1 files changed, 353 insertions, 0 deletions
diff --git a/source/Plugins/LanguageRuntime/CPlusPlus/CPPLanguageRuntime.cpp b/source/Plugins/LanguageRuntime/CPlusPlus/CPPLanguageRuntime.cpp
new file mode 100644
index 000000000000..b392282c3eb1
--- /dev/null
+++ b/source/Plugins/LanguageRuntime/CPlusPlus/CPPLanguageRuntime.cpp
@@ -0,0 +1,353 @@
+//===-- CPPLanguageRuntime.cpp
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <string.h>
+
+#include <memory>
+
+#include "CPPLanguageRuntime.h"
+
+#include "llvm/ADT/StringRef.h"
+
+#include "lldb/Symbol/Block.h"
+#include "lldb/Symbol/Variable.h"
+#include "lldb/Symbol/VariableList.h"
+
+#include "lldb/Core/PluginManager.h"
+#include "lldb/Core/UniqueCStringMap.h"
+#include "lldb/Symbol/ClangASTContext.h"
+#include "lldb/Target/ABI.h"
+#include "lldb/Target/ExecutionContext.h"
+#include "lldb/Target/RegisterContext.h"
+#include "lldb/Target/SectionLoadList.h"
+#include "lldb/Target/StackFrame.h"
+#include "lldb/Target/ThreadPlanRunToAddress.h"
+#include "lldb/Target/ThreadPlanStepInRange.h"
+
+using namespace lldb;
+using namespace lldb_private;
+
+static ConstString g_this = ConstString("this");
+
+char CPPLanguageRuntime::ID = 0;
+
+// Destructor
+CPPLanguageRuntime::~CPPLanguageRuntime() {}
+
+CPPLanguageRuntime::CPPLanguageRuntime(Process *process)
+    : LanguageRuntime(process) {}
+
+bool CPPLanguageRuntime::IsWhitelistedRuntimeValue(ConstString name) {
+  return name == g_this;
+}
+
+bool CPPLanguageRuntime::GetObjectDescription(Stream &str,
+                                              ValueObject &object) {
+  // C++ has no generic way to do this.
+  return false;
+}
+
+bool CPPLanguageRuntime::GetObjectDescription(
+    Stream &str, Value &value, ExecutionContextScope *exe_scope) {
+  // C++ has no generic way to do this.
+  return false;
+}
+
+CPPLanguageRuntime::LibCppStdFunctionCallableInfo
+CPPLanguageRuntime::FindLibCppStdFunctionCallableInfo(
+    lldb::ValueObjectSP &valobj_sp) {
+  LibCppStdFunctionCallableInfo optional_info;
+
+  if (!valobj_sp)
+    return optional_info;
+
+  // Member __f_ has type __base*, the contents of which will hold:
+  // 1) a vtable entry which may hold type information needed to discover the
+  //    lambda being called
+  // 2) possibly hold a pointer to the callable object
+  // e.g.
+  //
+  // (lldb) frame var -R  f_display
+  // (std::__1::function<void (int)>) f_display = {
+  //  __buf_ = {
+  //  …
+  // }
+  //  __f_ = 0x00007ffeefbffa00
+  // }
+  // (lldb) memory read -fA 0x00007ffeefbffa00
+  // 0x7ffeefbffa00: ... `vtable for std::__1::__function::__func<void (*) ...
+  // 0x7ffeefbffa08: ... `print_num(int) at std_function_cppreference_exam ...
+  //
+  // We will be handling five cases below, std::function is wrapping:
+  //
+  // 1) a lambda we know at compile time. We will obtain the name of the lambda
+  //    from the first template pameter from __func's vtable. We will look up
+  //    the lambda's operator()() and obtain the line table entry.
+  // 2) a lambda we know at runtime. A pointer to the lambdas __invoke method
+  //    will be stored after the vtable. We will obtain the lambdas name from
+  //    this entry and lookup operator()() and obtain the line table entry.
+  // 3) a callable object via operator()(). We will obtain the name of the
+  //    object from the first template parameter from __func's vtable. We will
+  //    look up the objectc operator()() and obtain the line table entry.
+  // 4) a member function. A pointer to the function will stored after the
+  //    we will obtain the name from this pointer.
+  // 5) a free function. A pointer to the function will stored after the vtable
+  //    we will obtain the name from this pointer.
