xref: /freebsd-src/contrib/llvm-project/lldb/source/Target/ABI.cpp (revision b97ee269eae3cbaf35c18f51a459aea581c2a7dc)
1 //===-- ABI.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/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/MC/TargetRegistry.h"
20 #include <cctype>
21 
22 using namespace lldb;
23 using namespace lldb_private;
24 
25 ABISP
26 ABI::FindPlugin(lldb::ProcessSP process_sp, const ArchSpec &arch) {
27   ABISP abi_sp;
28   ABICreateInstance create_callback;
29 
30   for (uint32_t idx = 0;
31        (create_callback = PluginManager::GetABICreateCallbackAtIndex(idx)) !=
32        nullptr;
33        ++idx) {
34     abi_sp = create_callback(process_sp, arch);
35 
36     if (abi_sp)
37       return abi_sp;
38   }
39   abi_sp.reset();
40   return abi_sp;
41 }
42 
43 ABI::~ABI() = default;
44 
45 bool RegInfoBasedABI::GetRegisterInfoByName(llvm::StringRef name,
46                                             RegisterInfo &info) {
47   uint32_t count = 0;
48   const RegisterInfo *register_info_array = GetRegisterInfoArray(count);
49   if (register_info_array) {
50     uint32_t i;
51     for (i = 0; i < count; ++i) {
52       const char *reg_name = register_info_array[i].name;
53       if (reg_name == name) {
54         info = register_info_array[i];
55         return true;
56       }
57     }
58     for (i = 0; i < count; ++i) {
59       const char *reg_alt_name = register_info_array[i].alt_name;
60       if (reg_alt_name == name) {
61         info = register_info_array[i];
62         return true;
63       }
64     }
65   }
66   return false;
67 }
68 
69 ValueObjectSP ABI::GetReturnValueObject(Thread &thread, CompilerType &ast_type,
70                                         bool persistent) const {
71   if (!ast_type.IsValid())
72     return ValueObjectSP();
73 
74   ValueObjectSP return_valobj_sp;
75 
76   return_valobj_sp = GetReturnValueObjectImpl(thread, ast_type);
77   if (!return_valobj_sp)
78     return return_valobj_sp;
79 
80   // Now turn this into a persistent variable.
81   // FIXME: This code is duplicated from Target::EvaluateExpression, and it is
82   // used in similar form in a couple
83   // of other places.  Figure out the correct Create function to do all this
84   // work.
85 
86   if (persistent) {
87     Target &target = *thread.CalculateTarget();
88     PersistentExpressionState *persistent_expression_state =
89         target.GetPersistentExpressionStateForLanguage(
90             ast_type.GetMinimumLanguage());
91 
92     if (!persistent_expression_state)
93       return {};
94 
95     ConstString persistent_variable_name =
96         persistent_expression_state->GetNextPersistentVariableName();
97 
98     lldb::ValueObjectSP const_valobj_sp;
99 
100     // Check in case our value is already a constant value
101     if (return_valobj_sp->GetIsConstant()) {
102       const_valobj_sp = return_valobj_sp;
103       const_valobj_sp->SetName(persistent_variable_name);
104     } else
105       const_valobj_sp =
106           return_valobj_sp->CreateConstantValue(persistent_variable_name);
107 
108     lldb::ValueObjectSP live_valobj_sp = return_valobj_sp;
109 
110     return_valobj_sp = const_valobj_sp;
111 
112     ExpressionVariableSP expr_variable_sp(
113         persistent_expression_state->CreatePersistentVariable(
114             return_valobj_sp));
115 
116     assert(expr_variable_sp);
117 
118     // Set flags and live data as appropriate
119 
120     const Value &result_value = live_valobj_sp->GetValue();
121 
122     switch (result_value.GetValueType()) {
123     case Value::ValueType::Invalid:
124       return {};
125     case Value::ValueType::HostAddress:
126     case Value::ValueType::FileAddress:
127       // we odon't do anything with these for now
128       break;
129     case Value::ValueType::Scalar:
130       expr_variable_sp->m_flags |=
131           ExpressionVariable::EVIsFreezeDried;
132       expr_variable_sp->m_flags |=
133           ExpressionVariable::EVIsLLDBAllocated;
134       expr_variable_sp->m_flags |=
135           ExpressionVariable::EVNeedsAllocation;
136       break;
137     case Value::ValueType::LoadAddress:
138       expr_variable_sp->m_live_sp = live_valobj_sp;
139       expr_variable_sp->m_flags |=
140           ExpressionVariable::EVIsProgramReference;
141       break;
142     }
143 
144     return_valobj_sp = expr_variable_sp->GetValueObject();
145   }
146   return return_valobj_sp;
147 }
148 
149 ValueObjectSP ABI::GetReturnValueObject(Thread &thread, llvm::Type &ast_type,
150                                         bool persistent) const {
151   ValueObjectSP return_valobj_sp;
152   return_valobj_sp = GetReturnValueObjectImpl(thread, ast_type);
153   return return_valobj_sp;
154 }
155 
156 // specialized to work with llvm IR types
157 //
158 // for now we will specify a default implementation so that we don't need to
159 // modify other ABIs
160 lldb::ValueObjectSP ABI::GetReturnValueObjectImpl(Thread &thread,
161                                                   llvm::Type &ir_type) const {
162   ValueObjectSP return_valobj_sp;
163 
164   /* this is a dummy and will only be called if an ABI does not override this */
165 
166   return return_valobj_sp;
167 }
168 
169 bool ABI::PrepareTrivialCall(Thread &thread, lldb::addr_t sp,
170                              lldb::addr_t functionAddress,
171                              lldb::addr_t returnAddress, llvm::Type &returntype,
172                              llvm::ArrayRef<ABI::CallArgument> args) const {
173   // dummy prepare trivial call
174   llvm_unreachable("Should never get here!");
175 }
176 
177 bool ABI::GetFallbackRegisterLocation(
178     const RegisterInfo *reg_info,
179     UnwindPlan::Row::RegisterLocation &unwind_regloc) {
180   // Did the UnwindPlan fail to give us the caller's stack pointer? The stack
181   // pointer is defined to be the same as THIS frame's CFA, so return the CFA
182   // value as the caller's stack pointer.  This is true on x86-32/x86-64 at
183   // least.
