1//===-- UserExpression.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 <cstdio>
10#include <sys/types.h>
11
12#include <cstdlib>
13#include <map>
14#include <string>
15
16#include "lldb/Core/Module.h"
17#include "lldb/Core/Progress.h"
18#include "lldb/Expression/DiagnosticManager.h"
19#include "lldb/Expression/ExpressionVariable.h"
20#include "lldb/Expression/IRExecutionUnit.h"
21#include "lldb/Expression/IRInterpreter.h"
22#include "lldb/Expression/Materializer.h"
23#include "lldb/Expression/UserExpression.h"
24#include "lldb/Host/HostInfo.h"
25#include "lldb/Symbol/Block.h"
26#include "lldb/Symbol/Function.h"
27#include "lldb/Symbol/ObjectFile.h"
28#include "lldb/Symbol/SymbolVendor.h"
29#include "lldb/Symbol/Type.h"
30#include "lldb/Symbol/TypeSystem.h"
31#include "lldb/Symbol/VariableList.h"
32#include "lldb/Target/ExecutionContext.h"
33#include "lldb/Target/Process.h"
34#include "lldb/Target/StackFrame.h"
35#include "lldb/Target/Target.h"
36#include "lldb/Target/ThreadPlan.h"
37#include "lldb/Target/ThreadPlanCallUserExpression.h"
38#include "lldb/Utility/LLDBLog.h"
39#include "lldb/Utility/Log.h"
40#include "lldb/Utility/State.h"
41#include "lldb/Utility/StreamString.h"
42#include "lldb/ValueObject/ValueObjectConstResult.h"
43#include "llvm/BinaryFormat/Dwarf.h"
44
45using namespace lldb_private;
46
47char UserExpression::ID;
48
49UserExpression::UserExpression(ExecutionContextScope &exe_scope,
50 llvm::StringRef expr, llvm::StringRef prefix,
51 SourceLanguage language, ResultType desired_type,
52 const EvaluateExpressionOptions &options)
53 : Expression(exe_scope), m_expr_text(std::string(expr)),
54 m_expr_prefix(std::string(prefix)), m_language(language),
55 m_desired_type(desired_type), m_options(options) {}
56
57UserExpression::~UserExpression() = default;
58
59void UserExpression::InstallContext(ExecutionContext &exe_ctx) {
60 m_jit_process_wp = exe_ctx.GetProcessSP();
61
62 lldb::StackFrameSP frame_sp = exe_ctx.GetFrameSP();
63
64 if (frame_sp)
65 m_address = frame_sp->GetFrameCodeAddress();
66}
67
68bool UserExpression::LockAndCheckContext(ExecutionContext &exe_ctx,
69 lldb::TargetSP &target_sp,
70 lldb::ProcessSP &process_sp,
71 lldb::StackFrameSP &frame_sp) {
72 lldb::ProcessSP expected_process_sp = m_jit_process_wp.lock();
73 process_sp = exe_ctx.GetProcessSP();
74
75 if (process_sp != expected_process_sp)
76 return false;
77
78 process_sp = exe_ctx.GetProcessSP();
79 target_sp = exe_ctx.GetTargetSP();
80 frame_sp = exe_ctx.GetFrameSP();
81
82 if (m_address.IsValid()) {
83 if (!frame_sp)
84 return false;
85 return (Address::CompareLoadAddress(lhs: m_address,
86 rhs: frame_sp->GetFrameCodeAddress(),
87 target: target_sp.get()) == 0);
88 }
89
90 return true;
91}
92
93bool UserExpression::MatchesContext(ExecutionContext &exe_ctx) {
94 lldb::TargetSP target_sp;
95 lldb::ProcessSP process_sp;
96 lldb::StackFrameSP frame_sp;
97
98 return LockAndCheckContext(exe_ctx, target_sp, process_sp, frame_sp);
99}
100
101lldb::ValueObjectSP UserExpression::GetObjectPointerValueObject(
102 lldb::StackFrameSP frame_sp, llvm::StringRef object_name, Status &err) {
103 err.Clear();
104
105 if (!frame_sp) {
106 err = Status::FromErrorStringWithFormatv(
107 format: "Couldn't load '{0}' because the context is incomplete", args&: object_name);
108 return {};
109 }
110
111 lldb::VariableSP var_sp;
112 lldb::ValueObjectSP valobj_sp;
113
114 return frame_sp->GetValueForVariableExpressionPath(
115 var_expr: object_name, use_dynamic: lldb::eNoDynamicValues,
116 options: StackFrame::eExpressionPathOptionCheckPtrVsMember |
117 StackFrame::eExpressionPathOptionsNoFragileObjcIvar |
118 StackFrame::eExpressionPathOptionsNoSyntheticChildren |
119 StackFrame::eExpressionPathOptionsNoSyntheticArrayRange,
120 var_sp, error&: err);
121}
122
123lldb::addr_t UserExpression::GetObjectPointer(lldb::StackFrameSP frame_sp,
124 llvm::StringRef object_name,
125 Status &err) {
126 auto valobj_sp =
127 GetObjectPointerValueObject(frame_sp: std::move(frame_sp), object_name, err);
128
