[libc++] Drop dependency on __functional/operations.h from <atomic>

[ldionne]

This should reduce the preprocessed size of the atomic header and other headers in the synchronization library.

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Louis Dionne (ldionne)

Changes

This should reduce the preprocessed size of the atomic header and other headers in the synchronization library.

---

Full diff: https://github.com/llvm/llvm-project/pull/117302.diff

1 Files Affected:

• (modified) libcxx/include/__atomic/atomic.h (+4-3)

diff --git a/libcxx/include/__atomic/atomic.h b/libcxx/include/__atomic/atomic.h
index ae0475693f22b4..d83719c8733d7e 100644
--- a/libcxx/include/__atomic/atomic.h
+++ b/libcxx/include/__atomic/atomic.h
@@ -16,7 +16,6 @@
 #include <__atomic/memory_order.h>
 #include <__config>
 #include <__cstddef/ptrdiff_t.h>
-#include <__functional/operations.h>
 #include <__memory/addressof.h>
 #include <__type_traits/enable_if.h>
 #include <__type_traits/is_floating_point.h>
@@ -376,7 +375,8 @@ struct atomic<_Tp> : __atomic_base<_Tp> {
     auto __builtin_op = [](auto __a, auto __builtin_operand, auto __order) {
       return std::__cxx_atomic_fetch_add(__a, __builtin_operand, __order);
     };
-    return __rmw_op(std::forward<_This>(__self), __operand, __m, std::plus<>{}, __builtin_op);
+    auto __plus = [](auto __a, auto __b) { return __a + __b; };
+    return __rmw_op(std::forward<_This>(__self), __operand, __m, __plus, __builtin_op);
   }
 
   template <class _This>
@@ -384,7 +384,8 @@ struct atomic<_Tp> : __atomic_base<_Tp> {
     auto __builtin_op = [](auto __a, auto __builtin_operand, auto __order) {
       return std::__cxx_atomic_fetch_sub(__a, __builtin_operand, __order);
     };
-    return __rmw_op(std::forward<_This>(__self), __operand, __m, std::minus<>{}, __builtin_op);
+    auto __minus = [](auto __a, auto __b) { return __a - __b; };
+    return __rmw_op(std::forward<_This>(__self), __operand, __m, __minus, __builtin_op);
   }
 
 public:

[philnik777]

This makes me wonder whether we should instead split up __functional/operations.h more. We already have a few of comments splitting the header into multiple categories: arithmetic, bitwise, comparison and logical operators.

[ldionne]

@philnik777 Did this actually result in an improvement to the header sizes? If not, probably not worth pushing in that direction.

[ldionne]

Merging since this can't hurt. If we want to split operations.h itself, we could do that separately.