506 lines
18 KiB
C++
506 lines
18 KiB
C++
//===- llvm-link.cpp - Low-level LLVM linker ------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This utility may be invoked in the following manner:
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// llvm-link a.bc b.bc c.bc -o x.bc
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/BinaryFormat/Magic.h"
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#include "llvm/Bitcode/BitcodeReader.h"
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#include "llvm/Bitcode/BitcodeWriter.h"
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#include "llvm/IR/AutoUpgrade.h"
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#include "llvm/IR/DiagnosticInfo.h"
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#include "llvm/IR/DiagnosticPrinter.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/ModuleSummaryIndex.h"
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#include "llvm/IR/Verifier.h"
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#include "llvm/IRReader/IRReader.h"
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#include "llvm/Linker/Linker.h"
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#include "llvm/Object/Archive.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/FileSystem.h"
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#include "llvm/Support/InitLLVM.h"
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#include "llvm/Support/Path.h"
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#include "llvm/Support/SourceMgr.h"
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#include "llvm/Support/SystemUtils.h"
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#include "llvm/Support/ToolOutputFile.h"
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#include "llvm/Support/WithColor.h"
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#include "llvm/Transforms/IPO/FunctionImport.h"
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#include "llvm/Transforms/IPO/Internalize.h"
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#include "llvm/Transforms/Utils/FunctionImportUtils.h"
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#include <memory>
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#include <utility>
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using namespace llvm;
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static cl::OptionCategory LinkCategory("Link Options");
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static cl::list<std::string> InputFilenames(cl::Positional, cl::OneOrMore,
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cl::desc("<input bitcode files>"),
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cl::cat(LinkCategory));
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static cl::list<std::string> OverridingInputs(
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"override", cl::ZeroOrMore, cl::value_desc("filename"),
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cl::desc(
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"input bitcode file which can override previously defined symbol(s)"),
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cl::cat(LinkCategory));
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// Option to simulate function importing for testing. This enables using
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// llvm-link to simulate ThinLTO backend processes.
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static cl::list<std::string> Imports(
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"import", cl::ZeroOrMore, cl::value_desc("function:filename"),
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cl::desc("Pair of function name and filename, where function should be "
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"imported from bitcode in filename"),
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cl::cat(LinkCategory));
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// Option to support testing of function importing. The module summary
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// must be specified in the case were we request imports via the -import
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// option, as well as when compiling any module with functions that may be
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// exported (imported by a different llvm-link -import invocation), to ensure
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// consistent promotion and renaming of locals.
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static cl::opt<std::string>
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SummaryIndex("summary-index", cl::desc("Module summary index filename"),
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cl::init(""), cl::value_desc("filename"),
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cl::cat(LinkCategory));
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static cl::opt<std::string>
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OutputFilename("o", cl::desc("Override output filename"), cl::init("-"),
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cl::value_desc("filename"), cl::cat(LinkCategory));
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static cl::opt<bool> Internalize("internalize",
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cl::desc("Internalize linked symbols"),
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cl::cat(LinkCategory));
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static cl::opt<bool>
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DisableDITypeMap("disable-debug-info-type-map",
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cl::desc("Don't use a uniquing type map for debug info"),
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cl::cat(LinkCategory));
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static cl::opt<bool> OnlyNeeded("only-needed",
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cl::desc("Link only needed symbols"),
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cl::cat(LinkCategory));
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static cl::opt<bool> Force("f", cl::desc("Enable binary output on terminals"),
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cl::cat(LinkCategory));
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static cl::opt<bool> DisableLazyLoad("disable-lazy-loading",
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cl::desc("Disable lazy module loading"),
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cl::cat(LinkCategory));
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static cl::opt<bool> OutputAssembly("S",
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cl::desc("Write output as LLVM assembly"),
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cl::Hidden, cl::cat(LinkCategory));
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static cl::opt<bool> Verbose("v",
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cl::desc("Print information about actions taken"),
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cl::cat(LinkCategory));
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static cl::opt<bool> DumpAsm("d", cl::desc("Print assembly as linked"),
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cl::Hidden, cl::cat(LinkCategory));
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static cl::opt<bool> SuppressWarnings("suppress-warnings",
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cl::desc("Suppress all linking warnings"),
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cl::init(false), cl::cat(LinkCategory));
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static cl::opt<bool> PreserveBitcodeUseListOrder(
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"preserve-bc-uselistorder",
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cl::desc("Preserve use-list order when writing LLVM bitcode."),
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cl::init(true), cl::Hidden, cl::cat(LinkCategory));
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static cl::opt<bool> PreserveAssemblyUseListOrder(
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"preserve-ll-uselistorder",
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cl::desc("Preserve use-list order when writing LLVM assembly."),
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cl::init(false), cl::Hidden, cl::cat(LinkCategory));
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static cl::opt<bool> NoVerify("disable-verify",
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cl::desc("Do not run the verifier"), cl::Hidden,
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cl::cat(LinkCategory));
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static ExitOnError ExitOnErr;
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// Read the specified bitcode file in and return it. This routine searches the
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// link path for the specified file to try to find it...
