1 //===- ModuleSymbolTable.cpp - symbol table for in-memory IR --------------===//
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 class represents a symbol table built from in-memory IR. It provides
10 // access to GlobalValues and should only be used if such access is required
11 // (e.g. in the LTO implementation).
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/Object/ModuleSymbolTable.h"
16 #include "RecordStreamer.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/SmallString.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/ADT/StringRef.h"
21 #include "llvm/ADT/Triple.h"
22 #include "llvm/IR/Function.h"
23 #include "llvm/IR/GlobalAlias.h"
24 #include "llvm/IR/GlobalValue.h"
25 #include "llvm/IR/GlobalVariable.h"
26 #include "llvm/IR/InlineAsm.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/MC/MCAsmInfo.h"
29 #include "llvm/MC/MCContext.h"
30 #include "llvm/MC/MCDirectives.h"
31 #include "llvm/MC/MCInstrInfo.h"
32 #include "llvm/MC/MCObjectFileInfo.h"
33 #include "llvm/MC/MCParser/MCAsmParser.h"
34 #include "llvm/MC/MCParser/MCTargetAsmParser.h"
35 #include "llvm/MC/MCRegisterInfo.h"
36 #include "llvm/MC/MCSubtargetInfo.h"
37 #include "llvm/MC/MCSymbol.h"
38 #include "llvm/MC/MCTargetOptions.h"
39 #include "llvm/Object/SymbolicFile.h"
40 #include "llvm/Support/Casting.h"
41 #include "llvm/Support/CodeGen.h"
42 #include "llvm/Support/ErrorHandling.h"
43 #include "llvm/Support/MemoryBuffer.h"
44 #include "llvm/Support/SMLoc.h"
45 #include "llvm/Support/SourceMgr.h"
46 #include "llvm/Support/TargetRegistry.h"
47 #include "llvm/Support/raw_ostream.h"
48 #include <algorithm>
49 #include <cassert>
50 #include <cstdint>
51 #include <memory>
52 #include <string>
53
54 using namespace llvm;
55 using namespace object;
56
addModule(Module * M)57 void ModuleSymbolTable::addModule(Module *M) {
58 if (FirstMod)
59 assert(FirstMod->getTargetTriple() == M->getTargetTriple());
60 else
61 FirstMod = M;
62
63 for (GlobalValue &GV : M->global_values())
64 SymTab.push_back(&GV);
65
66 CollectAsmSymbols(*M, [this](StringRef Name, BasicSymbolRef::Flags Flags) {
67 SymTab.push_back(new (AsmSymbols.Allocate())
68 AsmSymbol(std::string(Name), Flags));
69 });
70 }
71
72 static void
initializeRecordStreamer(const Module & M,function_ref<void (RecordStreamer &)> Init)73 initializeRecordStreamer(const Module &M,
74 function_ref<void(RecordStreamer &)> Init) {
75 StringRef InlineAsm = M.getModuleInlineAsm();
76 if (InlineAsm.empty())
77 return;
78
79 std::string Err;
80 const Triple TT(M.getTargetTriple());
81 const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
82 assert(T && T->hasMCAsmParser());
83
84 std::unique_ptr<MCRegisterInfo> MRI(T->createMCRegInfo(TT.str()));
85 if (!MRI)
86 return;
87
88 MCTargetOptions MCOptions;
89 std::unique_ptr<MCAsmInfo> MAI(T->createMCAsmInfo(*MRI, TT.str(), MCOptions));
90 if (!MAI)
91 return;
92
93 std::unique_ptr<MCSubtargetInfo> STI(
94 T->createMCSubtargetInfo(TT.str(), "", ""));
95 if (!STI)
96 return;
97
98 std::unique_ptr<MCInstrInfo> MCII(T->createMCInstrInfo());
99 if (!MCII)
100 return;
101
102 MCContext MCCtx(TT, MAI.get(), MRI.get(), STI.get());
103 std::unique_ptr<MCObjectFileInfo> MOFI(
104 T->createMCObjectFileInfo(MCCtx, /*PIC=*/false));
105 MOFI->setSDKVersion(M.getSDKVersion());
106 MCCtx.setObjectFileInfo(MOFI.get());
107 RecordStreamer Streamer(MCCtx, M);
108 T->createNullTargetStreamer(Streamer);
109
110 std::unique_ptr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer(InlineAsm));
111 SourceMgr SrcMgr;
112 SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
113 std::unique_ptr<MCAsmParser> Parser(
114 createMCAsmParser(SrcMgr, MCCtx, Streamer, *MAI));
115
116 std::unique_ptr<MCTargetAsmParser> TAP(
117 T->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
118 if (!TAP)
119 return;
120
121 // Module-level inline asm is assumed to use At&t syntax (see
122 // AsmPrinter::doInitialization()).
