1 //===- Interpreter.cpp - Top-Level LLVM Interpreter Implementation --------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // 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/CodeGen/IntrinsicLowering.h"
18 #include "llvm/DerivedTypes.h"
19 #include "llvm/Module.h"
20 #include "llvm/ModuleProvider.h"
21 #include <cstring>
22 using namespace llvm;
23 
24 namespace {
25 
26 static struct RegisterInterp {
27   RegisterInterp() { Interpreter::Register(); }
28 } InterpRegistrator;
29 
30 }
31 
32 namespace llvm {
33   void LinkInInterpreter() {
34   }
35 }
36 
37 /// create - Create a new interpreter object.  This can never fail.
38 ///
39 ExecutionEngine *Interpreter::create(ModuleProvider *MP, std::string* ErrStr,
40                                      CodeGenOpt::Level OptLevel /*unused*/) {
41   // Tell this ModuleProvide to materialize and release the module
42   if (!MP->materializeModule(ErrStr))
43     // We got an error, just return 0
44     return 0;
45 
46   return new Interpreter(MP);
47 }
48 
49 //===----------------------------------------------------------------------===//
50 // Interpreter ctor - Initialize stuff
51 //
52 Interpreter::Interpreter(ModuleProvider *M)
53   : ExecutionEngine(M), TD(M->getModule()) {
54 
55   memset(&ExitValue.Untyped, 0, sizeof(ExitValue.Untyped));
56   setTargetData(&TD);
57   // Initialize the "backend"
58   initializeExecutionEngine();
59   initializeExternalFunctions();
60   emitGlobals();
61 
62   IL = new IntrinsicLowering(TD);
63 }
64 
65 Interpreter::~Interpreter() {
66   delete IL;
67 }
68 
69 void Interpreter::runAtExitHandlers () {
70   while (!AtExitHandlers.empty()) {
71     callFunction(AtExitHandlers.back(), std::vector<GenericValue>());
72     AtExitHandlers.pop_back();
73     run();
74   }
75 }
76 
77 /// run - Start execution with the specified function and arguments.
78 ///
79 GenericValue
80 Interpreter::runFunction(Function *F,
81                          const std::vector<GenericValue> &ArgValues) {
82   assert (F && "Function *F was null at entry to run()");
83 
84   // Try extra hard not to pass extra args to a function that isn't
85   // expecting them.  C programmers frequently bend the rules and
86   // declare main() with fewer parameters than it actually gets
87   // passed, and the interpreter barfs if you pass a function more
88   // parameters than it is declared to take. This does not attempt to
89   // take into account gratuitous differences in declared types,
90   // though.
91   std::vector<GenericValue> ActualArgs;
92   const unsigned ArgCount = F->getFunctionType()->getNumParams();
93   for (unsigned i = 0; i < ArgCount; ++i)
94     ActualArgs.push_back(ArgValues[i]);
95 
96   // Set up the function call.
97   callFunction(F, ActualArgs);
98 
99   // Start executing the function.
100   run();
101 
102   return ExitValue;
103 }
104 
105