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//
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static std::unique_ptr<Module> loadFile(const char *argv0,
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std::unique_ptr<MemoryBuffer> Buffer,
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LLVMContext &Context,
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bool MaterializeMetadata = true) {
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SMDiagnostic Err;
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if (Verbose)
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errs() << "Loading '" << Buffer->getBufferIdentifier() << "'\n";
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std::unique_ptr<Module> Result;
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if (DisableLazyLoad)
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Result = parseIR(*Buffer, Err, Context);
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else
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Result =
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getLazyIRModule(std::move(Buffer), Err, Context, !MaterializeMetadata);
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if (!Result) {
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Err.print(argv0, errs());
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return nullptr;
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}
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if (MaterializeMetadata) {
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ExitOnErr(Result->materializeMetadata());
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UpgradeDebugInfo(*Result);
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}
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return Result;
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}
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static std::unique_ptr<Module> loadArFile(const char *Argv0,
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std::unique_ptr<MemoryBuffer> Buffer,
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LLVMContext &Context) {
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std::unique_ptr<Module> Result(new Module("ArchiveModule", Context));
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StringRef ArchiveName = Buffer->getBufferIdentifier();
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if (Verbose)
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errs() << "Reading library archive file '" << ArchiveName
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<< "' to memory\n";
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Error Err = Error::success();
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object::Archive Archive(*Buffer, Err);
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ExitOnErr(std::move(Err));
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Linker L(*Result);
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for (const object::Archive::Child &C : Archive.children(Err)) {
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Expected<StringRef> Ename = C.getName();
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if (Error E = Ename.takeError()) {
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errs() << Argv0 << ": ";
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WithColor::error() << " failed to read name of archive member"
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<< ArchiveName << "'\n";
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return nullptr;
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}
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std::string ChildName = Ename.get().str();
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if (Verbose)
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errs() << "Parsing member '" << ChildName
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<< "' of archive library to module.\n";
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SMDiagnostic ParseErr;
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Expected<MemoryBufferRef> MemBuf = C.getMemoryBufferRef();
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if (Error E = MemBuf.takeError()) {
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errs() << Argv0 << ": ";
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WithColor::error() << " loading memory for member '" << ChildName
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<< "' of archive library failed'" << ArchiveName
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<< "'\n";
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return nullptr;
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};
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if (!isBitcode(reinterpret_cast<const unsigned char *>(
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MemBuf.get().getBufferStart()),
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reinterpret_cast<const unsigned char *>(
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MemBuf.get().getBufferEnd()))) {
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errs() << Argv0 << ": ";
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WithColor::error() << " member of archive is not a bitcode file: '"
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<< ChildName << "'\n";
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return nullptr;
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}
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std::unique_ptr<Module> M;
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if (DisableLazyLoad)
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M = parseIR(MemBuf.get(), ParseErr, Context);
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else
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M = getLazyIRModule(MemoryBuffer::getMemBuffer(MemBuf.get(), false),
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ParseErr, Context);
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if (!M.get()) {
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errs() << Argv0 << ": ";
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WithColor::error() << " parsing member '" << ChildName
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<< "' of archive library failed'" << ArchiveName
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<< "'\n";
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return nullptr;
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}
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if (Verbose)
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errs() << "Linking member '" << ChildName << "' of archive library.\n";
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if (L.linkInModule(std::move(M)))
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return nullptr;
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} // end for each child
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ExitOnErr(std::move(Err));
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return Result;
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}
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namespace {
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/// Helper to load on demand a Module from file and cache it for subsequent
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/// queries during function importing.
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class ModuleLazyLoaderCache {
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/// Cache of lazily loaded module for import.
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StringMap<std::unique_ptr<Module>> ModuleMap;
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/// Retrieve a Module from the cache or lazily load it on demand.
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std::function<std::unique_ptr<Module>(const char *argv0,
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const std::string &FileName)>
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createLazyModule;
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public:
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/// Create the loader, Module will be initialized in \p Context.
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ModuleLazyLoaderCache(std::function<std::unique_ptr<Module>(
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const char *argv0, const std::string &FileName)>
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createLazyModule)
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: createLazyModule(std::move(createLazyModule)) {}
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/// Retrieve a Module from the cache or lazily load it on demand.