129 if (!err.Success() || !valobj_sp.get())
130 return LLDB_INVALID_ADDRESS;
131
132 lldb::addr_t ret = valobj_sp->GetValueAsUnsigned(LLDB_INVALID_ADDRESS);
133
134 if (ret == LLDB_INVALID_ADDRESS) {
135 err = Status::FromErrorStringWithFormatv(
136 format: "Couldn't load '{0}' because its value couldn't be evaluated",
137 args&: object_name);
138 return LLDB_INVALID_ADDRESS;
139 }
140
141 return ret;
142}
143
144lldb::ExpressionResults
145UserExpression::Evaluate(ExecutionContext &exe_ctx,
146 const EvaluateExpressionOptions &options,
147 llvm::StringRef expr, llvm::StringRef prefix,
148 lldb::ValueObjectSP &result_valobj_sp,
149 std::string *fixed_expression, ValueObject *ctx_obj) {
150 Log *log(GetLog(mask: LLDBLog::Expressions | LLDBLog::Step));
151 auto set_error = [&](Status error) {
152 result_valobj_sp = ValueObjectConstResult::Create(
153 exe_scope: exe_ctx.GetBestExecutionContextScope(), error: std::move(error));
154 };
155
156 if (ctx_obj) {
157 static unsigned const ctx_type_mask = lldb::TypeFlags::eTypeIsClass |
158 lldb::TypeFlags::eTypeIsStructUnion |
159 lldb::TypeFlags::eTypeIsReference;
160 if (!(ctx_obj->GetTypeInfo() & ctx_type_mask)) {
161 LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a context object of "
162 "an invalid type, can't run expressions.");
163 set_error(Status("a context object of an invalid type passed"));
164 return lldb::eExpressionSetupError;
165 }
166 }
167
168 if (ctx_obj && ctx_obj->GetTypeInfo() & lldb::TypeFlags::eTypeIsReference) {
169 Status error;
170 lldb::ValueObjectSP deref_ctx_sp = ctx_obj->Dereference(error);
171 if (!error.Success()) {
172 LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a context object of "
173 "a reference type that can't be dereferenced, can't run "
174 "expressions.");
175 set_error(Status(
176 "passed context object of an reference type cannot be deferenced"));
177 return lldb::eExpressionSetupError;
178 }
179
180 ctx_obj = deref_ctx_sp.get();
181 }
182
183 lldb_private::ExecutionPolicy execution_policy = options.GetExecutionPolicy();
184 SourceLanguage language = options.GetLanguage();
185 const ResultType desired_type = options.DoesCoerceToId()
186 ? UserExpression::eResultTypeId
187 : UserExpression::eResultTypeAny;
188 Target *target = exe_ctx.GetTargetPtr();
189 if (!target) {
190 LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a NULL target, can't "
191 "run expressions.");
192 set_error(Status("expression passed a null target"));
193 return lldb::eExpressionSetupError;
194 }
195
196 Process *process = exe_ctx.GetProcessPtr();
197
198 if (!process && execution_policy == eExecutionPolicyAlways) {
199 LLDB_LOG(log, "== [UserExpression::Evaluate] No process, but the policy is "
200 "eExecutionPolicyAlways");
201
202 set_error(Status("expression needed to run but couldn't: no process"));
203
204 return lldb::eExpressionSetupError;
205 }
206
207 // Since we might need to allocate memory, we need to be stopped to run
208 // an expression.
209 if (process && process->GetState() != lldb::eStateStopped) {
210 set_error(Status::FromErrorStringWithFormatv(
211 format: "unable to evaluate expression while the process is {0}: the process "
212 "must be stopped because the expression might require allocating "
213 "memory.",
214 args: StateAsCString(state: process->GetState())));
215 return lldb::eExpressionSetupError;
216 }
217
218 // Explicitly force the IR interpreter to evaluate the expression when the
219 // there is no process that supports running the expression for us. Don't
220 // change the execution policy if we have the special top-level policy that
221 // doesn't contain any expression and there is nothing to interpret.
222 if (execution_policy != eExecutionPolicyTopLevel &&
223 (process == nullptr || !process->CanJIT()))
224 execution_policy = eExecutionPolicyNever;
225
226 // We need to set the expression execution thread here, turns out parse can
227 // call functions in the process of looking up symbols, which will escape the
228 // context set by exe_ctx passed to Execute.
