1 files changed, 375 insertions, 0 deletions
diff --git a/contrib/llvm/lib/LTO/LTOBackend.cpp b/contrib/llvm/lib/LTO/LTOBackend.cpp
new file mode 100644
index 0000000..809db80
--- /dev/null
+++ b/contrib/llvm/lib/LTO/LTOBackend.cpp
@@ -0,0 +1,375 @@
+//===-LTOBackend.cpp - LLVM Link Time Optimizer Backend -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the "backend" phase of LTO, i.e. it performs
+// optimization and code generation on a loaded module. It is generally used
+// internally by the LTO class but can also be used independently, for example
+// to implement a standalone ThinLTO backend.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/LTO/LTOBackend.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/CGSCCPassManager.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/Bitcode/BitcodeReader.h"
+#include "llvm/Bitcode/BitcodeWriter.h"
+#include "llvm/IR/LegacyPassManager.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/Verifier.h"
+#include "llvm/LTO/LTO.h"
+#include "llvm/LTO/legacy/UpdateCompilerUsed.h"
+#include "llvm/MC/SubtargetFeature.h"
+#include "llvm/Passes/PassBuilder.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/ThreadPool.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/IPO/PassManagerBuilder.h"
+#include "llvm/Transforms/Scalar/LoopPassManager.h"
+#include "llvm/Transforms/Utils/FunctionImportUtils.h"
+#include "llvm/Transforms/Utils/SplitModule.h"
+
+using namespace llvm;
+using namespace lto;
+
+LLVM_ATTRIBUTE_NORETURN static void reportOpenError(StringRef Path, Twine Msg) {
+  errs() << "failed to open " << Path << ": " << Msg << '\n';
+  errs().flush();
+  exit(1);
+}
+
+Error Config::addSaveTemps(std::string OutputFileName,
+                           bool UseInputModulePath) {
+  ShouldDiscardValueNames = false;
+
+  std::error_code EC;
+  ResolutionFile = llvm::make_unique<raw_fd_ostream>(
+      OutputFileName + "resolution.txt", EC, sys::fs::OpenFlags::F_Text);
+  if (EC)
+    return errorCodeToError(EC);
+
+  auto setHook = [&](std::string PathSuffix, ModuleHookFn &Hook) {
+    // Keep track of the hook provided by the linker, which also needs to run.
+    ModuleHookFn LinkerHook = Hook;
+    Hook = [=](unsigned Task, const Module &M) {
+      // If the linker's hook returned false, we need to pass that result
+      // through.
+      if (LinkerHook && !LinkerHook(Task, M))
+        return false;
+
+      std::string PathPrefix;
+      // If this is the combined module (not a ThinLTO backend compile) or the
+      // user hasn't requested using the input module's path, emit to a file
+      // named from the provided OutputFileName with the Task ID appended.
+      if (M.getModuleIdentifier() == "ld-temp.o" || !UseInputModulePath) {
+        PathPrefix = OutputFileName + utostr(Task);
+      } else
+        PathPrefix = M.getModuleIdentifier();
+      std::string Path = PathPrefix + "." + PathSuffix + ".bc";
+      std::error_code EC;
+      raw_fd_ostream OS(Path, EC, sys::fs::OpenFlags::F_None);
+      // Because -save-temps is a debugging feature, we report the error
+      // directly and exit.
+      if (EC)
+        reportOpenError(Path, EC.message());
+      WriteBitcodeToFile(&M, OS, /*ShouldPreserveUseListOrder=*/false);
+      return true;
+    };
+  };
+
+  setHook("0.preopt", PreOptModuleHook);
+  setHook("1.promote", PostPromoteModuleHook);
+  setHook("2.internalize", PostInternalizeModuleHook);
+  setHook("3.import", PostImportModuleHook);
+  setHook("4.opt", PostOptModuleHook);
+  setHook("5.precodegen", PreCodeGenModuleHook);
+
+  CombinedIndexHook = [=](const ModuleSummaryIndex &Index) {
+    std::string Path = OutputFileName + "index.bc";
+    std::error_code EC;
+    raw_fd_ostream OS(Path, EC, sys::fs::OpenFlags::F_None);
+    // Because -save-temps is a debugging feature, we report the error
+    // directly and exit.