+  ValueObjectSP member__f_(
+      valobj_sp->GetChildMemberWithName(ConstString("__f_"), true));
+
+  if (member__f_) {
+    ValueObjectSP sub_member__f_(
+       member__f_->GetChildMemberWithName(ConstString("__f_"), true));
+
+    if (sub_member__f_)
+        member__f_ = sub_member__f_;
+  }
+
+  lldb::addr_t member__f_pointer_value = member__f_->GetValueAsUnsigned(0);
+
+  optional_info.member__f_pointer_value = member__f_pointer_value;
+
+  ExecutionContext exe_ctx(valobj_sp->GetExecutionContextRef());
+  Process *process = exe_ctx.GetProcessPtr();
+
+  if (process == nullptr)
+    return optional_info;
+
+  uint32_t address_size = process->GetAddressByteSize();
+  Status status;
+
+  // First item pointed to by __f_ should be the pointer to the vtable for
+  // a __base object.
+  lldb::addr_t vtable_address =
+      process->ReadPointerFromMemory(member__f_pointer_value, status);
+
+  if (status.Fail())
+    return optional_info;
+
+  lldb::addr_t address_after_vtable = member__f_pointer_value + address_size;
+  // As commened above we may not have a function pointer but if we do we will
+  // need it.
+  lldb::addr_t possible_function_address =
+      process->ReadPointerFromMemory(address_after_vtable, status);
+
+  if (status.Fail())
+    return optional_info;
+
+  Target &target = process->GetTarget();
+
+  if (target.GetSectionLoadList().IsEmpty())
+    return optional_info;
+
+  Address vtable_addr_resolved;
+  SymbolContext sc;
+  Symbol *symbol;
+
+  if (!target.GetSectionLoadList().ResolveLoadAddress(vtable_address,
+                                                      vtable_addr_resolved))
+    return optional_info;
+
+  target.GetImages().ResolveSymbolContextForAddress(
+      vtable_addr_resolved, eSymbolContextEverything, sc);
+  symbol = sc.symbol;
+
+  if (symbol == nullptr)
+    return optional_info;
+
+  llvm::StringRef vtable_name(symbol->GetName().GetCString());
+  bool found_expected_start_string =
+      vtable_name.startswith("vtable for std::__1::__function::__func<");
+
+  if (!found_expected_start_string)
+    return optional_info;
+
+  // Given case 1 or 3 we have a vtable name, we are want to extract the first
+  // template parameter
+  //
+  //  ... __func<main::$_0, std::__1::allocator<main::$_0> ...
+  //             ^^^^^^^^^
+  //
+  // We do this by find the first < and , and extracting in between.
+  //
+  // This covers the case of the lambda known at compile time.
+  size_t first_open_angle_bracket = vtable_name.find('<') + 1;
+  size_t first_comma = vtable_name.find(',');
+
+  llvm::StringRef first_template_parameter =
+      vtable_name.slice(first_open_angle_bracket, first_comma);
+
+  Address function_address_resolved;
+
+  // Setup for cases 2, 4 and 5 we have a pointer to a function after the
+  // vtable. We will use a process of elimination to drop through each case
+  // and obtain the data we need.
+  if (target.GetSectionLoadList().ResolveLoadAddress(
+          possible_function_address, function_address_resolved)) {
+    target.GetImages().ResolveSymbolContextForAddress(
+        function_address_resolved, eSymbolContextEverything, sc);
+    symbol = sc.symbol;
+  }
+
+  auto get_name = [&first_template_parameter, &symbol]() {
+    // Given case 1:
+    //
+    //    main::$_0
+    //
+    // we want to append ::operator()()
+    if (first_template_parameter.contains("$_"))
+      return llvm::Regex::escape(first_template_parameter.str()) +
+             R"(::operator\(\)\(.*\))";
+
+    if (symbol != nullptr &&
+        symbol->GetName().GetStringRef().contains("__invoke")) {
+
+      llvm::StringRef symbol_name = symbol->GetName().GetStringRef();
+      size_t pos2 = symbol_name.find_last_of(':');
+
+      // Given case 2:
+      //
+      //    main::$_1::__invoke(...)
