2bcd521a68
Impact: feature to profile if statements
This patch adds a branch profiler for all if () statements.
The results will be found in:
/debugfs/tracing/profile_branch
For example:
miss hit % Function File Line
------- --------- - -------- ---- ----
0 1 100 x86_64_start_reservations head64.c 127
0 1 100 copy_bootdata head64.c 69
1 0 0 x86_64_start_kernel head64.c 111
32 0 0 set_intr_gate desc.h 319
1 0 0 reserve_ebda_region head.c 51
1 0 0 reserve_ebda_region head.c 47
0 1 100 reserve_ebda_region head.c 42
0 0 X maxcpus main.c 165
Miss means the branch was not taken. Hit means the branch was taken.
The percent is the percentage the branch was taken.
This adds a significant amount of overhead and should only be used
by those analyzing their system.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
281 lines
7.7 KiB
C
281 lines
7.7 KiB
C
#ifndef __LINUX_COMPILER_H
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#define __LINUX_COMPILER_H
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#ifndef __ASSEMBLY__
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#ifdef __CHECKER__
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# define __user __attribute__((noderef, address_space(1)))
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# define __kernel /* default address space */
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# define __safe __attribute__((safe))
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# define __force __attribute__((force))
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# define __nocast __attribute__((nocast))
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# define __iomem __attribute__((noderef, address_space(2)))
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# define __acquires(x) __attribute__((context(x,0,1)))
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# define __releases(x) __attribute__((context(x,1,0)))
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# define __acquire(x) __context__(x,1)
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# define __release(x) __context__(x,-1)
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# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
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extern void __chk_user_ptr(const volatile void __user *);
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extern void __chk_io_ptr(const volatile void __iomem *);
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#else
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# define __user
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# define __kernel
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# define __safe
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# define __force
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# define __nocast
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# define __iomem
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# define __chk_user_ptr(x) (void)0
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# define __chk_io_ptr(x) (void)0
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# define __builtin_warning(x, y...) (1)
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# define __acquires(x)
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# define __releases(x)
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# define __acquire(x) (void)0
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# define __release(x) (void)0
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# define __cond_lock(x,c) (c)
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#endif
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#ifdef __KERNEL__
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#if __GNUC__ >= 4
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# include <linux/compiler-gcc4.h>
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#elif __GNUC__ == 3 && __GNUC_MINOR__ >= 2
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# include <linux/compiler-gcc3.h>
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#else
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# error Sorry, your compiler is too old/not recognized.
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#endif
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#define notrace __attribute__((no_instrument_function))
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/* Intel compiler defines __GNUC__. So we will overwrite implementations
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* coming from above header files here
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*/
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#ifdef __INTEL_COMPILER
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# include <linux/compiler-intel.h>
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#endif
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/*
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* Generic compiler-dependent macros required for kernel
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* build go below this comment. Actual compiler/compiler version
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* specific implementations come from the above header files
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*/
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struct ftrace_branch_data {
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const char *func;
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const char *file;
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unsigned line;
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union {
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struct {
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unsigned long correct;
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unsigned long incorrect;
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};
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struct {
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unsigned long miss;
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unsigned long hit;
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};
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};
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};
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/*
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* Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
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* to disable branch tracing on a per file basis.
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*/
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#if defined(CONFIG_TRACE_BRANCH_PROFILING) && !defined(DISABLE_BRANCH_PROFILING)
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void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
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#define likely_notrace(x) __builtin_expect(!!(x), 1)
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#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
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#define __branch_check__(x, expect) ({ \
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int ______r; \
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static struct ftrace_branch_data \
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__attribute__((__aligned__(4))) \
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__attribute__((section("_ftrace_annotated_branch"))) \
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______f = { \
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.func = __func__, \
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.file = __FILE__, \
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.line = __LINE__, \
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}; \
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______r = likely_notrace(x); \
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ftrace_likely_update(&______f, ______r, expect); \
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______r; \
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})
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/*
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* Using __builtin_constant_p(x) to ignore cases where the return
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* value is always the same. This idea is taken from a similar patch
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* written by Daniel Walker.