229 lldb::ThreadSP thread_sp = exe_ctx.GetThreadSP();
230 ThreadList::ExpressionExecutionThreadPusher execution_thread_pusher(
231 thread_sp);
232
233 llvm::StringRef full_prefix;
234 llvm::StringRef option_prefix(options.GetPrefix());
235 std::string full_prefix_storage;
236 if (!prefix.empty() && !option_prefix.empty()) {
237 full_prefix_storage = std::string(prefix);
238 full_prefix_storage.append(str: std::string(option_prefix));
239 full_prefix = full_prefix_storage;
240 } else if (!prefix.empty())
241 full_prefix = prefix;
242 else
243 full_prefix = option_prefix;
244
245 // If the language was not specified in the expression command, set it to the
246 // language in the target's properties if specified, else default to the
247 // langage for the frame.
248 if (!language) {
249 if (target->GetLanguage() != lldb::eLanguageTypeUnknown)
250 language = target->GetLanguage();
251 else if (StackFrame *frame = exe_ctx.GetFramePtr())
252 language = frame->GetLanguage();
253 }
254
255 Status error;
256 lldb::UserExpressionSP user_expression_sp(
257 target->GetUserExpressionForLanguage(
258 expr, prefix: full_prefix, language, desired_type, options, ctx_obj, error));
259 if (error.Fail() || !user_expression_sp) {
260 LLDB_LOG(log, "== [UserExpression::Evaluate] Getting expression: {0} ==",
261 error.AsCString());
262 set_error(std::move(error));
263 return lldb::eExpressionSetupError;
264 }
265
266 LLDB_LOG(log, "== [UserExpression::Evaluate] Parsing expression {0} ==",
267 expr.str());
268
269 const bool keep_expression_in_memory = true;
270 const bool generate_debug_info = options.GetGenerateDebugInfo();
271
272 if (options.InvokeCancelCallback(phase: lldb::eExpressionEvaluationParse)) {
273 set_error(Status("expression interrupted by callback before parse"));
274 return lldb::eExpressionInterrupted;
275 }
276
277 DiagnosticManager diagnostic_manager;
278
279 bool parse_success =
280 user_expression_sp->Parse(diagnostic_manager, exe_ctx, execution_policy,
281 keep_result_in_memory: keep_expression_in_memory, generate_debug_info);
282
283 // Calculate the fixed expression always, since we need it for errors.
284 std::string tmp_fixed_expression;
285 if (fixed_expression == nullptr)
286 fixed_expression = &tmp_fixed_expression;
287
288 *fixed_expression = user_expression_sp->GetFixedText().str();
289 lldb::ExpressionResults execution_results = lldb::eExpressionSetupError;
290
291 // If there is a fixed expression, try to parse it:
292 if (!parse_success) {
293 // Delete the expression that failed to parse before attempting to parse
294 // the next expression.
295 user_expression_sp.reset();
296
297 execution_results = lldb::eExpressionParseError;
298 if (!fixed_expression->empty() && options.GetAutoApplyFixIts()) {
299 const uint64_t max_fix_retries = options.GetRetriesWithFixIts();
300 for (uint64_t i = 0; i < max_fix_retries; ++i) {
301 // Try parsing the fixed expression.
302 lldb::UserExpressionSP fixed_expression_sp(
303 target->GetUserExpressionForLanguage(
304 expr: fixed_expression->c_str(), prefix: full_prefix, language, desired_type,
305 options, ctx_obj, error));
306 if (!fixed_expression_sp)
307 break;
308 DiagnosticManager fixed_diagnostic_manager;
309 parse_success = fixed_expression_sp->Parse(
310 diagnostic_manager&: fixed_diagnostic_manager, exe_ctx, execution_policy,
311 keep_result_in_memory: keep_expression_in_memory, generate_debug_info);
312 if (parse_success) {
313 diagnostic_manager.Clear();
314 user_expression_sp = fixed_expression_sp;
315 break;
316 }
317 // The fixed expression also didn't parse. Let's check for any new
318 // fixits we could try.
319 if (!fixed_expression_sp->GetFixedText().empty()) {
320 *fixed_expression = fixed_expression_sp->GetFixedText().str();
321 } else {
322 // Fixed expression didn't compile without a fixit, don't retry and
323 // don't tell the user about it.
