1 //===-- ValueObjectChild.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 "lldb/Core/ValueObjectChild.h"
10 
11 #include "lldb/Core/Value.h"
12 #include "lldb/Symbol/CompilerType.h"
13 #include "lldb/Target/ExecutionContext.h"
14 #include "lldb/Target/Process.h"
15 #include "lldb/Utility/Flags.h"
16 #include "lldb/Utility/Scalar.h"
17 #include "lldb/Utility/Status.h"
18 #include "lldb/lldb-forward.h"
19 
20 #include <functional>
21 #include <memory>
22 #include <vector>
23 
24 #include <stdio.h>
25 #include <string.h>
26 
27 using namespace lldb_private;
28 
ValueObjectChild(ValueObject & parent,const CompilerType & compiler_type,ConstString name,uint64_t byte_size,int32_t byte_offset,uint32_t bitfield_bit_size,uint32_t bitfield_bit_offset,bool is_base_class,bool is_deref_of_parent,AddressType child_ptr_or_ref_addr_type,uint64_t language_flags)29 ValueObjectChild::ValueObjectChild(
30     ValueObject &parent, const CompilerType &compiler_type,
31     ConstString name, uint64_t byte_size, int32_t byte_offset,
32     uint32_t bitfield_bit_size, uint32_t bitfield_bit_offset,
33     bool is_base_class, bool is_deref_of_parent,
34     AddressType child_ptr_or_ref_addr_type, uint64_t language_flags)
35     : ValueObject(parent), m_compiler_type(compiler_type),
36       m_byte_size(byte_size), m_byte_offset(byte_offset),
37       m_bitfield_bit_size(bitfield_bit_size),
38       m_bitfield_bit_offset(bitfield_bit_offset),
39       m_is_base_class(is_base_class), m_is_deref_of_parent(is_deref_of_parent),
40       m_can_update_with_invalid_exe_ctx() {
41   m_name = name;
42   SetAddressTypeOfChildren(child_ptr_or_ref_addr_type);
43   SetLanguageFlags(language_flags);
44 }
45 
~ValueObjectChild()46 ValueObjectChild::~ValueObjectChild() {}
47 
GetValueType() const48 lldb::ValueType ValueObjectChild::GetValueType() const {
49   return m_parent->GetValueType();
50 }
51 
CalculateNumChildren(uint32_t max)52 size_t ValueObjectChild::CalculateNumChildren(uint32_t max) {
53   ExecutionContext exe_ctx(GetExecutionContextRef());
54   auto children_count = GetCompilerType().GetNumChildren(true, &exe_ctx);
55   return children_count <= max ? children_count : max;
56 }
57 
AdjustForBitfieldness(ConstString & name,uint8_t bitfield_bit_size)58 static void AdjustForBitfieldness(ConstString &name,
59                                   uint8_t bitfield_bit_size) {
60   if (name && bitfield_bit_size)
61     name.SetString(llvm::formatv("{0}:{1}", name, bitfield_bit_size).str());
62 }
63 
GetTypeName()64 ConstString ValueObjectChild::GetTypeName() {
65   if (m_type_name.IsEmpty()) {
66     m_type_name = GetCompilerType().GetTypeName();
67     AdjustForBitfieldness(m_type_name, m_bitfield_bit_size);
68   }
69   return m_type_name;
70 }
71 
GetQualifiedTypeName()72 ConstString ValueObjectChild::GetQualifiedTypeName() {
73   ConstString qualified_name = GetCompilerType().GetTypeName();
74   AdjustForBitfieldness(qualified_name, m_bitfield_bit_size);
75   return qualified_name;
76 }
77 
GetDisplayTypeName()78 ConstString ValueObjectChild::GetDisplayTypeName() {
79   ConstString display_name = GetCompilerType().GetDisplayTypeName();
80   AdjustForBitfieldness(display_name, m_bitfield_bit_size);
81   return display_name;
82 }
83 
CanUpdateWithInvalidExecutionContext()84 LazyBool ValueObjectChild::CanUpdateWithInvalidExecutionContext() {
85   if (m_can_update_with_invalid_exe_ctx.hasValue())
86     return m_can_update_with_invalid_exe_ctx.getValue();
87   if (m_parent) {
88     ValueObject *opinionated_parent =
89         m_parent->FollowParentChain([](ValueObject *valobj) -> bool {
90           return (valobj->CanUpdateWithInvalidExecutionContext() ==
91                   eLazyBoolCalculate);
92         });
93     if (opinionated_parent)
94       return (m_can_update_with_invalid_exe_ctx =
95                   opinionated_parent->CanUpdateWithInvalidExecutionContext())
96           .getValue();
97   }
98   return (m_can_update_with_invalid_exe_ctx =
99               this->ValueObject::CanUpdateWithInvalidExecutionContext())
100       .getValue();
101 }
102 
UpdateValue()103 bool ValueObjectChild::UpdateValue() {
104   m_error.Clear();
105   SetValueIsValid(false);
106   ValueObject *parent = m_parent;
107   if (parent) {
108     if (parent->UpdateValueIfNeeded(false)) {
109       m_value.SetCompilerType(GetCompilerType());
110 
111       CompilerType parent_type(parent->GetCompilerType());
112       // Copy the parent scalar value and the scalar value type
113       m_value.GetScalar() = parent->GetValue().GetScalar();
114       m_value.SetValueType(parent->GetValue().GetValueType());
115 
116       Flags parent_type_flags(parent_type.GetTypeInfo());
