1 //===-- ClangFunctionCaller.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 "ClangFunctionCaller.h"
10 
11 #include "ASTStructExtractor.h"
12 #include "ClangExpressionParser.h"
13 
14 #include "clang/AST/ASTContext.h"
15 #include "clang/AST/RecordLayout.h"
16 #include "clang/CodeGen/CodeGenAction.h"
17 #include "clang/CodeGen/ModuleBuilder.h"
18 #include "clang/Frontend/CompilerInstance.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/ADT/Triple.h"
21 #include "llvm/ExecutionEngine/ExecutionEngine.h"
22 #include "llvm/IR/Module.h"
23 
24 #include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
25 #include "lldb/Core/Module.h"
26 #include "lldb/Core/ValueObject.h"
27 #include "lldb/Core/ValueObjectList.h"
28 #include "lldb/Expression/IRExecutionUnit.h"
29 #include "lldb/Interpreter/CommandReturnObject.h"
30 #include "lldb/Symbol/Function.h"
31 #include "lldb/Symbol/Type.h"
32 #include "lldb/Target/ExecutionContext.h"
33 #include "lldb/Target/Process.h"
34 #include "lldb/Target/RegisterContext.h"
35 #include "lldb/Target/Target.h"
36 #include "lldb/Target/Thread.h"
37 #include "lldb/Target/ThreadPlan.h"
38 #include "lldb/Target/ThreadPlanCallFunction.h"
39 #include "lldb/Utility/DataExtractor.h"
40 #include "lldb/Utility/LLDBLog.h"
41 #include "lldb/Utility/Log.h"
42 #include "lldb/Utility/State.h"
43 
44 using namespace lldb_private;
45 
46 char ClangFunctionCaller::ID;
47 
48 // ClangFunctionCaller constructor
49 ClangFunctionCaller::ClangFunctionCaller(ExecutionContextScope &exe_scope,
50                                          const CompilerType &return_type,
51                                          const Address &functionAddress,
52                                          const ValueList &arg_value_list,
53                                          const char *name)
54     : FunctionCaller(exe_scope, return_type, functionAddress, arg_value_list,
55                      name),
56       m_type_system_helper(*this) {
57   m_jit_process_wp = lldb::ProcessWP(exe_scope.CalculateProcess());
58   // Can't make a ClangFunctionCaller without a process.
59   assert(m_jit_process_wp.lock());
60 }
61 
62 // Destructor
63 ClangFunctionCaller::~ClangFunctionCaller() = default;
64 
65 unsigned
66 
67 ClangFunctionCaller::CompileFunction(lldb::ThreadSP thread_to_use_sp,
68                                      DiagnosticManager &diagnostic_manager) {
69   if (m_compiled)
70     return 0;
71 
72   // Compilation might call code, make sure to keep on the thread the caller
73   // indicated.
74   ThreadList::ExpressionExecutionThreadPusher execution_thread_pusher(
75       thread_to_use_sp);
76 
77   // FIXME: How does clang tell us there's no return value?  We need to handle
78   // that case.
79   unsigned num_errors = 0;
80 
81   std::string return_type_str(
82       m_function_return_type.GetTypeName().AsCString(""));
83 
84   // Cons up the function we're going to wrap our call in, then compile it...
85   // We declare the function "extern "C"" because the compiler might be in C++
86   // mode which would mangle the name and then we couldn't find it again...
87   m_wrapper_function_text.clear();
88   m_wrapper_function_text.append("extern \"C\" void ");
89   m_wrapper_function_text.append(m_wrapper_function_name);
90   m_wrapper_function_text.append(" (void *input)\n{\n    struct ");
91   m_wrapper_function_text.append(m_wrapper_struct_name);
92   m_wrapper_function_text.append(" \n  {\n");
93   m_wrapper_function_text.append("    ");
94   m_wrapper_function_text.append(return_type_str);
95   m_wrapper_function_text.append(" (*fn_ptr) (");
96 
97   // Get the number of arguments.  If we have a function type and it is
98   // prototyped, trust that, otherwise use the values we were given.
99 
100   // FIXME: This will need to be extended to handle Variadic functions.  We'll
101   // need
102   // to pull the defined arguments out of the function, then add the types from
103   // the arguments list for the variable arguments.
104 
105   uint32_t num_args = UINT32_MAX;
106   bool trust_function = false;
107   // GetArgumentCount returns -1 for an unprototyped function.
