[deliverable/linux.git] / include / linux / compiler-gcc.h

#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.
 */
#define GCC_VERSION (__GNUC__ * 10000 \
		   + __GNUC_MINOR__ * 100 \
		   + __GNUC_PATCHLEVEL__)


/* 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)); })

/* Make the optimizer believe the variable can be manipulated arbitrarily. */
#define OPTIMIZER_HIDE_VAR(var) __asm__ ("" : "=r" (var) : "0" (var))

#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)) notrace
# define __inline__	__inline__	__attribute__((always_inline)) notrace
# define __inline	__inline	__attribute__((always_inline)) notrace
#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))
Commit	Line	Data
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	*/
3f3f8d2f DS	8	#define GCC_VERSION (__GNUC__ * 10000 \
	9	+ __GNUC_MINOR__ * 100 \
	10	+ __GNUC_PATCHLEVEL__)
1da177e4 LT	11
	12
	13	/* Optimization barrier */
	14	/* The "volatile" is due to gcc bugs */
	15	#define barrier() __asm__ __volatile__("": : :"memory")
	16
c8d52465	17	/*
85c210ed AK	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	*
c8d52465 AB	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	*/
1da177e4 LT	35	#define RELOC_HIDE(ptr, off) \
1da177e4 LT	36	({ unsigned long __ptr; \
c8d52465	37	__asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
1da177e4	38	(typeof(ptr)) (__ptr + (off)); })
a1365647	39
fe8c8a12 CEB	40	/* Make the optimizer believe the variable can be manipulated arbitrarily. */
	41	#define OPTIMIZER_HIDE_VAR(var) __asm__ ("" : "=r" (var) : "0" (var))
	42
5bd7e6a3 KM	43	#ifdef __CHECKER__
	44	#define __must_be_array(arr) 0
	45	#else
c5e631cf	46	/* &a[0] degrades to a pointer: a different type from an array */
ea6b101d	47	#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
5bd7e6a3	48	#endif
a1365647	49
60a3cdd0	50	/*
ae3a0064 IM	51	* Force always-inline if the user requests it so via the .config,
ae3a0064 IM	52	* or if gcc is too old:
60a3cdd0	53	*/
765c68bd	54	#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) \|\| \
ae3a0064	55	!defined(CONFIG_OPTIMIZE_INLINING) \|\| (__GNUC__ < 4)
93b3cca1 SR	56	# define inline inline __attribute__((always_inline)) notrace
	57	# define __inline__ __inline__ __attribute__((always_inline)) notrace
	58	# define __inline __inline __attribute__((always_inline)) notrace
45959ee7 SR	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
60a3cdd0 IM	64	#endif
60a3cdd0 IM	65
a1365647	66	#define __deprecated __attribute__((deprecated))
82ddcb04 RD	67	#define __packed __attribute__((packed))
82ddcb04 RD	68	#define __weak __attribute__((weak))
446c92b2 UKK	69
	70	/*
	71	* it doesn't make sense on ARM (currently the only user of __naked) to trace
	72	* naked functions because then mcount is called without stack and frame pointer
	73	* being set up and there is no chance to restore the lr register to the value
	74	* before mcount was called.
9c695203 MP	75	*
	76	* The asm() bodies of naked functions often depend on standard calling conventions,
	77	* therefore they must be noinline and noclone. GCC 4.[56] currently fail to enforce
	78	* this, so we must do so ourselves. See GCC PR44290.
446c92b2	79	*/
9c695203	80	#define __naked __attribute__((naked)) noinline __noclone notrace
446c92b2	81
82ddcb04	82	#define __noreturn __attribute__((noreturn))
e8c44319 RB	83
	84	/*
	85	* From the GCC manual:
	86	*
	87	* Many functions have no effects except the return value and their
	88	* return value depends only on the parameters and/or global
	89	* variables. Such a function can be subject to common subexpression
	90	* elimination and loop optimization just as an arithmetic operator
	91	* would be.
	92	* [...]
	93	*/
82ddcb04 RD	94	#define __pure __attribute__((pure))
82ddcb04 RD	95	#define __aligned(x) __attribute__((aligned(x)))
6061d949 JP	96	#define __printf(a, b) __attribute__((format(printf, a, b)))
6061d949 JP	97	#define __scanf(a, b) __attribute__((format(scanf, a, b)))
a1365647	98	#define noinline __attribute__((noinline))
a1365647	99	#define __attribute_const__ __attribute__((__const__))
0d7ebbbc	100	#define __maybe_unused __attribute__((unused))
7b2a3513	101	#define __always_unused __attribute__((unused))
f153b821 LT	102
	103	#define __gcc_header(x) #x
	104	#define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h)
	105	#define gcc_header(x) _gcc_header(x)
	106	#include gcc_header(__GNUC__)
9c695203 MP	107
	108	#if !defined(__noclone)
	109	#define __noclone /* not needed */
	110	#endif
c837fb37 BP	111
	112	/*
	113	* A trick to suppress uninitialized variable warning without generating any
	114	* code
	115	*/
	116	#define uninitialized_var(x) x = x
	117
	118	#define __always_inline inline __attribute__((always_inline))