[libcxx-commits] [libcxx] [libcxx] Support providing symbol suffix through compiler define (PR #122570)

[via libcxx-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Petr Hosek (petrhosek)

<details>
<summary>Changes</summary>

When -funique-internal-linkage-names option is enabled, Clang will append a unique suffix `.uniq.<MD5 hash of the source file>` to all internal symbols. Since we cannot detect when this option is enabled or compute the source file hash from within the source file itself, the unique suffix needs to be supplied by the build system. The `_LIBCPP_SYMBOL_SUFFIX` can be used for that purpose.

---
Full diff: https://github.com/llvm/llvm-project/pull/122570.diff


1 Files Affected:

- (modified) libcxx/src/include/overridable_function.h (+12-3) 


``````````diff
diff --git a/libcxx/src/include/overridable_function.h b/libcxx/src/include/overridable_function.h
index 7372e347831bb4..7eee4ecd06a98d 100644
--- a/libcxx/src/include/overridable_function.h
+++ b/libcxx/src/include/overridable_function.h
@@ -56,6 +56,15 @@
 // with this macro must be defined at global scope.
 //
 
+// When -funique-internal-linkage-names option is enabled, Clang will append a unique suffix
+// `.uniq.<MD5 hash of the source file>` to all internal symbols. Since we cannot detect when
+// this option is enabled or compute the source file hash from within the source file itself,
+// the unique suffix needs to be supplied by the build system. The `_LIBCPP_SYMBOL_SUFFIX` can
+// be used for that purpose.
+#ifndef _LIBCPP_SYMBOL_SUFFIX
+#define _LIBCPP_SYMBOL_SUFFIX
+#endif
+
 #if defined(_LIBCPP_OBJECT_FORMAT_MACHO)
 
 _LIBCPP_BEGIN_NAMESPACE_STD
@@ -68,8 +77,8 @@ _LIBCPP_END_NAMESPACE_STD
 #  define _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION 1
 #  define _LIBCPP_OVERRIDABLE_FUNCTION(symbol, type, name, arglist)                                                    \
     static __attribute__((used)) type symbol##_impl__ arglist __asm__("_" _LIBCPP_TOSTRING(symbol));                   \
-    __asm__(".globl _" _LIBCPP_TOSTRING(symbol));                                                                      \
-    __asm__(".weak_definition _" _LIBCPP_TOSTRING(symbol));                                                            \
+    __asm__(".globl _" _LIBCPP_TOSTRING(symbol) _LIBCPP_SYMBOL_SUFFIX);                                                \
+    __asm__(".weak_definition _" _LIBCPP_TOSTRING(symbol) _LIBCPP_SYMBOL_SUFFIX);                                      \
     extern __typeof(symbol##_impl__) name __attribute__((weak_import));                                                \
     _LIBCPP_BEGIN_NAMESPACE_STD                                                                                        \
     template <>                                                                                                        \
@@ -91,7 +100,7 @@ _LIBCPP_END_NAMESPACE_STD
 #  define _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION 1
 #  define _LIBCPP_OVERRIDABLE_FUNCTION(symbol, type, name, arglist)                                                    \
     static type symbol##_impl__ arglist __asm__(_LIBCPP_TOSTRING(symbol##_impl__));                                    \
-    [[gnu::weak, gnu::alias(_LIBCPP_TOSTRING(symbol##_impl__))]] type name arglist;                                    \
+    [[gnu::weak, gnu::alias(_LIBCPP_TOSTRING(symbol##_impl__) _LIBCPP_SYMBOL_SUFFIX)]] type name arglist;              \
     _LIBCPP_BEGIN_NAMESPACE_STD                                                                                        \
     template <>                                                                                                        \
     inline bool __is_function_overridden<static_cast<type(*) arglist>(name)>() {                                       \

``````````

</details>


https://github.com/llvm/llvm-project/pull/122570