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llvm-project/lldb/source/Expression/UserExpression.cpp
Adrian Prantl 6a8a4d51a4
[lldb] Refactor UserExpression::Evaluate to only have one error channel. (#117186) 
Prior to this patch, the function returned an exit status, sometimes a
ValueObject with an error and a Status object. This patch removes the
Status object and ensures the error is consistently returned as the
error of the ValueObject.
2024-11-21 15:37:04 -08:00

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//===-- UserExpression.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 <cstdio>
#include <sys/types.h>
#include <cstdlib>
#include <map>
#include <string>
#include "lldb/Core/Module.h"
#include "lldb/Expression/DiagnosticManager.h"
#include "lldb/Expression/ExpressionVariable.h"
#include "lldb/Expression/IRExecutionUnit.h"
#include "lldb/Expression/IRInterpreter.h"
#include "lldb/Expression/Materializer.h"
#include "lldb/Expression/UserExpression.h"
#include "lldb/Host/HostInfo.h"
#include "lldb/Symbol/Block.h"
#include "lldb/Symbol/Function.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Symbol/SymbolVendor.h"
#include "lldb/Symbol/Type.h"
#include "lldb/Symbol/TypeSystem.h"
#include "lldb/Symbol/VariableList.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/StackFrame.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/ThreadPlan.h"
#include "lldb/Target/ThreadPlanCallUserExpression.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/State.h"
#include "lldb/Utility/StreamString.h"
#include "lldb/ValueObject/ValueObjectConstResult.h"
#include "llvm/BinaryFormat/Dwarf.h"
using namespace lldb_private;
char UserExpression::ID;
UserExpression::UserExpression(ExecutionContextScope &exe_scope,
llvm::StringRef expr, llvm::StringRef prefix,
SourceLanguage language, ResultType desired_type,
const EvaluateExpressionOptions &options)
: Expression(exe_scope), m_expr_text(std::string(expr)),
m_expr_prefix(std::string(prefix)), m_language(language),
m_desired_type(desired_type), m_options(options) {}
UserExpression::~UserExpression() = default;
void UserExpression::InstallContext(ExecutionContext &exe_ctx) {
m_jit_process_wp = exe_ctx.GetProcessSP();
lldb::StackFrameSP frame_sp = exe_ctx.GetFrameSP();
if (frame_sp)
m_address = frame_sp->GetFrameCodeAddress();
}
bool UserExpression::LockAndCheckContext(ExecutionContext &exe_ctx,
lldb::TargetSP &target_sp,
lldb::ProcessSP &process_sp,
lldb::StackFrameSP &frame_sp) {
lldb::ProcessSP expected_process_sp = m_jit_process_wp.lock();
process_sp = exe_ctx.GetProcessSP();
if (process_sp != expected_process_sp)
return false;
process_sp = exe_ctx.GetProcessSP();
target_sp = exe_ctx.GetTargetSP();
frame_sp = exe_ctx.GetFrameSP();
if (m_address.IsValid()) {
if (!frame_sp)
return false;
return (Address::CompareLoadAddress(m_address,
frame_sp->GetFrameCodeAddress(),
target_sp.get()) == 0);
}
return true;
}
bool UserExpression::MatchesContext(ExecutionContext &exe_ctx) {
lldb::TargetSP target_sp;
lldb::ProcessSP process_sp;
lldb::StackFrameSP frame_sp;
return LockAndCheckContext(exe_ctx, target_sp, process_sp, frame_sp);
}
lldb::ValueObjectSP UserExpression::GetObjectPointerValueObject(
lldb::StackFrameSP frame_sp, llvm::StringRef object_name, Status &err) {
err.Clear();
if (!frame_sp) {
err = Status::FromErrorStringWithFormatv(
"Couldn't load '{0}' because the context is incomplete", object_name);
return {};
}
lldb::VariableSP var_sp;
lldb::ValueObjectSP valobj_sp;
return frame_sp->GetValueForVariableExpressionPath(
object_name, lldb::eNoDynamicValues,
StackFrame::eExpressionPathOptionCheckPtrVsMember |
