Interpreter.h revision 276f4b523564d205e59c8049a12c75705dd24b78 
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
26namespace llvm {
27
28class IntrinsicLowering;
29struct FunctionInfo;
30template<typename T> class generic_gep_type_iterator;
31class ConstantExpr;
32typedef 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//
39class AllocaHolder {
40  friend class AllocaHolderHandle;
41  std::vector<void*> Allocations;
42  unsigned RefCnt;
43public:
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//
55class AllocaHolderHandle {
56  AllocaHolder *H;
57public:
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
65typedef std::vector<GenericValue> ValuePlaneTy;
66
67// ExecutionContext struct - This struct represents one stack frame currently
68// executing.
69//
70struct 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//
83class 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
96public:
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:
177public:
178  GenericValue executeGEPOperation(Value *Ptr, gep_type_iterator I,
179                                   gep_type_iterator E, ExecutionContext &SF);
180
181private:  // 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
202