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Module &operator()(const char *argv0, const std::string &FileName);
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std::unique_ptr<Module> takeModule(const std::string &FileName) {
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auto I = ModuleMap.find(FileName);
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assert(I != ModuleMap.end());
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std::unique_ptr<Module> Ret = std::move(I->second);
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ModuleMap.erase(I);
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return Ret;
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}
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};
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// Get a Module for \p FileName from the cache, or load it lazily.
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Module &ModuleLazyLoaderCache::operator()(const char *argv0,
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const std::string &Identifier) {
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auto &Module = ModuleMap[Identifier];
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if (!Module) {
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Module = createLazyModule(argv0, Identifier);
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assert(Module && "Failed to create lazy module!");
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}
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return *Module;
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}
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} // anonymous namespace
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namespace {
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struct LLVMLinkDiagnosticHandler : public DiagnosticHandler {
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bool handleDiagnostics(const DiagnosticInfo &DI) override {
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unsigned Severity = DI.getSeverity();
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switch (Severity) {
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case DS_Error:
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WithColor::error();
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break;
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case DS_Warning:
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if (SuppressWarnings)
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return true;
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WithColor::warning();
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break;
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case DS_Remark:
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case DS_Note:
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llvm_unreachable("Only expecting warnings and errors");
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}
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DiagnosticPrinterRawOStream DP(errs());
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DI.print(DP);
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errs() << '\n';
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return true;
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}
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};
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} // namespace
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/// Import any functions requested via the -import option.
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static bool importFunctions(const char *argv0, Module &DestModule) {
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if (SummaryIndex.empty())
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return true;
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std::unique_ptr<ModuleSummaryIndex> Index =
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ExitOnErr(llvm::getModuleSummaryIndexForFile(SummaryIndex));
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// Map of Module -> List of globals to import from the Module
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FunctionImporter::ImportMapTy ImportList;
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auto ModuleLoader = [&DestModule](const char *argv0,
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const std::string &Identifier) {
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std::unique_ptr<MemoryBuffer> Buffer =
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ExitOnErr(errorOrToExpected(MemoryBuffer::getFileOrSTDIN(Identifier)));
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return loadFile(argv0, std::move(Buffer), DestModule.getContext(), false);
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};
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ModuleLazyLoaderCache ModuleLoaderCache(ModuleLoader);
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for (const auto &Import : Imports) {
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// Identify the requested function and its bitcode source file.
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size_t Idx = Import.find(':');
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if (Idx == std::string::npos) {
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errs() << "Import parameter bad format: " << Import << "\n";
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return false;
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}
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std::string FunctionName = Import.substr(0, Idx);
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std::string FileName = Import.substr(Idx + 1, std::string::npos);
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// Load the specified source module.
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auto &SrcModule = ModuleLoaderCache(argv0, FileName);
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if (!NoVerify && verifyModule(SrcModule, &errs())) {
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errs() << argv0 << ": " << FileName;
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WithColor::error() << "input module is broken!\n";
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return false;
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}
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Function *F = SrcModule.getFunction(FunctionName);
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if (!F) {
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errs() << "Ignoring import request for non-existent function "
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<< FunctionName << " from " << FileName << "\n";
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continue;
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}
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// We cannot import weak_any functions without possibly affecting the
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// order they are seen and selected by the linker, changing program
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// semantics.
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if (F->hasWeakAnyLinkage()) {
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errs() << "Ignoring import request for weak-any function " << FunctionName
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<< " from " << FileName << "\n";
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continue;
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}
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if (Verbose)
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errs() << "Importing " << FunctionName << " from " << FileName << "\n";
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auto &Entry = ImportList[FileName];
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Entry.insert(F->getGUID());
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}
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auto CachedModuleLoader = [&](StringRef Identifier) {
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return ModuleLoaderCache.takeModule(std::string(Identifier));
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};
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FunctionImporter Importer(*Index, CachedModuleLoader,
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/*ClearDSOLocalOnDeclarations=*/false);
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ExitOnErr(Importer.importFunctions(DestModule, ImportList));
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return true;
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}
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static bool linkFiles(const char *argv0, LLVMContext &Context, Linker &L,
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const cl::list<std::string> &Files, unsigned Flags) {
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// Filter out flags that don't apply to the first file we load.
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unsigned ApplicableFlags = Flags & Linker::Flags::OverrideFromSrc;
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// Similar to some flags, internalization doesn't apply to the first file.
