 100644
--- a/drivers/gpu/drm/xe/xe_args.h
+++ b/drivers/gpu/drm/xe/xe_args.h
@@ -121,6 +121,24 @@
 #define PICK_ARG11(args...)            PICK_ARG10(DROP_FIRST_ARG(args))
 #define PICK_ARG12(args...)            PICK_ARG11(DROP_FIRST_ARG(args))
 
+/**
+ * IF_ARGS() - Make selection based on optional argument list.
+ * @then: token to return if arguments are present
+ * @else: token to return if arguments are empty
+ * @...: arguments to check (optional)
+ *
+ * This macro allows to select a token based on the presence of the argument 
list.
+ *
+ * Example:
+ *
+ *     #define foo     X, Y
+ *     #define bar     IF_ARGS(Z, Q, foo)
+ *     #define buz     IF_ARGS(Z, Q, DROP_FIRST_ARG(FIRST_ARG(foo)))
+ *
+ *     With above definitions bar expands to Z while buz expands to Q.
+ */
+#define IF_ARGS(then, else, ...)       FIRST_ARG(__VA_OPT__(then,) else)
+
 /**
  * ARGS_SEP_COMMA - Definition of a comma character.
  *
-- 
2.47.1

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