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) : ""(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) \
39 BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(typeof(a), typeof(&a[0])))
40
41 /*
42 * Force always-inline if the user requests it so via the .config,
43 * or if gcc is too old:
44 */
45 #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
46 !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
47 # define inline inline __attribute__((always_inline))
48 # define __inline__ __inline__ __attribute__((always_inline))
49 # define __inline __inline __attribute__((always_inline))
50 #endif
51
52 #define __deprecated __attribute__((deprecated))
53 #define __packed __attribute__((packed))
54 #define __weak __attribute__((weak))
55
56 /*
57 * it doesn't make sense on ARM (currently the only user of __naked) to trace
58 * naked functions because then mcount is called without stack and frame pointer
59 * being set up and there is no chance to restore the lr register to the value
60 * before mcount was called.
61 */
62 #define __naked __attribute__((naked)) notrace
63
64 #define __noreturn __attribute__((noreturn))
65
66 /*
67 * From the GCC manual:
68 *
69 * Many functions have no effects except the return value and their
70 * return value depends only on the parameters and/or global
71 * variables. Such a function can be subject to common subexpression
72 * elimination and loop optimization just as an arithmetic operator
73 * would be.
74 * [...]
75 */
76 #define __pure __attribute__((pure))
77 #define __aligned(x) __attribute__((aligned(x)))
78 #define __printf(a,b) __attribute__((format(printf,a,b)))
79 #define noinline __attribute__((noinline))
80 #define __attribute_const__ __attribute__((__const__))
81 #define __maybe_unused __attribute__((unused))
82
83 #define __gcc_header(x) #x
84 #define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h)
85 #define gcc_header(x) _gcc_header(x)
86 #include gcc_header(__GNUC__)
87
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