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/CallSite.h"
19#include "llvm/IR/DataLayout.h"
20#include "llvm/IR/Function.h"
21#include "llvm/IR/InstVisitor.h"
22#include "llvm/Support/DataTypes.h"
23#include "llvm/Support/ErrorHandling.h"
24#include "llvm/Support/raw_ostream.h"
25namespace llvm {
26
27class IntrinsicLowering;
28template<typename T> class generic_gep_type_iterator;
29class ConstantExpr;
30typedef generic_gep_type_iterator<User::const_op_iterator> gep_type_iterator;
31
32
33// AllocaHolder - Object to track all of the blocks of memory allocated by
34// alloca.  When the function returns, this object is popped off the execution
35// stack, which causes the dtor to be run, which frees all the alloca'd memory.
36//
37class AllocaHolder {
38  std::vector<void *> Allocations;
39
40public:
41  AllocaHolder() {}
42
43  // Make this type move-only.
44  AllocaHolder(AllocaHolder &&) = default;
45  AllocaHolder &operator=(AllocaHolder &&RHS) = default;
46
47  ~AllocaHolder() {
48    for (void *Allocation : Allocations)
49      free(Allocation);
50  }
51
52  void add(void *Mem) { Allocations.push_back(Mem); }
53};
54
55typedef std::vector<GenericValue> ValuePlaneTy;
56
57// ExecutionContext struct - This struct represents one stack frame currently
58// executing.
59//
60struct ExecutionContext {
61  Function             *CurFunction;// The currently executing function
62  BasicBlock           *CurBB;      // The currently executing BB
63  BasicBlock::iterator  CurInst;    // The next instruction to execute
64  CallSite             Caller;     // Holds the call that called subframes.
65                                   // NULL if main func or debugger invoked fn
66  std::map<Value *, GenericValue> Values; // LLVM values used in this invocation
67  std::vector<GenericValue>  VarArgs; // Values passed through an ellipsis
68  AllocaHolder Allocas;            // Track memory allocated by alloca
69
70  ExecutionContext() : CurFunction(nullptr), CurBB(nullptr), CurInst(nullptr) {}
71};
72
73// Interpreter - This class represents the entirety of the interpreter.
74//
75class Interpreter : public ExecutionEngine, public InstVisitor<Interpreter> {
76  GenericValue ExitValue;          // The return value of the called function
77  IntrinsicLowering *IL;
78
79  // The runtime stack of executing code.  The top of the stack is the current
80  // function record.
81  std::vector<ExecutionContext> ECStack;
82
83  // AtExitHandlers - List of functions to call when the program exits,
84  // registered with the atexit() library function.
85  std::vector<Function*> AtExitHandlers;
86
87public:
88  explicit Interpreter(std::unique_ptr<Module> M);
89  ~Interpreter() override;
90
91  /// runAtExitHandlers - Run any functions registered by the program's calls to
92  /// atexit(3), which we intercept and store in AtExitHandlers.
93  ///
94  void runAtExitHandlers();
95
96  static void Register() {
97    InterpCtor = create;
98  }
99
100  /// Create an interpreter ExecutionEngine.
101  ///
102  static ExecutionEngine *create(std::unique_ptr<Module> M,
103                                 std::string *ErrorStr = nullptr);
104
105  /// run - Start execution with the specified function and arguments.
106  ///
107  GenericValue runFunction(Function *F,
108                           ArrayRef<GenericValue> ArgValues) override;
109
110  void *getPointerToNamedFunction(StringRef Name,
111                                  bool AbortOnFailure = true) override {
112    // FIXME: not implemented.
113    return nullptr;
114  }
115
116  // Methods used to execute code:
117  // Place a call on the stack
118  void callFunction(Function *F, ArrayRef<GenericValue> ArgVals);
119  void run();                // Execute instructions until nothing left to do
120
121  // Opcode Implementations
122  void visitReturnInst(ReturnInst &I);
123  void visitBranchInst(BranchInst &I);
124  void visitSwitchInst(SwitchInst &I);
125  void visitIndirectBrInst(IndirectBrInst &I);
126
127  void visitUnaryOperator(UnaryOperator &I);
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);
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);
154  void visitCallInst(CallInst &I) { visitCallSite (CallSite (&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
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
187private:  // 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  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