forked from OSchip/llvm-project
535 lines
18 KiB
C++
535 lines
18 KiB
C++
//===- Driver.cpp ---------------------------------------------------------===//
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//
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// The LLVM Linker
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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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#include "lld/Common/Driver.h"
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#include "Config.h"
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#include "InputChunks.h"
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#include "InputGlobal.h"
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#include "MarkLive.h"
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#include "SymbolTable.h"
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#include "Writer.h"
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#include "lld/Common/Args.h"
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#include "lld/Common/ErrorHandler.h"
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#include "lld/Common/Memory.h"
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#include "lld/Common/Strings.h"
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#include "lld/Common/Threads.h"
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#include "lld/Common/Version.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/Object/Wasm.h"
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#include "llvm/Option/ArgList.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Path.h"
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#include "llvm/Support/Process.h"
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#include "llvm/Support/TargetSelect.h"
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#define DEBUG_TYPE "lld"
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using namespace llvm;
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using namespace llvm::sys;
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using namespace llvm::wasm;
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using namespace lld;
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using namespace lld::wasm;
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Configuration *lld::wasm::Config;
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namespace {
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// Create enum with OPT_xxx values for each option in Options.td
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enum {
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OPT_INVALID = 0,
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#define OPTION(_1, _2, ID, _4, _5, _6, _7, _8, _9, _10, _11, _12) OPT_##ID,
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#include "Options.inc"
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#undef OPTION
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};
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// This function is called on startup. We need this for LTO since
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// LTO calls LLVM functions to compile bitcode files to native code.
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// Technically this can be delayed until we read bitcode files, but
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// we don't bother to do lazily because the initialization is fast.
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static void initLLVM() {
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InitializeAllTargets();
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InitializeAllTargetMCs();
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InitializeAllAsmPrinters();
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InitializeAllAsmParsers();
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}
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class LinkerDriver {
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public:
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void link(ArrayRef<const char *> ArgsArr);
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private:
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void createFiles(opt::InputArgList &Args);
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void addFile(StringRef Path);
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void addLibrary(StringRef Name);
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// True if we are in --whole-archive and --no-whole-archive.
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bool InWholeArchive = false;
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std::vector<InputFile *> Files;
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};
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} // anonymous namespace
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bool lld::wasm::link(ArrayRef<const char *> Args, bool CanExitEarly,
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raw_ostream &Error) {
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errorHandler().LogName = sys::path::filename(Args[0]);
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errorHandler().ErrorOS = &Error;
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errorHandler().ColorDiagnostics = Error.has_colors();
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errorHandler().ErrorLimitExceededMsg =
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"too many errors emitted, stopping now (use "
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"-error-limit=0 to see all errors)";
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Config = make<Configuration>();
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Symtab = make<SymbolTable>();
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initLLVM();
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LinkerDriver().link(Args);
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// Exit immediately if we don't need to return to the caller.
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// This saves time because the overhead of calling destructors
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// for all globally-allocated objects is not negligible.
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if (CanExitEarly)
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exitLld(errorCount() ? 1 : 0);
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freeArena();
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return !errorCount();
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}
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// Create prefix string literals used in Options.td
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#define PREFIX(NAME, VALUE) const char *const NAME[] = VALUE;
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#include "Options.inc"
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#undef PREFIX
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// Create table mapping all options defined in Options.td
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static const opt::OptTable::Info OptInfo[] = {
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#define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12) \
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{X1, X2, X10, X11, OPT_##ID, opt::Option::KIND##Class, \
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X9, X8, OPT_##GROUP, OPT_##ALIAS, X7, X12},
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#include "Options.inc"
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#undef OPTION
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};
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namespace {
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class WasmOptTable : public llvm::opt::OptTable {
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public:
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WasmOptTable() : OptTable(OptInfo) {}
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opt::InputArgList parse(ArrayRef<const char *> Argv);
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};
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} // namespace
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// Set color diagnostics according to -color-diagnostics={auto,always,never}
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// or -no-color-diagnostics flags.
