blob: cb4c1eb7778e4f776bf9343f93d5f9c8636ab148 [file] [log] [blame]
Robert P. J. Day94f582f2007-10-16 23:26:11 -07001#ifndef __LINUX_COMPILER_H
2#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
3#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07004
5/*
6 * Common definitions for all gcc versions go here.
7 */
8
9
10/* Optimization barrier */
11/* The "volatile" is due to gcc bugs */
12#define barrier() __asm__ __volatile__("": : :"memory")
13
Anton Blanchardc8d52462006-01-10 18:21:20 +110014/*
Andi Kleen85c210e2009-01-09 16:40:53 -080015 * This macro obfuscates arithmetic on a variable address so that gcc
16 * shouldn't recognize the original var, and make assumptions about it.
17 *
18 * This is needed because the C standard makes it undefined to do
19 * pointer arithmetic on "objects" outside their boundaries and the
20 * gcc optimizers assume this is the case. In particular they
21 * assume such arithmetic does not wrap.
22 *
23 * A miscompilation has been observed because of this on PPC.
24 * To work around it we hide the relationship of the pointer and the object
25 * using this macro.
26 *
Anton Blanchardc8d52462006-01-10 18:21:20 +110027 * Versions of the ppc64 compiler before 4.1 had a bug where use of
28 * RELOC_HIDE could trash r30. The bug can be worked around by changing
29 * the inline assembly constraint from =g to =r, in this particular
30 * case either is valid.
31 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#define RELOC_HIDE(ptr, off) \
33 ({ unsigned long __ptr; \
Anton Blanchardc8d52462006-01-10 18:21:20 +110034 __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
Linus Torvalds1da177e2005-04-16 15:20:36 -070035 (typeof(ptr)) (__ptr + (off)); })
Andrew Mortona1365642006-01-08 01:04:09 -080036
Rusty Russellc5e631c2007-05-06 14:51:05 -070037/* &a[0] degrades to a pointer: a different type from an array */
Rusty Russellea6b1012010-08-09 17:20:18 -070038#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
Andrew Mortona1365642006-01-08 01:04:09 -080039
Ingo Molnar60a3cdd2008-03-03 12:38:52 +010040/*
Ingo Molnarae3a0062008-04-30 00:15:31 +020041 * Force always-inline if the user requests it so via the .config,
42 * or if gcc is too old:
Ingo Molnar60a3cdd2008-03-03 12:38:52 +010043 */
Ingo Molnar765c68b2008-04-09 11:03:37 +020044#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
Ingo Molnarae3a0062008-04-30 00:15:31 +020045 !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
Ingo Molnar60a3cdd2008-03-03 12:38:52 +010046# define inline inline __attribute__((always_inline))
47# define __inline__ __inline__ __attribute__((always_inline))
48# define __inline __inline __attribute__((always_inline))
49#endif
50
Andrew Mortona1365642006-01-08 01:04:09 -080051#define __deprecated __attribute__((deprecated))
Robert P. J. Day82ddcb02007-02-10 01:46:20 -080052#define __packed __attribute__((packed))
53#define __weak __attribute__((weak))
Uwe Kleine-König446c92b2009-03-12 18:03:16 +010054
55/*
56 * it doesn't make sense on ARM (currently the only user of __naked) to trace
57 * naked functions because then mcount is called without stack and frame pointer
58 * being set up and there is no chance to restore the lr register to the value
59 * before mcount was called.
Mikael Pettersson9c695202010-06-29 15:05:25 -070060 *
61 * The asm() bodies of naked functions often depend on standard calling conventions,
62 * therefore they must be noinline and noclone. GCC 4.[56] currently fail to enforce
63 * this, so we must do so ourselves. See GCC PR44290.
Uwe Kleine-König446c92b2009-03-12 18:03:16 +010064 */
Mikael Pettersson9c695202010-06-29 15:05:25 -070065#define __naked __attribute__((naked)) noinline __noclone notrace
Uwe Kleine-König446c92b2009-03-12 18:03:16 +010066
Robert P. J. Day82ddcb02007-02-10 01:46:20 -080067#define __noreturn __attribute__((noreturn))
Ralf Baechlee8c44312007-10-18 03:07:07 -070068
69/*
70 * From the GCC manual:
71 *
72 * Many functions have no effects except the return value and their
73 * return value depends only on the parameters and/or global
74 * variables. Such a function can be subject to common subexpression
75 * elimination and loop optimization just as an arithmetic operator
76 * would be.
77 * [...]
78 */
Robert P. J. Day82ddcb02007-02-10 01:46:20 -080079#define __pure __attribute__((pure))
80#define __aligned(x) __attribute__((aligned(x)))
81#define __printf(a,b) __attribute__((format(printf,a,b)))
Andrew Mortona1365642006-01-08 01:04:09 -080082#define noinline __attribute__((noinline))
Andrew Mortona1365642006-01-08 01:04:09 -080083#define __attribute_const__ __attribute__((__const__))
David Rientjes0d7ebbb2007-05-09 02:35:27 -070084#define __maybe_unused __attribute__((unused))
Li Zefan7b2a3512009-11-02 08:50:52 +080085#define __always_unused __attribute__((unused))
Linus Torvaldsf153b822009-01-02 09:23:03 -080086
87#define __gcc_header(x) #x
88#define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h)
89#define gcc_header(x) _gcc_header(x)
90#include gcc_header(__GNUC__)
Mikael Pettersson9c695202010-06-29 15:05:25 -070091
92#if !defined(__noclone)
93#define __noclone /* not needed */
94#endif
Borislav Petkovc837fb32011-03-22 16:33:55 -070095
96/*
97 * A trick to suppress uninitialized variable warning without generating any
98 * code
99 */
100#define uninitialized_var(x) x = x
101
102#define __always_inline inline __attribute__((always_inline))