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*/
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# ifndef likely
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# define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
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# endif
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# ifndef unlikely
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# define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
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# endif
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#ifdef CONFIG_PROFILE_ALL_BRANCHES
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/*
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* "Define 'is'", Bill Clinton
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* "Define 'if'", Steven Rostedt
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*/
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#define if(cond) if (__builtin_constant_p((cond)) ? !!(cond) : \
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({ \
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int ______r; \
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static struct ftrace_branch_data \
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__attribute__((__aligned__(4))) \
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__attribute__((section("_ftrace_branch"))) \
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______f = { \
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.func = __func__, \
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.file = __FILE__, \
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.line = __LINE__, \
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}; \
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______r = !!(cond); \
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if (______r) \
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______f.hit++; \
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else \
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______f.miss++; \
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______r; \
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}))
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#endif /* CONFIG_PROFILE_ALL_BRANCHES */
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#else
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# define likely(x) __builtin_expect(!!(x), 1)
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# define unlikely(x) __builtin_expect(!!(x), 0)
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#endif
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/* Optimization barrier */
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#ifndef barrier
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# define barrier() __memory_barrier()
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#endif
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#ifndef RELOC_HIDE
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# define RELOC_HIDE(ptr, off) \
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({ unsigned long __ptr; \
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__ptr = (unsigned long) (ptr); \
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(typeof(ptr)) (__ptr + (off)); })
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#endif
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#endif /* __KERNEL__ */
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#endif /* __ASSEMBLY__ */
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#ifdef __KERNEL__
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/*
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* Allow us to mark functions as 'deprecated' and have gcc emit a nice
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* warning for each use, in hopes of speeding the functions removal.
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* Usage is:
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* int __deprecated foo(void)
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*/
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#ifndef __deprecated
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# define __deprecated /* unimplemented */
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#endif
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#ifdef MODULE
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#define __deprecated_for_modules __deprecated
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#else
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#define __deprecated_for_modules
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#endif
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#ifndef __must_check
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#define __must_check
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#endif
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#ifndef CONFIG_ENABLE_MUST_CHECK
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#undef __must_check
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#define __must_check
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#endif
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#ifndef CONFIG_ENABLE_WARN_DEPRECATED
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#undef __deprecated
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#undef __deprecated_for_modules
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#define __deprecated
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#define __deprecated_for_modules
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#endif
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/*
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* Allow us to avoid 'defined but not used' warnings on functions and data,
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* as well as force them to be emitted to the assembly file.
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*
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* As of gcc 3.4, static functions that are not marked with attribute((used))
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* may be elided from the assembly file. As of gcc 3.4, static data not so
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* marked will not be elided, but this may change in a future gcc version.
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*
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* NOTE: Because distributions shipped with a backported unit-at-a-time
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* compiler in gcc 3.3, we must define __used to be __attribute__((used))
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* for gcc >=3.3 instead of 3.4.
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*
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* In prior versions of gcc, such functions and data would be emitted, but
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* would be warned about except with attribute((unused)).
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*
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* Mark functions that are referenced only in inline assembly as __used so
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* the code is emitted even though it appears to be unreferenced.
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*/
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#ifndef __used
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# define __used /* unimplemented */
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#endif
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#ifndef __maybe_unused
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# define __maybe_unused /* unimplemented */
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#endif
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#ifndef noinline
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#define noinline
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#endif
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/*
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* Rather then using noinline to prevent stack consumption, use
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* noinline_for_stack instead. For documentaiton reasons.
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*/
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#define noinline_for_stack noinline
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#ifndef __always_inline
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#define __always_inline inline
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#endif
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#endif /* __KERNEL__ */
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/*
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* From the GCC manual:
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*
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* Many functions do not examine any values except their arguments,
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* and have no effects except the return value. Basically this is
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* just slightly more strict class than the `pure' attribute above,
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* since function is not allowed to read global memory.
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*
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* Note that a function that has pointer arguments and examines the
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* data pointed to must _not_ be declared `const'. Likewise, a
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* function that calls a non-`const' function usually must not be
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* `const'. It does not make sense for a `const' function to return
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* `void'.
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*/
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#ifndef __attribute_const__
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# define __attribute_const__ /* unimplemented */
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#endif
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/*
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* Tell gcc if a function is cold. The compiler will assume any path
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* directly leading to the call is unlikely.
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*/
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#ifndef __cold
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#define __cold
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#endif
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/* Simple shorthand for a section definition */
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#ifndef __section
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# define __section(S) __attribute__ ((__section__(#S)))
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#endif
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/*
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* Prevent the compiler from merging or refetching accesses. The compiler
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* is also forbidden from reordering successive instances of ACCESS_ONCE(),
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* but only when the compiler is aware of some particular ordering. One way
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* to make the compiler aware of ordering is to put the two invocations of
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* ACCESS_ONCE() in different C statements.
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*
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* This macro does absolutely -nothing- to prevent the CPU from reordering,
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* merging, or refetching absolutely anything at any time. Its main intended
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* use is to mediate communication between process-level code and irq/NMI
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* handlers, all running on the same CPU.
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*/
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#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
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#endif /* __LINUX_COMPILER_H */
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