lib/ExecutionEngine/Interpreter/Interpreter.h

   1 //===-- Interpreter.h ------------------------------------------*- C++ -*--===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and is distributed under
   6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This header file defines the interpreter structure
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLI_INTERPRETER_H
  15 #define LLI_INTERPRETER_H
  16
  17 #include "llvm/Function.h"
  18 #include "llvm/ExecutionEngine/ExecutionEngine.h"
  19 #include "llvm/ExecutionEngine/GenericValue.h"
  20 #include "llvm/Support/InstVisitor.h"
  21 #include "llvm/Support/CallSite.h"
  22 #include "llvm/Target/TargetData.h"
  23 #include "llvm/Support/DataTypes.h"
  24 #include <iostream>
  25
  26 namespace llvm {
  27
  28 class IntrinsicLowering;
  29 struct FunctionInfo;
  30 template<typename T> class generic_gep_type_iterator;
  31 class ConstantExpr;
  32 typedef generic_gep_type_iterator<User::const_op_iterator> gep_type_iterator;
  33
  34
  35 // AllocaHolder - Object to track all of the blocks of memory allocated by
  36 // alloca.  When the function returns, this object is popped off the execution
  37 // stack, which causes the dtor to be run, which frees all the alloca'd memory.
  38 //
  39 class AllocaHolder {
  40   friend class AllocaHolderHandle;
  41   std::vector<void*> Allocations;
  42   unsigned RefCnt;
  43 public:
  44   AllocaHolder() : RefCnt(0) {}
  45   void add(void *mem) { Allocations.push_back(mem); }
  46   ~AllocaHolder() {
  47     for (unsigned i = 0; i < Allocations.size(); ++i)
  48       free(Allocations[i]);
  49   }
  50 };
  51
  52 // AllocaHolderHandle gives AllocaHolder value semantics so we can stick it into
  53 // a vector...
  54 //
  55 class AllocaHolderHandle {
  56   AllocaHolder *H;
  57 public:
  58   AllocaHolderHandle() : H(new AllocaHolder()) { H->RefCnt++; }
  59   AllocaHolderHandle(const AllocaHolderHandle &AH) : H(AH.H) { H->RefCnt++; }
  60   ~AllocaHolderHandle() { if (--H->RefCnt == 0) delete H; }
  61
  62   void add(void *mem) { H->add(mem); }
  63 };
  64
  65 typedef std::vector<GenericValue> ValuePlaneTy;
  66
  67 // ExecutionContext struct - This struct represents one stack frame currently
  68 // executing.
  69 //
  70 struct ExecutionContext {
  71   Function             *CurFunction;// The currently executing function
  72   BasicBlock           *CurBB;      // The currently executing BB
  73   BasicBlock::iterator  CurInst;    // The next instruction to execute
  74   std::map<Value *, GenericValue> Values; // LLVM values used in this invocation
  75   std::vector<GenericValue>  VarArgs; // Values passed through an ellipsis
  76   CallSite             Caller;     // Holds the call that called subframes.
  77                                    // NULL if main func or debugger invoked fn
  78   AllocaHolderHandle    Allocas;    // Track memory allocated by alloca
  79 };
  80
  81 // Interpreter - This class represents the entirety of the interpreter.
  82 //
  83 class Interpreter : public ExecutionEngine, public InstVisitor<Interpreter> {
  84   GenericValue ExitValue;          // The return value of the called function
  85   TargetData TD;
  86   IntrinsicLowering *IL;
  87
  88   // The runtime stack of executing code.  The top of the stack is the current
  89   // function record.
  90   std::vector<ExecutionContext> ECStack;
  91
  92   // AtExitHandlers - List of functions to call when the program exits,
  93   // registered with the atexit() library function.
  94   std::vector<Function*> AtExitHandlers;
  95
  96 public:
  97   Interpreter(Module *M);
  98   ~Interpreter();
  99
 100   /// runAtExitHandlers - Run any functions registered by the program's calls to
 101   /// atexit(3), which we intercept and store in AtExitHandlers.
