1 //===-- Interpreter.h ------------------------------------------*- 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 // This header file defines the interpreter structure
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_LIB_EXECUTIONENGINE_INTERPRETER_INTERPRETER_H
14 #define LLVM_LIB_EXECUTIONENGINE_INTERPRETER_INTERPRETER_H
15 
16 #include "llvm/ExecutionEngine/ExecutionEngine.h"
17 #include "llvm/ExecutionEngine/GenericValue.h"
18 #include "llvm/IR/DataLayout.h"
19 #include "llvm/IR/Function.h"
20 #include "llvm/IR/InstVisitor.h"
21 #include "llvm/Support/DataTypes.h"
22 #include "llvm/Support/ErrorHandling.h"
23 #include "llvm/Support/raw_ostream.h"
24 namespace llvm {
25 
26 class IntrinsicLowering;
27 template<typename T> class generic_gep_type_iterator;
28 class ConstantExpr;
29 typedef generic_gep_type_iterator<User::const_op_iterator> gep_type_iterator;
30 
31 
32 // AllocaHolder - Object to track all of the blocks of memory allocated by
33 // alloca.  When the function returns, this object is popped off the execution
34 // stack, which causes the dtor to be run, which frees all the alloca'd memory.
35 //
36 class AllocaHolder {
37   std::vector<void *> Allocations;
38 
39 public:
40   AllocaHolder() = default;
41 
42   // Make this type move-only.
43   AllocaHolder(AllocaHolder &&) = default;
44   AllocaHolder &operator=(AllocaHolder &&RHS) = default;
45 
46   ~AllocaHolder() {
47     for (void *Allocation : Allocations)
48       free(Allocation);
49   }
50 
51   void add(void *Mem) { Allocations.push_back(Mem); }
52 };
53 
54 typedef std::vector<GenericValue> ValuePlaneTy;
55 
56 // ExecutionContext struct - This struct represents one stack frame currently
57 // executing.
58 //
59 struct ExecutionContext {
60   Function             *CurFunction;// The currently executing function
61   BasicBlock           *CurBB;      // The currently executing BB
62   BasicBlock::iterator  CurInst;    // The next instruction to execute
63   CallBase             *Caller;     // Holds the call that called subframes.
64                                     // NULL if main func or debugger invoked fn
65   std::map<Value *, GenericValue> Values; // LLVM values used in this invocation
66   std::vector<GenericValue>  VarArgs; // Values passed through an ellipsis
67   AllocaHolder Allocas;            // Track memory allocated by alloca
68 
69   ExecutionContext() : CurFunction(nullptr), CurBB(nullptr), CurInst(nullptr) {}
70 };
71 
72 // Interpreter - This class represents the entirety of the interpreter.
73 //
74 class Interpreter : public ExecutionEngine, public InstVisitor<Interpreter> {
75   GenericValue ExitValue;          // The return value of the called function
76   IntrinsicLowering *IL;
77 
78   // The runtime stack of executing code.  The top of the stack is the current
79   // function record.
80   std::vector<ExecutionContext> ECStack;
81 
82   // AtExitHandlers - List of functions to call when the program exits,
83   // registered with the atexit() library function.
84   std::vector<Function*> AtExitHandlers;
85 
86 public:
87   explicit Interpreter(std::unique_ptr<Module> M);
88   ~Interpreter() override;
89 
90   /// runAtExitHandlers - Run any functions registered by the program's calls to
91   /// atexit(3), which we intercept and store in AtExitHandlers.
92   ///
93   void runAtExitHandlers();
94 
95   static void Register() {
96     InterpCtor = create;
97   }
98 
99   /// Create an interpreter ExecutionEngine.
100   ///
101   static ExecutionEngine *create(std::unique_ptr<Module> M,
102                                  std::string *ErrorStr = nullptr);
103 
104   /// run - Start execution with the specified function and arguments.
105   ///
106   GenericValue runFunction(Function *F,
107                            ArrayRef<GenericValue> ArgValues) override;
108 
109   void *getPointerToNamedFunction(StringRef Name,
110                                   bool AbortOnFailure = true) override {
111     // FIXME: not implemented.
