lib/ExecutionEngine/Interpreter/Interpreter.h

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