llvm/lib/ExecutionEngine/Orc/LinkGraphLayer.cpp

   1 //===----- LinkGraphLayer.cpp - Add LinkGraphs to an ExecutionSession -----===//
   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 #include "llvm/ExecutionEngine/Orc/LinkGraphLayer.h"
  10
  11 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
  12 #include "llvm/ExecutionEngine/Orc/Shared/MachOObjectFormat.h"
  13 #include "llvm/ExecutionEngine/Orc/Shared/ObjectFormats.h"
  14
  15 #define DEBUG_TYPE "orc"
  16
  17 using namespace llvm;
  18 using namespace llvm::jitlink;
  19 using namespace llvm::orc;
  20
  21 namespace {
  22
  23 bool hasInitializerSection(LinkGraph &G) {
  24   bool IsMachO = G.getTargetTriple().isOSBinFormatMachO();
  25   bool IsElf = G.getTargetTriple().isOSBinFormatELF();
  26   if (!IsMachO && !IsElf)
  27     return false;
  28
  29   for (auto &Sec : G.sections()) {
  30     if (IsMachO && isMachOInitializerSection(Sec.getName()))
  31       return true;
  32     if (IsElf && isELFInitializerSection(Sec.getName()))
  33       return true;
  34   }
  35
  36   return false;
  37 }
  38
  39 } // end anonymous namespace
  40
  41 namespace llvm::orc {
  42
  43 LinkGraphLayer::~LinkGraphLayer() = default;
  44
  45 MaterializationUnit::Interface LinkGraphLayer::getInterface(LinkGraph &G) {
  46
  47   MaterializationUnit::Interface LGI;
  48
  49   auto AddSymbol = [&](Symbol *Sym) {
  50     // Skip local symbols.
  51     if (Sym->getScope() == Scope::Local)
  52       return;
  53     assert(Sym->hasName() && "Anonymous non-local symbol?");
  54
  55     LGI.SymbolFlags[Sym->getName()] = getJITSymbolFlagsForSymbol(*Sym);
  56   };
  57
  58   for (auto *Sym : G.defined_symbols())
  59     AddSymbol(Sym);
  60   for (auto *Sym : G.absolute_symbols())
  61     AddSymbol(Sym);
  62
  63   if (hasInitializerSection(G)) {
  64     std::string InitSymString;
  65     {
  66       raw_string_ostream(InitSymString)
  67           << "$." << G.getName() << ".__inits" << Counter++;
  68     }
  69     LGI.InitSymbol = ES.intern(InitSymString);
  70   }
  71
  72   return LGI;
  73 }
  74
  75 JITSymbolFlags LinkGraphLayer::getJITSymbolFlagsForSymbol(Symbol &Sym) {
  76   JITSymbolFlags Flags;
  77
  78   if (Sym.getLinkage() == Linkage::Weak)
  79     Flags |= JITSymbolFlags::Weak;
  80
  81   if (Sym.getScope() == Scope::Default)
  82     Flags |= JITSymbolFlags::Exported;
  83   else if (Sym.getScope() == Scope::SideEffectsOnly)
  84     Flags |= JITSymbolFlags::MaterializationSideEffectsOnly;
  85
  86   if (Sym.isCallable())
  87     Flags |= JITSymbolFlags::Callable;
  88
  89   return Flags;
  90 }
  91
  92 StringRef LinkGraphMaterializationUnit::getName() const { return G->getName(); }
  93
  94 void LinkGraphMaterializationUnit::discard(const JITDylib &JD,
  95                                            const SymbolStringPtr &Name) {
  96   for (auto *Sym : G->defined_symbols())
  97     if (Sym->getName() == Name) {
  98       assert(Sym->getLinkage() == Linkage::Weak &&
  99              "Discarding non-weak definition");
 100       G->makeExternal(*Sym);
 101       break;
 102     }
 103 }
 104
 105 } // namespace llvm::orc