117       const bool is_instance_ptr_base =
118           ((m_is_base_class) &&
119            (parent_type_flags.AnySet(lldb::eTypeInstanceIsPointer)));
120 
121       if (parent->GetCompilerType().ShouldTreatScalarValueAsAddress()) {
122         m_value.GetScalar() = parent->GetPointerValue();
123 
124         switch (parent->GetAddressTypeOfChildren()) {
125         case eAddressTypeFile: {
126           lldb::ProcessSP process_sp(GetProcessSP());
127           if (process_sp && process_sp->IsAlive())
128             m_value.SetValueType(Value::eValueTypeLoadAddress);
129           else
130             m_value.SetValueType(Value::eValueTypeFileAddress);
131         } break;
132         case eAddressTypeLoad:
133           m_value.SetValueType(is_instance_ptr_base
134                                    ? Value::eValueTypeScalar
135                                    : Value::eValueTypeLoadAddress);
136           break;
137         case eAddressTypeHost:
138           m_value.SetValueType(Value::eValueTypeHostAddress);
139           break;
140         case eAddressTypeInvalid:
141           // TODO: does this make sense?
142           m_value.SetValueType(Value::eValueTypeScalar);
143           break;
144         }
145       }
146       switch (m_value.GetValueType()) {
147       case Value::eValueTypeLoadAddress:
148       case Value::eValueTypeFileAddress:
149       case Value::eValueTypeHostAddress: {
150         lldb::addr_t addr = m_value.GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
151         if (addr == LLDB_INVALID_ADDRESS) {
152           m_error.SetErrorString("parent address is invalid.");
153         } else if (addr == 0) {
154           m_error.SetErrorString("parent is NULL");
155         } else {
156           // If a bitfield doesn't fit into the child_byte_size'd window at
157           // child_byte_offset, move the window forward until it fits.  The
158           // problem here is that Value has no notion of bitfields and thus the
159           // Value's DataExtractor is sized like the bitfields CompilerType; a
160           // sequence of bitfields, however, can be larger than their underlying
161           // type.
162           if (m_bitfield_bit_offset) {
163             const bool thread_and_frame_only_if_stopped = true;
164             ExecutionContext exe_ctx(GetExecutionContextRef().Lock(
165                 thread_and_frame_only_if_stopped));
166             if (auto type_bit_size = GetCompilerType().GetBitSize(
167                     exe_ctx.GetBestExecutionContextScope())) {
168               uint64_t bitfield_end =
169                   m_bitfield_bit_size + m_bitfield_bit_offset;
170               if (bitfield_end > *type_bit_size) {
171                 uint64_t overhang_bytes =
172                     (bitfield_end - *type_bit_size + 7) / 8;
173                 m_byte_offset += overhang_bytes;
174                 m_bitfield_bit_offset -= overhang_bytes * 8;
175               }
176             }
177           }
178 
179           // Set this object's scalar value to the address of its value by
180           // adding its byte offset to the parent address
181           m_value.GetScalar() += m_byte_offset;
182         }
183       } break;
184 
185       case Value::eValueTypeScalar:
186         // try to extract the child value from the parent's scalar value
187         {
188           Scalar scalar(m_value.GetScalar());
189           scalar.ExtractBitfield(8 * m_byte_size, 8 * m_byte_offset);
190           m_value.GetScalar() = scalar;
191         }
192         break;
193       }
194 
195       if (m_error.Success()) {
196         const bool thread_and_frame_only_if_stopped = true;
197         ExecutionContext exe_ctx(
198             GetExecutionContextRef().Lock(thread_and_frame_only_if_stopped));
199         if (GetCompilerType().GetTypeInfo() & lldb::eTypeHasValue) {
200           Value &value = is_instance_ptr_base ? m_parent->GetValue() : m_value;
201           m_error =
202               value.GetValueAsData(&exe_ctx, m_data, GetModule().get());
203         } else {
204           m_error.Clear(); // No value so nothing to read...
205         }
206       }
207 
208     } else {
209       m_error.SetErrorStringWithFormat("parent failed to evaluate: %s",
210                                        parent->GetError().AsCString());
211     }
212   } else {
213     m_error.SetErrorString("ValueObjectChild has a NULL parent ValueObject.");
214   }
215 
216   return m_error.Success();
217 }
218 
IsInScope()219 bool ValueObjectChild::IsInScope() {
220   ValueObject *root(GetRoot());
221   if (root)
222     return root->IsInScope();
223   return false;
224 }
225