C++ GlobalAlias::replaceAllUsesWith方法代码示例

bool ResolveAliases::runOnModule(Module &M) {
  bool Modified = false;

  for (auto I = M.alias_begin(), E = M.alias_end(); I != E;) {
    GlobalAlias *Alias = &*I++;
    Alias->replaceAllUsesWith(Alias->getAliasee());
    Alias->eraseFromParent();
    Modified = true;
  }
  return Modified;
}

static void convertAliasToDeclaration(GlobalAlias &GA, Module &M) {
  GlobalValue *GVal = GA.getBaseObject();
  GlobalValue *NewGV;
  if (auto *GVar = dyn_cast<GlobalVariable>(GVal)) {
    GlobalVariable *NewGVar = new GlobalVariable(
        M, GVar->getType()->getElementType(), GVar->isConstant(),
        GVar->getLinkage(), /*init*/ nullptr, GA.getName(), GVar,
        GVar->getThreadLocalMode(), GVar->getType()->getAddressSpace());
    NewGV = NewGVar;
    NewGV->copyAttributesFrom(GVar);
  } else {
    auto *F = dyn_cast<Function>(GVal);
    assert(F);
    Function *NewF = Function::Create(F->getFunctionType(), F->getLinkage(),
                                      GA.getName(), &M);
    NewGV = NewF;
    NewGV->copyAttributesFrom(F);
  }
  GA.replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, GA.getType()));
  GA.eraseFromParent();
}

// destructively move the contents of src into dest
// this assumes that the targets of the two modules are the same
// including the DataLayout and ModuleFlags (for example)
// and that there is no module-level assembly
static void jl_merge_module(Module *dest, std::unique_ptr<Module> src)
{
    assert(dest != src.get());
    for (Module::global_iterator I = src->global_begin(), E = src->global_end(); I != E;) {
        GlobalVariable *sG = &*I;
        GlobalValue *dG = dest->getNamedValue(sG->getName());
        ++I;
        // Replace a declaration with the definition:
        if (dG) {
            if (sG->isDeclaration()) {
                sG->replaceAllUsesWith(dG);
                sG->eraseFromParent();
                continue;
            }
            else {
                dG->replaceAllUsesWith(sG);
                dG->eraseFromParent();
            }
        }
        // Reparent the global variable:
        sG->removeFromParent();
        dest->getGlobalList().push_back(sG);
        // Comdat is owned by the Module, recreate it in the new parent:
        addComdat(sG);
    }

    for (Module::iterator I = src->begin(), E = src->end(); I != E;) {
        Function *sG = &*I;
        GlobalValue *dG = dest->getNamedValue(sG->getName());
        ++I;
        // Replace a declaration with the definition:
        if (dG) {
            if (sG->isDeclaration()) {
                sG->replaceAllUsesWith(dG);
                sG->eraseFromParent();
                continue;
            }
            else {
                dG->replaceAllUsesWith(sG);
                dG->eraseFromParent();
            }
        }
        // Reparent the global variable:
        sG->removeFromParent();
        dest->getFunctionList().push_back(sG);
        // Comdat is owned by the Module, recreate it in the new parent:
        addComdat(sG);
    }

    for (Module::alias_iterator I = src->alias_begin(), E = src->alias_end(); I != E;) {
        GlobalAlias *sG = &*I;
        GlobalValue *dG = dest->getNamedValue(sG->getName());
        ++I;
        if (dG) {
            if (!dG->isDeclaration()) { // aliases are always definitions, so this test is reversed from the above two
                sG->replaceAllUsesWith(dG);
                sG->eraseFromParent();
                continue;
            }
            else {
                dG->replaceAllUsesWith(sG);
                dG->eraseFromParent();
            }
        }
        sG->removeFromParent();
        dest->getAliasList().push_back(sG);
    }

    // metadata nodes need to be explicitly merged not just copied
    // so there are special passes here for each known type of metadata
    NamedMDNode *sNMD = src->getNamedMetadata("llvm.dbg.cu");
    if (sNMD) {
        NamedMDNode *dNMD = dest->getOrInsertNamedMetadata("llvm.dbg.cu");
#ifdef LLVM35
        for (NamedMDNode::op_iterator I = sNMD->op_begin(), E = sNMD->op_end(); I != E; ++I) {
            dNMD->addOperand(*I);
        }
#else
        for (unsigned i = 0, l = sNMD->getNumOperands(); i < l; i++) {
            dNMD->addOperand(sNMD->getOperand(i));
        }
#endif
    }
}