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static void handleColorDiagnostics(opt::InputArgList &Args) {
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auto *Arg = Args.getLastArg(OPT_color_diagnostics, OPT_color_diagnostics_eq,
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OPT_no_color_diagnostics);
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if (!Arg)
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return;
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if (Arg->getOption().getID() == OPT_color_diagnostics) {
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errorHandler().ColorDiagnostics = true;
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} else if (Arg->getOption().getID() == OPT_no_color_diagnostics) {
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errorHandler().ColorDiagnostics = false;
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} else {
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StringRef S = Arg->getValue();
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if (S == "always")
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errorHandler().ColorDiagnostics = true;
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else if (S == "never")
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errorHandler().ColorDiagnostics = false;
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else if (S != "auto")
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error("unknown option: --color-diagnostics=" + S);
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}
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}
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// Find a file by concatenating given paths.
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static Optional<std::string> findFile(StringRef Path1, const Twine &Path2) {
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SmallString<128> S;
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path::append(S, Path1, Path2);
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if (fs::exists(S))
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return S.str().str();
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return None;
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}
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opt::InputArgList WasmOptTable::parse(ArrayRef<const char *> Argv) {
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SmallVector<const char *, 256> Vec(Argv.data(), Argv.data() + Argv.size());
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unsigned MissingIndex;
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unsigned MissingCount;
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// Expand response files (arguments in the form of @<filename>)
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cl::ExpandResponseFiles(Saver, cl::TokenizeGNUCommandLine, Vec);
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opt::InputArgList Args = this->ParseArgs(Vec, MissingIndex, MissingCount);
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handleColorDiagnostics(Args);
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for (auto *Arg : Args.filtered(OPT_UNKNOWN))
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error("unknown argument: " + Arg->getSpelling());
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return Args;
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}
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// Currently we allow a ".imports" to live alongside a library. This can
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// be used to specify a list of symbols which can be undefined at link
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// time (imported from the environment. For example libc.a include an
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// import file that lists the syscall functions it relies on at runtime.
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// In the long run this information would be better stored as a symbol
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// attribute/flag in the object file itself.
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// See: https://github.com/WebAssembly/tool-conventions/issues/35
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static void readImportFile(StringRef Filename) {
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if (Optional<MemoryBufferRef> Buf = readFile(Filename))
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for (StringRef Sym : args::getLines(*Buf))
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Config->AllowUndefinedSymbols.insert(Sym);
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}
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// Returns slices of MB by parsing MB as an archive file.
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// Each slice consists of a member file in the archive.
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std::vector<MemoryBufferRef> static getArchiveMembers(
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MemoryBufferRef MB) {
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std::unique_ptr<Archive> File =
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CHECK(Archive::create(MB),
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MB.getBufferIdentifier() + ": failed to parse archive");
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std::vector<MemoryBufferRef> V;
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Error Err = Error::success();
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for (const ErrorOr<Archive::Child> &COrErr : File->children(Err)) {
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Archive::Child C =
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CHECK(COrErr, MB.getBufferIdentifier() +
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": could not get the child of the archive");
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MemoryBufferRef MBRef =
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CHECK(C.getMemoryBufferRef(),
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MB.getBufferIdentifier() +
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": could not get the buffer for a child of the archive");
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V.push_back(MBRef);
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}
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if (Err)
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fatal(MB.getBufferIdentifier() + ": Archive::children failed: " +
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toString(std::move(Err)));
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// Take ownership of memory buffers created for members of thin archives.
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for (std::unique_ptr<MemoryBuffer> &MB : File->takeThinBuffers())
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make<std::unique_ptr<MemoryBuffer>>(std::move(MB));
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return V;
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}
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void LinkerDriver::addFile(StringRef Path) {
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Optional<MemoryBufferRef> Buffer = readFile(Path);
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if (!Buffer.hasValue())
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return;
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MemoryBufferRef MBRef = *Buffer;
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switch (identify_magic(MBRef.getBuffer())) {
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case file_magic::archive: {
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// Handle -whole-archive.
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if (InWholeArchive) {
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for (MemoryBufferRef &M : getArchiveMembers(MBRef))
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Files.push_back(createObjectFile(M));
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return;
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}
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SmallString<128> ImportFile = Path;
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path::replace_extension(ImportFile, ".imports");
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if (fs::exists(ImportFile))
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readImportFile(ImportFile.str());
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Files.push_back(make<ArchiveFile>(MBRef));
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return;
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}
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case file_magic::bitcode:
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case file_magic::wasm_object:
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Files.push_back(createObjectFile(MBRef));
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break;
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default:
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error("unknown file type: " + MBRef.getBufferIdentifier());
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}
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}
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// Add a given library by searching it from input search paths.
