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 /* Make the optimizer believe the variable can be manipulated arbitrarily. */ 41 #define OPTIMIZER_HIDE_VAR(var) __asm__ ("" : "=r" (var) : "0" (var)) 42 43 #ifdef __CHECKER__ 44 #define __must_be_array(arr) 0 45 #else 46 /* &a[0] degrades to a pointer: a different type from an array */ 47 #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) 48 #endif 49 50 /* 51 * Force always-inline if the user requests it so via the .config, 52 * or if gcc is too old: 53 */ 54 #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ 55 !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) 56 # define inline inline __attribute__((always_inline)) notrace 57 # define __inline__ __inline__ __attribute__((always_inline)) notrace 58 # define __inline __inline __attribute__((always_inline)) notrace 59 #else 60 /* A lot of inline functions can cause havoc with function tracing */ 61 # define inline inline notrace 62 # define __inline__ __inline__ notrace 63 # define __inline __inline notrace 64 #endif 65 66 #define __deprecated __attribute__((deprecated)) 67 #define __packed __attribute__((packed)) 68 #define __weak __attribute__((weak)) 69 #define __alias(symbol) __attribute__((alias(#symbol))) 70 71 /* 72 * it doesn't make sense on ARM (currently the only user of __naked) to trace 73 * naked functions because then mcount is called without stack and frame pointer 74 * being set up and there is no chance to restore the lr register to the value 75 * before mcount was called. 76 * 77 * The asm() bodies of naked functions often depend on standard calling conventions, 78 * therefore they must be noinline and noclone. GCC 4.[56] currently fail to enforce 79 * this, so we must do so ourselves. See GCC PR44290. 80 */ 81 #define __naked __attribute__((naked)) noinline __noclone notrace 82 83 #define __noreturn __attribute__((noreturn)) 84 85 /* 86 * From the GCC manual: 87 * 88 * Many functions have no effects except the return value and their 89 * return value depends only on the parameters and/or global 90 * variables. Such a function can be subject to common subexpression 91 * elimination and loop optimization just as an arithmetic operator 92 * would be. 93 * [...] 94 */ 95 #define __pure __attribute__((pure)) 96 #define __aligned(x) __attribute__((aligned(x))) 97 #define __printf(a, b) __attribute__((format(printf, a, b))) 98 #define __scanf(a, b) __attribute__((format(scanf, a, b))) 99 #define noinline __attribute__((noinline)) 100 #define __attribute_const__ __attribute__((__const__)) 101 #define __maybe_unused __attribute__((unused)) 102 #define __always_unused __attribute__((unused)) 103 104 #define __gcc_header(x) #x 105 #define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h) 106 #define gcc_header(x) _gcc_header(x) 107 #include gcc_header(__GNUC__) 108 109 #if !defined(__noclone) 110 #define __noclone /* not needed */ 111 #endif 112 113 /* 114 * A trick to suppress uninitialized variable warning without generating any 115 * code 116 */ 117 #define uninitialized_var(x) x = x 118 119 #define __always_inline inline __attribute__((always_inline)) 120