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CPPLanguageRuntime.cpp
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1//===-- CPPLanguageRuntime.cpp---------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include <cstring>
10
11#include <memory>
12
13#include "CPPLanguageRuntime.h"
14
15#include "llvm/ADT/StringRef.h"
16
17#include "lldb/Symbol/Block.h"
20
24#include "lldb/Target/ABI.h"
31#include "lldb/Utility/Timer.h"
32
33using namespace lldb;
34using namespace lldb_private;
35
37// Artificial coroutine-related variables emitted by clang.
38static ConstString g_promise = ConstString("__promise");
39static ConstString g_coro_frame = ConstString("__coro_frame");
40
42
44 : LanguageRuntime(process) {}
45
47 return name == g_this || name == g_promise || name == g_coro_frame;
48}
49
51 ValueObject &object) {
52 // C++ has no generic way to do this.
53 return false;
54}
55
57 Stream &str, Value &value, ExecutionContextScope *exe_scope) {
58 // C++ has no generic way to do this.
59 return false;
60}
61
62bool contains_lambda_identifier(llvm::StringRef &str_ref) {
63 return str_ref.contains("$_") || str_ref.contains("'lambda'");
64}
65
67line_entry_helper(Target &target, const SymbolContext &sc, Symbol *symbol,
68 llvm::StringRef first_template_param_sref,
69 bool has_invoke) {
70
72
73 AddressRange range;
74 sc.GetAddressRange(eSymbolContextEverything, 0, false, range);
75
76 Address address = range.GetBaseAddress();
77
78 Address addr;
79 if (target.ResolveLoadAddress(address.GetCallableLoadAddress(&target),
80 addr)) {
81 LineEntry line_entry;
82 addr.CalculateSymbolContextLineEntry(line_entry);
83
84 if (contains_lambda_identifier(first_template_param_sref) || has_invoke) {
85 // Case 1 and 2
88 } else {
89 // Case 3
92 }
93
94 optional_info.callable_symbol = *symbol;
95 optional_info.callable_line_entry = line_entry;
96 optional_info.callable_address = addr;
97 }
98
99 return optional_info;
100}
101
104 lldb::ValueObjectSP &valobj_sp) {
106
107 LibCppStdFunctionCallableInfo optional_info;
108
109 if (!valobj_sp)
110 return optional_info;
111
112 // Member __f_ has type __base*, the contents of which will hold:
113 // 1) a vtable entry which may hold type information needed to discover the
114 // lambda being called
115 // 2) possibly hold a pointer to the callable object
116 // e.g.
117 //
118 // (lldb) frame var -R f_display
119 // (std::__1::function<void (int)>) f_display = {
120 // __buf_ = {
121 // …
122 // }
123 // __f_ = 0x00007ffeefbffa00
124 // }
125 // (lldb) memory read -fA 0x00007ffeefbffa00
126 // 0x7ffeefbffa00: ... `vtable for std::__1::__function::__func<void (*) ...
127 // 0x7ffeefbffa08: ... `print_num(int) at std_function_cppreference_exam ...
128 //
129 // We will be handling five cases below, std::function is wrapping:
130 //
131 // 1) a lambda we know at compile time. We will obtain the name of the lambda
132 // from the first template pameter from __func's vtable. We will look up
133 // the lambda's operator()() and obtain the line table entry.
134 // 2) a lambda we know at runtime. A pointer to the lambdas __invoke method
135 // will be stored after the vtable. We will obtain the lambdas name from
136 // this entry and lookup operator()() and obtain the line table entry.
137 // 3) a callable object via operator()(). We will obtain the name of the
138 // object from the first template parameter from __func's vtable. We will
139 // look up the objects operator()() and obtain the line table entry.
140 // 4) a member function. A pointer to the function will stored after the
141 // we will obtain the name from this pointer.
142 // 5) a free function. A pointer to the function will stored after the vtable
143 // we will obtain the name from this pointer.
144 ValueObjectSP member_f_(valobj_sp->GetChildMemberWithName("__f_"));
145
146 if (member_f_) {
147 ValueObjectSP sub_member_f_(member_f_->GetChildMemberWithName("__f_"));
148
149 if (sub_member_f_)
150 member_f_ = sub_member_f_;
151 }
152
153 if (!member_f_)
154 return optional_info;
155
156 lldb::addr_t member_f_pointer_value = member_f_->GetValueAsUnsigned(0);
157
158 optional_info.member_f_pointer_value = member_f_pointer_value;
159
160 if (!member_f_pointer_value)
161 return optional_info;
162
163 ExecutionContext exe_ctx(valobj_sp->GetExecutionContextRef());
164 Process *process = exe_ctx.GetProcessPtr();
165
166 if (process == nullptr)
167 return optional_info;
168
169 uint32_t address_size = process->GetAddressByteSize();
170 Status status;
171
172 // First item pointed to by __f_ should be the pointer to the vtable for
173 // a __base object.