112     return nullptr;
113   }
114 
115   // Methods used to execute code:
116   // Place a call on the stack
117   void callFunction(Function *F, ArrayRef<GenericValue> ArgVals);
118   void run();                // Execute instructions until nothing left to do
119 
120   // Opcode Implementations
121   void visitReturnInst(ReturnInst &I);
122   void visitBranchInst(BranchInst &I);
123   void visitSwitchInst(SwitchInst &I);
124   void visitIndirectBrInst(IndirectBrInst &I);
125 
126   void visitUnaryOperator(UnaryOperator &I);
127   void visitBinaryOperator(BinaryOperator &I);
128   void visitICmpInst(ICmpInst &I);
129   void visitFCmpInst(FCmpInst &I);
130   void visitAllocaInst(AllocaInst &I);
131   void visitLoadInst(LoadInst &I);
132   void visitStoreInst(StoreInst &I);
133   void visitGetElementPtrInst(GetElementPtrInst &I);
134   void visitPHINode(PHINode &PN) {
135     llvm_unreachable("PHI nodes already handled!");
136   }
137   void visitTruncInst(TruncInst &I);
138   void visitZExtInst(ZExtInst &I);
139   void visitSExtInst(SExtInst &I);
140   void visitFPTruncInst(FPTruncInst &I);
141   void visitFPExtInst(FPExtInst &I);
142   void visitUIToFPInst(UIToFPInst &I);
143   void visitSIToFPInst(SIToFPInst &I);
144   void visitFPToUIInst(FPToUIInst &I);
145   void visitFPToSIInst(FPToSIInst &I);
146   void visitPtrToIntInst(PtrToIntInst &I);
147   void visitIntToPtrInst(IntToPtrInst &I);
148   void visitBitCastInst(BitCastInst &I);
149   void visitSelectInst(SelectInst &I);
150 
151   void visitVAStartInst(VAStartInst &I);
152   void visitVAEndInst(VAEndInst &I);
153   void visitVACopyInst(VACopyInst &I);
154   void visitIntrinsicInst(IntrinsicInst &I);
155   void visitCallBase(CallBase &I);
156   void visitUnreachableInst(UnreachableInst &I);
157 
158   void visitShl(BinaryOperator &I);
159   void visitLShr(BinaryOperator &I);
160   void visitAShr(BinaryOperator &I);
161 
162   void visitVAArgInst(VAArgInst &I);
163   void visitExtractElementInst(ExtractElementInst &I);
164   void visitInsertElementInst(InsertElementInst &I);
165   void visitShuffleVectorInst(ShuffleVectorInst &I);
166 
167   void visitExtractValueInst(ExtractValueInst &I);
168   void visitInsertValueInst(InsertValueInst &I);
169 
170   void visitInstruction(Instruction &I) {
171     errs() << I << "\n";
172     llvm_unreachable("Instruction not interpretable yet!");
173   }
174 
175   GenericValue callExternalFunction(Function *F,
176                                     ArrayRef<GenericValue> ArgVals);
177   void exitCalled(GenericValue GV);
178 
179   void addAtExitHandler(Function *F) {
180     AtExitHandlers.push_back(F);
181   }
182 
183   GenericValue *getFirstVarArg () {
184     return &(ECStack.back ().VarArgs[0]);
185   }
186 
187 private:  // Helper functions
188   GenericValue executeGEPOperation(Value *Ptr, gep_type_iterator I,
189                                    gep_type_iterator E, ExecutionContext &SF);
190 
191   // SwitchToNewBasicBlock - Start execution in a new basic block and run any
192   // PHI nodes in the top of the block.  This is used for intraprocedural
193   // control flow.
194   //
195   void SwitchToNewBasicBlock(BasicBlock *Dest, ExecutionContext &SF);
196 
197   void *getPointerToFunction(Function *F) override { return (void*)F; }
198 
199   void initializeExecutionEngine() { }
200   void initializeExternalFunctions();
201   GenericValue getConstantExprValue(ConstantExpr *CE, ExecutionContext &SF);
202   GenericValue getOperandValue(Value *V, ExecutionContext &SF);
203   GenericValue executeTruncInst(Value *SrcVal, Type *DstTy,
204                                 ExecutionContext &SF);
205   GenericValue executeSExtInst(Value *SrcVal, Type *DstTy,
206                                ExecutionContext &SF);
207   GenericValue executeZExtInst(Value *SrcVal, Type *DstTy,
208                                ExecutionContext &SF);
209   GenericValue executeFPTruncInst(Value *SrcVal, Type *DstTy,
210                                   ExecutionContext &SF);
211   GenericValue executeFPExtInst(Value *SrcVal, Type *DstTy,
212                                 ExecutionContext &SF);
213   GenericValue executeFPToUIInst(Value *SrcVal, Type *DstTy,
214                                  ExecutionContext &SF);
215   GenericValue executeFPToSIInst(Value *SrcVal, Type *DstTy,
216                                  ExecutionContext &SF);
217   GenericValue executeUIToFPInst(Value *SrcVal, Type *DstTy,
218                                  ExecutionContext &SF);
219   GenericValue executeSIToFPInst(Value *SrcVal, Type *DstTy,
220                                  ExecutionContext &SF);
221   GenericValue executePtrToIntInst(Value *SrcVal, Type *DstTy,
222                                    ExecutionContext &SF);
223   GenericValue executeIntToPtrInst(Value *SrcVal, Type *DstTy,
224                                    ExecutionContext &SF);
225   GenericValue executeBitCastInst(Value *SrcVal, Type *DstTy,
226                                   ExecutionContext &SF);
227   void popStackAndReturnValueToCaller(Type *RetTy, GenericValue Result);
228 
229 };
230 
231 } // End llvm namespace
232 
233 #endif
234