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bool InternalizeLinkedSymbols = false;
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for (const auto &File : Files) {
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std::unique_ptr<MemoryBuffer> Buffer =
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ExitOnErr(errorOrToExpected(MemoryBuffer::getFileOrSTDIN(File)));
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std::unique_ptr<Module> M =
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identify_magic(Buffer->getBuffer()) == file_magic::archive
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? loadArFile(argv0, std::move(Buffer), Context)
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: loadFile(argv0, std::move(Buffer), Context);
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if (!M.get()) {
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errs() << argv0 << ": ";
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WithColor::error() << " loading file '" << File << "'\n";
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return false;
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}
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// Note that when ODR merging types cannot verify input files in here When
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// doing that debug metadata in the src module might already be pointing to
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// the destination.
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if (DisableDITypeMap && !NoVerify && verifyModule(*M, &errs())) {
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errs() << argv0 << ": " << File << ": ";
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WithColor::error() << "input module is broken!\n";
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return false;
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}
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// If a module summary index is supplied, load it so linkInModule can treat
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// local functions/variables as exported and promote if necessary.
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if (!SummaryIndex.empty()) {
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std::unique_ptr<ModuleSummaryIndex> Index =
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ExitOnErr(llvm::getModuleSummaryIndexForFile(SummaryIndex));
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// Conservatively mark all internal values as promoted, since this tool
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// does not do the ThinLink that would normally determine what values to
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// promote.
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for (auto &I : *Index) {
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for (auto &S : I.second.SummaryList) {
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if (GlobalValue::isLocalLinkage(S->linkage()))
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S->setLinkage(GlobalValue::ExternalLinkage);
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}
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}
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// Promotion
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if (renameModuleForThinLTO(*M, *Index,
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/*ClearDSOLocalOnDeclarations=*/false))
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return true;
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}
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if (Verbose)
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errs() << "Linking in '" << File << "'\n";
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bool Err = false;
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if (InternalizeLinkedSymbols) {
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Err = L.linkInModule(
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std::move(M), ApplicableFlags, [](Module &M, const StringSet<> &GVS) {
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internalizeModule(M, [&GVS](const GlobalValue &GV) {
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return !GV.hasName() || (GVS.count(GV.getName()) == 0);
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});
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});
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} else {
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Err = L.linkInModule(std::move(M), ApplicableFlags);
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}
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if (Err)
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return false;
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// Internalization applies to linking of subsequent files.
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InternalizeLinkedSymbols = Internalize;
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// All linker flags apply to linking of subsequent files.
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ApplicableFlags = Flags;
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}
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return true;
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}
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int main(int argc, char **argv) {
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InitLLVM X(argc, argv);
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ExitOnErr.setBanner(std::string(argv[0]) + ": ");
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LLVMContext Context;
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Context.setDiagnosticHandler(std::make_unique<LLVMLinkDiagnosticHandler>(),
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true);
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cl::HideUnrelatedOptions({&LinkCategory, &getColorCategory()});
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cl::ParseCommandLineOptions(argc, argv, "llvm linker\n");
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if (!DisableDITypeMap)
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Context.enableDebugTypeODRUniquing();
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auto Composite = std::make_unique<Module>("llvm-link", Context);
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Linker L(*Composite);
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unsigned Flags = Linker::Flags::None;
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if (OnlyNeeded)
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Flags |= Linker::Flags::LinkOnlyNeeded;
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// First add all the regular input files
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if (!linkFiles(argv[0], Context, L, InputFilenames, Flags))
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return 1;
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// Next the -override ones.
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if (!linkFiles(argv[0], Context, L, OverridingInputs,
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Flags | Linker::Flags::OverrideFromSrc))
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return 1;
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// Import any functions requested via -import
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if (!importFunctions(argv[0], *Composite))
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return 1;
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if (DumpAsm)
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errs() << "Here's the assembly:\n" << *Composite;
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std::error_code EC;
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ToolOutputFile Out(OutputFilename, EC,
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OutputAssembly ? sys::fs::OF_TextWithCRLF
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: sys::fs::OF_None);
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if (EC) {
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WithColor::error() << EC.message() << '\n';
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return 1;
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}
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if (!NoVerify && verifyModule(*Composite, &errs())) {
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errs() << argv[0] << ": ";
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WithColor::error() << "linked module is broken!\n";
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return 1;
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}
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if (Verbose)
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errs() << "Writing bitcode...\n";
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if (OutputAssembly) {
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Composite->print(Out.os(), nullptr, PreserveAssemblyUseListOrder);
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} else if (Force || !CheckBitcodeOutputToConsole(Out.os()))
|
|
WriteBitcodeToFile(*Composite, Out.os(), PreserveBitcodeUseListOrder);
|
|
|
|
// Declare success.
|
|
Out.keep();
|
|
|
|
return 0;
|
|
}
|