path: root/lib/Linker/LinkModules.cpp

//===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the LLVM module linker.
//
// Specifically, this:
//  * Merges global variables between the two modules
//    * Uninit + Uninit = Init, Init + Uninit = Init, Init + Init = Error if !=
//  * Merges functions between two modules
//
//===----------------------------------------------------------------------===//

#include "llvm/Linker.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/SymbolTable.h"
#include "llvm/TypeSymbolTable.h"
#include "llvm/Instructions.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Support/Streams.h"
#include "llvm/System/Path.h"
#include <sstream>
using namespace llvm;

// Error - Simple wrapper function to conditionally assign to E and return true.
// This just makes error return conditions a little bit simpler...
static inline bool Error(std::string *E, const std::string &Message) {
  if (E) *E = Message;
  return true;
}

// ToStr - Simple wrapper function to convert a type to a string.
static std::string ToStr(const Type *Ty, const Module *M) {
  std::ostringstream OS;
  WriteTypeSymbolic(OS, Ty, M);
  return OS.str();
}

//
// Function: ResolveTypes()
//
// Description:
//  Attempt to link the two specified types together.
//
// Inputs:
//  DestTy - The type to which we wish to resolve.
//  SrcTy  - The original type which we want to resolve.
//  Name   - The name of the type.
//
// Outputs:
//  DestST - The symbol table in which the new type should be placed.
//
// Return value:
//  true  - There is an error and the types cannot yet be linked.
//  false - No errors.
//
static bool ResolveTypes(const Type *DestTy, const Type *SrcTy,
                         TypeSymbolTable *DestST, const std::string &Name) {
  if (DestTy == SrcTy) return false;       // If already equal, noop

  // Does the type already exist in the module?
  if (DestTy && !isa<OpaqueType>(DestTy)) {  // Yup, the type already exists...
    if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) {
      const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy);
    } else {
      return true;  // Cannot link types... neither is opaque and not-equal
    }
  } else {                       // Type not in dest module.  Add it now.
    if (DestTy)                  // Type _is_ in module, just opaque...
      const_cast<OpaqueType*>(cast<OpaqueType>(DestTy))
                           ->refineAbstractTypeTo(SrcTy);
    else if (!Name.empty())
      DestST->insert(Name, const_cast<Type*>(SrcTy));
  }
  return false;
}

static const FunctionType *getFT(const PATypeHolder &TH) {
  return cast<FunctionType>(TH.get());
}
static const StructType *getST(const PATypeHolder &TH) {
  return cast<StructType>(TH.get());
}

// RecursiveResolveTypes - This is just like ResolveTypes, except that it
// recurses down into derived types, merging the used types if the parent types
// are compatible.
static bool RecursiveResolveTypesI(const PATypeHolder &DestTy,
                                   const PATypeHolder &SrcTy,
                                   TypeSymbolTable *DestST, 
                                   const std::string &Name,
                std::vector<std::pair<PATypeHolder, PATypeHolder> > &Pointers) {
  const Type *SrcTyT = SrcTy.get();
  const Type *DestTyT = DestTy.get();
  if (DestTyT == SrcTyT) return false;       // If already equal, noop

  // If we found our opaque type, resolve it now!
  if (isa<OpaqueType>(DestTyT) || isa<OpaqueType>(SrcTyT))
    return ResolveTypes(DestTyT, SrcTyT, DestST, Name);

  // Two types cannot be resolved together if they are of different primitive
  // type.  For example, we cannot resolve an int to a float.
  if (DestTyT->getTypeID() != SrcTyT->getTypeID()) return true;

  // Otherwise, resolve the used type used by this derived type...
  switch (DestTyT->getTypeID()) {
  case Type::IntegerTyID: {
    if (cast<IntegerType>(DestTyT)->getBitWidth() !=
        cast<IntegerType>(SrcTyT)->getBitWidth())
      return true;
    return false;
  }
  case Type::FunctionTyID: {
    if (cast<FunctionType>(DestTyT)->isVarArg() !=
        cast<FunctionType>(SrcTyT)->isVarArg() ||
        cast<FunctionType>(DestTyT)->getNumContainedTypes() !=
        cast<FunctionType>(SrcTyT)->getNumContainedTypes())
      return true;
    for (unsigned i = 0, e = getFT(DestTy)->getNumContainedTypes(); i != e; ++i)
      if (RecursiveResolveTypesI(getFT(DestTy)->getContainedType(i),