+    if (EC)
+      reportOpenError(Path, EC.message());
+    WriteIndexToFile(Index, OS);
+    return true;
+  };
+
+  return Error::success();
+}
+
+namespace {
+
+std::unique_ptr<TargetMachine>
+createTargetMachine(Config &Conf, StringRef TheTriple,
+                    const Target *TheTarget) {
+  SubtargetFeatures Features;
+  Features.getDefaultSubtargetFeatures(Triple(TheTriple));
+  for (const std::string &A : Conf.MAttrs)
+    Features.AddFeature(A);
+
+  return std::unique_ptr<TargetMachine>(TheTarget->createTargetMachine(
+      TheTriple, Conf.CPU, Features.getString(), Conf.Options, Conf.RelocModel,
+      Conf.CodeModel, Conf.CGOptLevel));
+}
+
+static void runNewPMCustomPasses(Module &Mod, TargetMachine *TM,
+                                 std::string PipelineDesc,
+                                 std::string AAPipelineDesc,
+                                 bool DisableVerify) {
+  PassBuilder PB(TM);
+  AAManager AA;
+
+  // Parse a custom AA pipeline if asked to.
+  if (!AAPipelineDesc.empty())
+    if (!PB.parseAAPipeline(AA, AAPipelineDesc))
+      report_fatal_error("unable to parse AA pipeline description: " +
+                         AAPipelineDesc);
+
+  LoopAnalysisManager LAM;
+  FunctionAnalysisManager FAM;
+  CGSCCAnalysisManager CGAM;
+  ModuleAnalysisManager MAM;
+
+  // Register the AA manager first so that our version is the one used.
+  FAM.registerPass([&] { return std::move(AA); });
+
+  // Register all the basic analyses with the managers.
+  PB.registerModuleAnalyses(MAM);
+  PB.registerCGSCCAnalyses(CGAM);
+  PB.registerFunctionAnalyses(FAM);
+  PB.registerLoopAnalyses(LAM);
+  PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
+
+  ModulePassManager MPM;
+
+  // Always verify the input.
+  MPM.addPass(VerifierPass());
+
+  // Now, add all the passes we've been requested to.
+  if (!PB.parsePassPipeline(MPM, PipelineDesc))
+    report_fatal_error("unable to parse pass pipeline description: " +
+                       PipelineDesc);
+
+  if (!DisableVerify)
+    MPM.addPass(VerifierPass());
+  MPM.run(Mod, MAM);
+}
+
+static void runOldPMPasses(Config &Conf, Module &Mod, TargetMachine *TM,
+                           bool IsThinLTO) {
+  legacy::PassManager passes;
+  passes.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
+
+  PassManagerBuilder PMB;
+  PMB.LibraryInfo = new TargetLibraryInfoImpl(Triple(TM->getTargetTriple()));
+  PMB.Inliner = createFunctionInliningPass();
+  // Unconditionally verify input since it is not verified before this
+  // point and has unknown origin.
