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72115d5fb6
Summary:
Currently llvm::SplitModule as the first step globalizes all local objects, which might not be desirable in some scenarios.
This change adds a new flag to llvm::SplitModule that uses SCC approach to search for a balanced partition without the need to externalize symbols.
Such partition might not be possible or fully balanced for a given number of partitions, and is a function of the module properties (global/local dependencies within the module).
Joint development Tobias Edler von Koch (tobias@codeaurora.org) and Sergei Larin (slarin@codeaurora.org)
Subscribers: llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D16124
llvm-svn: 258083
98 lines
3.8 KiB
C++
98 lines
3.8 KiB
C++
//===-- ParallelCG.cpp ----------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines functions that can be used for parallel code generation.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/ParallelCG.h"
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#include "llvm/Bitcode/ReaderWriter.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/LegacyPassManager.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Support/ErrorOr.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/Support/TargetRegistry.h"
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#include "llvm/Support/thread.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Transforms/Utils/SplitModule.h"
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using namespace llvm;
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static void codegen(Module *M, llvm::raw_pwrite_stream &OS,
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const Target *TheTarget, StringRef CPU, StringRef Features,
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const TargetOptions &Options, Reloc::Model RM,
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CodeModel::Model CM, CodeGenOpt::Level OL,
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TargetMachine::CodeGenFileType FileType) {
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std::unique_ptr<TargetMachine> TM(TheTarget->createTargetMachine(
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M->getTargetTriple(), CPU, Features, Options, RM, CM, OL));
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legacy::PassManager CodeGenPasses;
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if (TM->addPassesToEmitFile(CodeGenPasses, OS, FileType))
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report_fatal_error("Failed to setup codegen");
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CodeGenPasses.run(*M);
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}
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std::unique_ptr<Module>
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llvm::splitCodeGen(std::unique_ptr<Module> M,
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ArrayRef<llvm::raw_pwrite_stream *> OSs, StringRef CPU,
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StringRef Features, const TargetOptions &Options,
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Reloc::Model RM, CodeModel::Model CM, CodeGenOpt::Level OL,
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TargetMachine::CodeGenFileType FileType,
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bool PreserveLocals) {
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StringRef TripleStr = M->getTargetTriple();
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std::string ErrMsg;
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const Target *TheTarget = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
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if (!TheTarget)
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report_fatal_error(Twine("Target not found: ") + ErrMsg);
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if (OSs.size() == 1) {
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codegen(M.get(), *OSs[0], TheTarget, CPU, Features, Options, RM, CM,
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OL, FileType);
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return M;
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}
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std::vector<thread> Threads;
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SplitModule(std::move(M), OSs.size(), [&](std::unique_ptr<Module> MPart) {
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// We want to clone the module in a new context to multi-thread the codegen.
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// We do it by serializing partition modules to bitcode (while still on the
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// main thread, in order to avoid data races) and spinning up new threads
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// which deserialize the partitions into separate contexts.
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// FIXME: Provide a more direct way to do this in LLVM.
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SmallVector<char, 0> BC;
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raw_svector_ostream BCOS(BC);
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WriteBitcodeToFile(MPart.get(), BCOS);
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llvm::raw_pwrite_stream *ThreadOS = OSs[Threads.size()];
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Threads.emplace_back(
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[TheTarget, CPU, Features, Options, RM, CM, OL, FileType,
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ThreadOS](const SmallVector<char, 0> &BC) {
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LLVMContext Ctx;
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ErrorOr<std::unique_ptr<Module>> MOrErr =
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parseBitcodeFile(MemoryBufferRef(StringRef(BC.data(), BC.size()),
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"<split-module>"),
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Ctx);
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if (!MOrErr)
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report_fatal_error("Failed to read bitcode");
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std::unique_ptr<Module> MPartInCtx = std::move(MOrErr.get());
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codegen(MPartInCtx.get(), *ThreadOS, TheTarget, CPU, Features,
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Options, RM, CM, OL, FileType);
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},
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// Pass BC using std::move to ensure that it get moved rather than
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// copied into the thread's context.
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std::move(BC));
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}, PreserveLocals);
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for (thread &T : Threads)
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T.join();
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return {};
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}
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