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 extern "C" void LLVMLinkInInterpreter() { }
33 
34 /// create - Create a new interpreter object.  This can never fail.
35 ///
36 ExecutionEngine *Interpreter::create(ModuleProvider *MP, std::string* ErrStr) {
37   // Tell this ModuleProvide to materialize and release the module
38   if (!MP->materializeModule(ErrStr))
39     // We got an error, just return 0
40     return 0;
41 
42   return new Interpreter(MP);
43 }
44 
45 //===----------------------------------------------------------------------===//
46 // Interpreter ctor - Initialize stuff
47 //
48 Interpreter::Interpreter(ModuleProvider *M)
49   : ExecutionEngine(M), TD(M->getModule()) {
50 
51   memset(&ExitValue.Untyped, 0, sizeof(ExitValue.Untyped));
52   setTargetData(&TD);
53   // Initialize the "backend"
54   initializeExecutionEngine();
55   initializeExternalFunctions();
56   emitGlobals();
57 
58   IL = new IntrinsicLowering(TD);
59 }
60 
61 Interpreter::~Interpreter() {
62   delete IL;
63 }
64 
65 void Interpreter::runAtExitHandlers () {
66   while (!AtExitHandlers.empty()) {
67     callFunction(AtExitHandlers.back(), std::vector<GenericValue>());
68     AtExitHandlers.pop_back();
69     run();
70   }
71 }
72 
73 /// run - Start execution with the specified function and arguments.
74 ///
75 GenericValue
76 Interpreter::runFunction(Function *F,
77                          const std::vector<GenericValue> &ArgValues) {
78   assert (F && "Function *F was null at entry to run()");
79 
80   // Try extra hard not to pass extra args to a function that isn't
81   // expecting them.  C programmers frequently bend the rules and
82   // declare main() with fewer parameters than it actually gets
83   // passed, and the interpreter barfs if you pass a function more
84   // parameters than it is declared to take. This does not attempt to
85   // take into account gratuitous differences in declared types,
86   // though.
87   std::vector<GenericValue> ActualArgs;
88   const unsigned ArgCount = F->getFunctionType()->getNumParams();
89   for (unsigned i = 0; i < ArgCount; ++i)
90     ActualArgs.push_back(ArgValues[i]);
91 
92   // Set up the function call.
93   callFunction(F, ActualArgs);
94 
95   // Start executing the function.
96   run();
97 
98   return ExitValue;
99 }
100