Hashing etc.

Author: elsteveogrande

libcxx/include/__stacktrace/basic_stacktrace.h

@@ -76,6 +76,10 @@ struct _Trace {
   _LIBCPP_EXPORTED_FROM_ABI ostream& write_to(ostream& __os) const;
   _LIBCPP_EXPORTED_FROM_ABI string to_string() const;
 
+  _LIBCPP_EXPORTED_FROM_ABI size_t hash() const;
+  _LIBCPP_HIDE_FROM_ABI static _Trace& base(auto& __trace);
+  _LIBCPP_HIDE_FROM_ABI static _Trace const& base(auto const& __trace);
+
 #  ifdef _WIN32
   // Windows impl uses dbghelp and psapi DLLs to do the full stacktrace operation.
   _LIBCPP_EXPORTED_FROM_ABI void windows_impl(size_t skip, size_t max_depth);
@@ -95,7 +99,6 @@ class stacktrace_entry;
 
 template <class _Allocator>
 class basic_stacktrace : private __stacktrace::_Trace {
-  friend struct hash<basic_stacktrace<_Allocator>>;
   friend struct __stacktrace::_Trace;
 
   vector<stacktrace_entry, _Allocator> __entries_;
@@ -285,11 +288,7 @@ _LIBCPP_HIDE_FROM_ABI inline ostream& operator<<(ostream& __os, const basic_stac
 template <class _Allocator>
 struct hash<basic_stacktrace<_Allocator>> {
   _LIBCPP_HIDE_FROM_ABI size_t operator()(basic_stacktrace<_Allocator> const& __trace) const noexcept {
-    size_t __ret = 0xc3a5c85c97cb3127ull; // just a big prime number; taken from __functional/hash.h
-    for (stacktrace_entry const& __e : __trace.__entries_) {
-      __ret = (__ret << 1) ^ __e.__base_.hash();
-    }
-    return __ret;
+    return __stacktrace::_Trace::base(__trace).hash();
   }
 };
 
@@ -337,6 +336,9 @@ _LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE inline void _Trace::populate_addrs(s
 
 #  endif // _WIN32
 
+_Trace& _Trace::base(auto& __trace) { return *static_cast<_Trace*>(&__trace); }
+_Trace const& _Trace::base(auto const& __trace) { return *static_cast<_Trace const*>(&__trace); }
+
 } // namespace __stacktrace
 _LIBCPP_END_NAMESPACE_STD
 

libcxx/include/__stacktrace/stacktrace_entry.h

@@ -85,7 +85,9 @@ struct _Entry {
   _LIBCPP_EXPORTED_FROM_ABI string to_string() const;
 #  endif // _LIBCPP_HAS_LOCALIZATION
 
-  _LIBCPP_HIDE_FROM_ABI size_t hash() const { return std::__hash_memory(&__addr_, sizeof(uintptr_t)); }
+  _LIBCPP_EXPORTED_FROM_ABI size_t hash() const;
+  _LIBCPP_HIDE_FROM_ABI static _Entry& base(stacktrace_entry& __entry);
+  _LIBCPP_HIDE_FROM_ABI static _Entry const& base(stacktrace_entry const& __entry);
 
   _LIBCPP_HIDE_FROM_ABI uintptr_t adjusted_addr() const;
 
@@ -97,13 +99,12 @@ struct _Entry {
   _LIBCPP_HIDE_FROM_ABI constexpr _Entry& operator=(_Entry&&)      = default;
 };
 
+struct _Trace;
+
 } // namespace __stacktrace
 
 class stacktrace_entry {
-  friend _LIBCPP_HIDE_FROM_ABI inline ostream& operator<<(ostream& __os, std::stacktrace_entry const& __entry);
-  friend _LIBCPP_HIDE_FROM_ABI inline string to_string(std::stacktrace_entry const& __entry);
-  friend _LIBCPP_HIDE_FROM_ABI struct hash<stacktrace_entry>;
-
+  _LIBCPP_HIDE_FROM_ABI friend struct __stacktrace::_Entry;
   __stacktrace::_Entry __base_{};
 
 public:
@@ -143,11 +144,11 @@ class stacktrace_entry {
 #  if _LIBCPP_HAS_LOCALIZATION
 
 _LIBCPP_HIDE_FROM_ABI inline string to_string(const std::stacktrace_entry& __entry) {
-  return __entry.__base_.to_string();
+  return __stacktrace::_Entry::base(__entry).to_string();
 }
 
-_LIBCPP_HIDE_FROM_ABI inline ostream& operator<<(ostream& __os, const std::stacktrace_entry& __entry) {
-  return __entry.__base_.write_to(__os);
+_LIBCPP_HIDE_FROM_ABI inline ostream& operator<<(ostream& __os, const stacktrace_entry& __entry) {
+  return __stacktrace::_Entry::base(__entry).write_to(__os);
 }
 
 #  endif // _LIBCPP_HAS_LOCALIZATION
@@ -161,11 +162,18 @@ _LIBCPP_HIDE_FROM_ABI inline ostream& operator<<(ostream& __os, const std::stack
 
 template <>
 struct hash<stacktrace_entry> {
-  _LIBCPP_HIDE_FROM_ABI size_t operator()(stacktrace_entry const& __entry) const noexcept {
-    return __entry.__base_.hash();
+  _LIBCPP_HIDE_FROM_ABI size_t operator()(const stacktrace_entry& __entry) const noexcept {
+    return __stacktrace::_Entry::base(__entry).hash();
   }
 };
 
+namespace __stacktrace {
+
+_LIBCPP_HIDE_FROM_ABI inline _Entry& _Entry::base(stacktrace_entry& __entry) { return __entry.__base_; }
+_LIBCPP_HIDE_FROM_ABI inline _Entry const& _Entry::base(stacktrace_entry const& __entry) { return __entry.__base_; }
+
+} // namespace __stacktrace
+
 _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP_STD_VER >= 23 && _LIBCPP_AVAILABILITY_HAS_STACKTRACE

libcxx/src/stacktrace/entry.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include <__config>
+#include <__functional/hash.h>
 #include <__stacktrace/basic_stacktrace.h>
 #include <__stacktrace/stacktrace_entry.h>
 #include <string>
@@ -55,6 +56,8 @@ _LIBCPP_HIDE_FROM_ABI uintptr_t _Entry::adjusted_addr() const {
   return __addr_ - sub;
 }
 
+_LIBCPP_EXPORTED_FROM_ABI size_t _Entry::hash() const { return std::__hash_memory(&__addr_, sizeof(uintptr_t)); }
+
 } // namespace __stacktrace
 
 _LIBCPP_END_NAMESPACE_STD

libcxx/src/stacktrace/trace.cpp

@@ -49,6 +49,14 @@ _LIBCPP_EXPORTED_FROM_ABI string _Trace::to_string() const {
 
 #endif // _LIBCPP_HAS_LOCALIZATION
 
+_LIBCPP_EXPORTED_FROM_ABI size_t _Trace::hash() const {
+  size_t __ret = 0xc3a5c85c97cb3127ull; // just a big prime number; taken from __functional/hash.h
+  for (_Entry const& __e : __entry_iters_()) {
+    __ret = (__ret << 1) ^ __e.hash();
+  }
+  return __ret;
+}
+
 } // namespace __stacktrace
 
 _LIBCPP_END_NAMESPACE_STD

libcxx/test/std/diagnostics/stacktrace/basic.hash.pass.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // REQUIRES: std-at-least-c++23
+// ADDITIONAL_COMPILE_FLAGS: -O0 -g
 // XFAIL: availability-stacktrace-missing
 
 /*