bolt/lib/RuntimeLibs/HugifyRuntimeLibrary.cpp

   1 //===- bolt/RuntimeLibs/HugifyRuntimeLibrary.cpp - Hugify RT Library ------===//
   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 file implements the HugifyRuntimeLibrary class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "bolt/RuntimeLibs/HugifyRuntimeLibrary.h"
  14 #include "bolt/Core/BinaryFunction.h"
  15 #include "bolt/Core/Linker.h"
  16 #include "llvm/MC/MCStreamer.h"
  17 #include "llvm/Support/Alignment.h"
  18 #include "llvm/Support/CommandLine.h"
  19
  20 using namespace llvm;
  21 using namespace bolt;
  22
  23 namespace opts {
  24
  25 extern cl::OptionCategory BoltOptCategory;
  26
  27 extern cl::opt<bool> HotText;
  28
  29 cl::opt<bool>
  30     Hugify("hugify",
  31            cl::desc("Automatically put hot code on 2MB page(s) (hugify) at "
  32                     "runtime. No manual call to hugify is needed in the binary "
  33                     "(which is what --hot-text relies on)."),
  34            cl::cat(BoltOptCategory));
  35
  36 static cl::opt<std::string> RuntimeHugifyLib(
  37     "runtime-hugify-lib",
  38     cl::desc("specify file name of the runtime hugify library"),
  39     cl::init("libbolt_rt_hugify.a"), cl::cat(BoltOptCategory));
  40
  41 } // namespace opts
  42
  43 void HugifyRuntimeLibrary::adjustCommandLineOptions(
  44     const BinaryContext &BC) const {
  45   if (opts::HotText) {
  46     errs()
  47         << "BOLT-ERROR: -hot-text should be applied to binaries with "
  48            "pre-compiled manual hugify support, while -hugify will add hugify "
  49            "support automatically. These two options cannot both be present.\n";
  50     exit(1);
  51   }
  52   // After the check, we set HotText to be true because automated hugify support
  53   // relies on it.
  54   opts::HotText = true;
  55   if (!BC.StartFunctionAddress) {
  56     errs() << "BOLT-ERROR: hugify runtime libraries require a known entry "
  57               "point of "
  58               "the input binary\n";
  59     exit(1);
  60   }
  61 }
  62
  63 void HugifyRuntimeLibrary::link(BinaryContext &BC, StringRef ToolPath,
  64                                 BOLTLinker &Linker,
  65                                 BOLTLinker::SectionsMapper MapSections) {
  66
  67   std::string LibPath = getLibPath(ToolPath, opts::RuntimeHugifyLib);
  68   loadLibrary(LibPath, Linker, MapSections);
  69
  70   assert(!RuntimeStartAddress &&
  71          "We don't currently support linking multiple runtime libraries");
  72   RuntimeStartAddress = Linker.lookupSymbol("__bolt_hugify_self").value_or(0);
  73   if (!RuntimeStartAddress) {
  74     errs() << "BOLT-ERROR: instrumentation library does not define "
  75               "__bolt_hugify_self: "
  76            << LibPath << "\n";
  77     exit(1);
  78   }
  79 }