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      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/IR/DerivedTypes.h"
     19 #include "llvm/IR/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   setDataLayout(&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 }
     99