 102   ///
 103   void runAtExitHandlers();
 104
 105   static void Register() {
 106     InterpCtor = create;
 107   }
 108
 109   /// create - Create an interpreter ExecutionEngine. This can never fail.
 110   ///
 111   static ExecutionEngine *create(ModuleProvider *M);
 112
 113   /// run - Start execution with the specified function and arguments.
 114   ///
 115   virtual GenericValue runFunction(Function *F,
 116                                    const std::vector<GenericValue> &ArgValues);
 117
 118   /// recompileAndRelinkFunction - For the interpreter, functions are always
 119   /// up-to-date.
 120   ///
 121   virtual void *recompileAndRelinkFunction(Function *F) {
 122     return getPointerToFunction(F);
 123   }
 124
 125   /// freeMachineCodeForFunction - The interpreter does not generate any code.
 126   ///
 127   void freeMachineCodeForFunction(Function *F) { }
 128
 129   // Methods used to execute code:
 130   // Place a call on the stack
 131   void callFunction(Function *F, const std::vector<GenericValue> &ArgVals);
 132   void run();                // Execute instructions until nothing left to do
 133
 134   // Opcode Implementations
 135   void visitReturnInst(ReturnInst &I);
 136   void visitBranchInst(BranchInst &I);
 137   void visitSwitchInst(SwitchInst &I);
 138
 139   void visitBinaryOperator(BinaryOperator &I);
 140   void visitAllocationInst(AllocationInst &I);
 141   void visitFreeInst(FreeInst &I);
 142   void visitLoadInst(LoadInst &I);
 143   void visitStoreInst(StoreInst &I);
 144   void visitGetElementPtrInst(GetElementPtrInst &I);
 145   void visitPHINode(PHINode &PN) { assert(0 && "PHI nodes already handled!"); }
 146   void visitCastInst(CastInst &I);
 147   void visitSelectInst(SelectInst &I);
 148
 149
 150   void visitCallSite(CallSite CS);
 151   void visitCallInst(CallInst &I) { visitCallSite (CallSite (&I)); }
 152   void visitInvokeInst(InvokeInst &I) { visitCallSite (CallSite (&I)); }
 153   void visitUnwindInst(UnwindInst &I);
 154   void visitUnreachableInst(UnreachableInst &I);
 155
 156   void visitShl(ShiftInst &I);
 157   void visitShr(ShiftInst &I);
 158   void visitVAArgInst(VAArgInst &I);
 159   void visitInstruction(Instruction &I) {
 160     std::cerr << I;
 161     assert(0 && "Instruction not interpretable yet!");
 162   }
 163
 164   GenericValue callExternalFunction(Function *F,
 165                                     const std::vector<GenericValue> &ArgVals);
 166   void exitCalled(GenericValue GV);
 167
 168   void addAtExitHandler(Function *F) {
 169     AtExitHandlers.push_back(F);
 170   }
 171
 172   GenericValue *getFirstVarArg () {
 173     return &(ECStack.back ().VarArgs[0]);
 174   }
 175
 176   //FIXME: private:
 177 public:
 178   GenericValue executeGEPOperation(Value *Ptr, gep_type_iterator I,
 179                                    gep_type_iterator E, ExecutionContext &SF);
 180
 181 private:  // Helper functions
 182   // SwitchToNewBasicBlock - Start execution in a new basic block and run any
 183   // PHI nodes in the top of the block.  This is used for intraprocedural
 184   // control flow.
 185   //
 186   void SwitchToNewBasicBlock(BasicBlock *Dest, ExecutionContext &SF);
 187
 188   void *getPointerToFunction(Function *F) { return (void*)F; }
 189
 190   void initializeExecutionEngine();
 191   void initializeExternalFunctions();
 192   GenericValue getConstantExprValue(ConstantExpr *CE, ExecutionContext &SF);
 193   GenericValue getOperandValue(Value *V, ExecutionContext &SF);
 194   GenericValue executeCastOperation(Value *SrcVal, const Type *Ty,
 195                                     ExecutionContext &SF);
 196   void popStackAndReturnValueToCaller(const Type *RetTy, GenericValue Result);
 197 };
 198
 199 } // End llvm namespace
 200
 201 #endif