linux-kernel - [PATCH 3/7] Compiler Attributes: remove unneeded tests

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Date:   Fri, 31 Aug 2018 19:05:10 +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>,
        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>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: [PATCH 3/7] 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. See https://godbolt.org/z/no0OZH

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: 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: Nick Desaulniers <ndesaulniers@...gle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
---
 include/linux/compiler_types.h | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 7cd958360ead..3662b19599fc 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 __const			__attribute__((const))
 #define __aligned(x)		__attribute__((aligned(x)))
 #define __aligned_largest	__attribute__((aligned))
 #define __printf(a, b)		__attribute__((format(printf, a, b)))
@@ -227,17 +224,7 @@ 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
+#define __gnu_inline	__attribute__((gnu_inline))
 
 /*
  * Force always-inline if the user requests it so via the .config.
@@ -263,9 +250,7 @@ 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
-- 
2.17.1