From: Lucas De Marchi <lucas.demarchi@intel.com>
To: gfx-internal-devel@eclists.intel.com
Cc: Daniel Vetter <daniel.vetter@intel.com>,
dri-devel@lists.freedesktop.org,
Masahiro Yamada <masahiroy@kernel.org>,
linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] drm/i915/utils: do not depend on config being defined
Date: Wed, 29 Sep 2021 11:16:31 -0700 [thread overview]
Message-ID: <20210929181632.1489847-3-lucas.demarchi@intel.com> (raw)
In-Reply-To: <20210929181632.1489847-1-lucas.demarchi@intel.com>
Like the IS_ENABLED() counterpart, we can make IS_CONFIG_NONZERO() to
return the right thing when the config is not defined rather than a
build error, with the limitation that it can't be used on preprocessor
context.
The trick here is that macro names can't start with a number or dash, so
we stringify the argument and check that the first char is a number != 0
(or starting with a dash to cover negative numbers). Except for -O0
builds the strings are all eliminated.
Taking CONFIG_DRM_I915_REQUEST_TIMEOUT in
drivers/gpu/drm/i915/gem/i915_gem_context.c as example, we have the
following output of the preprocessor:
old:
if (((20000) != 0) &&
new:
if (( ("20000"[0] > '0' && "20000"[0] < '9') || "20000"[0] == '-' ) &&
New one looks worse, but is also eliminated from the object:
$ size drivers/gpu/drm/i915/gem/i915_gem_context.o.*
text data bss dec hex filename
52021 1070 232 53323 d04b drivers/gpu/drm/i915/gem/i915_gem_context.o.new
52021 1070 232 53323 d04b drivers/gpu/drm/i915/gem/i915_gem_context.o.old
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
---
drivers/gpu/drm/i915/i915_utils.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index 02bbfa4d68d3..436ce612c46a 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -28,6 +28,7 @@
#include <linux/list.h>
#include <linux/overflow.h>
#include <linux/sched.h>
+#include <linux/stringify.h>
#include <linux/types.h>
#include <linux/workqueue.h>
@@ -469,6 +470,9 @@ static inline bool timer_expired(const struct timer_list *t)
*
* Returns 0 if @config is 0, 1 if set to any value.
*/
-#define IS_CONFIG_NONZERO(config) ((config) != 0)
+#define IS_CONFIG_NONZERO(config) ( \
+ (__stringify_1(config)[0] > '0' && __stringify_1(config)[0] < '9') || \
+ __stringify_1(config)[0] == '-' \
+)
#endif /* !__I915_UTILS_H */
--
2.33.0
next prev parent reply other threads:[~2021-09-29 18:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-29 18:16 [PATCH 0/3] Rename IS_ACTIVE() and move to kconfig.h Lucas De Marchi
2021-09-29 18:16 ` [PATCH 1/3] drm/i915: rename IS_ACTIVE Lucas De Marchi
2021-09-29 18:16 ` Lucas De Marchi [this message]
2021-09-29 18:16 ` [PATCH 3/3] Move IS_CONFIG_NONZERO() to kconfig.h Lucas De Marchi
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