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     ++IP;
29   } else {
30     // Otherwise, move I before IP and return IP.
31     I->moveBefore(&*IP);
32   }
33   return IP;
34 }
35 
36 /// Instrumentation passes often insert conditional checks into entry blocks.
37 /// Call this function before splitting the entry block to move instructions
38 /// that must remain in the entry block up before the split point. Static
39 /// allocas and llvm.localescape calls, for example, must remain in the entry
40 /// block.
41 BasicBlock::iterator llvm::PrepareToSplitEntryBlock(BasicBlock &BB,
42                                                     BasicBlock::iterator IP) {
43   assert(&BB.getParent()->getEntryBlock() == &BB);
44   for (auto I = IP, E = BB.end(); I != E; ++I) {
45     bool KeepInEntry = false;
46     if (auto *AI = dyn_cast<AllocaInst>(I)) {
47       if (AI->isStaticAlloca())
48         KeepInEntry = true;
49     } else if (auto *II = dyn_cast<IntrinsicInst>(I)) {
50       if (II->getIntrinsicID() == llvm::Intrinsic::localescape)
51         KeepInEntry = true;
52     }
53     if (KeepInEntry)
54       IP = moveBeforeInsertPoint(I, IP);
55   }
56   return IP;
57 }
58 
59 // Create a constant for Str so that we can pass it to the run-time lib.
60 GlobalVariable *llvm::createPrivateGlobalForString(Module &M, StringRef Str,
61                                                    bool AllowMerging,
62                                                    const char *NamePrefix) {
63   Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
64   // We use private linkage for module-local strings. If they can be merged
65   // with another one, we set the unnamed_addr attribute.
66   GlobalVariable *GV =
67       new GlobalVariable(M, StrConst->getType(), true,
68                          GlobalValue::PrivateLinkage, StrConst, NamePrefix);
69   if (AllowMerging)
70     GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
71   GV->setAlignment(Align::None()); // Strings may not be merged w/o setting
72                                    // alignment explicitly.
73   return GV;
74 }
75 
76 Comdat *llvm::GetOrCreateFunctionComdat(Function &F, Triple &T,
77                                         const std::string &ModuleId) {
78   if (auto Comdat = F.getComdat()) return Comdat;
79   assert(F.hasName());
80   Module *M = F.getParent();
81   std::string Name = F.getName();
82 
83   // Make a unique comdat name for internal linkage things on ELF. On COFF, the
84   // name of the comdat group identifies the leader symbol of the comdat group.
85   // The linkage of the leader symbol is considered during comdat resolution,
86   // and internal symbols with the same name from different objects will not be
87   // merged.
88   if (T.isOSBinFormatELF() && F.hasLocalLinkage()) {
89     if (ModuleId.empty())
90       return nullptr;
91     Name += ModuleId;
92   }
93 
94   // Make a new comdat for the function. Use the "no duplicates" selection kind
95   // for non-weak symbols if the object file format supports it.
96   Comdat *C = M->getOrInsertComdat(Name);
97   if (T.isOSBinFormatCOFF() && !F.isWeakForLinker())
98     C->setSelectionKind(Comdat::NoDuplicates);
99   F.setComdat(C);
100   return C;
101 }
102 
103 /// initializeInstrumentation - Initialize all passes in the TransformUtils
104 /// library.
105 void llvm::initializeInstrumentation(PassRegistry &Registry) {
106   initializeAddressSanitizerLegacyPassPass(Registry);
107   initializeModuleAddressSanitizerLegacyPassPass(Registry);
108   initializeBoundsCheckingLegacyPassPass(Registry);
109   initializeControlHeightReductionLegacyPassPass(Registry);
110   initializeGCOVProfilerLegacyPassPass(Registry);
111   initializePGOInstrumentationGenLegacyPassPass(Registry);
112   initializePGOInstrumentationUseLegacyPassPass(Registry);
113   initializePGOIndirectCallPromotionLegacyPassPass(Registry);
114   initializePGOMemOPSizeOptLegacyPassPass(Registry);
115   initializeInstrOrderFileLegacyPassPass(Registry);
116   initializeInstrProfilingLegacyPassPass(Registry);
117   initializeMemorySanitizerLegacyPassPass(Registry);
118   initializeHWAddressSanitizerLegacyPassPass(Registry);
119   initializeThreadSanitizerLegacyPassPass(Registry);
120   initializeModuleSanitizerCoverageLegacyPassPass(Registry);
121   initializeDataFlowSanitizerPass(Registry);
122 }
123 
124 /// LLVMInitializeInstrumentation - C binding for
125 /// initializeInstrumentation.
126 void LLVMInitializeInstrumentation(LLVMPassRegistryRef R) {
127   initializeInstrumentation(*unwrap(R));
128 }
129