123 Parser->setAssemblerDialect(InlineAsm::AD_ATT);
124
125 Parser->setTargetParser(*TAP);
126 if (Parser->Run(false))
127 return;
128
129 Init(Streamer);
130 }
131
CollectAsmSymbols(const Module & M,function_ref<void (StringRef,BasicSymbolRef::Flags)> AsmSymbol)132 void ModuleSymbolTable::CollectAsmSymbols(
133 const Module &M,
134 function_ref<void(StringRef, BasicSymbolRef::Flags)> AsmSymbol) {
135 initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
136 Streamer.flushSymverDirectives();
137
138 for (auto &KV : Streamer) {
139 StringRef Key = KV.first();
140 RecordStreamer::State Value = KV.second;
141 // FIXME: For now we just assume that all asm symbols are executable.
142 uint32_t Res = BasicSymbolRef::SF_Executable;
143 switch (Value) {
144 case RecordStreamer::NeverSeen:
145 llvm_unreachable("NeverSeen should have been replaced earlier");
146 case RecordStreamer::DefinedGlobal:
147 Res |= BasicSymbolRef::SF_Global;
148 break;
149 case RecordStreamer::Defined:
150 break;
151 case RecordStreamer::Global:
152 case RecordStreamer::Used:
153 Res |= BasicSymbolRef::SF_Undefined;
154 Res |= BasicSymbolRef::SF_Global;
155 break;
156 case RecordStreamer::DefinedWeak:
157 Res |= BasicSymbolRef::SF_Weak;
158 Res |= BasicSymbolRef::SF_Global;
159 break;
160 case RecordStreamer::UndefinedWeak:
161 Res |= BasicSymbolRef::SF_Weak;
162 Res |= BasicSymbolRef::SF_Undefined;
163 }
164 AsmSymbol(Key, BasicSymbolRef::Flags(Res));
165 }
166 });
167 }
168
CollectAsmSymvers(const Module & M,function_ref<void (StringRef,StringRef)> AsmSymver)169 void ModuleSymbolTable::CollectAsmSymvers(
170 const Module &M, function_ref<void(StringRef, StringRef)> AsmSymver) {
171 initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
172 for (auto &KV : Streamer.symverAliases())
173 for (auto &Alias : KV.second)
174 AsmSymver(KV.first->getName(), Alias);
175 });
176 }
177
printSymbolName(raw_ostream & OS,Symbol S) const178 void ModuleSymbolTable::printSymbolName(raw_ostream &OS, Symbol S) const {
179 if (S.is<AsmSymbol *>()) {
180 OS << S.get<AsmSymbol *>()->first;
181 return;
182 }
183
184 auto *GV = S.get<GlobalValue *>();
185 if (GV->hasDLLImportStorageClass())
186 OS << "__imp_";
187
188 Mang.getNameWithPrefix(OS, GV, false);
189 }
190
getSymbolFlags(Symbol S) const191 uint32_t ModuleSymbolTable::getSymbolFlags(Symbol S) const {
192 if (S.is<AsmSymbol *>())
193 return S.get<AsmSymbol *>()->second;
194
195 auto *GV = S.get<GlobalValue *>();
196
197 uint32_t Res = BasicSymbolRef::SF_None;
198 if (GV->isDeclarationForLinker())
199 Res |= BasicSymbolRef::SF_Undefined;
200 else if (GV->hasHiddenVisibility() && !GV->hasLocalLinkage())
201 Res |= BasicSymbolRef::SF_Hidden;
202 if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
203 if (GVar->isConstant())
204 Res |= BasicSymbolRef::SF_Const;
205 }
206 if (dyn_cast_or_null<Function>(GV->getBaseObject()))
207 Res |= BasicSymbolRef::SF_Executable;
208 if (isa<GlobalAlias>(GV))
209 Res |= BasicSymbolRef::SF_Indirect;
210 if (GV->hasPrivateLinkage())
211 Res |= BasicSymbolRef::SF_FormatSpecific;
212 if (!GV->hasLocalLinkage())
213 Res |= BasicSymbolRef::SF_Global;
214 if (GV->hasCommonLinkage())
215 Res |= BasicSymbolRef::SF_Common;
216 if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() ||
217 GV->hasExternalWeakLinkage())
218 Res |= BasicSymbolRef::SF_Weak;
219
220 if (GV->getName().startswith("llvm."))
221 Res |= BasicSymbolRef::SF_FormatSpecific;
222 else if (auto *Var = dyn_cast<GlobalVariable>(GV)) {
223 if (Var->getSection() == "llvm.metadata")
224 Res |= BasicSymbolRef::SF_FormatSpecific;
225 }
226
227 return Res;
228 }
229