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
54using namespace llvm;
55using namespace object;
56
57void 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
72static void
73initializeRecordStreamer(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  MCObjectFileInfo MOFI;
103  MCContext MCCtx(MAI.get(), MRI.get(), &MOFI);
104  MOFI.InitMCObjectFileInfo(TT, /*PIC*/ false, MCCtx);
105  MOFI.setSDKVersion(M.getSDKVersion());
106  RecordStreamer Streamer(MCCtx, M);
107  T->createNullTargetStreamer(Streamer);
108
109  std::unique_ptr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer(InlineAsm));
110  SourceMgr SrcMgr;
111  SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
112  std::unique_ptr<MCAsmParser> Parser(
113      createMCAsmParser(SrcMgr, MCCtx, Streamer, *MAI));
114
115  std::unique_ptr<MCTargetAsmParser> TAP(
116      T->createMCAsmParser(*STI, *Parser, *MCII, MCOptions));
117  if (!TAP)
118    return;
119
120  // Module-level inline asm is assumed to use At&t syntax (see
121  // AsmPrinter::doInitialization()).
122  Parser->setAssemblerDialect(InlineAsm::AD_ATT);
123
124  Parser->setTargetParser(*TAP);
125  if (Parser->Run(false))
126    return;
127
128  Init(Streamer);
129}
130
131void ModuleSymbolTable::CollectAsmSymbols(
132    const Module &M,
133    function_ref<void(StringRef, BasicSymbolRef::Flags)> AsmSymbol) {
134  initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
135    Streamer.flushSymverDirectives();
136
137    for (auto &KV : Streamer) {
138      StringRef Key = KV.first();
139      RecordStreamer::State Value = KV.second;
140      // FIXME: For now we just assume that all asm symbols are executable.
141      uint32_t Res = BasicSymbolRef::SF_Executable;
142      switch (Value) {
143      case RecordStreamer::NeverSeen:
144        llvm_unreachable("NeverSeen should have been replaced earlier");
145      case RecordStreamer::DefinedGlobal:
146        Res |= BasicSymbolRef::SF_Global;
147        break;
148      case RecordStreamer::Defined:
149        break;
150      case RecordStreamer::Global:
151      case RecordStreamer::Used:
152        Res |= BasicSymbolRef::SF_Undefined;
153        Res |= BasicSymbolRef::SF_Global;
154        break;
155      case RecordStreamer::DefinedWeak:
156        Res |= BasicSymbolRef::SF_Weak;
157        Res |= BasicSymbolRef::SF_Global;
158        break;
159      case RecordStreamer::UndefinedWeak:
160        Res |= BasicSymbolRef::SF_Weak;
161        Res |= BasicSymbolRef::SF_Undefined;
162      }
163      AsmSymbol(Key, BasicSymbolRef::Flags(Res));
164    }
165  });
166}
167
168void ModuleSymbolTable::CollectAsmSymvers(
169    const Module &M, function_ref<void(StringRef, StringRef)> AsmSymver) {
170  initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
171    for (auto &KV : Streamer.symverAliases())
172      for (auto &Alias : KV.second)
173        AsmSymver(KV.first->getName(), Alias);
174  });
175}
176
177void ModuleSymbolTable::printSymbolName(raw_ostream &OS, Symbol S) const {
178  if (S.is<AsmSymbol *>()) {
179    OS << S.get<AsmSymbol *>()->first;
180    return;
181  }
182
183  auto *GV = S.get<GlobalValue *>();
184  if (GV->hasDLLImportStorageClass())
185    OS << "__imp_";
186
187  Mang.getNameWithPrefix(OS, GV, false);
188}
189
190uint32_t ModuleSymbolTable::getSymbolFlags(Symbol S) const {
191  if (S.is<AsmSymbol *>())
192    return S.get<AsmSymbol *>()->second;
193
194  auto *GV = S.get<GlobalValue *>();
195
196  uint32_t Res = BasicSymbolRef::SF_None;
197  if (GV->isDeclarationForLinker())
198    Res |= BasicSymbolRef::SF_Undefined;
199  else if (GV->hasHiddenVisibility() && !GV->hasLocalLinkage())
200    Res |= BasicSymbolRef::SF_Hidden;
201  if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
202    if (GVar->isConstant())
203      Res |= BasicSymbolRef::SF_Const;
204  }
205  if (dyn_cast_or_null<Function>(GV->getBaseObject()))
206    Res |= BasicSymbolRef::SF_Executable;
207  if (isa<GlobalAlias>(GV))
208    Res |= BasicSymbolRef::SF_Indirect;
209  if (GV->hasPrivateLinkage())
210    Res |= BasicSymbolRef::SF_FormatSpecific;
211  if (!GV->hasLocalLinkage())
212    Res |= BasicSymbolRef::SF_Global;
213  if (GV->hasCommonLinkage())
214    Res |= BasicSymbolRef::SF_Common;
215  if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() ||
216      GV->hasExternalWeakLinkage())
217    Res |= BasicSymbolRef::SF_Weak;
218
219  if (GV->getName().startswith("llvm."))
220    Res |= BasicSymbolRef::SF_FormatSpecific;
221  else if (auto *Var = dyn_cast<GlobalVariable>(GV)) {
222    if (Var->getSection() == "llvm.metadata")
223      Res |= BasicSymbolRef::SF_FormatSpecific;
224  }
225
226  return Res;
227}
228