1 //===-- ABI.cpp -------------------------------------------------*- C++ -*-===//
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/Target/ABI.h"
10 #include "lldb/Core/PluginManager.h"
11 #include "lldb/Core/Value.h"
12 #include "lldb/Core/ValueObjectConstResult.h"
13 #include "lldb/Expression/ExpressionVariable.h"
14 #include "lldb/Symbol/CompilerType.h"
15 #include "lldb/Symbol/TypeSystem.h"
16 #include "lldb/Target/Target.h"
17 #include "lldb/Target/Thread.h"
18 #include "lldb/Utility/Log.h"
19 #include "llvm/Support/TargetRegistry.h"
20 
21 using namespace lldb;
22 using namespace lldb_private;
23 
24 ABISP
25 ABI::FindPlugin(lldb::ProcessSP process_sp, const ArchSpec &arch) {
26   ABISP abi_sp;
27   ABICreateInstance create_callback;
28 
29   for (uint32_t idx = 0;
30        (create_callback = PluginManager::GetABICreateCallbackAtIndex(idx)) !=
31        nullptr;
32        ++idx) {
33     abi_sp = create_callback(process_sp, arch);
34 
35     if (abi_sp)
36       return abi_sp;
37   }
38   abi_sp.reset();
39   return abi_sp;
40 }
41 
42 ABI::~ABI() = default;
43 
44 bool ABI::GetRegisterInfoByName(ConstString name, RegisterInfo &info) {
45   uint32_t count = 0;
46   const RegisterInfo *register_info_array = GetRegisterInfoArray(count);
47   if (register_info_array) {
48     const char *unique_name_cstr = name.GetCString();
49     uint32_t i;
50     for (i = 0; i < count; ++i) {
51       if (register_info_array[i].name == unique_name_cstr) {
52         info = register_info_array[i];
53         return true;
54       }
55     }
56     for (i = 0; i < count; ++i) {
57       if (register_info_array[i].alt_name == unique_name_cstr) {
58         info = register_info_array[i];
59         return true;
60       }
61     }
62   }
63   return false;
64 }
65 
66 bool ABI::GetRegisterInfoByKind(RegisterKind reg_kind, uint32_t reg_num,
67                                 RegisterInfo &info) {
68   if (reg_kind < eRegisterKindEHFrame || reg_kind >= kNumRegisterKinds)
69     return false;
70 
71   uint32_t count = 0;
72   const RegisterInfo *register_info_array = GetRegisterInfoArray(count);
73   if (register_info_array) {
74     for (uint32_t i = 0; i < count; ++i) {
75       if (register_info_array[i].kinds[reg_kind] == reg_num) {
76         info = register_info_array[i];
77         return true;
78       }
79     }
80   }
81   return false;
82 }
83 
84 ValueObjectSP ABI::GetReturnValueObject(Thread &thread, CompilerType &ast_type,
85                                         bool persistent) const {
86   if (!ast_type.IsValid())
87     return ValueObjectSP();
88 
89   ValueObjectSP return_valobj_sp;
90 
91   return_valobj_sp = GetReturnValueObjectImpl(thread, ast_type);
92   if (!return_valobj_sp)
93     return return_valobj_sp;
94 
95   // Now turn this into a persistent variable.
96   // FIXME: This code is duplicated from Target::EvaluateExpression, and it is
97   // used in similar form in a couple
98   // of other places.  Figure out the correct Create function to do all this
99   // work.
