1 //===-- Instrumentation.cpp - TransformUtils Infrastructure ---------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines the common initialization infrastructure for the
10 // Instrumentation library.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Transforms/Instrumentation.h"
15 #include "llvm-c/Initialization.h"
16 #include "llvm/ADT/Triple.h"
17 #include "llvm/IR/IntrinsicInst.h"
18 #include "llvm/IR/Module.h"
19 #include "llvm/InitializePasses.h"
20 #include "llvm/PassRegistry.h"
21 
22 using namespace llvm;
23 
24 /// Moves I before IP. Returns new insert point.
25 static BasicBlock::iterator moveBeforeInsertPoint(BasicBlock::iterator I, BasicBlock::iterator IP) {
26   // If I is IP, move the insert point down.
27   if (I == IP)
28     return ++IP;
29   // Otherwise, move I before IP and return IP.
30   I->moveBefore(&*IP);
31   return IP;
32 }
33 
34 /// Instrumentation passes often insert conditional checks into entry blocks.
35 /// Call this function before splitting the entry block to move instructions
36 /// that must remain in the entry block up before the split point. Static
37 /// allocas and llvm.localescape calls, for example, must remain in the entry
38 /// block.
39 BasicBlock::iterator llvm::PrepareToSplitEntryBlock(BasicBlock &BB,
40                                                     BasicBlock::iterator IP) {
41   assert(&BB.getParent()->getEntryBlock() == &BB);
42   for (auto I = IP, E = BB.end(); I != E; ++I) {
43     bool KeepInEntry = false;
44     if (auto *AI = dyn_cast<AllocaInst>(I)) {
45       if (AI->isStaticAlloca())
46         KeepInEntry = true;
47     } else if (auto *II = dyn_cast<IntrinsicInst>(I)) {
48       if (II->getIntrinsicID() == llvm::Intrinsic::localescape)
49         KeepInEntry = true;
50     }
51     if (KeepInEntry)
52       IP = moveBeforeInsertPoint(I, IP);
53   }
54   return IP;
55 }
56 
57 // Create a constant for Str so that we can pass it to the run-time lib.
58 GlobalVariable *llvm::createPrivateGlobalForString(Module &M, StringRef Str,
59                                                    bool AllowMerging,
60                                                    const char *NamePrefix) {
61   Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
62   // We use private linkage for module-local strings. If they can be merged
63   // with another one, we set the unnamed_addr attribute.
64   GlobalVariable *GV =
65       new GlobalVariable(M, StrConst->getType(), true,
66                          GlobalValue::PrivateLinkage, StrConst, NamePrefix);
67   if (AllowMerging)
68     GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
69   GV->setAlignment(1);  // Strings may not be merged w/o setting align 1.
70   return GV;
71 }
72 
73 Comdat *llvm::GetOrCreateFunctionComdat(Function &F, Triple &T,
74                                         const std::string &ModuleId) {
75   if (auto Comdat = F.getComdat()) return Comdat;
76   assert(F.hasName());
77   Module *M = F.getParent();
78   std::string Name = F.getName();
79 
80   // Make a unique comdat name for internal linkage things on ELF. On COFF, the
81   // name of the comdat group identifies the leader symbol of the comdat group.
82   // The linkage of the leader symbol is considered during comdat resolution,
83   // and internal symbols with the same name from different objects will not be
84   // merged.
85   if (T.isOSBinFormatELF() && F.hasLocalLinkage()) {
86     if (ModuleId.empty())
87       return nullptr;
88     Name += ModuleId;
89   }
90 
91   // Make a new comdat for the function. Use the "no duplicates" selection kind
92   // for non-weak symbols if the object file format supports it.
93   Comdat *C = M->getOrInsertComdat(Name);
94   if (T.isOSBinFormatCOFF() && !F.isWeakForLinker())
95     C->setSelectionKind(Comdat::NoDuplicates);
96   F.setComdat(C);
97   return C;
98 }
99 
100 /// initializeInstrumentation - Initialize all passes in the TransformUtils
101 /// library.
102 void llvm::initializeInstrumentation(PassRegistry &Registry) {
103   initializeAddressSanitizerPass(Registry);
104   initializeAddressSanitizerModulePass(Registry);
105   initializeBoundsCheckingLegacyPassPass(Registry);
106   initializeControlHeightReductionLegacyPassPass(Registry);
107   initializeGCOVProfilerLegacyPassPass(Registry);
108   initializePGOInstrumentationGenLegacyPassPass(Registry);
109   initializePGOInstrumentationUseLegacyPassPass(Registry);
110   initializePGOIndirectCallPromotionLegacyPassPass(Registry);
111   initializePGOMemOPSizeOptLegacyPassPass(Registry);
112   initializeInstrProfilingLegacyPassPass(Registry);
113   initializeMemorySanitizerLegacyPassPass(Registry);
114   initializeHWAddressSanitizerPass(Registry);
115   initializeThreadSanitizerLegacyPassPass(Registry);
116   initializeSanitizerCoverageModulePass(Registry);
117   initializeDataFlowSanitizerPass(Registry);
118   initializeEfficiencySanitizerPass(Registry);
119 }
120 
121 /// LLVMInitializeInstrumentation - C binding for
122 /// initializeInstrumentation.
123 void LLVMInitializeInstrumentation(LLVMPassRegistryRef R) {
124   initializeInstrumentation(*unwrap(R));
125 }
126