~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/include/linux/compiler-gcc.h

Version: ~ [ linux-5.15-rc7 ] ~ [ linux-5.14.14 ] ~ [ linux-5.13.19 ] ~ [ linux-5.12.19 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.75 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.155 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.213 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.252 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.287 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.289 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 /* Optimization barrier */
 13 
 14 /* The "volatile" is due to gcc bugs */
 15 #define barrier() __asm__ __volatile__("": : :"memory")
 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")
 30 
 31 /*
 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  *
 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  */
 49 #define RELOC_HIDE(ptr, off)                                    \
 50   ({ unsigned long __ptr;                                       \
 51     __asm__ ("" : "=r"(__ptr) : ""(ptr));              \
 52     (typeof(ptr)) (__ptr + (off)); })
 53 
 54 /* Make the optimizer believe the variable can be manipulated arbitrarily. */
 55 #define OPTIMIZER_HIDE_VAR(var) __asm__ ("" : "=r" (var) : "" (var))
 56 
 57 #ifdef __CHECKER__
 58 #define __must_be_array(arr) 0
 59 #else
 60 /* &a[0] degrades to a pointer: a different type from an array */
 61 #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
 62 #endif
 63 
 64 /*
 65  * Force always-inline if the user requests it so via the .config,
 66  * or if gcc is too old:
 67  */
 68 #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
 69     !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
 70 # define inline         inline          __attribute__((always_inline)) notrace
 71 # define __inline__     __inline__      __attribute__((always_inline)) notrace
 72 # define __inline       __inline        __attribute__((always_inline)) notrace
 73 #else
 74 /* A lot of inline functions can cause havoc with function tracing */
 75 # define inline         inline          notrace
 76 # define __inline__     __inline__      notrace
 77 # define __inline       __inline        notrace
 78 #endif
 79 
 80 #define __deprecated                    __attribute__((deprecated))
 81 #define __packed                        __attribute__((packed))
 82 #define __weak                          __attribute__((weak))
 83 
 84 /*
 85  * it doesn't make sense on ARM (currently the only user of __naked) to trace
 86  * naked functions because then mcount is called without stack and frame pointer
 87  * being set up and there is no chance to restore the lr register to the value
 88  * before mcount was called.
 89  *
 90  * The asm() bodies of naked functions often depend on standard calling conventions,
 91  * therefore they must be noinline and noclone.  GCC 4.[56] currently fail to enforce
 92  * this, so we must do so ourselves.  See GCC PR44290.
 93  */
 94 #define __naked                         __attribute__((naked)) noinline __noclone notrace
 95 
 96 #define __noreturn                      __attribute__((noreturn))
 97 
 98 /*
 99  * From the GCC manual:
100  *
101  * Many functions have no effects except the return value and their
102  * return value depends only on the parameters and/or global
103  * variables.  Such a function can be subject to common subexpression
104  * elimination and loop optimization just as an arithmetic operator
105  * would be.
106  * [...]
107  */
108 #define __pure                          __attribute__((pure))
109 #define __aligned(x)                    __attribute__((aligned(x)))
110 #define __printf(a, b)                  __attribute__((format(printf, a, b)))
111 #define __scanf(a, b)                   __attribute__((format(scanf, a, b)))
112 #define  noinline                       __attribute__((noinline))
113 #define __attribute_const__             __attribute__((__const__))
114 #define __maybe_unused                  __attribute__((unused))
115 #define __always_unused                 __attribute__((unused))
116 
117 /* gcc version specific checks */
118 
119 #if GCC_VERSION < 30200
120 # error Sorry, your compiler is too old - please upgrade it.
