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2d3eb26eeb
Add a top-level STRTAB block containing a string table blob, and start storing strings for module codes FUNCTION, GLOBALVAR, ALIAS, IFUNC and COMDAT in the string table. This change allows us to share names between globals and comdats as well as between modules, and improves the efficiency of loading bitcode files by no longer using a bit encoding for symbol names. Once we start writing the irsymtab to the bitcode file we will also be able to share strings between it and the module. On my machine, link time for Chromium for Linux with ThinLTO decreases by about 7% for no-op incremental builds or about 1% for full builds. Total bitcode file size decreases by about 3%. As discussed on llvm-dev: http://lists.llvm.org/pipermail/llvm-dev/2017-April/111732.html Differential Revision: https://reviews.llvm.org/D31838 llvm-svn: 300464
81 lines
2.8 KiB
C++
81 lines
2.8 KiB
C++
//===-- llvm-cat.cpp - LLVM module concatenation utility ------------------===//
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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 program is for testing features that rely on multi-module bitcode files.
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// It takes a list of input modules and uses them to create a multi-module
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// bitcode file.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Bitcode/BitcodeReader.h"
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#include "llvm/Bitcode/BitcodeWriter.h"
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#include "llvm/IRReader/IRReader.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/FileSystem.h"
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using namespace llvm;
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static cl::opt<bool>
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BinaryCat("b", cl::desc("Whether to perform binary concatenation"));
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static cl::opt<std::string> OutputFilename("o", cl::Required,
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cl::desc("Output filename"),
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cl::value_desc("filename"));
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static cl::list<std::string> InputFilenames(cl::Positional, cl::ZeroOrMore,
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cl::desc("<input files>"));
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int main(int argc, char **argv) {
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cl::ParseCommandLineOptions(argc, argv, "Module concatenation");
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ExitOnError ExitOnErr("llvm-cat: ");
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LLVMContext Context;
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SmallVector<char, 0> Buffer;
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BitcodeWriter Writer(Buffer);
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if (BinaryCat) {
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for (const auto &InputFilename : InputFilenames) {
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std::unique_ptr<MemoryBuffer> MB = ExitOnErr(
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errorOrToExpected(MemoryBuffer::getFileOrSTDIN(InputFilename)));
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std::vector<BitcodeModule> Mods = ExitOnErr(getBitcodeModuleList(*MB));
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for (auto &BitcodeMod : Mods) {
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Buffer.insert(Buffer.end(), BitcodeMod.getBuffer().begin(),
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BitcodeMod.getBuffer().end());
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Writer.copyStrtab(BitcodeMod.getStrtab());
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}
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}
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} else {
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// The string table does not own strings added to it, some of which are
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// owned by the modules; keep them alive until we write the string table.
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std::vector<std::unique_ptr<Module>> OwnedMods;
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for (const auto &InputFilename : InputFilenames) {
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SMDiagnostic Err;
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std::unique_ptr<Module> M = parseIRFile(InputFilename, Err, Context);
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if (!M) {
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Err.print(argv[0], errs());
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return 1;
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}
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Writer.writeModule(M.get());
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OwnedMods.push_back(std::move(M));
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}
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Writer.writeStrtab();
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}
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std::error_code EC;
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raw_fd_ostream OS(OutputFilename, EC, sys::fs::OpenFlags::F_None);
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if (EC) {
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llvm::errs() << argv[0] << ": cannot open " << OutputFilename
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<< " for writing: " << EC.message();
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return 1;
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}
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OS.write(Buffer.data(), Buffer.size());
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return 0;
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}
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