StackFrame::eExpressionPathOptionsNoFragileObjcIvar |
StackFrame::eExpressionPathOptionsNoSyntheticChildren |
StackFrame::eExpressionPathOptionsNoSyntheticArrayRange,
var_sp, err);
}
lldb::addr_t UserExpression::GetObjectPointer(lldb::StackFrameSP frame_sp,
llvm::StringRef object_name,
Status &err) {
auto valobj_sp =
GetObjectPointerValueObject(std::move(frame_sp), object_name, err);
if (!err.Success() || !valobj_sp.get())
return LLDB_INVALID_ADDRESS;
lldb::addr_t ret = valobj_sp->GetValueAsUnsigned(LLDB_INVALID_ADDRESS);
if (ret == LLDB_INVALID_ADDRESS) {
err = Status::FromErrorStringWithFormatv(
"Couldn't load '{0}' because its value couldn't be evaluated",
object_name);
return LLDB_INVALID_ADDRESS;
}
return ret;
}
lldb::ExpressionResults
UserExpression::Evaluate(ExecutionContext &exe_ctx,
const EvaluateExpressionOptions &options,
llvm::StringRef expr, llvm::StringRef prefix,
lldb::ValueObjectSP &result_valobj_sp,
std::string *fixed_expression, ValueObject *ctx_obj) {
Log *log(GetLog(LLDBLog::Expressions | LLDBLog::Step));
auto set_error = [&](Status error) {
result_valobj_sp = ValueObjectConstResult::Create(
exe_ctx.GetBestExecutionContextScope(), std::move(error));
};
if (ctx_obj) {
static unsigned const ctx_type_mask = lldb::TypeFlags::eTypeIsClass |
lldb::TypeFlags::eTypeIsStructUnion |
lldb::TypeFlags::eTypeIsReference;
if (!(ctx_obj->GetTypeInfo() & ctx_type_mask)) {
LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a context object of "
"an invalid type, can't run expressions.");
set_error(Status("a context object of an invalid type passed"));
return lldb::eExpressionSetupError;
}
}
if (ctx_obj && ctx_obj->GetTypeInfo() & lldb::TypeFlags::eTypeIsReference) {
Status error;
lldb::ValueObjectSP deref_ctx_sp = ctx_obj->Dereference(error);
if (!error.Success()) {
LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a context object of "
"a reference type that can't be dereferenced, can't run "
"expressions.");
set_error(Status(
"passed context object of an reference type cannot be deferenced"));
return lldb::eExpressionSetupError;
}
ctx_obj = deref_ctx_sp.get();
}
lldb_private::ExecutionPolicy execution_policy = options.GetExecutionPolicy();
SourceLanguage language = options.GetLanguage();
const ResultType desired_type = options.DoesCoerceToId()
? UserExpression::eResultTypeId
: UserExpression::eResultTypeAny;
Target *target = exe_ctx.GetTargetPtr();
if (!target) {
LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a NULL target, can't "
"run expressions.");
set_error(Status("expression passed a null target"));
return lldb::eExpressionSetupError;
}
Process *process = exe_ctx.GetProcessPtr();
if (!process && execution_policy == eExecutionPolicyAlways) {
LLDB_LOG(log, "== [UserExpression::Evaluate] No process, but the policy is "
"eExecutionPolicyAlways");
set_error(Status("expression needed to run but couldn't: no process"));
return lldb::eExpressionSetupError;
}
// Since we might need to allocate memory, we need to be stopped to run
// an expression.
if (process && process->GetState() != lldb::eStateStopped) {
set_error(Status::FromErrorStringWithFormatv(
"unable to evaluate expression while the process is {0}: the process "
"must be stopped because the expression might require allocating "
"memory.",
StateAsCString(process->GetState())));
return lldb::eExpressionSetupError;
}
// Explicitly force the IR interpreter to evaluate the expression when the
// there is no process that supports running the expression for us. Don't
// change the execution policy if we have the special top-level policy that
// doesn't contain any expression and there is nothing to interpret.