174 lldb::addr_t vtable_address =
175 process->ReadPointerFromMemory(member_f_pointer_value, status);
176
177 if (status.Fail())
178 return optional_info;
179
180 lldb::addr_t vtable_address_first_entry =
181 process->ReadPointerFromMemory(vtable_address + address_size, status);
182
183 if (status.Fail())
184 return optional_info;
185
186 lldb::addr_t address_after_vtable = member_f_pointer_value + address_size;
187 // As commented above we may not have a function pointer but if we do we will
188 // need it.
189 lldb::addr_t possible_function_address =
190 process->ReadPointerFromMemory(address_after_vtable, status);
191
192 if (status.Fail())
193 return optional_info;
194
195 Target &target = process->GetTarget();
196
197 if (target.GetSectionLoadList().IsEmpty())
198 return optional_info;
199
200 Address vtable_first_entry_resolved;
201
203 vtable_address_first_entry, vtable_first_entry_resolved))
204 return optional_info;
205
206 Address vtable_addr_resolved;
207 SymbolContext sc;
208 Symbol *symbol = nullptr;
209
210 if (!target.GetSectionLoadList().ResolveLoadAddress(vtable_address,
211 vtable_addr_resolved))
212 return optional_info;
213
215 vtable_addr_resolved, eSymbolContextEverything, sc);
216 symbol = sc.symbol;
217
218 if (symbol == nullptr)
219 return optional_info;
220
221 llvm::StringRef vtable_name(symbol->GetName().GetStringRef());
222 bool found_expected_start_string =
223 vtable_name.starts_with("vtable for std::__1::__function::__func<");
224
225 if (!found_expected_start_string)
226 return optional_info;
227
228 // Given case 1 or 3 we have a vtable name, we are want to extract the first
229 // template parameter
230 //
231 // ... __func<main::$_0, std::__1::allocator<main::$_0> ...
232 // ^^^^^^^^^
233 //
234 // We could see names such as:
235 // main::$_0
236 // Bar::add_num2(int)::'lambda'(int)
237 // Bar
238 //
239 // We do this by find the first < and , and extracting in between.
240 //
241 // This covers the case of the lambda known at compile time.
242 size_t first_open_angle_bracket = vtable_name.find('<') + 1;
243 size_t first_comma = vtable_name.find(',');
244
245 llvm::StringRef first_template_parameter =
246 vtable_name.slice(first_open_angle_bracket, first_comma);
247
248 Address function_address_resolved;
249
250 // Setup for cases 2, 4 and 5 we have a pointer to a function after the
251 // vtable. We will use a process of elimination to drop through each case
252 // and obtain the data we need.
254 possible_function_address, function_address_resolved)) {
256 function_address_resolved, eSymbolContextEverything, sc);
257 symbol = sc.symbol;
258 }
259
260 // These conditions are used several times to simplify statements later on.
261 bool has_invoke =
262 (symbol ? symbol->GetName().GetStringRef().contains("__invoke") : false);
263 auto calculate_symbol_context_helper = [](auto &t,
264 SymbolContextList &sc_list) {
265 SymbolContext sc;
266 t->CalculateSymbolContext(&sc);
267 sc_list.Append(sc);
268 };
269
270 // Case 2
271 if (has_invoke) {
273 calculate_symbol_context_helper(symbol, scl);
274
275 return line_entry_helper(target, scl[0], symbol, first_template_parameter,
276 has_invoke);
277 }
278
279 // Case 4 or 5
280 if (symbol && !symbol->GetName().GetStringRef().starts_with("vtable for") &&
281 !contains_lambda_identifier(first_template_parameter) && !has_invoke) {
282 optional_info.callable_case =
284 optional_info.callable_address = function_address_resolved;
285 optional_info.callable_symbol = *symbol;
286
287 return optional_info;
288 }
289
290 std::string func_to_match = first_template_parameter.str();
291
292 auto it = CallableLookupCache.find(func_to_match);
293 if (it != CallableLookupCache.end())
294 return it->second;
295
297
298 CompileUnit *vtable_cu =
299 vtable_first_entry_resolved.CalculateSymbolContextCompileUnit();
300 llvm::StringRef name_to_use = func_to_match;
301
302 // Case 3, we have a callable object instead of a lambda
303 //
304 // TODO
305 // We currently don't support this case a callable object may have multiple
306 // operator()() varying on const/non-const and number of arguments and we
307 // don't have a way to currently distinguish them so we will bail out now.
