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![Marco Elver](/assets/img/avatar_default.png)
If the compiler supports C11's _Generic, use it to speed up compilation times of __unqual_scalar_typeof(). GCC version 4.9 or later and all supported versions of Clang support the feature (the oldest supported compiler that doesn't support _Generic is GCC 4.8, for which we use the slower alternative). The non-_Generic variant relies on multiple expansions of __pick_integer_type -> __pick_scalar_type -> __builtin_choose_expr, which increases pre-processed code size, and can cause compile times to increase in files with numerous expansions of READ_ONCE(), or other users of __unqual_scalar_typeof(). Summary of compile-time benchmarking done by Arnd Bergmann: <baseline normalized time> clang-11 gcc-9 this patch 0.78 0.91 ideal 0.76 0.86 See https://lkml.kernel.org/r/CAK8P3a3UYQeXhiufUevz=rwe09WM_vSTCd9W+KvJHJcOeQyWVA@mail.gmail.com Further compile-testing done with: gcc 4.8, 4.9, 5.5, 6.4, 7.5, 8.4; clang 9, 10. Reported-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Tested-by: Arnd Bergmann <arnd@arndb.de> Link: https://lkml.kernel.org/r/20200527103236.148700-1-elver@google.com Link: https://lkml.kernel.org/r/CAK8P3a0RJtbVi1JMsfik=jkHCNFv+DJn_FeDg-YLW+ueQW3tNg@mail.gmail.com [will: tweak new macros to make them a bit more readable] Signed-off-by: Will Deacon <will@kernel.org>
284 lines
8.6 KiB
C
284 lines
8.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_COMPILER_TYPES_H
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#define __LINUX_COMPILER_TYPES_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 __attribute__((address_space(0)))
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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 __must_hold(x) __attribute__((context(x,1,1)))
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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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# define __percpu __attribute__((noderef, address_space(3)))
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# define __rcu __attribute__((noderef, address_space(4)))
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# define __private __attribute__((noderef))
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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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# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member))
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#else /* __CHECKER__ */
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# ifdef STRUCTLEAK_PLUGIN
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# define __user __attribute__((user))
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# else
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# define __user
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# endif
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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 __must_hold(x)
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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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# define __percpu
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# define __rcu
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# define __private
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# define ACCESS_PRIVATE(p, member) ((p)->member)
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#endif /* __CHECKER__ */
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/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
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#define ___PASTE(a,b) a##b
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#define __PASTE(a,b) ___PASTE(a,b)
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#ifdef __KERNEL__
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/* Attributes */
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#include <linux/compiler_attributes.h>
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/* Compiler specific macros. */
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#ifdef __clang__
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#include <linux/compiler-clang.h>
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#elif defined(__INTEL_COMPILER)
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#include <linux/compiler-intel.h>
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#elif defined(__GNUC__)
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/* The above compilers also define __GNUC__, so order is important here. */
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#include <linux/compiler-gcc.h>
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#else
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#error "Unknown compiler"
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#endif
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/*
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* Some architectures need to provide custom definitions of macros provided
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* by linux/compiler-*.h, and can do so using asm/compiler.h. We include that
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* conditionally rather than using an asm-generic wrapper in order to avoid
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* build failures if any C compilation, which will include this file via an
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* -include argument in c_flags, occurs prior to the asm-generic wrappers being
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* generated.
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*/
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#ifdef CONFIG_HAVE_ARCH_COMPILER_H
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#include <asm/compiler.h>
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#endif
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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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unsigned long miss_hit[2];
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};
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};
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struct ftrace_likely_data {
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struct ftrace_branch_data data;
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unsigned long constant;
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};
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#ifdef CONFIG_ENABLE_MUST_CHECK
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#define __must_check __attribute__((__warn_unused_result__))
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#else
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#define __must_check
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#endif
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#if defined(CC_USING_HOTPATCH)
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#define notrace __attribute__((hotpatch(0, 0)))
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#elif defined(CC_USING_PATCHABLE_FUNCTION_ENTRY)
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#define notrace __attribute__((patchable_function_entry(0, 0)))
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#else
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#define notrace __attribute__((__no_instrument_function__))
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#endif
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/*
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* it doesn't make sense on ARM (currently the only user of __naked)
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* to trace naked functions because then mcount is called without
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* stack and frame pointer being set up and there is no chance to
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* restore the lr register to the value before mcount was called.
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*/
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#define __naked __attribute__((__naked__)) notrace
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#define __compiler_offsetof(a, b) __builtin_offsetof(a, b)
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/*
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* Prefer gnu_inline, so that extern inline functions do not emit an
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* externally visible function. This makes extern inline behave as per gnu89
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* semantics rather than c99. This prevents multiple symbol definition errors
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* of extern inline functions at link time.
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* A lot of inline functions can cause havoc with function tracing.