if (execution_policy != eExecutionPolicyTopLevel &&
(process == nullptr || !process->CanJIT()))
execution_policy = eExecutionPolicyNever;
// We need to set the expression execution thread here, turns out parse can
// call functions in the process of looking up symbols, which will escape the
// context set by exe_ctx passed to Execute.
lldb::ThreadSP thread_sp = exe_ctx.GetThreadSP();
ThreadList::ExpressionExecutionThreadPusher execution_thread_pusher(
thread_sp);
llvm::StringRef full_prefix;
llvm::StringRef option_prefix(options.GetPrefix());
std::string full_prefix_storage;
if (!prefix.empty() && !option_prefix.empty()) {
full_prefix_storage = std::string(prefix);
full_prefix_storage.append(std::string(option_prefix));
full_prefix = full_prefix_storage;
} else if (!prefix.empty())
full_prefix = prefix;
else
full_prefix = option_prefix;
// If the language was not specified in the expression command, set it to the
// language in the target's properties if specified, else default to the
// langage for the frame.
if (!language) {
if (target->GetLanguage() != lldb::eLanguageTypeUnknown)
language = target->GetLanguage();
else if (StackFrame *frame = exe_ctx.GetFramePtr())
language = frame->GetLanguage();
}
Status error;
lldb::UserExpressionSP user_expression_sp(
target->GetUserExpressionForLanguage(
expr, full_prefix, language, desired_type, options, ctx_obj, error));
if (error.Fail() || !user_expression_sp) {
LLDB_LOG(log, "== [UserExpression::Evaluate] Getting expression: {0} ==",
error.AsCString());
set_error(std::move(error));
return lldb::eExpressionSetupError;
}
LLDB_LOG(log, "== [UserExpression::Evaluate] Parsing expression {0} ==",
expr.str());
const bool keep_expression_in_memory = true;
const bool generate_debug_info = options.GetGenerateDebugInfo();
if (options.InvokeCancelCallback(lldb::eExpressionEvaluationParse)) {
set_error(Status("expression interrupted by callback before parse"));
return lldb::eExpressionInterrupted;
}
DiagnosticManager diagnostic_manager;
bool parse_success =
user_expression_sp->Parse(diagnostic_manager, exe_ctx, execution_policy,
keep_expression_in_memory, generate_debug_info);
// Calculate the fixed expression always, since we need it for errors.
std::string tmp_fixed_expression;
if (fixed_expression == nullptr)
fixed_expression = &tmp_fixed_expression;
*fixed_expression = user_expression_sp->GetFixedText().str();
lldb::ExpressionResults execution_results = lldb::eExpressionSetupError;
// If there is a fixed expression, try to parse it:
if (!parse_success) {
// Delete the expression that failed to parse before attempting to parse
// the next expression.
user_expression_sp.reset();
execution_results = lldb::eExpressionParseError;
if (!fixed_expression->empty() && options.GetAutoApplyFixIts()) {
const uint64_t max_fix_retries = options.GetRetriesWithFixIts();
for (uint64_t i = 0; i < max_fix_retries; ++i) {
// Try parsing the fixed expression.
lldb::UserExpressionSP fixed_expression_sp(
target->GetUserExpressionForLanguage(
fixed_expression->c_str(), full_prefix, language, desired_type,
options, ctx_obj, error));
if (!fixed_expression_sp)
break;
DiagnosticManager fixed_diagnostic_manager;
parse_success = fixed_expression_sp->Parse(
fixed_diagnostic_manager, exe_ctx, execution_policy,
keep_expression_in_memory, generate_debug_info);
if (parse_success) {
diagnostic_manager.Clear();
user_expression_sp = fixed_expression_sp;
break;
}
// The fixed expression also didn't parse. Let's check for any new
// fixits we could try.
if (!fixed_expression_sp->GetFixedText().empty()) {
*fixed_expression = fixed_expression_sp->GetFixedText().str();
} else {
// Fixed expression didn't compile without a fixit, don't retry and
// don't tell the user about it.
