/* SPDX-License-Identifier: GPL-2.0 */ #ifndef __LINUX_COMPILER_ATTRIBUTES_H #define __LINUX_COMPILER_ATTRIBUTES_H /* * The attributes in this file are unconditionally defined and they directly * map to compiler attribute(s), unless one of the compilers does not support * the attribute. In that case, __has_attribute is used to check for support * and the reason is stated in its comment ("Optional: ..."). * * Any other "attributes" (i.e. those that depend on a configuration option, * on a compiler, on an architecture, on plugins, on other attributes...) * should be defined elsewhere (e.g. compiler_types.h or compiler-*.h). * The intention is to keep this file as simple as possible, as well as * compiler- and version-agnostic (e.g. avoiding GCC_VERSION checks). * * This file is meant to be sorted (by actual attribute name, * not by #define identifier). Use the __attribute__((__name__)) syntax * (i.e. with underscores) to avoid future collisions with other macros. * Provide links to the documentation of each supported compiler, if it exists. */ /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alias-function-attribute */ #define __alias(symbol) … /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-aligned-function-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-aligned-type-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-aligned-variable-attribute */ #define __aligned(x) … #define __aligned_largest … /* * Note: do not use this directly. Instead, use __alloc_size() since it is conditionally * available and includes other attributes. For GCC < 9.1, __alloc_size__ gets undefined * in compiler-gcc.h, due to misbehaviors. * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alloc_005fsize-function-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#alloc-size */ #define __alloc_size__(x, ...) … /* * Note: users of __always_inline currently do not write "inline" themselves, * which seems to be required by gcc to apply the attribute according * to its docs (and also "warning: always_inline function might not be * inlinable [-Wattributes]" is emitted). * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-always_005finline-function-attribute * clang: mentioned */ #define __always_inline … /* * The second argument is optional (default 0), so we use a variadic macro * to make the shorthand. * * Beware: Do not apply this to functions which may return * ERR_PTRs. Also, it is probably unwise to apply it to functions * returning extra information in the low bits (but in that case the * compiler should see some alignment anyway, when the return value is * massaged by 'flags = ptr & 3; ptr &= ~3;'). * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#assume-aligned */ #define __assume_aligned(a, ...) … /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-cleanup-variable-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#cleanup */ #define __cleanup(func) … /* * Note the long name. * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute */ #define __attribute_const__ … /* * Optional: only supported since gcc >= 9 * Optional: not supported by clang * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute */ #if __has_attribute(__copy__) #define __copy … #else #define __copy(symbol) … #endif /* * Optional: only supported since gcc >= 15 * Optional: only supported since clang >= 18 * * gcc: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896 * clang: https://github.com/llvm/llvm-project/pull/76348 */ #if __has_attribute(__counted_by__) #define __counted_by(member) … #else #define __counted_by … #endif /* * Optional: not supported by gcc * Optional: only supported since clang >= 14.0 * * clang: https://clang.llvm.org/docs/AttributeReference.html#diagnose_as_builtin */ #if __has_attribute(__diagnose_as_builtin__) #define __diagnose_as(builtin...) … #else #define __diagnose_as … #endif /* * Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated' * attribute warnings entirely and for good") for more information. * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-deprecated-function-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-deprecated-type-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-deprecated-variable-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Enumerator-Attributes.html#index-deprecated-enumerator-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#deprecated */ #define __deprecated /* * Optional: not supported by clang * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute */ #if __has_attribute(__designated_init__) #define __designated_init … #else #define __designated_init #endif /* * Optional: only supported since clang >= 14.0 * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-error-function-attribute */ #if __has_attribute(__error__) #define __compiletime_error(msg) … #else #define __compiletime_error … #endif /* * Optional: not supported by clang * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute */ #if __has_attribute(__externally_visible__) #define __visible … #else #define __visible #endif /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#format */ #define __printf(a, b) … #define __scanf(a, b) … /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline */ #define __gnu_inline … /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#malloc */ #define __malloc … /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute */ #define __mode(x) … /* * Optional: only supported since gcc >= 7 * * gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86 * clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers */ #if __has_attribute(__no_caller_saved_registers__) #define __no_caller_saved_registers … #else #define __no_caller_saved_registers #endif /* * Optional: not supported by clang * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute */ #if __has_attribute(__noclone__) #define __noclone … #else #define __noclone #endif /* * Add the pseudo keyword 'fallthrough' so case statement blocks * must end with any of these keywords: * break; * fallthrough; * continue; * goto <label>; * return [expression]; * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes */ #if __has_attribute(__fallthrough__) #define fallthrough … #else #define fallthrough … #endif /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes * clang: https://clang.llvm.org/docs/AttributeReference.html#flatten */ #define __flatten … /* * Note the missing underscores. * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute * clang: mentioned */ #define noinline … /* * Optional: only supported since gcc >= 8 * Optional: not supported by clang * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute */ #if __has_attribute(__nonstring__) #define __nonstring … #else #define __nonstring #endif /* * Optional: only supported since GCC >= 7.1, clang >= 13.0. * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fprofile_005finstrument_005ffunction-function-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#no-profile-instrument-function */ #if __has_attribute(__no_profile_instrument_function__) #define __no_profile … #else #define __no_profile #endif /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn * clang: https://clang.llvm.org/docs/AttributeReference.html#id1 */ #define __noreturn … /* * Optional: only supported since GCC >= 11.1, clang >= 7.0. * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fstack_005fprotector-function-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#no-stack-protector-safebuffers */ #if __has_attribute(__no_stack_protector__) #define __no_stack_protector … #else #define __no_stack_protector #endif /* * Optional: not supported by gcc. * * clang: https://clang.llvm.org/docs/AttributeReference.html#overloadable */ #if __has_attribute(__overloadable__) #define __overloadable … #else #define __overloadable #endif /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute * clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute */ #define __packed … /* * Note: the "type" argument should match any __builtin_object_size(p, type) usage. * * Optional: not supported by gcc. * * clang: https://clang.llvm.org/docs/AttributeReference.html#pass-object-size-pass-dynamic-object-size */ #if __has_attribute(__pass_dynamic_object_size__) #define __pass_dynamic_object_size(type) … #else #define __pass_dynamic_object_size … #endif #if __has_attribute(__pass_object_size__) #define __pass_object_size(type) … #else #define __pass_object_size … #endif /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute */ #define __pure … /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate */ #define __section(section) … /* * Optional: only supported since gcc >= 12 * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-uninitialized-variable-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#uninitialized */ #if __has_attribute(__uninitialized__) #define __uninitialized … #else #define __uninitialized #endif /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused */ #define __always_unused … #define __maybe_unused … /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute */ #define __used … /* * The __used attribute guarantees that the attributed variable will be * always emitted by a compiler. It doesn't prevent the compiler from * throwing 'unused' warnings when it can't detect how the variable is * actually used. It's a compiler implementation details either emit * the warning in that case or not. * * The combination of both 'used' and 'unused' attributes ensures that * the variable would be emitted, and will not trigger 'unused' warnings. * The attribute is applicable for functions, static and global variables. */ #define __always_used … /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warn_005funused_005fresult-function-attribute * clang: https://clang.llvm.org/docs/AttributeReference.html#nodiscard-warn-unused-result */ #define __must_check … /* * Optional: only supported since clang >= 14.0 * * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warning-function-attribute */ #if __has_attribute(__warning__) #define __compiletime_warning(msg) … #else #define __compiletime_warning … #endif /* * Optional: only supported since clang >= 14.0 * * clang: https://clang.llvm.org/docs/AttributeReference.html#disable-sanitizer-instrumentation * * disable_sanitizer_instrumentation is not always similar to * no_sanitize((<sanitizer-name>)): the latter may still let specific sanitizers * insert code into functions to prevent false positives. Unlike that, * disable_sanitizer_instrumentation prevents all kinds of instrumentation to * functions with the attribute. */ #if __has_attribute(disable_sanitizer_instrumentation) #define __disable_sanitizer_instrumentation … #else #define __disable_sanitizer_instrumentation #endif /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute */ #define __weak … /* * Used by functions that use '__builtin_return_address'. These function * don't want to be splited or made inline, which can make * the '__builtin_return_address' get unexpected address. */ #define __fix_address … #endif /* __LINUX_COMPILER_ATTRIBUTES_H */
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