lib/ExecutionEngine/JITLink/BasicGOTAndStubsBuilder.h

   1 //===--- BasicGOTAndStubsBuilder.h - Generic GOT/Stub creation --*- C++ -*-===//
   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 // A base for simple GOT and stub creation.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef LLVM_LIB_EXECUTIONENGINE_JITLINK_BASICGOTANDSTUBSBUILDER_H
  14 #define LLVM_LIB_EXECUTIONENGINE_JITLINK_BASICGOTANDSTUBSBUILDER_H
  15
  16 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
  17
  18 namespace llvm {
  19 namespace jitlink {
  20
  21 template <typename BuilderImpl> class BasicGOTAndStubsBuilder {
  22 public:
  23   BasicGOTAndStubsBuilder(AtomGraph &G) : G(G) {}
  24
  25   void run() {
  26     // We're going to be adding new atoms, but we don't want to iterate over
  27     // the newly added ones, so just copy the existing atoms out.
  28     std::vector<DefinedAtom *> DAs(G.defined_atoms().begin(),
  29                                    G.defined_atoms().end());
  30
  31     for (auto *DA : DAs)
  32       for (auto &E : DA->edges())
  33         if (impl().isGOTEdge(E))
  34           impl().fixGOTEdge(E, getGOTEntryAtom(E.getTarget()));
  35         else if (impl().isExternalBranchEdge(E))
  36           impl().fixExternalBranchEdge(E, getStubAtom(E.getTarget()));
  37   }
  38
  39 protected:
  40   Atom &getGOTEntryAtom(Atom &Target) {
  41     assert(Target.hasName() && "GOT edge cannot point to anonymous target");
  42
  43     auto GOTEntryI = GOTEntries.find(Target.getName());
  44
  45     // Build the entry if it doesn't exist.
  46     if (GOTEntryI == GOTEntries.end()) {
  47       auto &GOTEntry = impl().createGOTEntry(Target);
  48       GOTEntryI =
  49           GOTEntries.insert(std::make_pair(Target.getName(), &GOTEntry)).first;
  50     }
  51
  52     assert(GOTEntryI != GOTEntries.end() && "Could not get GOT entry atom");
  53     return *GOTEntryI->second;
  54   }
  55
  56   Atom &getStubAtom(Atom &Target) {
  57     assert(Target.hasName() &&
  58            "External branch edge can not point to an anonymous target");
  59     auto StubI = Stubs.find(Target.getName());
  60
  61     if (StubI == Stubs.end()) {
  62       auto &StubAtom = impl().createStub(Target);
  63       StubI = Stubs.insert(std::make_pair(Target.getName(), &StubAtom)).first;
  64     }
  65
  66     assert(StubI != Stubs.end() && "Count not get stub atom");
  67     return *StubI->second;
  68   }
  69
  70   AtomGraph &G;
  71
  72 private:
  73   BuilderImpl &impl() { return static_cast<BuilderImpl &>(*this); }
  74
  75   DenseMap<StringRef, DefinedAtom *> GOTEntries;
  76   DenseMap<StringRef, DefinedAtom *> Stubs;
  77 };
  78
  79 } // end namespace jitlink
  80 } // end namespace llvm
  81
  82 #endif // LLVM_LIB_EXECUTIONENGINE_JITLINK_BASICGOTANDSTUBSBUILDER_H