1//===-- ModuleUtils.cpp - Functions to manipulate Modules -----------------===//
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 family of functions perform manipulations on Modules.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Transforms/Utils/ModuleUtils.h"
15#include "llvm/DerivedTypes.h"
16#include "llvm/Function.h"
17#include "llvm/IRBuilder.h"
18#include "llvm/Module.h"
19
20using namespace llvm;
21
22static void appendToGlobalArray(const char *Array,
23                                Module &M, Function *F, int Priority) {
24  IRBuilder<> IRB(M.getContext());
25  FunctionType *FnTy = FunctionType::get(IRB.getVoidTy(), false);
26  StructType *Ty = StructType::get(
27      IRB.getInt32Ty(), PointerType::getUnqual(FnTy), NULL);
28
29  Constant *RuntimeCtorInit = ConstantStruct::get(
30      Ty, IRB.getInt32(Priority), F, NULL);
31
32  // Get the current set of static global constructors and add the new ctor
33  // to the list.
34  SmallVector<Constant *, 16> CurrentCtors;
35  if (GlobalVariable * GVCtor = M.getNamedGlobal(Array)) {
36    if (Constant *Init = GVCtor->getInitializer()) {
37      unsigned n = Init->getNumOperands();
38      CurrentCtors.reserve(n + 1);
39      for (unsigned i = 0; i != n; ++i)
40        CurrentCtors.push_back(cast<Constant>(Init->getOperand(i)));
41    }
42    GVCtor->eraseFromParent();
43  }
44
45  CurrentCtors.push_back(RuntimeCtorInit);
46
47  // Create a new initializer.
48  ArrayType *AT = ArrayType::get(RuntimeCtorInit->getType(),
49                                 CurrentCtors.size());
50  Constant *NewInit = ConstantArray::get(AT, CurrentCtors);
51
52  // Create the new global variable and replace all uses of
53  // the old global variable with the new one.
54  (void)new GlobalVariable(M, NewInit->getType(), false,
55                           GlobalValue::AppendingLinkage, NewInit, Array);
56}
57
58void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority) {
59  appendToGlobalArray("llvm.global_ctors", M, F, Priority);
60}
61
62void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority) {
63  appendToGlobalArray("llvm.global_dtors", M, F, Priority);
64}
65