LLDB mainline
CPPLanguageRuntime.cpp
Go to the documentation of this file.
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
39
41 : LanguageRuntime(process) {}
42
44 return name == g_this;
45}
46
48 ValueObject &object) {
49 // C++ has no generic way to do this.
50 return false;
51}
52
54 Stream &str, Value &value, ExecutionContextScope *exe_scope) {
55 // C++ has no generic way to do this.
56 return false;
57}
58
59bool contains_lambda_identifier(llvm::StringRef &str_ref) {
60 return str_ref.contains("$_") || str_ref.contains("'lambda'");
61}
62
64line_entry_helper(Target &target, const SymbolContext &sc, Symbol *symbol,
65 llvm::StringRef first_template_param_sref,
66 bool has_invoke) {
67
69
70 AddressRange range;
71 sc.GetAddressRange(eSymbolContextEverything, 0, false, range);
72
73 Address address = range.GetBaseAddress();
74
75 Address addr;
76 if (target.ResolveLoadAddress(address.GetCallableLoadAddress(&target),
77 addr)) {
78 LineEntry line_entry;
79 addr.CalculateSymbolContextLineEntry(line_entry);
80
81 if (contains_lambda_identifier(first_template_param_sref) || has_invoke) {
82 // Case 1 and 2
85 } else {
86 // Case 3
89 }
90
91 optional_info.callable_symbol = *symbol;
92 optional_info.callable_line_entry = line_entry;
93 optional_info.callable_address = addr;
94 }
95
96 return optional_info;
97}
98
101 lldb::ValueObjectSP &valobj_sp) {
103
104 LibCppStdFunctionCallableInfo optional_info;
105
106 if (!valobj_sp)
107 return optional_info;
108
109 // Member __f_ has type __base*, the contents of which will hold:
110 // 1) a vtable entry which may hold type information needed to discover the
111 // lambda being called
112 // 2) possibly hold a pointer to the callable object
113 // e.g.
114 //
115 // (lldb) frame var -R f_display
116 // (std::__1::function<void (int)>) f_display = {
117 // __buf_ = {
118 // …
119 // }
120 // __f_ = 0x00007ffeefbffa00
121 // }
122 // (lldb) memory read -fA 0x00007ffeefbffa00
123 // 0x7ffeefbffa00: ... `vtable for std::__1::__function::__func<void (*) ...
124 // 0x7ffeefbffa08: ... `print_num(int) at std_function_cppreference_exam ...
125 //
126 // We will be handling five cases below, std::function is wrapping:
127 //
128 // 1) a lambda we know at compile time. We will obtain the name of the lambda
129 // from the first template pameter from __func's vtable. We will look up
130 // the lambda's operator()() and obtain the line table entry.
131 // 2) a lambda we know at runtime. A pointer to the lambdas __invoke method
132 // will be stored after the vtable. We will obtain the lambdas name from
133 // this entry and lookup operator()() and obtain the line table entry.
134 // 3) a callable object via operator()(). We will obtain the name of the
135 // object from the first template parameter from __func's vtable. We will
136 // look up the objects operator()() and obtain the line table entry.
137 // 4) a member function. A pointer to the function will stored after the
138 // we will obtain the name from this pointer.
139 // 5) a free function. A pointer to the function will stored after the vtable
140 // we will obtain the name from this pointer.
141 ValueObjectSP member_f_(
142 valobj_sp->GetChildMemberWithName(ConstString("__f_"), true));
143
144 if (member_f_) {
145 ValueObjectSP sub_member_f_(
146 member_f_->GetChildMemberWithName(ConstString("__f_"), true));
147
148 if (sub_member_f_)
149 member_f_ = sub_member_f_;
150 }
151
152 if (!member_f_)
153 return optional_info;
154
155 lldb::addr_t member_f_pointer_value = member_f_->GetValueAsUnsigned(0);
156
157 optional_info.member_f_pointer_value = member_f_pointer_value;
158
159 if (!member_f_pointer_value)
160 return optional_info;
161
162 ExecutionContext exe_ctx(valobj_sp->GetExecutionContextRef());
163 Process *process = exe_ctx.GetProcessPtr();
164
165 if (process == nullptr)
166 return optional_info;
167
168 uint32_t address_size = process->GetAddressByteSize();
169 Status status;
170
171 // First item pointed to by __f_ should be the pointer to the vtable for
172 // a __base object.
173 lldb::addr_t vtable_address =
174 process->ReadPointerFromMemory(member_f_pointer_value, status);
175
176 if (status.Fail())
177 return optional_info;
178
179 lldb::addr_t vtable_address_first_entry =
180 process->ReadPointerFromMemory(vtable_address + address_size, status);
181
182 if (status.Fail())
183 return optional_info;
184
185 lldb::addr_t address_after_vtable = member_f_pointer_value + address_size;
186 // As commented above we may not have a function pointer but if we do we will
187 // need it.
