1 //===-- Interpreter.h ------------------------------------------*- C++ -*--===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This header file defines the interpreter structure
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_EXECUTIONENGINE_INTERPRETER_INTERPRETER_H
15 #define LLVM_LIB_EXECUTIONENGINE_INTERPRETER_INTERPRETER_H
16 
17 #include "llvm/ExecutionEngine/ExecutionEngine.h"
18 #include "llvm/ExecutionEngine/GenericValue.h"
19 #include "llvm/IR/CallSite.h"
20 #include "llvm/IR/DataLayout.h"
21 #include "llvm/IR/Function.h"
22 #include "llvm/IR/InstVisitor.h"
23 #include "llvm/Support/DataTypes.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/raw_ostream.h"
26 namespace llvm {
27 
28 class IntrinsicLowering;
29 template<typename T> class generic_gep_type_iterator;
30 class ConstantExpr;
31 typedef generic_gep_type_iterator<User::const_op_iterator> gep_type_iterator;
32 
33 
34 // AllocaHolder - Object to track all of the blocks of memory allocated by
35 // alloca.  When the function returns, this object is popped off the execution
36 // stack, which causes the dtor to be run, which frees all the alloca'd memory.
37 //
38 class AllocaHolder {
39   std::vector<void *> Allocations;
40 
41 public:
AllocaHolder()42   AllocaHolder() {}
43 
44   // Make this type move-only.
45   AllocaHolder(AllocaHolder &&) = default;
46   AllocaHolder &operator=(AllocaHolder &&RHS) = default;
47 
~AllocaHolder()48   ~AllocaHolder() {
49     for (void *Allocation : Allocations)
50       free(Allocation);
51   }
52 
add(void * Mem)53   void add(void *Mem) { Allocations.push_back(Mem); }
54 };
55 
56 typedef std::vector<GenericValue> ValuePlaneTy;
57 
58 // ExecutionContext struct - This struct represents one stack frame currently
59 // executing.
60 //
61 struct ExecutionContext {
62   Function             *CurFunction;// The currently executing function
63   BasicBlock           *CurBB;      // The currently executing BB
64   BasicBlock::iterator  CurInst;    // The next instruction to execute
65   CallSite             Caller;     // Holds the call that called subframes.
66                                    // NULL if main func or debugger invoked fn
67   std::map<Value *, GenericValue> Values; // LLVM values used in this invocation
68   std::vector<GenericValue>  VarArgs; // Values passed through an ellipsis
69   AllocaHolder Allocas;            // Track memory allocated by alloca
70 
ExecutionContextExecutionContext71   ExecutionContext() : CurFunction(nullptr), CurBB(nullptr), CurInst(nullptr) {}
72 };
73 
74 // Interpreter - This class represents the entirety of the interpreter.
75 //
76 class Interpreter : public ExecutionEngine, public InstVisitor<Interpreter> {
77   GenericValue ExitValue;          // The return value of the called function
78   IntrinsicLowering *IL;
79 
80   // The runtime stack of executing code.  The top of the stack is the current
81   // function record.
82   std::vector<ExecutionContext> ECStack;
83 
84   // AtExitHandlers - List of functions to call when the program exits,
85   // registered with the atexit() library function.
86   std::vector<Function*> AtExitHandlers;
87 
88 public:
89   explicit Interpreter(std::unique_ptr<Module> M);
90   ~Interpreter() override;
91 
92   /// runAtExitHandlers - Run any functions registered by the program's calls to
93   /// atexit(3), which we intercept and store in AtExitHandlers.
94   ///
95   void runAtExitHandlers();
96 
Register()97   static void Register() {
98     InterpCtor = create;
99   }
100 
101   /// Create an interpreter ExecutionEngine.
102   ///
103   static ExecutionEngine *create(std::unique_ptr<Module> M,
104                                  std::string *ErrorStr = nullptr);
105 
106   /// run - Start execution with the specified function and arguments.
107   ///
108   GenericValue runFunction(Function *F,
109                            ArrayRef<GenericValue> ArgValues) override;
110 
111   void *getPointerToNamedFunction(StringRef Name,
112                                   bool AbortOnFailure = true) override {
113     // FIXME: not implemented.
114     return nullptr;
115   }
116 
117   // Methods used to execute code:
118   // Place a call on the stack
119   void callFunction(Function *F, ArrayRef<GenericValue> ArgVals);
120   void run();                // Execute instructions until nothing left to do
121 
122   // Opcode Implementations
123   void visitReturnInst(ReturnInst &I);
124   void visitBranchInst(BranchInst &I);
125   void visitSwitchInst(SwitchInst &I);
126   void visitIndirectBrInst(IndirectBrInst &I);
127 
128   void visitBinaryOperator(BinaryOperator &I);
129   void visitICmpInst(ICmpInst &I);
130   void visitFCmpInst(FCmpInst &I);
131   void visitAllocaInst(AllocaInst &I);
132   void visitLoadInst(LoadInst &I);
133   void visitStoreInst(StoreInst &I);
134   void visitGetElementPtrInst(GetElementPtrInst &I);
visitPHINode(PHINode & PN)135   void visitPHINode(PHINode &PN) {
136     llvm_unreachable("PHI nodes already handled!");
137   }
138   void visitTruncInst(TruncInst &I);
139   void visitZExtInst(ZExtInst &I);
140   void visitSExtInst(SExtInst &I);
141   void visitFPTruncInst(FPTruncInst &I);
142   void visitFPExtInst(FPExtInst &I);
143   void visitUIToFPInst(UIToFPInst &I);
144   void visitSIToFPInst(SIToFPInst &I);
145   void visitFPToUIInst(FPToUIInst &I);
146   void visitFPToSIInst(FPToSIInst &I);
147   void visitPtrToIntInst(PtrToIntInst &I);
148   void visitIntToPtrInst(IntToPtrInst &I);
149   void visitBitCastInst(BitCastInst &I);
150   void visitSelectInst(SelectInst &I);
151 
152 
153   void visitCallSite(CallSite CS);
visitCallInst(CallInst & I)154   void visitCallInst(CallInst &I) { visitCallSite (CallSite (&I)); }
visitInvokeInst(InvokeInst & I)155   void visitInvokeInst(InvokeInst &I) { visitCallSite (CallSite (&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 
visitInstruction(Instruction & I)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 
addAtExitHandler(Function * F)179   void addAtExitHandler(Function *F) {
180     AtExitHandlers.push_back(F);
181   }
182 
getFirstVarArg()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 
getPointerToFunction(Function * F)197   void *getPointerToFunction(Function *F) override { return (void*)F; }
198 
initializeExecutionEngine()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   GenericValue executeCastOperation(Instruction::CastOps opcode, Value *SrcVal,
228                                     Type *Ty, ExecutionContext &SF);
229   void popStackAndReturnValueToCaller(Type *RetTy, GenericValue Result);
230 
231 };
232 
233 } // End llvm namespace
234 
235 #endif
236