linux-kernel - [PATCH 03/12] Compiler Attributes: remove unneeded tests

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Date:   Mon,  3 Sep 2018 22:33:07 +0200
From:   Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        Eli Friedman <efriedma@...eaurora.org>,
        Christopher Li <sparse@...isli.org>,
        Kees Cook <keescook@...omium.org>,
        Ingo Molnar <mingo@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Joe Perches <joe@...ches.com>,
        Dominique Martinet <asmadeus@...ewreck.org>,
        linux-sparse@...r.kernel.org
Subject: [PATCH 03/12] Compiler Attributes: remove unneeded tests

Attributes const and always_inline have tests around them
which are unneeded, since they are supported by gcc >= 4.6,
clang >= 3 and icc >= 13. https://godbolt.org/z/DFPq37

In the case of gnu_inline, we do not need to test for
__GNUC_STDC_INLINE__ because, regardless of the current
inlining behavior, we can simply always force the old
GCC inlining behavior by using the attribute in all cases.

Cc: Rasmus Villemoes <linux@...musvillemoes.dk>
Cc: Luc Van Oostenryck <luc.vanoostenryck@...il.com>
Cc: Eli Friedman <efriedma@...eaurora.org>
Cc: Christopher Li <sparse@...isli.org>
Cc: Kees Cook <keescook@...omium.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc: Joe Perches <joe@...ches.com>
Cc: Dominique Martinet <asmadeus@...ewreck.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-sparse@...r.kernel.org
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
---
 include/linux/compiler_types.h | 24 +++---------------------
 1 file changed, 3 insertions(+), 21 deletions(-)

diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 2bc0f94df38e..759b3fea9216 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -158,10 +158,6 @@ struct ftrace_likely_data {
 	(sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || \
 	 sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
 
-#ifndef __attribute_const__
-#define __attribute_const__	__attribute__((__const__))
-#endif
-
 #ifndef __noclone
 #define __noclone
 #endif
@@ -196,6 +192,7 @@ struct ftrace_likely_data {
  * [...]
  */
 #define __pure			__attribute__((__pure__))
+#define __attribute_const__	__attribute__((__const__))
 #define __aligned(x)		__attribute__((__aligned__(x)))
 #define __aligned_largest	__attribute__((__aligned__))
 #define __printf(a, b)		__attribute__((__format__(printf, a, b)))
@@ -211,7 +208,8 @@ struct ftrace_likely_data {
 #define __alias(symbol)		__attribute__((__alias__(#symbol)))
 #define __cold			__attribute__((__cold__))
 #define __section(S)		__attribute__((__section__(#S)))
-
+#define __gnu_inline		__attribute__((__gnu_inline__))
+#define __always_inline		inline __attribute__((__always_inline__))
 
 #ifdef CONFIG_ENABLE_MUST_CHECK
 #define __must_check		__attribute__((__warn_unused_result__))
@@ -227,18 +225,6 @@ struct ftrace_likely_data {
 
 #define __compiler_offsetof(a, b)	__builtin_offsetof(a, b)
 
-/*
- * Feature detection for gnu_inline (gnu89 extern inline semantics). Either
- * __GNUC_STDC_INLINE__ is defined (not using gnu89 extern inline semantics,
- * and we opt in to the gnu89 semantics), or __GNUC_STDC_INLINE__ is not
- * defined so the gnu89 semantics are the default.
- */
-#ifdef __GNUC_STDC_INLINE__
-# define __gnu_inline	__attribute__((__gnu_inline__))
-#else
-# define __gnu_inline
-#endif
-
 /*
  * Force always-inline if the user requests it so via the .config.
  * GCC does not warn about unused static inline functions for
@@ -263,10 +249,6 @@ struct ftrace_likely_data {
 #define __inline inline
 #define noinline	__attribute__((__noinline__))
 
-#ifndef __always_inline
-#define __always_inline inline __attribute__((__always_inline__))
-#endif
-
 /*
  * Rather then using noinline to prevent stack consumption, use
  * noinline_for_stack instead.  For documentation reasons.
-- 
2.17.1