Linux kernel mirror (for testing)
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linux
1#ifndef __LINUX_COMPILER_H
2#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
3#endif
4
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
14/*
15 * 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 *
27 * 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 */
32#define RELOC_HIDE(ptr, off) \
33 ({ unsigned long __ptr; \
34 __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
35 (typeof(ptr)) (__ptr + (off)); })
36
37/* &a[0] degrades to a pointer: a different type from an array */
38#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
39
40/*
41 * Force always-inline if the user requests it so via the .config,
42 * or if gcc is too old:
43 */
44#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
45 !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
46# define inline inline __attribute__((always_inline))
47# define __inline__ __inline__ __attribute__((always_inline))
48# define __inline __inline __attribute__((always_inline))
49#endif
50
51#define __deprecated __attribute__((deprecated))
52#define __packed __attribute__((packed))
53#define __weak __attribute__((weak))
54
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.
60 *
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.
64 */
65#define __naked __attribute__((naked)) noinline __noclone notrace
66
67#define __noreturn __attribute__((noreturn))
68
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 */
79#define __pure __attribute__((pure))
80#define __aligned(x) __attribute__((aligned(x)))
81#define __printf(a,b) __attribute__((format(printf,a,b)))
82#define noinline __attribute__((noinline))
83#define __attribute_const__ __attribute__((__const__))
84#define __maybe_unused __attribute__((unused))
85#define __always_unused __attribute__((unused))
86
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__)
91
92#if !defined(__noclone)
93#define __noclone /* not needed */
94#endif
95
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))