184   if (reg_info->kinds[eRegisterKindGeneric] == LLDB_REGNUM_GENERIC_SP) {
185     unwind_regloc.SetIsCFAPlusOffset(0);
186     return true;
187   }
188 
189   // If a volatile register is being requested, we don't want to forward the
190   // next frame's register contents up the stack -- the register is not
191   // retrievable at this frame.
192   if (RegisterIsVolatile(reg_info)) {
193     unwind_regloc.SetUndefined();
194     return true;
195   }
196 
197   return false;
198 }
199 
200 std::unique_ptr<llvm::MCRegisterInfo> ABI::MakeMCRegisterInfo(const ArchSpec &arch) {
201   std::string triple = arch.GetTriple().getTriple();
202   std::string lookup_error;
203   const llvm::Target *target =
204       llvm::TargetRegistry::lookupTarget(triple, lookup_error);
205   if (!target) {
206     LLDB_LOG(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PROCESS),
207              "Failed to create an llvm target for {0}: {1}", triple,
208              lookup_error);
209     return nullptr;
210   }
211   std::unique_ptr<llvm::MCRegisterInfo> info_up(
212       target->createMCRegInfo(triple));
213   assert(info_up);
214   return info_up;
215 }
216 
217 void RegInfoBasedABI::AugmentRegisterInfo(
218     std::vector<DynamicRegisterInfo::Register> &regs) {
219   for (DynamicRegisterInfo::Register &info : regs) {
220     if (info.regnum_ehframe != LLDB_INVALID_REGNUM &&
221         info.regnum_dwarf != LLDB_INVALID_REGNUM)
222       continue;
223 
224     RegisterInfo abi_info;
225     if (!GetRegisterInfoByName(info.name.GetStringRef(), abi_info))
226       continue;
227 
228     if (info.regnum_ehframe == LLDB_INVALID_REGNUM)
229       info.regnum_ehframe = abi_info.kinds[eRegisterKindEHFrame];
230     if (info.regnum_dwarf == LLDB_INVALID_REGNUM)
231       info.regnum_dwarf = abi_info.kinds[eRegisterKindDWARF];
232     if (info.regnum_generic == LLDB_INVALID_REGNUM)
233       info.regnum_generic = abi_info.kinds[eRegisterKindGeneric];
234   }
235 }
236 
237 void MCBasedABI::AugmentRegisterInfo(
238     std::vector<DynamicRegisterInfo::Register> &regs) {
239   for (DynamicRegisterInfo::Register &info : regs) {
240     uint32_t eh, dwarf;
241     std::tie(eh, dwarf) = GetEHAndDWARFNums(info.name.GetStringRef());
242 
243     if (info.regnum_ehframe == LLDB_INVALID_REGNUM)
244       info.regnum_ehframe = eh;
245     if (info.regnum_dwarf == LLDB_INVALID_REGNUM)
246       info.regnum_dwarf = dwarf;
247     if (info.regnum_generic == LLDB_INVALID_REGNUM)
248       info.regnum_generic = GetGenericNum(info.name.GetStringRef());
249   }
250 }
251 
252 std::pair<uint32_t, uint32_t>
253 MCBasedABI::GetEHAndDWARFNums(llvm::StringRef name) {
254   std::string mc_name = GetMCName(name.str());
255   for (char &c : mc_name)
256     c = std::toupper(c);
257   int eh = -1;
258   int dwarf = -1;
259   for (unsigned reg = 0; reg < m_mc_register_info_up->getNumRegs(); ++reg) {
260     if (m_mc_register_info_up->getName(reg) == mc_name) {
261       eh = m_mc_register_info_up->getDwarfRegNum(reg, /*isEH=*/true);
262       dwarf = m_mc_register_info_up->getDwarfRegNum(reg, /*isEH=*/false);
263       break;
264     }
265   }
266   return std::pair<uint32_t, uint32_t>(eh == -1 ? LLDB_INVALID_REGNUM : eh,
267                                        dwarf == -1 ? LLDB_INVALID_REGNUM
268                                                    : dwarf);
269 }
270 
271 void MCBasedABI::MapRegisterName(std::string &name, llvm::StringRef from_prefix,
272                                  llvm::StringRef to_prefix) {
273   llvm::StringRef name_ref = name;
274   if (!name_ref.consume_front(from_prefix))
275     return;
276   uint64_t _;
277   if (name_ref.empty() || to_integer(name_ref, _, 10))
278     name = (to_prefix + name_ref).str();
279 }
280