Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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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#define GCC_VERSION (__GNUC__ * 10000 \
9 + __GNUC_MINOR__ * 100 \
10 + __GNUC_PATCHLEVEL__)
11
12
13/* Optimization barrier */
14/* The "volatile" is due to gcc bugs */
15#define barrier() __asm__ __volatile__("": : :"memory")
16
17/*
18 * This macro obfuscates arithmetic on a variable address so that gcc
19 * shouldn't recognize the original var, and make assumptions about it.
20 *
21 * This is needed because the C standard makes it undefined to do
22 * pointer arithmetic on "objects" outside their boundaries and the
23 * gcc optimizers assume this is the case. In particular they
24 * assume such arithmetic does not wrap.
25 *
26 * A miscompilation has been observed because of this on PPC.
27 * To work around it we hide the relationship of the pointer and the object
28 * using this macro.
29 *
30 * Versions of the ppc64 compiler before 4.1 had a bug where use of
31 * RELOC_HIDE could trash r30. The bug can be worked around by changing
32 * the inline assembly constraint from =g to =r, in this particular
33 * case either is valid.
34 */
35#define RELOC_HIDE(ptr, off) \
36 ({ unsigned long __ptr; \
37 __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
38 (typeof(ptr)) (__ptr + (off)); })
39
40#ifdef __CHECKER__
41#define __must_be_array(arr) 0
42#else
43/* &a[0] degrades to a pointer: a different type from an array */
44#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
45#endif
46
47/*
48 * Force always-inline if the user requests it so via the .config,
49 * or if gcc is too old:
50 */
51#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
52 !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
53# define inline inline __attribute__((always_inline)) notrace
54# define __inline__ __inline__ __attribute__((always_inline)) notrace
55# define __inline __inline __attribute__((always_inline)) notrace
56#else
57/* A lot of inline functions can cause havoc with function tracing */
58# define inline inline notrace
59# define __inline__ __inline__ notrace
60# define __inline __inline notrace
61#endif
62
63#define __deprecated __attribute__((deprecated))
64#define __packed __attribute__((packed))
65#define __weak __attribute__((weak))
66
67/*
68 * it doesn't make sense on ARM (currently the only user of __naked) to trace
69 * naked functions because then mcount is called without stack and frame pointer
70 * being set up and there is no chance to restore the lr register to the value
71 * before mcount was called.
72 *
73 * The asm() bodies of naked functions often depend on standard calling conventions,
74 * therefore they must be noinline and noclone. GCC 4.[56] currently fail to enforce
75 * this, so we must do so ourselves. See GCC PR44290.
76 */
77#define __naked __attribute__((naked)) noinline __noclone notrace
78
79#define __noreturn __attribute__((noreturn))
80
81/*
82 * From the GCC manual:
83 *
84 * Many functions have no effects except the return value and their
85 * return value depends only on the parameters and/or global
86 * variables. Such a function can be subject to common subexpression
87 * elimination and loop optimization just as an arithmetic operator
88 * would be.
89 * [...]
90 */
91#define __pure __attribute__((pure))
92#define __aligned(x) __attribute__((aligned(x)))
93#define __printf(a, b) __attribute__((format(printf, a, b)))
94#define __scanf(a, b) __attribute__((format(scanf, a, b)))
95#define noinline __attribute__((noinline))
96#define __attribute_const__ __attribute__((__const__))
97#define __maybe_unused __attribute__((unused))
98#define __always_unused __attribute__((unused))
99
100#define __gcc_header(x) #x
101#define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h)
102#define gcc_header(x) _gcc_header(x)
103#include gcc_header(__GNUC__)
104
105#if !defined(__noclone)
106#define __noclone /* not needed */
107#endif
108
109/*
110 * A trick to suppress uninitialized variable warning without generating any
111 * code
112 */
113#define uninitialized_var(x) x = x
114
115#define __always_inline inline __attribute__((always_inline))