324 fixed_expression->clear();
325 break;
326 }
327 }
328 }
329
330 if (!parse_success) {
331 if (target->GetEnableNotifyAboutFixIts() && fixed_expression &&
332 !fixed_expression->empty()) {
333 std::string fixit =
334 "fixed expression suggested:\n " + *fixed_expression;
335 diagnostic_manager.AddDiagnostic(message: fixit, severity: lldb::eSeverityInfo,
336 origin: eDiagnosticOriginLLDB);
337 }
338 if (diagnostic_manager.Diagnostics().empty())
339 error = Status::FromError(error: llvm::make_error<ExpressionError>(
340 Args&: execution_results,
341 Args: "expression failed to parse (no further compiler diagnostics)"));
342 else
343 error =
344 Status::FromError(error: diagnostic_manager.GetAsError(result: execution_results));
345 }
346 }
347
348 if (parse_success) {
349 lldb::ExpressionVariableSP expr_result;
350
351 if (execution_policy == eExecutionPolicyNever &&
352 !user_expression_sp->CanInterpret()) {
353 LLDB_LOG(log, "== [UserExpression::Evaluate] Expression may not run, but "
354 "is not constant ==");
355
356 if (diagnostic_manager.Diagnostics().empty())
357 error = Status::FromError(error: llvm::make_error<ExpressionError>(
358 Args: lldb::eExpressionSetupError,
359 Args: "expression needed to run but couldn't"));
360 } else if (execution_policy == eExecutionPolicyTopLevel) {
361 set_error(Status(UserExpression::kNoResult, lldb::eErrorTypeGeneric));
362 return lldb::eExpressionCompleted;
363 } else {
364 if (options.InvokeCancelCallback(phase: lldb::eExpressionEvaluationExecution)) {
365 set_error(Status::FromError(error: llvm::make_error<ExpressionError>(
366 Args: lldb::eExpressionInterrupted,
367 Args: "expression interrupted by callback before execution")));
368 return lldb::eExpressionInterrupted;
369 }
370
371 diagnostic_manager.Clear();
372
373 LLDB_LOG(log, "== [UserExpression::Evaluate] Executing expression ==");
374
375 execution_results =
376 user_expression_sp->Execute(diagnostic_manager, exe_ctx, options,
377 shared_ptr_to_me&: user_expression_sp, result&: expr_result);
378
379 if (execution_results != lldb::eExpressionCompleted) {
380 LLDB_LOG(log, "== [UserExpression::Evaluate] Execution completed "
381 "abnormally ==");
382
383 if (diagnostic_manager.Diagnostics().empty())
384 error = Status::FromError(error: llvm::make_error<ExpressionError>(
385 Args&: execution_results,
386 Args: "expression failed to execute, unknown error"));
387 else
388 error = Status::FromError(
389 error: diagnostic_manager.GetAsError(result: execution_results));
390 } else {
391 if (expr_result) {
392 result_valobj_sp = expr_result->GetValueObject();
393 result_valobj_sp->SetPreferredDisplayLanguage(
394 language.AsLanguageType());
395
396 LLDB_LOG(log,
397 "== [UserExpression::Evaluate] Execution completed "
398 "normally with result {0} ==",
399 result_valobj_sp->GetValueAsCString());
400 } else {
401 LLDB_LOG(log, "== [UserExpression::Evaluate] Execution completed "
402 "normally with no result ==");
403
404 error = Status(UserExpression::kNoResult, lldb::eErrorTypeGeneric);
405 }
406 }
407 }
408 }
409
410 if (options.InvokeCancelCallback(phase: lldb::eExpressionEvaluationComplete)) {
411 set_error(Status::FromError(error: llvm::make_error<ExpressionError>(
412 Args: lldb::eExpressionInterrupted,
413 Args: "expression interrupted by callback after complete")));
414 return lldb::eExpressionInterrupted;
415 }
416
417 if (error.Fail())
418 set_error(std::move(error));
419 return execution_results;
420}
421
422lldb::ExpressionResults
423UserExpression::Execute(DiagnosticManager &diagnostic_manager,
424 ExecutionContext &exe_ctx,
425 const EvaluateExpressionOptions &options,
426 lldb::UserExpressionSP &shared_ptr_to_me,
427 lldb::ExpressionVariableSP &result_var) {
428 Debugger *debugger =
429 exe_ctx.GetTargetPtr() ? &exe_ctx.GetTargetPtr()->GetDebugger() : nullptr;
430 std::string details;
431 if (m_options.IsForUtilityExpr())
432 details = "LLDB utility";
433 else if (m_expr_text.size() > 15)
434 details = m_expr_text.substr(pos: 0, n: 14) + "…";
435 else
436 details = m_expr_text;
437
438 Progress progress("Running expression", details, {}, debugger);
439
440 lldb::ExpressionResults expr_result = DoExecute(
441 diagnostic_manager, exe_ctx, options, shared_ptr_to_me, result&: result_var);
442 Target *target = exe_ctx.GetTargetPtr();
443 if (options.GetSuppressPersistentResult() && result_var && target) {
444 if (auto *persistent_state =
445 target->GetPersistentExpressionStateForLanguage(
446 language: m_language.AsLanguageType()))
447 persistent_state->RemovePersistentVariable(variable: result_var);
448 }
449 return expr_result;
450}
451

source code of lldb/source/Expression/UserExpression.cpp