This way we get some type checking.
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I think kasan builds need similar treatment, otherwise LGTM.
Now that I wrote I think an extra bit would be nice: checking alignment
This depends on specific compiler, its error settings, and user' override of system defaults. In particular, for clang it requires -Werror -Wincompatible-pointer-types or like.
I think a better way would be to do something like this:
#define atomic_load_int(p) ({ \ _Static_assert(sizeof(*p) == sizeof(int), "XXX"); \ (*(volatile int *)p); \ })
Or even better, assuming that the header is used with C11, is to be more portable and use the generic selector, which checks all correctness assumptions, including alignment:
#define atomic_load_int(p) ({ \ _Static_assert(_Generic(*p, \ int: 1, unsigned int: 1, default: 0) == 1, "XXX"); \ (*(volatile int *)p); \ })
-Wpointer-sign, I think.
I tried writing an implementation using _Generic. It's not the same as what you suggested, it avoids _Static_assert since the compiler will already complain if _Generic is unmatched.
sys/sys/atomic_common.h | ||
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106 | Uh #define __atomic_load_generic(p, t, ut, n) __atomic_load_ ## n (p) #define __atomic_store_generic(p, v, t, ut, n) __atomic_store_ ## n (p, v) of course... |
this breaks buildworld on all archs:
/usr/src/contrib/llvm-project/compiler-rt/lib/builtins/atomic.c:272:1: error: too many arguments provided to function- like macro invocation OPTIMISED_CASES ^ /usr/src/contrib/llvm-project/compiler-rt/lib/builtins/atomic.c:259:3: note: expanded from macro 'OPTIMISED_CASES' OPTIMISED_CASE(8, IS_LOCK_FREE_8, uint64_t) ^ /usr/src/contrib/llvm-project/compiler-rt/lib/builtins/atomic.c:263:37: note: expanded from macro 'OPTIMISED_CASE' type __atomic_load_##n(type *src, int model) { \ ^ /usr/obj/usr/src/powerpc.powerpc/tmp/usr/include/sys/atomic_common.h:46:9: note: macro '__atomic_load_8' defined here #define __atomic_load_8(p) (*(volatile uint8_t *)(p)) ^ /usr/src/contrib/llvm-project/compiler-rt/lib/builtins/atomic.c:272:1: error: expected ';' after top level declarator OPTIMISED_CASES ^ /usr/src/contrib/llvm-project/compiler-rt/lib/builtins/atomic.c:259:3: note: expanded from macro 'OPTIMISED_CASES' OPTIMISED_CASE(8, IS_LOCK_FREE_8, uint64_t) ^ /usr/src/contrib/llvm-project/compiler-rt/lib/builtins/atomic.c:263:48: note: expanded from macro 'OPTIMISED_CASE' type __atomic_load_##n(type *src, int model) { \ ^ /usr/src/contrib/llvm-project/compiler-rt/lib/builtins/atomic.c:287:1: error: too many arguments provided to function-like macro invocation OPTIMISED_CASES ^ /usr/src/contrib/llvm-project/compiler-rt/lib/builtins/atomic.c:259:3: note: expanded from macro 'OPTIMISED_CASES' OPTIMISED_CASE(8, IS_LOCK_FREE_8, uint64_t) ^ /usr/src/contrib/llvm-project/compiler-rt/lib/builtins/atomic.c:276:49: note: expanded from macro 'OPTIMISED_CASE' void __atomic_store_##n(type *dest, type val, int model) { \ ^ /usr/obj/usr/src/powerpc.powerpc/tmp/usr/include/sys/atomic_common.h:59:9: note: macro '__atomic_store_8' defined here #define __atomic_store_8(p, v) \ ^ 3 errors generated.
- Apply suggestions.
- Rename the base primitives to avoid conflicting with libcompiler_rt.