+  PMB.VerifyInput = true;
+  PMB.VerifyOutput = !Conf.DisableVerify;
+  PMB.LoopVectorize = true;
+  PMB.SLPVectorize = true;
+  PMB.OptLevel = Conf.OptLevel;
+  PMB.PGOSampleUse = Conf.SampleProfile;
+  if (IsThinLTO)
+    PMB.populateThinLTOPassManager(passes);
+  else
+    PMB.populateLTOPassManager(passes);
+  passes.run(Mod);
+}
+
+bool opt(Config &Conf, TargetMachine *TM, unsigned Task, Module &Mod,
+         bool IsThinLTO) {
+  if (Conf.OptPipeline.empty())
+    runOldPMPasses(Conf, Mod, TM, IsThinLTO);
+  else
+    runNewPMCustomPasses(Mod, TM, Conf.OptPipeline, Conf.AAPipeline,
+                         Conf.DisableVerify);
+  return !Conf.PostOptModuleHook || Conf.PostOptModuleHook(Task, Mod);
+}
+
+void codegen(Config &Conf, TargetMachine *TM, AddStreamFn AddStream,
+             unsigned Task, Module &Mod) {
+  if (Conf.PreCodeGenModuleHook && !Conf.PreCodeGenModuleHook(Task, Mod))
+    return;
+
+  auto Stream = AddStream(Task);
+  legacy::PassManager CodeGenPasses;
+  if (TM->addPassesToEmitFile(CodeGenPasses, *Stream->OS,
+                              TargetMachine::CGFT_ObjectFile))
+    report_fatal_error("Failed to setup codegen");
+  CodeGenPasses.run(Mod);
+}
+
+void splitCodeGen(Config &C, TargetMachine *TM, AddStreamFn AddStream,
+                  unsigned ParallelCodeGenParallelismLevel,
+                  std::unique_ptr<Module> Mod) {
+  ThreadPool CodegenThreadPool(ParallelCodeGenParallelismLevel);
+  unsigned ThreadCount = 0;
+  const Target *T = &TM->getTarget();
+
+  SplitModule(
+      std::move(Mod), ParallelCodeGenParallelismLevel,
+      [&](std::unique_ptr<Module> MPart) {
+        // We want to clone the module in a new context to multi-thread the
+        // codegen. We do it by serializing partition modules to bitcode
+        // (while still on the main thread, in order to avoid data races) and
+        // spinning up new threads which deserialize the partitions into
+        // separate contexts.
+        // FIXME: Provide a more direct way to do this in LLVM.
+        SmallString<0> BC;
+        raw_svector_ostream BCOS(BC);
+        WriteBitcodeToFile(MPart.get(), BCOS);
+
+        // Enqueue the task
+        CodegenThreadPool.async(
+            [&](const SmallString<0> &BC, unsigned ThreadId) {
+              LTOLLVMContext Ctx(C);
+              Expected<std::unique_ptr<Module>> MOrErr = parseBitcodeFile(
+                  MemoryBufferRef(StringRef(BC.data(), BC.size()), "ld-temp.o"),
+                  Ctx);
+              if (!MOrErr)
+                report_fatal_error("Failed to read bitcode");
+              std::unique_ptr<Module> MPartInCtx = std::move(MOrErr.get());
+
+              std::unique_ptr<TargetMachine> TM =
+                  createTargetMachine(C, MPartInCtx->getTargetTriple(), T);
+
+              codegen(C, TM.get(), AddStream, ThreadId, *MPartInCtx);
+            },
+            // Pass BC using std::move to ensure that it get moved rather than
+            // copied into the thread's context.
+            std::move(BC), ThreadCount++);
+      },
+      false);
+
+  // Because the inner lambda (which runs in a worker thread) captures our local
+  // variables, we need to wait for the worker threads to terminate before we
+  // can leave the function scope.
+  CodegenThreadPool.wait();
+}
+
+Expected<const Target *> initAndLookupTarget(Config &C, Module &Mod) {
+  if (!C.OverrideTriple.empty())
+    Mod.setTargetTriple(C.OverrideTriple);
+  else if (Mod.getTargetTriple().empty())
+    Mod.setTargetTriple(C.DefaultTriple);
+
+  std::string Msg;
+  const Target *T = TargetRegistry::lookupTarget(Mod.getTargetTriple(), Msg);
+  if (!T)
+    return make_error<StringError>(Msg, inconvertibleErrorCode());
+  return T;
+}
+
+}
+
+static void handleAsmUndefinedRefs(Module &Mod, TargetMachine &TM) {
+  // Collect the list of undefined symbols used in asm and update
+  // llvm.compiler.used to prevent optimization to drop these from the output.