308 if (!contains_lambda_identifier(name_to_use))
309 return optional_info;
310
311 if (vtable_cu && !has_invoke) {
312 lldb::FunctionSP func_sp =
313 vtable_cu->FindFunction([name_to_use](const FunctionSP &f) {
314 auto name = f->GetName().GetStringRef();
315 if (name.starts_with(name_to_use) && name.contains("operator"))
316 return true;
317
318 return false;
319 });
320
321 if (func_sp) {
322 calculate_symbol_context_helper(func_sp, scl);
323 }
324 }
325
326 if (symbol == nullptr)
327 return optional_info;
328
329 // Case 1 or 3
330 if (scl.GetSize() >= 1) {
331 optional_info = line_entry_helper(target, scl[0], symbol,
332 first_template_parameter, has_invoke);
333 }
334
335 CallableLookupCache[func_to_match] = optional_info;
336
337 return optional_info;
338}
339
342 bool stop_others) {
343 ThreadPlanSP ret_plan_sp;
344
345 lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC();
346
347 TargetSP target_sp(thread.CalculateTarget());
348
349 if (target_sp->GetSectionLoadList().IsEmpty())
350 return ret_plan_sp;
351
352 Address pc_addr_resolved;
353 SymbolContext sc;
354 Symbol *symbol;
355
356 if (!target_sp->GetSectionLoadList().ResolveLoadAddress(curr_pc,
357 pc_addr_resolved))
358 return ret_plan_sp;
359
360 target_sp->GetImages().ResolveSymbolContextForAddress(
361 pc_addr_resolved, eSymbolContextEverything, sc);
362 symbol = sc.symbol;
363
364 if (symbol == nullptr)
365 return ret_plan_sp;
366
367 llvm::StringRef function_name(symbol->GetName().GetCString());
368
369 // Handling the case where we are attempting to step into std::function.
370 // The behavior will be that we will attempt to obtain the wrapped
371 // callable via FindLibCppStdFunctionCallableInfo() and if we find it we
372 // will return a ThreadPlanRunToAddress to the callable. Therefore we will
373 // step into the wrapped callable.
374 //
375 bool found_expected_start_string =
376 function_name.starts_with("std::__1::function<");
377
378 if (!found_expected_start_string)
379 return ret_plan_sp;
380
381 AddressRange range_of_curr_func;
382 sc.GetAddressRange(eSymbolContextEverything, 0, false, range_of_curr_func);
383
384 StackFrameSP frame = thread.GetStackFrameAtIndex(0);
385
386 if (frame) {
387 ValueObjectSP value_sp = frame->FindVariable(g_this);
388
391
393 value_sp->GetValueIsValid()) {
394 // We found the std::function wrapped callable and we have its address.
395 // We now create a ThreadPlan to run to the callable.
396 ret_plan_sp = std::make_shared<ThreadPlanRunToAddress>(
397 thread, callable_info.callable_address, stop_others);
398 return ret_plan_sp;
399 } else {
400 // We are in std::function but we could not obtain the callable.
401 // We create a ThreadPlan to keep stepping through using the address range
402 // of the current function.
403 ret_plan_sp = std::make_shared<ThreadPlanStepInRange>(
404 thread, range_of_curr_func, sc, nullptr, eOnlyThisThread,
406 return ret_plan_sp;
407 }
408 }
409
410 return ret_plan_sp;
411}
static ConstString g_promise
static ConstString g_coro_frame
bool contains_lambda_identifier(llvm::StringRef &str_ref)
static ConstString g_this
CPPLanguageRuntime::LibCppStdFunctionCallableInfo line_entry_helper(Target &target, const SymbolContext &sc, Symbol *symbol, llvm::StringRef first_template_param_sref, bool has_invoke)
#define LLDB_SCOPED_TIMER()
Definition: Timer.h:83
A section + offset based address range class.
Definition: AddressRange.h:25
Address & GetBaseAddress()
Get accessor for the base address of the range.
Definition: AddressRange.h:209
A section + offset based address class.
Definition: Address.h:62
lldb::addr_t GetCallableLoadAddress(Target *target, bool is_indirect=false) const
Get the load address as a callable code load address.
