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Diffstat (limited to 'include/linux/compiler-gcc.h')
-rw-r--r-- | include/linux/compiler-gcc.h | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h new file mode 100644 index 00000000..e5834aa2 --- /dev/null +++ b/include/linux/compiler-gcc.h @@ -0,0 +1,112 @@ +#ifndef __LINUX_COMPILER_H +#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead." +#endif + +/* + * Common definitions for all gcc versions go here. + */ + + +/* Optimization barrier */ +/* The "volatile" is due to gcc bugs */ +#define barrier() __asm__ __volatile__("": : :"memory") + +/* + * This macro obfuscates arithmetic on a variable address so that gcc + * shouldn't recognize the original var, and make assumptions about it. + * + * This is needed because the C standard makes it undefined to do + * pointer arithmetic on "objects" outside their boundaries and the + * gcc optimizers assume this is the case. In particular they + * assume such arithmetic does not wrap. + * + * A miscompilation has been observed because of this on PPC. + * To work around it we hide the relationship of the pointer and the object + * using this macro. + * + * Versions of the ppc64 compiler before 4.1 had a bug where use of + * RELOC_HIDE could trash r30. The bug can be worked around by changing + * the inline assembly constraint from =g to =r, in this particular + * case either is valid. + */ +#define RELOC_HIDE(ptr, off) \ + ({ unsigned long __ptr; \ + __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ + (typeof(ptr)) (__ptr + (off)); }) + +#ifdef __CHECKER__ +#define __must_be_array(arr) 0 +#else +/* &a[0] degrades to a pointer: a different type from an array */ +#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) +#endif + +/* + * Force always-inline if the user requests it so via the .config, + * or if gcc is too old: + */ +#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ + !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) +# define inline inline __attribute__((always_inline)) +# define __inline__ __inline__ __attribute__((always_inline)) +# define __inline __inline __attribute__((always_inline)) +#else +/* A lot of inline functions can cause havoc with function tracing */ +# define inline inline notrace +# define __inline__ __inline__ notrace +# define __inline __inline notrace +#endif + +#define __deprecated __attribute__((deprecated)) +#define __packed __attribute__((packed)) +#define __weak __attribute__((weak)) + +/* + * it doesn't make sense on ARM (currently the only user of __naked) to trace + * naked functions because then mcount is called without stack and frame pointer + * being set up and there is no chance to restore the lr register to the value + * before mcount was called. + * + * The asm() bodies of naked functions often depend on standard calling conventions, + * therefore they must be noinline and noclone. GCC 4.[56] currently fail to enforce + * this, so we must do so ourselves. See GCC PR44290. + */ +#define __naked __attribute__((naked)) noinline __noclone notrace + +#define __noreturn __attribute__((noreturn)) + +/* + * From the GCC manual: + * + * Many functions have no effects except the return value and their + * return value depends only on the parameters and/or global + * variables. Such a function can be subject to common subexpression + * elimination and loop optimization just as an arithmetic operator + * would be. + * [...] + */ +#define __pure __attribute__((pure)) +#define __aligned(x) __attribute__((aligned(x))) +#define __printf(a, b) __attribute__((format(printf, a, b))) +#define __scanf(a, b) __attribute__((format(scanf, a, b))) +#define noinline __attribute__((noinline)) +#define __attribute_const__ __attribute__((__const__)) +#define __maybe_unused __attribute__((unused)) +#define __always_unused __attribute__((unused)) + +#define __gcc_header(x) #x +#define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h) +#define gcc_header(x) _gcc_header(x) +#include gcc_header(__GNUC__) + +#if !defined(__noclone) +#define __noclone /* not needed */ +#endif + +/* + * A trick to suppress uninitialized variable warning without generating any + * code + */ +#define uninitialized_var(x) x = x + +#define __always_inline inline __attribute__((always_inline)) |