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"
24namespace llvm {
25
26class IntrinsicLowering;
27template<typename T> class generic_gep_type_iterator;
28class ConstantExpr;
29typedef 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//
36class AllocaHolder {
37  std::vector<void *> Allocations;
38
39public:
40  AllocaHolder() {}
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
54typedef std::vector<GenericValue> ValuePlaneTy;
55
56// ExecutionContext struct - This struct represents one stack frame currently
57// executing.
58//
59struct 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//
74class 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
86public:
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
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