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/Module.h"
18 #include "llvm/Support/IRBuilder.h"
19
20 using namespace llvm;
21
appendToGlobalArray(const char * Array,Module & M,Function * F,int Priority)22 static 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
appendToGlobalCtors(Module & M,Function * F,int Priority)58 void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority) {
59 appendToGlobalArray("llvm.global_ctors", M, F, Priority);
60 }
61
appendToGlobalDtors(Module & M,Function * F,int Priority)62 void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority) {
63 appendToGlobalArray("llvm.global_dtors", M, F, Priority);
64 }
65