121 #endif
122 
123 #if GCC_VERSION < 30300
124 # define __used                 __attribute__((__unused__))
125 #else
126 # define __used                 __attribute__((__used__))
127 #endif
128 
129 #ifdef CONFIG_GCOV_KERNEL
130 # if GCC_VERSION < 30400
131 #   error "GCOV profiling support for gcc versions below 3.4 not included"
132 # endif /* __GNUC_MINOR__ */
133 #endif /* CONFIG_GCOV_KERNEL */
134 
135 #if GCC_VERSION >= 30400
136 #define __must_check            __attribute__((warn_unused_result))
137 #endif
138 
139 #if GCC_VERSION >= 40000
140 
141 /* GCC 4.1.[01] miscompiles __weak */
142 #ifdef __KERNEL__
143 # if GCC_VERSION >= 40100 &&  GCC_VERSION <= 40101
144 #  error Your version of gcc miscompiles the __weak directive
145 # endif
146 #endif
147 
148 #define __used                  __attribute__((__used__))
149 #define __compiler_offsetof(a, b)                                       \
150         __builtin_offsetof(a, b)
151 
152 #if GCC_VERSION >= 40100 && GCC_VERSION < 40600
153 # define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
154 #endif
155 
156 #if GCC_VERSION >= 40300
157 /* Mark functions as cold. gcc will assume any path leading to a call
158  * to them will be unlikely.  This means a lot of manual unlikely()s
159  * are unnecessary now for any paths leading to the usual suspects
160  * like BUG(), printk(), panic() etc. [but let's keep them for now for
161  * older compilers]
162  *
163  * Early snapshots of gcc 4.3 don't support this and we can't detect this
164  * in the preprocessor, but we can live with this because they're unreleased.
165  * Maketime probing would be overkill here.
166  *
167  * gcc also has a __attribute__((__hot__)) to move hot functions into
168  * a special section, but I don't see any sense in this right now in
169  * the kernel context
170  */
171 #define __cold                  __attribute__((__cold__))
172 
173 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
174 
175 #ifndef __CHECKER__
176 # define __compiletime_warning(message) __attribute__((warning(message)))
177 # define __compiletime_error(message) __attribute__((error(message)))
178 #endif /* __CHECKER__ */
179 #endif /* GCC_VERSION >= 40300 */
180 
181 #if GCC_VERSION >= 40500
182 /*
183  * Mark a position in code as unreachable.  This can be used to
184  * suppress control flow warnings after asm blocks that transfer
185  * control elsewhere.
186  *
187  * Early snapshots of gcc 4.5 don't support this and we can't detect
188  * this in the preprocessor, but we can live with this because they're
189  * unreleased.  Really, we need to have autoconf for the kernel.
190  */
191 #define unreachable() __builtin_unreachable()
192 
193 /* Mark a function definition as prohibited from being cloned. */
194 #define __noclone       __attribute__((__noclone__, __optimize__("no-tracer")))
195 
196 #endif /* GCC_VERSION >= 40500 */
197 
198 #if GCC_VERSION >= 40600
199 /*
200  * Tell the optimizer that something else uses this function or variable.
201  */
202 #define __visible       __attribute__((externally_visible))
203 #endif
204 
205 /*
206  * GCC 'asm goto' miscompiles certain code sequences:
207  *
208  *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
209  *
210  * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
211  *
212  * (asm goto is automatically volatile - the naming reflects this.)
213  */
214 #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0)
215 
216 #ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
217 #if GCC_VERSION >= 40400
218 #define __HAVE_BUILTIN_BSWAP32__
219 #define __HAVE_BUILTIN_BSWAP64__
220 #endif
221 #if GCC_VERSION >= 40800 || (defined(__powerpc__) && GCC_VERSION >= 40600)
222 #define __HAVE_BUILTIN_BSWAP16__
223 #endif
224 #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
225 
226 #if GCC_VERSION >= 50000
227 #define KASAN_ABI_VERSION 4
228 #elif GCC_VERSION >= 40902
229 #define KASAN_ABI_VERSION 3
230 #endif
231 
232 #endif  /* gcc version >= 40000 specific checks */
233 
234 #if !defined(__noclone)
235 #define __noclone       /* not needed */
236 #endif
237 
238 /*
239  * A trick to suppress uninitialized variable warning without generating any
240  * code
241  */
242 #define uninitialized_var(x) x = x
243 
244 #define __always_inline         inline __attribute__((always_inline))
245 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp