diff options
| -rw-r--r-- | include/linux/compiler_types.h | 23 | ||||
| -rw-r--r-- | init/Kconfig | 10 |
2 files changed, 33 insertions, 0 deletions
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index 16755431fc11..2f3e80bf9f35 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -330,6 +330,29 @@ struct ftrace_likely_data { #endif /* + * The assume attribute is used to indicate that a certain condition is + * assumed to be true. If this condition is violated at runtime, the behavior + * is undefined. Compilers may or may not use this indication to generate + * optimized code. + * + * Note that the clang documentation states that optimizers may react + * differently to this attribute, and this may even have a negative + * performance impact. Therefore this attribute should be used with care. + * + * Optional: only supported since gcc >= 13 + * Optional: only supported since clang >= 19 + * + * gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#index-assume-statement-attribute + * clang: https://clang.llvm.org/docs/AttributeReference.html#id13 + * + */ +#ifdef CONFIG_CC_HAS_ASSUME +# define __assume(expr) __attribute__((__assume__(expr))) +#else +# define __assume(expr) +#endif + +/* * Optional: only supported since gcc >= 15 * Optional: only supported since clang >= 18 * diff --git a/init/Kconfig b/init/Kconfig index 836320251219..dabec90f18f6 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -112,6 +112,16 @@ config TOOLS_SUPPORT_RELR config CC_HAS_ASM_INLINE def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) +config CC_HAS_ASSUME + bool + # clang needs to be at least 19.1.0 since the meaning of the assume + # attribute changed: + # https://github.com/llvm/llvm-project/commit/c44fa3e8a9a44c2e9a575768a3c185354b9f6c17 + default y if CC_IS_CLANG && CLANG_VERSION >= 190100 + # supported since gcc 13.1.0 + # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106654 + default y if CC_IS_GCC && GCC_VERSION >= 130100 + config CC_HAS_NO_PROFILE_FN_ATTR def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) |