[libc-commits] [libc] [libc] Fix LIBC_LIKELY/LIBC_UNLIKELY and add LIBC_NOINLINE. (PR #230505)

[Joseph Huber via libc-commits]

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@@ -16,17 +16,24 @@
 
 // We use a template to implement likely/unlikely to make sure that we don't
 // accidentally pass an integer.
+// Note that `__builtin_expect` requires the second argument to be a constant
+// expression.
 namespace LIBC_NAMESPACE_DECL {
 namespace details {
 template <typename T>
-LIBC_INLINE constexpr bool expects_bool_condition(T value, T expected) {
-  return __builtin_expect(value, expected);
+LIBC_ALWAYS_INLINE constexpr bool expects_bool_condition(T value) = delete;
+
+template <>
+LIBC_ALWAYS_INLINE constexpr bool expects_bool_condition<bool>(bool value) {
+  return value;
 }
 } // namespace details
 } // namespace LIBC_NAMESPACE_DECL
-#define LIBC_LIKELY(x) LIBC_NAMESPACE::details::expects_bool_condition(x, true)
+#define LIBC_LIKELY(x)                                                         \
+  (__builtin_expect(LIBC_NAMESPACE::details::expects_bool_condition((x)), true))
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jhuber6 wrote:

Assuming that we do `#define __builtin_expect 0` if it's not defined or something.

https://github.com/llvm/llvm-project/pull/230505