+  StringSet<> AsmUndefinedRefs;
+  ModuleSymbolTable::CollectAsmSymbols(
+      Triple(Mod.getTargetTriple()), Mod.getModuleInlineAsm(),
+      [&AsmUndefinedRefs](StringRef Name, object::BasicSymbolRef::Flags Flags) {
+        if (Flags & object::BasicSymbolRef::SF_Undefined)
+          AsmUndefinedRefs.insert(Name);
+      });
+  updateCompilerUsed(Mod, TM, AsmUndefinedRefs);
+}
+
+Error lto::backend(Config &C, AddStreamFn AddStream,
+                   unsigned ParallelCodeGenParallelismLevel,
+                   std::unique_ptr<Module> Mod) {
+  Expected<const Target *> TOrErr = initAndLookupTarget(C, *Mod);
+  if (!TOrErr)
+    return TOrErr.takeError();
+
+  std::unique_ptr<TargetMachine> TM =
+      createTargetMachine(C, Mod->getTargetTriple(), *TOrErr);
+
+  handleAsmUndefinedRefs(*Mod, *TM);
+
+  if (!C.CodeGenOnly)
+    if (!opt(C, TM.get(), 0, *Mod, /*IsThinLTO=*/false))
+      return Error::success();
+
+  if (ParallelCodeGenParallelismLevel == 1) {
+    codegen(C, TM.get(), AddStream, 0, *Mod);
+  } else {
+    splitCodeGen(C, TM.get(), AddStream, ParallelCodeGenParallelismLevel,
+                 std::move(Mod));
+  }
+  return Error::success();
+}
+
+Error lto::thinBackend(Config &Conf, unsigned Task, AddStreamFn AddStream,
+                       Module &Mod, ModuleSummaryIndex &CombinedIndex,
+                       const FunctionImporter::ImportMapTy &ImportList,
+                       const GVSummaryMapTy &DefinedGlobals,
+                       MapVector<StringRef, BitcodeModule> &ModuleMap) {
+  Expected<const Target *> TOrErr = initAndLookupTarget(Conf, Mod);
+  if (!TOrErr)
+    return TOrErr.takeError();
+
+  std::unique_ptr<TargetMachine> TM =
+      createTargetMachine(Conf, Mod.getTargetTriple(), *TOrErr);
+
+  handleAsmUndefinedRefs(Mod, *TM);
+
+  if (Conf.CodeGenOnly) {
+    codegen(Conf, TM.get(), AddStream, Task, Mod);
+    return Error::success();
+  }
+
+  if (Conf.PreOptModuleHook && !Conf.PreOptModuleHook(Task, Mod))
+    return Error::success();
+
+  renameModuleForThinLTO(Mod, CombinedIndex);
+
+  thinLTOResolveWeakForLinkerModule(Mod, DefinedGlobals);
+
+  if (Conf.PostPromoteModuleHook && !Conf.PostPromoteModuleHook(Task, Mod))
+    return Error::success();
+
+  if (!DefinedGlobals.empty())
+    thinLTOInternalizeModule(Mod, DefinedGlobals);
+
+  if (Conf.PostInternalizeModuleHook &&
+      !Conf.PostInternalizeModuleHook(Task, Mod))
+    return Error::success();
+
+  auto ModuleLoader = [&](StringRef Identifier) {
+    assert(Mod.getContext().isODRUniquingDebugTypes() &&
+           "ODR Type uniquing should be enabled on the context");
+    auto I = ModuleMap.find(Identifier);
+    assert(I != ModuleMap.end());
+    return I->second.getLazyModule(Mod.getContext(),
+                                   /*ShouldLazyLoadMetadata=*/true,
+                                   /*IsImporting*/ true);
+  };
+
+  FunctionImporter Importer(CombinedIndex, ModuleLoader);
+  if (Error Err = Importer.importFunctions(Mod, ImportList).takeError())
+    return Err;
+
+  if (Conf.PostImportModuleHook && !Conf.PostImportModuleHook(Task, Mod))
+    return Error::success();
+
+  if (!opt(Conf, TM.get(), Task, Mod, /*IsThinLTO=*/true))
+    return Error::success();
+
+  codegen(Conf, TM.get(), AddStream, Task, Mod);
+  return Error::success();
+}