188 lldb::addr_t possible_function_address =
189 process->ReadPointerFromMemory(address_after_vtable, status);
190
191 if (status.Fail())
192 return optional_info;
193
194 Target &target = process->GetTarget();
195
196 if (target.GetSectionLoadList().IsEmpty())
197 return optional_info;
198
199 Address vtable_first_entry_resolved;
200
202 vtable_address_first_entry, vtable_first_entry_resolved))
203 return optional_info;
204
205 Address vtable_addr_resolved;
206 SymbolContext sc;
207 Symbol *symbol = nullptr;
208
209 if (!target.GetSectionLoadList().ResolveLoadAddress(vtable_address,
210 vtable_addr_resolved))
211 return optional_info;
212
214 vtable_addr_resolved, eSymbolContextEverything, sc);
215 symbol = sc.symbol;
216
217 if (symbol == nullptr)
218 return optional_info;
219
220 llvm::StringRef vtable_name(symbol->GetName().GetStringRef());
221 bool found_expected_start_string =
222 vtable_name.startswith("vtable for std::__1::__function::__func<");
223
224 if (!found_expected_start_string)
225 return optional_info;
226
227 // Given case 1 or 3 we have a vtable name, we are want to extract the first
228 // template parameter
229 //
230 // ... __func<main::$_0, std::__1::allocator<main::$_0> ...
231 // ^^^^^^^^^
232 //
233 // We could see names such as:
234 // main::$_0
235 // Bar::add_num2(int)::'lambda'(int)
236 // Bar
237 //
238 // We do this by find the first < and , and extracting in between.
239 //
240 // This covers the case of the lambda known at compile time.
241 size_t first_open_angle_bracket = vtable_name.find('<') + 1;
242 size_t first_comma = vtable_name.find(',');
243
244 llvm::StringRef first_template_parameter =
245 vtable_name.slice(first_open_angle_bracket, first_comma);
246
247 Address function_address_resolved;
248
249 // Setup for cases 2, 4 and 5 we have a pointer to a function after the
250 // vtable. We will use a process of elimination to drop through each case
251 // and obtain the data we need.
253 possible_function_address, function_address_resolved)) {
255 function_address_resolved, eSymbolContextEverything, sc);
256 symbol = sc.symbol;
257 }
258
259 // These conditions are used several times to simplify statements later on.
260 bool has_invoke =
261 (symbol ? symbol->GetName().GetStringRef().contains("__invoke") : false);
262 auto calculate_symbol_context_helper = [](auto &t,
263 SymbolContextList &sc_list) {
264 SymbolContext sc;
265 t->CalculateSymbolContext(&sc);
266 sc_list.Append(sc);
267 };
268
269 // Case 2
270 if (has_invoke) {
272 calculate_symbol_context_helper(symbol, scl);
273
274 return line_entry_helper(target, scl[0], symbol, first_template_parameter,
275 has_invoke);
276 }
277
278 // Case 4 or 5
279 if (symbol && !symbol->GetName().GetStringRef().startswith("vtable for") &&
280 !contains_lambda_identifier(first_template_parameter) && !has_invoke) {
281 optional_info.callable_case =
283 optional_info.callable_address = function_address_resolved;
284 optional_info.callable_symbol = *symbol;
285
286 return optional_info;
287 }
288
289 std::string func_to_match = first_template_parameter.str();
290
291 auto it = CallableLookupCache.find(func_to_match);
292 if (it != CallableLookupCache.end())
293 return it->second;
294
296
297 CompileUnit *vtable_cu =
298 vtable_first_entry_resolved.CalculateSymbolContextCompileUnit();
299 llvm::StringRef name_to_use = func_to_match;
300
301 // Case 3, we have a callable object instead of a lambda
302 //
303 // TODO
304 // We currently don't support this case a callable object may have multiple
305 // operator()() varying on const/non-const and number of arguments and we
306 // don't have a way to currently distinguish them so we will bail out now.
