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