| 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 | #ifdef __CHECKER__ |
| 38 | #define __must_be_array(arr) 0 |
| 39 | #else |
| 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])) |
| 42 | #endif |
| 43 | |
| 44 | /* |
| 45 | * Force always-inline if the user requests it so via the .config, |
| 46 | * or if gcc is too old: |
| 47 | */ |
| 48 | #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ |
| 49 | !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) |
| 50 | # define inline inline __attribute__((always_inline)) notrace |
| 51 | # define __inline__ __inline__ __attribute__((always_inline)) notrace |
| 52 | # define __inline __inline __attribute__((always_inline)) notrace |
| 53 | #else |
| 54 | /* A lot of inline functions can cause havoc with function tracing */ |
| 55 | # define inline inline notrace |
| 56 | # define __inline__ __inline__ notrace |
| 57 | # define __inline __inline notrace |
| 58 | #endif |
| 59 | |
| 60 | #define __deprecated __attribute__((deprecated)) |
| 61 | #define __packed __attribute__((packed)) |
| 62 | #define __weak __attribute__((weak)) |
| 63 | |
| 64 | /* |
| 65 | * it doesn't make sense on ARM (currently the only user of __naked) to trace |
| 66 | * naked functions because then mcount is called without stack and frame pointer |
| 67 | * being set up and there is no chance to restore the lr register to the value |
| 68 | * before mcount was called. |
| 69 | * |
| 70 | * The asm() bodies of naked functions often depend on standard calling conventions, |
| 71 | * therefore they must be noinline and noclone. GCC 4.[56] currently fail to enforce |
| 72 | * this, so we must do so ourselves. See GCC PR44290. |
| 73 | */ |
| 74 | #define __naked __attribute__((naked)) noinline __noclone notrace |
| 75 | |
| 76 | #define __noreturn __attribute__((noreturn)) |
| 77 | |
| 78 | /* |
| 79 | * From the GCC manual: |
| 80 | * |
| 81 | * Many functions have no effects except the return value and their |
| 82 | * return value depends only on the parameters and/or global |
| 83 | * variables. Such a function can be subject to common subexpression |
| 84 | * elimination and loop optimization just as an arithmetic operator |
| 85 | * would be. |
| 86 | * [...] |
| 87 | */ |
| 88 | #define __pure __attribute__((pure)) |
| 89 | #define __aligned(x) __attribute__((aligned(x))) |
| 90 | #define __printf(a, b) __attribute__((format(printf, a, b))) |
| 91 | #define __scanf(a, b) __attribute__((format(scanf, a, b))) |
| 92 | #define noinline __attribute__((noinline)) |
| 93 | #define __attribute_const__ __attribute__((__const__)) |
| 94 | #define __maybe_unused __attribute__((unused)) |
| 95 | #define __always_unused __attribute__((unused)) |
| 96 | |
| 97 | #define __gcc_header(x) #x |
| 98 | #define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h) |
| 99 | #define gcc_header(x) _gcc_header(x) |
| 100 | #include gcc_header(__GNUC__) |
| 101 | |
| 102 | #if !defined(__noclone) |
| 103 | #define __noclone /* not needed */ |
| 104 | #endif |
| 105 | |
| 106 | /* |
| 107 | * A trick to suppress uninitialized variable warning without generating any |
| 108 | * code |
| 109 | */ |
| 110 | #define uninitialized_var(x) x = x |
| 111 | |
| 112 | #define __always_inline inline __attribute__((always_inline)) |