307 if (!contains_lambda_identifier(name_to_use))
308 return optional_info;
309
310 if (vtable_cu && !has_invoke) {
311 lldb::FunctionSP func_sp =
312 vtable_cu->FindFunction([name_to_use](const FunctionSP &f) {
313 auto name = f->GetName().GetStringRef();
314 if (name.startswith(name_to_use) && name.contains("operator"))
315 return true;
316
317 return false;
318 });
319
320 if (func_sp) {
321 calculate_symbol_context_helper(func_sp, scl);
322 }
323 }
324
325 if (symbol == nullptr)
326 return optional_info;
327
328 // Case 1 or 3
329 if (scl.GetSize() >= 1) {
330 optional_info = line_entry_helper(target, scl[0], symbol,
331 first_template_parameter, has_invoke);
332 }
333
334 CallableLookupCache[func_to_match] = optional_info;
335
336 return optional_info;
337}
338
339lldb::ThreadPlanSP
341 bool stop_others) {
342 ThreadPlanSP ret_plan_sp;
343
344 lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC();
345
346 TargetSP target_sp(thread.CalculateTarget());
347
348 if (target_sp->GetSectionLoadList().IsEmpty())
349 return ret_plan_sp;
350
351 Address pc_addr_resolved;
352 SymbolContext sc;
353 Symbol *symbol;
354
355 if (!target_sp->GetSectionLoadList().ResolveLoadAddress(curr_pc,
356 pc_addr_resolved))
357 return ret_plan_sp;
358
359 target_sp->GetImages().ResolveSymbolContextForAddress(
360 pc_addr_resolved, eSymbolContextEverything, sc);
361 symbol = sc.symbol;
362
363 if (symbol == nullptr)
364 return ret_plan_sp;
365
366 llvm::StringRef function_name(symbol->GetName().GetCString());
367
368 // Handling the case where we are attempting to step into std::function.
369 // The behavior will be that we will attempt to obtain the wrapped
370 // callable via FindLibCppStdFunctionCallableInfo() and if we find it we
371 // will return a ThreadPlanRunToAddress to the callable. Therefore we will
372 // step into the wrapped callable.
373 //
374 bool found_expected_start_string =
375 function_name.startswith("std::__1::function<");
376
377 if (!found_expected_start_string)
378 return ret_plan_sp;
379
380 AddressRange range_of_curr_func;
381 sc.GetAddressRange(eSymbolContextEverything, 0, false, range_of_curr_func);
382
383 StackFrameSP frame = thread.GetStackFrameAtIndex(0);
384
385 if (frame) {
386 ValueObjectSP value_sp = frame->FindVariable(g_this);
387
390
392 value_sp->GetValueIsValid()) {
393 // We found the std::function wrapped callable and we have its address.
394 // We now create a ThreadPlan to run to the callable.
395 ret_plan_sp = std::make_shared<ThreadPlanRunToAddress>(
396 thread, callable_info.callable_address, stop_others);
397 return ret_plan_sp;
398 } else {
399 // We are in std::function but we could not obtain the callable.
400 // We create a ThreadPlan to keep stepping through using the address range
401 // of the current function.
402 ret_plan_sp = std::make_shared<ThreadPlanStepInRange>(
403 thread, range_of_curr_func, sc, nullptr, eOnlyThisThread,
405 return ret_plan_sp;
406 }
407 }
408
409 return ret_plan_sp;
410}
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:59
lldb::addr_t GetCallableLoadAddress(Target *target, bool is_indirect=false) const
Get the load address as a callable code load address.
Definition: Address.cpp:336
bool CalculateSymbolContextLineEntry(LineEntry &line_entry) const
Definition: Address.cpp:907
CompileUnit * CalculateSymbolContextCompileUnit() const
Definition: Address.cpp:851
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:77
A uniqued constant string class.
Definition: ConstString.h:39
llvm::StringRef GetStringRef() const
Get the string value as a llvm::StringRef.
Definition: ConstString.h:201
const char * GetCString() const
Get the string value as a C string.
Definition: ConstString.h:215
"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:679
A plug-in interface definition class for debugging a process.
Definition: Process.h:342
lldb::addr_t ReadPointerFromMemory(lldb::addr_t vm_addr, Status &error)
Definition: Process.cpp:2089
uint32_t GetAddressByteSize() const
Definition: Process.cpp:3367
Target & GetTarget()
Get the target object pointer for this module.
Definition: Process.h:1219
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:33
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:500
SectionLoadList & GetSectionLoadList()
Definition: Target.h:1101
bool ResolveLoadAddress(lldb::addr_t load_addr, Address &so_addr, uint32_t stop_id=SectionLoadHistory::eStopIDNow)
Definition: Target.cpp:3000
const ModuleList & GetImages() const
Get accessor for the images for this process.
Definition: Target.h:946
virtual lldb::StackFrameSP GetStackFrameAtIndex(uint32_t idx)
Definition: Thread.h:399
virtual lldb::RegisterContextSP GetRegisterContext()=0
lldb::TargetSP CalculateTarget() override
Definition: Thread.cpp:1406
A class that represents a running process on the host machine.
Definition: SBAddress.h:15
uint64_t addr_t
Definition: lldb-types.h:83
A line table entry class.
Definition: LineEntry.h:20