+      //
+      // We want to slice off __invoke(...) and append operator()()
+      std::string lambda_operator =
+          llvm::Regex::escape(symbol_name.slice(0, pos2 + 1).str()) +
+          R"(operator\(\)\(.*\))";
+
+      return lambda_operator;
+    }
+
+    // Case 3
+    return first_template_parameter.str() + R"(::operator\(\)\(.*\))";
+    ;
+  };
+
+  std::string func_to_match = get_name();
+
+  SymbolContextList scl;
+
+  target.GetImages().FindSymbolsMatchingRegExAndType(
+      RegularExpression{R"(^)" + func_to_match}, eSymbolTypeAny, scl, true);
+
+  // Case 1,2 or 3
+  if (scl.GetSize() >= 1) {
+    SymbolContext sc2 = scl[0];
+
+    AddressRange range;
+    sc2.GetAddressRange(eSymbolContextEverything, 0, false, range);
+
+    Address address = range.GetBaseAddress();
+
+    Address addr;
+    if (target.ResolveLoadAddress(address.GetCallableLoadAddress(&target),
+                                  addr)) {
+      LineEntry line_entry;
+      addr.CalculateSymbolContextLineEntry(line_entry);
+
+      if (first_template_parameter.contains("$_") ||
+          (symbol != nullptr &&
+           symbol->GetName().GetStringRef().contains("__invoke"))) {
+        // Case 1 and 2
+        optional_info.callable_case = LibCppStdFunctionCallableCase::Lambda;
+      } else {
+        // Case 3
+        optional_info.callable_case =
+            LibCppStdFunctionCallableCase::CallableObject;
+      }
+
+      optional_info.callable_symbol = *symbol;
+      optional_info.callable_line_entry = line_entry;
+      optional_info.callable_address = addr;
+      return optional_info;
+    }
+  }
+
+  // Case 4 or 5
+  if (symbol && !symbol->GetName().GetStringRef().startswith("vtable for")) {
+    optional_info.callable_case =
+        LibCppStdFunctionCallableCase::FreeOrMemberFunction;
+    optional_info.callable_address = function_address_resolved;
+    optional_info.callable_symbol = *symbol;
+
+    return optional_info;
+  }
+
+  return optional_info;
+}
+
+lldb::ThreadPlanSP
+CPPLanguageRuntime::GetStepThroughTrampolinePlan(Thread &thread,
+                                                 bool stop_others) {
+  ThreadPlanSP ret_plan_sp;
+
+  lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC();
+
+  TargetSP target_sp(thread.CalculateTarget());
+
+  if (target_sp->GetSectionLoadList().IsEmpty())
+    return ret_plan_sp;
+
+  Address pc_addr_resolved;
+  SymbolContext sc;
+  Symbol *symbol;
+
+  if (!target_sp->GetSectionLoadList().ResolveLoadAddress(curr_pc,
+                                                          pc_addr_resolved))
+    return ret_plan_sp;
+
+  target_sp->GetImages().ResolveSymbolContextForAddress(
+      pc_addr_resolved, eSymbolContextEverything, sc);
+  symbol = sc.symbol;
+
+  if (symbol == nullptr)
+    return ret_plan_sp;
+
+  llvm::StringRef function_name(symbol->GetName().GetCString());
+
+  // Handling the case where we are attempting to step into std::function.
+  // The behavior will be that we will attempt to obtain the wrapped
+  // callable via FindLibCppStdFunctionCallableInfo() and if we find it we
+  // will return a ThreadPlanRunToAddress to the callable. Therefore we will
+  // step into the wrapped callable.
+  //
+  bool found_expected_start_string =
+      function_name.startswith("std::__1::function<");
+
+  if (!found_expected_start_string)
+    return ret_plan_sp;
+
+  AddressRange range_of_curr_func;
+  sc.GetAddressRange(eSymbolContextEverything, 0, false, range_of_curr_func);
+
+  StackFrameSP frame = thread.GetStackFrameAtIndex(0);
+
+  if (frame) {
+    ValueObjectSP value_sp = frame->FindVariable(g_this);
+
+    CPPLanguageRuntime::LibCppStdFunctionCallableInfo callable_info =
+        FindLibCppStdFunctionCallableInfo(value_sp);
+
+    if (callable_info.callable_case != LibCppStdFunctionCallableCase::Invalid &&
+        value_sp->GetValueIsValid()) {
+      // We found the std::function wrapped callable and we have its address.
+      // We now create a ThreadPlan to run to the callable.
+      ret_plan_sp = std::make_shared<ThreadPlanRunToAddress>(
+          thread, callable_info.callable_address, stop_others);
+      return ret_plan_sp;
+    } else {
+      // We are in std::function but we could not obtain the callable.
+      // We create a ThreadPlan to keep stepping through using the address range
+      // of the current function.
+      ret_plan_sp = std::make_shared<ThreadPlanStepInRange>(
+          thread, range_of_curr_func, sc, eOnlyThisThread, eLazyBoolYes,
+          eLazyBoolYes);
+      return ret_plan_sp;
+    }
+  }
+
+  return ret_plan_sp;
+}