fixed_expression->clear();
break;
}
}
}
if (!parse_success) {
if (target->GetEnableNotifyAboutFixIts() && fixed_expression &&
!fixed_expression->empty()) {
std::string fixit =
"fixed expression suggested:\n " + *fixed_expression;
diagnostic_manager.AddDiagnostic(fixit, lldb::eSeverityInfo,
eDiagnosticOriginLLDB);
}
if (diagnostic_manager.Diagnostics().empty())
error = Status::FromError(llvm::make_error<ExpressionError>(
execution_results,
"expression failed to parse (no further compiler diagnostics)"));
else
error =
Status::FromError(diagnostic_manager.GetAsError(execution_results));
}
}
if (parse_success) {
lldb::ExpressionVariableSP expr_result;
if (execution_policy == eExecutionPolicyNever &&
!user_expression_sp->CanInterpret()) {
LLDB_LOG(log, "== [UserExpression::Evaluate] Expression may not run, but "
"is not constant ==");
if (diagnostic_manager.Diagnostics().empty())
error = Status::FromError(llvm::make_error<ExpressionError>(
lldb::eExpressionSetupError,
"expression needed to run but couldn't"));
} else if (execution_policy == eExecutionPolicyTopLevel) {
set_error(Status(UserExpression::kNoResult, lldb::eErrorTypeGeneric));
return lldb::eExpressionCompleted;
} else {
if (options.InvokeCancelCallback(lldb::eExpressionEvaluationExecution)) {
set_error(Status::FromError(llvm::make_error<ExpressionError>(
lldb::eExpressionInterrupted,
"expression interrupted by callback before execution")));
return lldb::eExpressionInterrupted;
}
diagnostic_manager.Clear();
LLDB_LOG(log, "== [UserExpression::Evaluate] Executing expression ==");
execution_results =
user_expression_sp->Execute(diagnostic_manager, exe_ctx, options,
user_expression_sp, expr_result);
if (execution_results != lldb::eExpressionCompleted) {
LLDB_LOG(log, "== [UserExpression::Evaluate] Execution completed "
"abnormally ==");
if (diagnostic_manager.Diagnostics().empty())
error = Status::FromError(llvm::make_error<ExpressionError>(
execution_results,
"expression failed to execute, unknown error"));
else
error = Status::FromError(
diagnostic_manager.GetAsError(execution_results));
} else {
if (expr_result) {
result_valobj_sp = expr_result->GetValueObject();
result_valobj_sp->SetPreferredDisplayLanguage(
language.AsLanguageType());
LLDB_LOG(log,
"== [UserExpression::Evaluate] Execution completed "
"normally with result {0} ==",
result_valobj_sp->GetValueAsCString());
} else {
LLDB_LOG(log, "== [UserExpression::Evaluate] Execution completed "
"normally with no result ==");
error = Status(UserExpression::kNoResult, lldb::eErrorTypeGeneric);
}
}
}
}
if (options.InvokeCancelCallback(lldb::eExpressionEvaluationComplete)) {
set_error(Status::FromError(llvm::make_error<ExpressionError>(
lldb::eExpressionInterrupted,
"expression interrupted by callback after complete")));
return lldb::eExpressionInterrupted;
}
if (error.Fail())
set_error(std::move(error));
return execution_results;
}
lldb::ExpressionResults
UserExpression::Execute(DiagnosticManager &diagnostic_manager,
ExecutionContext &exe_ctx,
const EvaluateExpressionOptions &options,
lldb::UserExpressionSP &shared_ptr_to_me,
lldb::ExpressionVariableSP &result_var) {
lldb::ExpressionResults expr_result = DoExecute(
diagnostic_manager, exe_ctx, options, shared_ptr_to_me, result_var);
Target *target = exe_ctx.GetTargetPtr();
if (options.GetSuppressPersistentResult() && result_var && target) {
if (auto *persistent_state =
target->GetPersistentExpressionStateForLanguage(
m_language.AsLanguageType()))
persistent_state->RemovePersistentVariable(result_var);
}
return expr_result;
}
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