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94f582f8 RD |
1 | #ifndef __LINUX_COMPILER_H |
2 | #error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead." | |
3 | #endif | |
1da177e4 LT |
4 | |
5 | /* | |
6 | * Common definitions for all gcc versions go here. | |
7 | */ | |
f6d133f8 JP |
8 | #define GCC_VERSION (__GNUC__ * 10000 \ |
9 | + __GNUC_MINOR__ * 100 \ | |
10 | + __GNUC_PATCHLEVEL__) | |
1da177e4 | 11 | |
1da177e4 | 12 | /* Optimization barrier */ |
7829fb09 | 13 | |
1da177e4 LT |
14 | /* The "volatile" is due to gcc bugs */ |
15 | #define barrier() __asm__ __volatile__("": : :"memory") | |
7829fb09 DB |
16 | /* |
17 | * This version is i.e. to prevent dead stores elimination on @ptr | |
18 | * where gcc and llvm may behave differently when otherwise using | |
19 | * normal barrier(): while gcc behavior gets along with a normal | |
20 | * barrier(), llvm needs an explicit input variable to be assumed | |
21 | * clobbered. The issue is as follows: while the inline asm might | |
22 | * access any memory it wants, the compiler could have fit all of | |
23 | * @ptr into memory registers instead, and since @ptr never escaped | |
24 | * from that, it proofed that the inline asm wasn't touching any of | |
25 | * it. This version works well with both compilers, i.e. we're telling | |
26 | * the compiler that the inline asm absolutely may see the contents | |
27 | * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 | |
28 | */ | |
29 | #define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") | |
1da177e4 | 30 | |
c8d52465 | 31 | /* |
85c210ed AK |
32 | * This macro obfuscates arithmetic on a variable address so that gcc |
33 | * shouldn't recognize the original var, and make assumptions about it. | |
34 | * | |
35 | * This is needed because the C standard makes it undefined to do | |
36 | * pointer arithmetic on "objects" outside their boundaries and the | |
37 | * gcc optimizers assume this is the case. In particular they | |
38 | * assume such arithmetic does not wrap. | |
39 | * | |
40 | * A miscompilation has been observed because of this on PPC. | |
41 | * To work around it we hide the relationship of the pointer and the object | |
42 | * using this macro. | |
43 | * | |
c8d52465 AB |
44 | * Versions of the ppc64 compiler before 4.1 had a bug where use of |
45 | * RELOC_HIDE could trash r30. The bug can be worked around by changing | |
46 | * the inline assembly constraint from =g to =r, in this particular | |
47 | * case either is valid. | |
48 | */ | |
f6d133f8 JP |
49 | #define RELOC_HIDE(ptr, off) \ |
50 | ({ \ | |
51 | unsigned long __ptr; \ | |
52 | __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ | |
53 | (typeof(ptr)) (__ptr + (off)); \ | |
54 | }) | |
a1365647 | 55 | |
fe8c8a12 | 56 | /* Make the optimizer believe the variable can be manipulated arbitrarily. */ |
f6d133f8 JP |
57 | #define OPTIMIZER_HIDE_VAR(var) \ |
58 | __asm__ ("" : "=r" (var) : "0" (var)) | |
fe8c8a12 | 59 | |
5bd7e6a3 | 60 | #ifdef __CHECKER__ |
f6d133f8 | 61 | #define __must_be_array(a) 0 |
5bd7e6a3 | 62 | #else |
c5e631cf | 63 | /* &a[0] degrades to a pointer: a different type from an array */ |
f6d133f8 | 64 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) |
5bd7e6a3 | 65 | #endif |
a1365647 | 66 | |
60a3cdd0 | 67 | /* |
ae3a0064 IM |
68 | * Force always-inline if the user requests it so via the .config, |
69 | * or if gcc is too old: | |
60a3cdd0 | 70 | */ |
f6d133f8 | 71 | #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ |
ae3a0064 | 72 | !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) |
f6d133f8 JP |
73 | #define inline inline __attribute__((always_inline)) notrace |
74 | #define __inline__ __inline__ __attribute__((always_inline)) notrace | |
75 | #define __inline __inline __attribute__((always_inline)) notrace | |
45959ee7 SR |
76 | #else |
77 | /* A lot of inline functions can cause havoc with function tracing */ | |
f6d133f8 JP |
78 | #define inline inline notrace |
79 | #define __inline__ __inline__ notrace | |
80 | #define __inline __inline notrace | |
60a3cdd0 IM |
81 | #endif |
82 | ||
f6d133f8 JP |
83 | #define __always_inline inline __attribute__((always_inline)) |
84 | #define noinline __attribute__((noinline)) | |
85 | ||
86 | #define __deprecated __attribute__((deprecated)) | |
87 | #define __packed __attribute__((packed)) | |
88 | #define __weak __attribute__((weak)) | |
89 | #define __alias(symbol) __attribute__((alias(#symbol))) | |
446c92b2 UKK |
90 | |
91 | /* | |
f6d133f8 JP |
92 | * it doesn't make sense on ARM (currently the only user of __naked) |
93 | * to trace naked functions because then mcount is called without | |
94 | * stack and frame pointer being set up and there is no chance to | |
95 | * restore the lr register to the value before mcount was called. | |
96 | * | |
97 | * The asm() bodies of naked functions often depend on standard calling | |
98 | * conventions, therefore they must be noinline and noclone. | |
9c695203 | 99 | * |
f6d133f8 JP |
100 | * GCC 4.[56] currently fail to enforce this, so we must do so ourselves. |
101 | * See GCC PR44290. | |
446c92b2 | 102 | */ |
f6d133f8 | 103 | #define __naked __attribute__((naked)) noinline __noclone notrace |
446c92b2 | 104 | |
f6d133f8 | 105 | #define __noreturn __attribute__((noreturn)) |
e8c44319 RB |
106 | |
107 | /* | |
108 | * From the GCC manual: | |
109 | * | |
110 | * Many functions have no effects except the return value and their | |
111 | * return value depends only on the parameters and/or global | |
112 | * variables. Such a function can be subject to common subexpression | |
113 | * elimination and loop optimization just as an arithmetic operator | |
114 | * would be. | |
115 | * [...] | |
116 | */ | |
f6d133f8 JP |
117 | #define __pure __attribute__((pure)) |
118 | #define __aligned(x) __attribute__((aligned(x))) | |
119 | #define __printf(a, b) __attribute__((format(printf, a, b))) | |
120 | #define __scanf(a, b) __attribute__((format(scanf, a, b))) | |
121 | #define __attribute_const__ __attribute__((__const__)) | |
122 | #define __maybe_unused __attribute__((unused)) | |
123 | #define __always_unused __attribute__((unused)) | |
f153b821 LT |
124 | |
125 | #define __gcc_header(x) #x | |
126 | #define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h) | |
127 | #define gcc_header(x) _gcc_header(x) | |
128 | #include gcc_header(__GNUC__) | |
9c695203 MP |
129 | |
130 | #if !defined(__noclone) | |
131 | #define __noclone /* not needed */ | |
132 | #endif | |
c837fb37 BP |
133 | |
134 | /* | |
135 | * A trick to suppress uninitialized variable warning without generating any | |
136 | * code | |
137 | */ | |
138 | #define uninitialized_var(x) x = x |