[libcxx-commits] [libcxx] [ASan][libc++] Update string ASan annotations to zero-overhead (PR #76165)

[via libcxx-commits]

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@@ -2075,27 +2095,43 @@ private:
 
   // Assigns the value in __s, guaranteed to be __n < __min_cap in length.
   inline _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& __assign_short(const value_type* __s, size_type __n) {
+#ifndef __LIBCPP_HAS_NO_ASAN
     size_type __old_size = size();
-    if (__n > __old_size)
-      __annotate_increase(__n - __old_size);
+    _LIBCPP_IF_ASAN() {
+      if (__n > __old_size)
+        __annotate_increase(__n - __old_size);
+    }
+#endif
     pointer __p =
         __is_long() ? (__set_long_size(__n), __get_long_pointer()) : (__set_short_size(__n), __get_short_pointer());
     traits_type::move(std::__to_address(__p), __s, __n);
     traits_type::assign(__p[__n], value_type());
-    if (__old_size > __n)
-      __annotate_shrink(__old_size);
+#ifndef __LIBCPP_HAS_NO_ASAN
+    _LIBCPP_IF_ASAN() {
+      if (__old_size > __n)
+        __annotate_shrink(__old_size);
+    }
+#endif
     return *this;
   }
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
   __null_terminate_at(value_type* __p, size_type __newsz) {
+#ifndef __LIBCPP_HAS_NO_ASAN
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AdvenamTacet wrote:

We definitely should consider how to refactor it. I can reduce number of lines like that by removing a few not necessary variables, in another patch soon, but not completely remove all cases.

https://github.com/llvm/llvm-project/pull/76165