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/IR/DerivedTypes.h"
16 #include "llvm/IR/Function.h"
17 #include "llvm/IR/IRBuilder.h"
18 #include "llvm/IR/Module.h"
19 #include "llvm/Support/raw_ostream.h"
20
21 using namespace llvm;
22
appendToGlobalArray(const char * Array,Module & M,Function * F,int Priority,Constant * Data)23 static void appendToGlobalArray(const char *Array, Module &M, Function *F,
24 int Priority, Constant *Data) {
25 IRBuilder<> IRB(M.getContext());
26 FunctionType *FnTy = FunctionType::get(IRB.getVoidTy(), false);
27
28 // Get the current set of static global constructors and add the new ctor
29 // to the list.
30 SmallVector<Constant *, 16> CurrentCtors;
31 StructType *EltTy;
32 if (GlobalVariable *GVCtor = M.getNamedGlobal(Array)) {
33 ArrayType *ATy = cast<ArrayType>(GVCtor->getValueType());
34 StructType *OldEltTy = cast<StructType>(ATy->getElementType());
35 // Upgrade a 2-field global array type to the new 3-field format if needed.
36 if (Data && OldEltTy->getNumElements() < 3)
37 EltTy = StructType::get(IRB.getInt32Ty(), PointerType::getUnqual(FnTy),
38 IRB.getInt8PtrTy(), nullptr);
39 else
40 EltTy = OldEltTy;
41 if (Constant *Init = GVCtor->getInitializer()) {
42 unsigned n = Init->getNumOperands();
43 CurrentCtors.reserve(n + 1);
44 for (unsigned i = 0; i != n; ++i) {
45 auto Ctor = cast<Constant>(Init->getOperand(i));
46 if (EltTy != OldEltTy)
47 Ctor = ConstantStruct::get(
48 EltTy, Ctor->getAggregateElement((unsigned)0),
49 Ctor->getAggregateElement(1),
50 Constant::getNullValue(IRB.getInt8PtrTy()), nullptr);
51 CurrentCtors.push_back(Ctor);
52 }
53 }
54 GVCtor->eraseFromParent();
55 } else {
56 // Use the new three-field struct if there isn't one already.
57 EltTy = StructType::get(IRB.getInt32Ty(), PointerType::getUnqual(FnTy),
58 IRB.getInt8PtrTy(), nullptr);
59 }
60
61 // Build a 2 or 3 field global_ctor entry. We don't take a comdat key.
62 Constant *CSVals[3];
63 CSVals[0] = IRB.getInt32(Priority);
64 CSVals[1] = F;
65 // FIXME: Drop support for the two element form in LLVM 4.0.
66 if (EltTy->getNumElements() >= 3)
67 CSVals[2] = Data ? ConstantExpr::getPointerCast(Data, IRB.getInt8PtrTy())
68 : Constant::getNullValue(IRB.getInt8PtrTy());
69 Constant *RuntimeCtorInit =
70 ConstantStruct::get(EltTy, makeArrayRef(CSVals, EltTy->getNumElements()));
71
72 CurrentCtors.push_back(RuntimeCtorInit);
73
74 // Create a new initializer.
75 ArrayType *AT = ArrayType::get(EltTy, CurrentCtors.size());
76 Constant *NewInit = ConstantArray::get(AT, CurrentCtors);
77
78 // Create the new global variable and replace all uses of
79 // the old global variable with the new one.
80 (void)new GlobalVariable(M, NewInit->getType(), false,
81 GlobalValue::AppendingLinkage, NewInit, Array);
82 }
83
appendToGlobalCtors(Module & M,Function * F,int Priority,Constant * Data)84 void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority, Constant *Data) {
85 appendToGlobalArray("llvm.global_ctors", M, F, Priority, Data);
86 }
87
appendToGlobalDtors(Module & M,Function * F,int Priority,Constant * Data)88 void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority, Constant *Data) {
89 appendToGlobalArray("llvm.global_dtors", M, F, Priority, Data);
90 }
91
checkSanitizerInterfaceFunction(Constant * FuncOrBitcast)92 Function *llvm::checkSanitizerInterfaceFunction(Constant *FuncOrBitcast) {
93 if (isa<Function>(FuncOrBitcast))
94 return cast<Function>(FuncOrBitcast);
95 FuncOrBitcast->dump();
96 std::string Err;
97 raw_string_ostream Stream(Err);
98 Stream << "Sanitizer interface function redefined: " << *FuncOrBitcast;
99 report_fatal_error(Err);
100 }
101
createSanitizerCtorAndInitFunctions(Module & M,StringRef CtorName,StringRef InitName,ArrayRef<Type * > InitArgTypes,ArrayRef<Value * > InitArgs,StringRef VersionCheckName)102 std::pair<Function *, Function *> llvm::createSanitizerCtorAndInitFunctions(
103 Module &M, StringRef CtorName, StringRef InitName,
104 ArrayRef<Type *> InitArgTypes, ArrayRef<Value *> InitArgs,
105 StringRef VersionCheckName) {
106 assert(!InitName.empty() && "Expected init function name");
107 assert(InitArgTypes.size() == InitArgTypes.size() &&
108 "Sanitizer's init function expects different number of arguments");
109 Function *Ctor = Function::Create(
110 FunctionType::get(Type::getVoidTy(M.getContext()), false),
111 GlobalValue::InternalLinkage, CtorName, &M);
112 BasicBlock *CtorBB = BasicBlock::Create(M.getContext(), "", Ctor);
113 IRBuilder<> IRB(ReturnInst::Create(M.getContext(), CtorBB));
114 Function *InitFunction =
115 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
116 InitName, FunctionType::get(IRB.getVoidTy(), InitArgTypes, false),
117 AttributeSet()));
118 InitFunction->setLinkage(Function::ExternalLinkage);
119 IRB.CreateCall(InitFunction, InitArgs);
120 if (!VersionCheckName.empty()) {
121 Function *VersionCheckFunction =
122 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
123 VersionCheckName, FunctionType::get(IRB.getVoidTy(), {}, false),
124 AttributeSet()));
125 IRB.CreateCall(VersionCheckFunction, {});
126 }
127 return std::make_pair(Ctor, InitFunction);
128 }
129