100 
101   if (persistent) {
102     Target &target = *thread.CalculateTarget();
103     PersistentExpressionState *persistent_expression_state =
104         target.GetPersistentExpressionStateForLanguage(
105             ast_type.GetMinimumLanguage());
106 
107     if (!persistent_expression_state)
108       return ValueObjectSP();
109 
110     auto prefix = persistent_expression_state->GetPersistentVariablePrefix();
111     ConstString persistent_variable_name =
112         persistent_expression_state->GetNextPersistentVariableName(target,
113                                                                    prefix);
114 
115     lldb::ValueObjectSP const_valobj_sp;
116 
117     // Check in case our value is already a constant value
118     if (return_valobj_sp->GetIsConstant()) {
119       const_valobj_sp = return_valobj_sp;
120       const_valobj_sp->SetName(persistent_variable_name);
121     } else
122       const_valobj_sp =
123           return_valobj_sp->CreateConstantValue(persistent_variable_name);
124 
125     lldb::ValueObjectSP live_valobj_sp = return_valobj_sp;
126 
127     return_valobj_sp = const_valobj_sp;
128 
129     ExpressionVariableSP expr_variable_sp(
130         persistent_expression_state->CreatePersistentVariable(
131             return_valobj_sp));
132 
133     assert(expr_variable_sp);
134 
135     // Set flags and live data as appropriate
136 
137     const Value &result_value = live_valobj_sp->GetValue();
138 
139     switch (result_value.GetValueType()) {
140     case Value::eValueTypeHostAddress:
141     case Value::eValueTypeFileAddress:
142       // we don't do anything with these for now
143       break;
144     case Value::eValueTypeScalar:
145     case Value::eValueTypeVector:
146       expr_variable_sp->m_flags |=
147           ExpressionVariable::EVIsFreezeDried;
148       expr_variable_sp->m_flags |=
149           ExpressionVariable::EVIsLLDBAllocated;
150       expr_variable_sp->m_flags |=
151           ExpressionVariable::EVNeedsAllocation;
152       break;
153     case Value::eValueTypeLoadAddress:
154       expr_variable_sp->m_live_sp = live_valobj_sp;
155       expr_variable_sp->m_flags |=
156           ExpressionVariable::EVIsProgramReference;
157       break;
158     }
159 
160     return_valobj_sp = expr_variable_sp->GetValueObject();
161   }
162   return return_valobj_sp;
163 }
164 
165 ValueObjectSP ABI::GetReturnValueObject(Thread &thread, llvm::Type &ast_type,
166                                         bool persistent) const {
167   ValueObjectSP return_valobj_sp;
168   return_valobj_sp = GetReturnValueObjectImpl(thread, ast_type);
169   return return_valobj_sp;
170 }
171 
172 // specialized to work with llvm IR types
173 //
174 // for now we will specify a default implementation so that we don't need to
175 // modify other ABIs
176 lldb::ValueObjectSP ABI::GetReturnValueObjectImpl(Thread &thread,
177                                                   llvm::Type &ir_type) const {
178   ValueObjectSP return_valobj_sp;
179 
180   /* this is a dummy and will only be called if an ABI does not override this */
181 
182   return return_valobj_sp;
183 }
184 
185 bool ABI::PrepareTrivialCall(Thread &thread, lldb::addr_t sp,
186                              lldb::addr_t functionAddress,
187                              lldb::addr_t returnAddress, llvm::Type &returntype,
188                              llvm::ArrayRef<ABI::CallArgument> args) const {
189   // dummy prepare trivial call
190   llvm_unreachable("Should never get here!");
191 }
192 
193 bool ABI::GetFallbackRegisterLocation(
194     const RegisterInfo *reg_info,
195     UnwindPlan::Row::RegisterLocation &unwind_regloc) {
196   // Did the UnwindPlan fail to give us the caller's stack pointer? The stack
197   // pointer is defined to be the same as THIS frame's CFA, so return the CFA
198   // value as the caller's stack pointer.  This is true on x86-32/x86-64 at
199   // least.
200   if (reg_info->kinds[eRegisterKindGeneric] == LLDB_REGNUM_GENERIC_SP) {
201     unwind_regloc.SetIsCFAPlusOffset(0);
202     return true;
203   }
204 
205   // If a volatile register is being requested, we don't want to forward the
206   // next frame's register contents up the stack -- the register is not
207   // retrievable at this frame.
208   if (RegisterIsVolatile(reg_info)) {
209     unwind_regloc.SetUndefined();
210     return true;
211   }
212 
213   return false;
214 }
215 
216 std::unique_ptr<llvm::MCRegisterInfo> ABI::MakeMCRegisterInfo(const ArchSpec &arch) {
217   std::string triple = arch.GetTriple().getTriple();
218   std::string lookup_error;
219   const llvm::Target *target =
220       llvm::TargetRegistry::lookupTarget(triple, lookup_error);
221   if (!target) {
222     LLDB_LOG(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PROCESS),
223              "Failed to create an llvm target for {0}: {1}", triple,
224              lookup_error);
225     return nullptr;
226   }
227   std::unique_ptr<llvm::MCRegisterInfo> info_up(
228       target->createMCRegInfo(triple));
229   assert(info_up);
230   return info_up;
231 }
232