108   CompilerType function_clang_type;
109   if (m_function_ptr) {
110     function_clang_type = m_function_ptr->GetCompilerType();
111     if (function_clang_type) {
112       int num_func_args = function_clang_type.GetFunctionArgumentCount();
113       if (num_func_args >= 0) {
114         trust_function = true;
115         num_args = num_func_args;
116       }
117     }
118   }
119 
120   if (num_args == UINT32_MAX)
121     num_args = m_arg_values.GetSize();
122 
123   std::string args_buffer; // This one stores the definition of all the args in
124                            // "struct caller".
125   std::string args_list_buffer; // This one stores the argument list called from
126                                 // the structure.
127   for (size_t i = 0; i < num_args; i++) {
128     std::string type_name;
129 
130     if (trust_function) {
131       type_name = function_clang_type.GetFunctionArgumentTypeAtIndex(i)
132                       .GetTypeName()
133                       .AsCString("");
134     } else {
135       CompilerType clang_qual_type =
136           m_arg_values.GetValueAtIndex(i)->GetCompilerType();
137       if (clang_qual_type) {
138         type_name = clang_qual_type.GetTypeName().AsCString("");
139       } else {
140         diagnostic_manager.Printf(
141             eDiagnosticSeverityError,
142             "Could not determine type of input value %" PRIu64 ".",
143             (uint64_t)i);
144         return 1;
145       }
146     }
147 
148     m_wrapper_function_text.append(type_name);
149     if (i < num_args - 1)
150       m_wrapper_function_text.append(", ");
151 
152     char arg_buf[32];
153     args_buffer.append("    ");
154     args_buffer.append(type_name);
155     snprintf(arg_buf, 31, "arg_%" PRIu64, (uint64_t)i);
156     args_buffer.push_back(' ');
157     args_buffer.append(arg_buf);
158     args_buffer.append(";\n");
159 
160     args_list_buffer.append("__lldb_fn_data->");
161     args_list_buffer.append(arg_buf);
162     if (i < num_args - 1)
163       args_list_buffer.append(", ");
164   }
165   m_wrapper_function_text.append(
166       ");\n"); // Close off the function calling prototype.
167 
168   m_wrapper_function_text.append(args_buffer);
169 
170   m_wrapper_function_text.append("    ");
171   m_wrapper_function_text.append(return_type_str);
172   m_wrapper_function_text.append(" return_value;");
173   m_wrapper_function_text.append("\n  };\n  struct ");
174   m_wrapper_function_text.append(m_wrapper_struct_name);
175   m_wrapper_function_text.append("* __lldb_fn_data = (struct ");
176   m_wrapper_function_text.append(m_wrapper_struct_name);
177   m_wrapper_function_text.append(" *) input;\n");
178 
179   m_wrapper_function_text.append(
180       "  __lldb_fn_data->return_value = __lldb_fn_data->fn_ptr (");
181   m_wrapper_function_text.append(args_list_buffer);
182   m_wrapper_function_text.append(");\n}\n");
183 
184   Log *log = GetLog(LLDBLog::Expressions);
185   LLDB_LOGF(log, "Expression: \n\n%s\n\n", m_wrapper_function_text.c_str());
186 
187   // Okay, now compile this expression
188 
189   lldb::ProcessSP jit_process_sp(m_jit_process_wp.lock());
190   if (jit_process_sp) {
191     const bool generate_debug_info = true;
192     auto *clang_parser = new ClangExpressionParser(jit_process_sp.get(), *this,
193                                                    generate_debug_info);
194     num_errors = clang_parser->Parse(diagnostic_manager);
195     m_parser.reset(clang_parser);
196   } else {
197     diagnostic_manager.PutString(eDiagnosticSeverityError,
198                                  "no process - unable to inject function");
199     num_errors = 1;
200   }
201 
202   m_compiled = (num_errors == 0);
203 
204   if (!m_compiled)
205     return num_errors;
206 
207   return num_errors;
208 }
209 
210 clang::ASTConsumer *
211 ClangFunctionCaller::ClangFunctionCallerHelper::ASTTransformer(
212     clang::ASTConsumer *passthrough) {
213   m_struct_extractor = std::make_unique<ASTStructExtractor>(
214       passthrough, m_owner.GetWrapperStructName(), m_owner);
215 
216   return m_struct_extractor.get();
217 }
218