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/ADT/SmallPtrSet.h"
16 #include "llvm/IR/DerivedTypes.h"
17 #include "llvm/IR/Function.h"
18 #include "llvm/IR/IRBuilder.h"
19 #include "llvm/IR/Module.h"
20
21 using namespace llvm;
22
appendToGlobalArray(const char * Array,Module & M,Function * F,int Priority)23 static void appendToGlobalArray(const char *Array,
24 Module &M, Function *F, int Priority) {
25 IRBuilder<> IRB(M.getContext());
26 FunctionType *FnTy = FunctionType::get(IRB.getVoidTy(), false);
27 StructType *Ty = StructType::get(
28 IRB.getInt32Ty(), PointerType::getUnqual(FnTy), NULL);
29
30 Constant *RuntimeCtorInit = ConstantStruct::get(
31 Ty, IRB.getInt32(Priority), F, NULL);
32
33 // Get the current set of static global constructors and add the new ctor
34 // to the list.
35 SmallVector<Constant *, 16> CurrentCtors;
36 if (GlobalVariable * GVCtor = M.getNamedGlobal(Array)) {
37 if (Constant *Init = GVCtor->getInitializer()) {
38 unsigned n = Init->getNumOperands();
39 CurrentCtors.reserve(n + 1);
40 for (unsigned i = 0; i != n; ++i)
41 CurrentCtors.push_back(cast<Constant>(Init->getOperand(i)));
42 }
43 GVCtor->eraseFromParent();
44 }
45
46 CurrentCtors.push_back(RuntimeCtorInit);
47
48 // Create a new initializer.
49 ArrayType *AT = ArrayType::get(RuntimeCtorInit->getType(),
50 CurrentCtors.size());
51 Constant *NewInit = ConstantArray::get(AT, CurrentCtors);
52
53 // Create the new global variable and replace all uses of
54 // the old global variable with the new one.
55 (void)new GlobalVariable(M, NewInit->getType(), false,
56 GlobalValue::AppendingLinkage, NewInit, Array);
57 }
58
appendToGlobalCtors(Module & M,Function * F,int Priority)59 void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority) {
60 appendToGlobalArray("llvm.global_ctors", M, F, Priority);
61 }
62
appendToGlobalDtors(Module & M,Function * F,int Priority)63 void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority) {
64 appendToGlobalArray("llvm.global_dtors", M, F, Priority);
65 }
66
67 GlobalVariable *
collectUsedGlobalVariables(Module & M,SmallPtrSet<GlobalValue *,8> & Set,bool CompilerUsed)68 llvm::collectUsedGlobalVariables(Module &M, SmallPtrSet<GlobalValue *, 8> &Set,
69 bool CompilerUsed) {
70 const char *Name = CompilerUsed ? "llvm.compiler.used" : "llvm.used";
71 GlobalVariable *GV = M.getGlobalVariable(Name);
72 if (!GV || !GV->hasInitializer())
73 return GV;
74
75 const ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
76 for (unsigned I = 0, E = Init->getNumOperands(); I != E; ++I) {
77 Value *Op = Init->getOperand(I);
78 GlobalValue *G = cast<GlobalValue>(Op->stripPointerCastsNoFollowAliases());
79 Set.insert(G);
80 }
81 return GV;
82 }
83