lib/ExecutionEngine/Interpreter/Interpreter.cpp

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