Definition: Address.cpp:338
bool CalculateSymbolContextLineEntry(LineEntry &line_entry) const
Definition: Address.cpp:913
CompileUnit * CalculateSymbolContextCompileUnit() const
Definition: Address.cpp:857
bool IsAllowedRuntimeValue(ConstString name) override
Identify whether a name is a runtime value that should not be hidden by from the user interface.
LibCppStdFunctionCallableInfo FindLibCppStdFunctionCallableInfo(lldb::ValueObjectSP &valobj_sp)
lldb::ThreadPlanSP GetStepThroughTrampolinePlan(Thread &thread, bool stop_others) override
Obtain a ThreadPlan to get us into C++ constructs such as std::function.
OperatorStringToCallableInfoMap CallableLookupCache
bool GetObjectDescription(Stream &str, ValueObject &object) override
A class that describes a compilation unit.
Definition: CompileUnit.h:41
lldb::FunctionSP FindFunction(llvm::function_ref< bool(const lldb::FunctionSP &)> matching_lambda)
Find a function in the compile unit based on the predicate matching_lambda.
Definition: CompileUnit.cpp:81
A uniqued constant string class.
Definition: ConstString.h:40
llvm::StringRef GetStringRef() const
Get the string value as a llvm::StringRef.
Definition: ConstString.h:197
const char * GetCString() const
Get the string value as a C string.
Definition: ConstString.h:214
"lldb/Target/ExecutionContextScope.h" Inherit from this if your object can reconstruct its execution ...
"lldb/Target/ExecutionContext.h" A class that contains an execution context.
Process * GetProcessPtr() const
Returns a pointer to the process object.
uint32_t ResolveSymbolContextForAddress(const Address &so_addr, lldb::SymbolContextItem resolve_scope, SymbolContext &sc) const
Resolve the symbol context for the given address. (const Address&,uint32_t,SymbolContext&)
Definition: ModuleList.cpp:682
A plug-in interface definition class for debugging a process.
Definition: Process.h:340
lldb::addr_t ReadPointerFromMemory(lldb::addr_t vm_addr, Status &error)
Definition: Process.cpp:2101
uint32_t GetAddressByteSize() const
Definition: Process.cpp:3403
Target & GetTarget()
Get the target object pointer for this module.
Definition: Process.h:1276
bool ResolveLoadAddress(lldb::addr_t load_addr, Address &so_addr, bool allow_section_end=false) const
An error handling class.
Definition: Status.h:44
bool Fail() const
Test for error condition.
Definition: Status.cpp:181
A stream class that can stream formatted output to a file.
Definition: Stream.h:28
Defines a list of symbol context objects.
uint32_t GetSize() const
Get accessor for a symbol context list size.
Defines a symbol context baton that can be handed other debug core functions.
Definition: SymbolContext.h:34
bool GetAddressRange(uint32_t scope, uint32_t range_idx, bool use_inline_block_range, AddressRange &range) const
Get the address range contained within a symbol context.
Symbol * symbol
The Symbol for a given query.
ConstString GetName() const
Definition: Symbol.cpp:552
SectionLoadList & GetSectionLoadList()
Definition: Target.h:1125
bool ResolveLoadAddress(lldb::addr_t load_addr, Address &so_addr, uint32_t stop_id=SectionLoadHistory::eStopIDNow)
Definition: Target.cpp:3110
const ModuleList & GetImages() const
Get accessor for the images for this process.
Definition: Target.h:970
virtual lldb::StackFrameSP GetStackFrameAtIndex(uint32_t idx)
Definition: Thread.h:405
virtual lldb::RegisterContextSP GetRegisterContext()=0
lldb::TargetSP CalculateTarget() override
Definition: Thread.cpp:1390
A class that represents a running process on the host machine.
Definition: SBAttachInfo.h:14
Definition: SBAddress.h:15
std::shared_ptr< lldb_private::Function > FunctionSP
Definition: lldb-forward.h:347
std::shared_ptr< lldb_private::ThreadPlan > ThreadPlanSP
Definition: lldb-forward.h:441
std::shared_ptr< lldb_private::StackFrame > StackFrameSP
Definition: lldb-forward.h:412
std::shared_ptr< lldb_private::ValueObject > ValueObjectSP
Definition: lldb-forward.h:472
uint64_t addr_t
Definition: lldb-types.h:79
std::shared_ptr< lldb_private::Target > TargetSP
Definition: lldb-forward.h:436
A line table entry class.
Definition: LineEntry.h:21