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*/
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#define inline inline __gnu_inline __inline_maybe_unused notrace
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/*
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* gcc provides both __inline__ and __inline as alternate spellings of
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* the inline keyword, though the latter is undocumented. New kernel
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* code should only use the inline spelling, but some existing code
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* uses __inline__. Since we #define inline above, to ensure
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* __inline__ has the same semantics, we need this #define.
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*
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* However, the spelling __inline is strictly reserved for referring
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* to the bare keyword.
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*/
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#define __inline__ inline
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/*
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* GCC does not warn about unused static inline functions for -Wunused-function.
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* Suppress the warning in clang as well by using __maybe_unused, but enable it
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* for W=1 build. This will allow clang to find unused functions. Remove the
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* __inline_maybe_unused entirely after fixing most of -Wunused-function warnings.
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*/
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#ifdef KBUILD_EXTRA_WARN1
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#define __inline_maybe_unused
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#else
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#define __inline_maybe_unused __maybe_unused
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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 documentation reasons.
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*/
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#define noinline_for_stack noinline
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#endif /* __KERNEL__ */
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#endif /* __ASSEMBLY__ */
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/*
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* The below symbols may be defined for one or more, but not ALL, of the above
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* compilers. We don't consider that to be an error, so set them to nothing.
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* For example, some of them are for compiler specific plugins.
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*/
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#ifndef __latent_entropy
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# define __latent_entropy
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#endif
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#ifndef __randomize_layout
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# define __randomize_layout __designated_init
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#endif
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#ifndef __no_randomize_layout
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# define __no_randomize_layout
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#endif
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#ifndef randomized_struct_fields_start
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# define randomized_struct_fields_start
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# define randomized_struct_fields_end
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#endif
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#ifndef asm_volatile_goto
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#define asm_volatile_goto(x...) asm goto(x)
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#endif
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#ifdef CONFIG_CC_HAS_ASM_INLINE
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#define asm_inline asm __inline
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#else
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#define asm_inline asm
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#endif
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#ifndef __no_fgcse
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# define __no_fgcse
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#endif
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/* Are two types/vars the same type (ignoring qualifiers)? */
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#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
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/*
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* __unqual_scalar_typeof(x) - Declare an unqualified scalar type, leaving
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* non-scalar types unchanged.
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*/
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#if defined(CONFIG_CC_IS_GCC) && CONFIG_GCC_VERSION < 40900
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/*
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* We build this out of a couple of helper macros in a vain attempt to
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* help you keep your lunch down while reading it.
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*/
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#define __pick_scalar_type(x, type, otherwise) \
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__builtin_choose_expr(__same_type(x, type), (type)0, otherwise)
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/*
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* 'char' is not type-compatible with either 'signed char' or 'unsigned char',
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* so we include the naked type here as well as the signed/unsigned variants.
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*/
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#define __pick_integer_type(x, type, otherwise) \
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__pick_scalar_type(x, type, \
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__pick_scalar_type(x, unsigned type, \
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__pick_scalar_type(x, signed type, otherwise)))
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#define __unqual_scalar_typeof(x) typeof( \
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__pick_integer_type(x, char, \
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__pick_integer_type(x, short, \
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__pick_integer_type(x, int, \
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__pick_integer_type(x, long, \
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__pick_integer_type(x, long long, x))))))
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#else
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/*
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* If supported, prefer C11 _Generic for better compile-times. As above, 'char'
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* is not type-compatible with 'signed char', and we define a separate case.
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*/
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#define __scalar_type_to_expr_cases(type) \
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unsigned type: (unsigned type)0, \
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signed type: (signed type)0
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#define __unqual_scalar_typeof(x) typeof( \
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_Generic((x), \
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char: (char)0, \
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__scalar_type_to_expr_cases(char), \
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__scalar_type_to_expr_cases(short), \
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__scalar_type_to_expr_cases(int), \
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__scalar_type_to_expr_cases(long), \
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__scalar_type_to_expr_cases(long long), \
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default: (x)))
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#endif
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/* Is this type a native word size -- useful for atomic operations */
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#define __native_word(t) \
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(sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || \
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sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
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/* Helpers for emitting diagnostics in pragmas. */
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#ifndef __diag
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#define __diag(string)
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#endif
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#ifndef __diag_GCC
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#define __diag_GCC(version, severity, string)
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#endif
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#define __diag_push() __diag(push)
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#define __diag_pop() __diag(pop)
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#define __diag_ignore(compiler, version, option, comment) \
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__diag_ ## compiler(version, ignore, option)
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#define __diag_warn(compiler, version, option, comment) \
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__diag_ ## compiler(version, warn, option)
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#define __diag_error(compiler, version, option, comment) \
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__diag_ ## compiler(version, error, option)
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#endif /* __LINUX_COMPILER_TYPES_H */
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