1 #ifndef __LINUX_COMPILER_H
2 #error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
6 * Common definitions for all gcc versions go here.
10 /* Optimization barrier */
11 /* The "volatile" is due to gcc bugs */
12 #define barrier() __asm__ __volatile__("": : :"memory")
15 * This macro obfuscates arithmetic on a variable address so that gcc
16 * shouldn't recognize the original var, and make assumptions about it.
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.
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
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.
32 #define RELOC_HIDE(ptr, off) \
33 ({ unsigned long __ptr; \
34 __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
35 (typeof(ptr)) (__ptr + (off)); })
38 #define __must_be_array(arr) 0
40 /* &a[0] degrades to a pointer: a different type from an array */
41 #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
45 * Force always-inline if the user requests it so via the .config,
46 * or if gcc is too old:
48 #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
49 !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
50 # define inline inline __attribute__((always_inline))
51 # define __inline__ __inline__ __attribute__((always_inline))
52 # define __inline __inline __attribute__((always_inline))
55 #define __deprecated __attribute__((deprecated))
56 #define __packed __attribute__((packed))
57 #define __weak __attribute__((weak))
60 * it doesn't make sense on ARM (currently the only user of __naked) to trace
61 * naked functions because then mcount is called without stack and frame pointer
62 * being set up and there is no chance to restore the lr register to the value
63 * before mcount was called.
65 * The asm() bodies of naked functions often depend on standard calling conventions,
66 * therefore they must be noinline and noclone. GCC 4.[56] currently fail to enforce
67 * this, so we must do so ourselves. See GCC PR44290.
69 #define __naked __attribute__((naked)) noinline __noclone notrace
71 #define __noreturn __attribute__((noreturn))
74 * From the GCC manual:
76 * Many functions have no effects except the return value and their
77 * return value depends only on the parameters and/or global
78 * variables. Such a function can be subject to common subexpression
79 * elimination and loop optimization just as an arithmetic operator
83 #define __pure __attribute__((pure))
84 #define __aligned(x) __attribute__((aligned(x)))
85 #define __printf(a,b) __attribute__((format(printf,a,b)))
86 #define noinline __attribute__((noinline))
87 #define __attribute_const__ __attribute__((__const__))
88 #define __maybe_unused __attribute__((unused))
89 #define __always_unused __attribute__((unused))
91 #define __gcc_header(x) #x
92 #define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h)
93 #define gcc_header(x) _gcc_header(x)
94 #include gcc_header(__GNUC__)
96 #if !defined(__noclone)
97 #define __noclone /* not needed */
101 * A trick to suppress uninitialized variable warning without generating any
104 #define uninitialized_var(x) x = x
106 #define __always_inline inline __attribute__((always_inline))