Interpreter.cpp revision 2cab55d7e1bde83cd5f5dccee9a331ada8c1a67c 
1//===- Interpreter.cpp - Top-Level LLVM Interpreter Implementation --------===//
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 file implements the top-level functionality for the LLVM interpreter.
11// This interpreter is designed to be a very simple, portable, inefficient
12// interpreter.
13//
14//===----------------------------------------------------------------------===//
15
16#include "Interpreter.h"
17#include "llvm/Module.h"
18#include "llvm/DerivedTypes.h"
19using namespace llvm;
20
21/// create - Create a new interpreter object.  This can never fail.
22///
23ExecutionEngine *Interpreter::create(Module *M){
24  bool isLittleEndian = false;
25  switch (M->getEndianness()) {
26  case Module::LittleEndian: isLittleEndian = true; break;
27  case Module::BigEndian:    isLittleEndian = false; break;
28  case Module::AnyPointerSize:
29    int Test = 0;
30    *(char*)&Test = 1;    // Return true if the host is little endian
31    isLittleEndian = (Test == 1);
32    break;
33  }
34
35  bool isLongPointer = false;
36  switch (M->getPointerSize()) {
37  case Module::Pointer32: isLongPointer = false; break;
38  case Module::Pointer64: isLongPointer = true; break;
39  case Module::AnyPointerSize:
40    isLongPointer = (sizeof(void*) == 8);  // Follow host
41    break;
42  }
43
44  return new Interpreter(M, isLittleEndian, isLongPointer);
45}
46
47//===----------------------------------------------------------------------===//
48// Interpreter ctor - Initialize stuff
49//
50Interpreter::Interpreter(Module *M, bool isLittleEndian, bool isLongPointer)
51  : ExecutionEngine(M), ExitCode(0),
52    TD("lli", isLittleEndian, isLongPointer ? 8 : 4, isLongPointer ? 8 : 4,
53       isLongPointer ? 8 : 4) {
54
55  setTargetData(TD);
56  // Initialize the "backend"
57  initializeExecutionEngine();
58  initializeExternalFunctions();
59  emitGlobals();
60}
61
62void Interpreter::runAtExitHandlers () {
63  while (!AtExitHandlers.empty()) {
64    callFunction(AtExitHandlers.back(), std::vector<GenericValue>());
65    AtExitHandlers.pop_back();
66    run();
67  }
68}
69
70/// run - Start execution with the specified function and arguments.
71///
72GenericValue Interpreter::runFunction(Function *F,
73			      const std::vector<GenericValue> &ArgValues) {
74  assert (F && "Function *F was null at entry to run()");
75
76  // Try extra hard not to pass extra args to a function that isn't
77  // expecting them.  C programmers frequently bend the rules and
78  // declare main() with fewer parameters than it actually gets
79  // passed, and the interpreter barfs if you pass a function more
80  // parameters than it is declared to take. This does not attempt to
81  // take into account gratuitous differences in declared types,
82  // though.
83  std::vector<GenericValue> ActualArgs;
84  const unsigned ArgCount = F->getFunctionType()->getParamTypes().size();
85  for (unsigned i = 0; i < ArgCount; ++i)
86    ActualArgs.push_back (ArgValues[i]);
87
88  // Set up the function call.
89  callFunction(F, ActualArgs);
90
91  // Start executing the function.
92  run();
93
94  GenericValue rv;
95  rv.IntVal = ExitCode;
96  return rv;
97}
98
99