bolt/lib/Passes/Hugify.cpp

   1 //===--- bolt/Passes/Hugify.cpp -------------------------------------------===//
   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 "bolt/Passes/Hugify.h"
  10
  11 #define DEBUG_TYPE "bolt-hugify"
  12
  13 using namespace llvm;
  14
  15 namespace llvm {
  16 namespace bolt {
  17
  18 Error HugePage::runOnFunctions(BinaryContext &BC) {
  19   auto *RtLibrary = BC.getRuntimeLibrary();
  20   if (!RtLibrary || !BC.isELF() || !BC.StartFunctionAddress) {
  21     return Error::success();
  22   }
  23
  24   auto createSimpleFunction =
  25       [&](std::string Title, std::vector<MCInst> Instrs) -> BinaryFunction * {
  26     BinaryFunction *Func = BC.createInjectedBinaryFunction(Title);
  27
  28     std::vector<std::unique_ptr<BinaryBasicBlock>> BBs;
  29     BBs.emplace_back(Func->createBasicBlock(nullptr));
  30     BBs.back()->addInstructions(Instrs.begin(), Instrs.end());
  31     BBs.back()->setCFIState(0);
  32     BBs.back()->setOffset(BinaryBasicBlock::INVALID_OFFSET);
  33
  34     Func->insertBasicBlocks(nullptr, std::move(BBs),
  35                             /*UpdateLayout=*/true,
  36                             /*UpdateCFIState=*/false);
  37     Func->updateState(BinaryFunction::State::CFG_Finalized);
  38     return Func;
  39   };
  40
  41   const BinaryFunction *const Start =
  42       BC.getBinaryFunctionAtAddress(*BC.StartFunctionAddress);
  43   assert(Start && "Entry point function not found");
  44   const MCSymbol *StartSym = Start->getSymbol();
  45   createSimpleFunction("__bolt_hugify_start_program",
  46                        BC.MIB->createSymbolTrampoline(StartSym, BC.Ctx.get()));
  47   return Error::success();
  48 }
  49 } // namespace bolt
  50 } // namespace llvm