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void LinkerDriver::addLibrary(StringRef Name) {
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for (StringRef Dir : Config->SearchPaths) {
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if (Optional<std::string> S = findFile(Dir, "lib" + Name + ".a")) {
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addFile(*S);
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return;
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}
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}
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error("unable to find library -l" + Name);
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}
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void LinkerDriver::createFiles(opt::InputArgList &Args) {
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for (auto *Arg : Args) {
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switch (Arg->getOption().getUnaliasedOption().getID()) {
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case OPT_l:
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addLibrary(Arg->getValue());
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break;
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case OPT_INPUT:
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addFile(Arg->getValue());
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break;
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case OPT_whole_archive:
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InWholeArchive = true;
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break;
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case OPT_no_whole_archive:
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InWholeArchive = false;
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break;
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}
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}
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}
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static StringRef getEntry(opt::InputArgList &Args, StringRef Default) {
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auto *Arg = Args.getLastArg(OPT_entry, OPT_no_entry);
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if (!Arg)
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return Default;
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if (Arg->getOption().getID() == OPT_no_entry)
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return "";
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return Arg->getValue();
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}
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static const uint8_t UnreachableFn[] = {
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0x03 /* ULEB length */, 0x00 /* ULEB num locals */,
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0x00 /* opcode unreachable */, 0x0b /* opcode end */
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};
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// For weak undefined functions, there may be "call" instructions that reference
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// the symbol. In this case, we need to synthesise a dummy/stub function that
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// will abort at runtime, so that relocations can still provided an operand to
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// the call instruction that passes Wasm validation.
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static void handleWeakUndefines() {
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for (Symbol *Sym : Symtab->getSymbols()) {
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if (!Sym->isUndefined() || !Sym->isWeak())
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continue;
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auto *FuncSym = dyn_cast<FunctionSymbol>(Sym);
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if (!FuncSym)
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continue;
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// It is possible for undefined functions not to have a signature (eg. if
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// added via "--undefined"), but weak undefined ones do have a signature.
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assert(FuncSym->FunctionType);
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const WasmSignature &Sig = *FuncSym->FunctionType;
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// Add a synthetic dummy for weak undefined functions. These dummies will
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// be GC'd if not used as the target of any "call" instructions.
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Optional<std::string> SymName = demangleItanium(Sym->getName());
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StringRef DebugName =
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Saver.save("undefined function " +
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(SymName ? StringRef(*SymName) : Sym->getName()));
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SyntheticFunction *Func =
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make<SyntheticFunction>(Sig, Sym->getName(), DebugName);
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Func->setBody(UnreachableFn);
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// Ensure it compares equal to the null pointer, and so that table relocs
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// don't pull in the stub body (only call-operand relocs should do that).
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Func->setTableIndex(0);
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Symtab->SyntheticFunctions.emplace_back(Func);
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// Hide our dummy to prevent export.
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uint32_t Flags = WASM_SYMBOL_VISIBILITY_HIDDEN;
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replaceSymbol<DefinedFunction>(Sym, Sym->getName(), Flags, nullptr, Func);
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}
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}
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// Force Sym to be entered in the output. Used for -u or equivalent.
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static Symbol *handleUndefined(StringRef Name) {
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Symbol *Sym = Symtab->find(Name);
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if (!Sym)
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return nullptr;
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// Since symbol S may not be used inside the program, LTO may
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// eliminate it. Mark the symbol as "used" to prevent it.
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Sym->IsUsedInRegularObj = true;
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if (auto *LazySym = dyn_cast<LazySymbol>(Sym))
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LazySym->fetch();
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return Sym;
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}
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void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
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WasmOptTable Parser;
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opt::InputArgList Args = Parser.parse(ArgsArr.slice(1));
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// Handle --help
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if (Args.hasArg(OPT_help)) {
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Parser.PrintHelp(outs(), ArgsArr[0], "LLVM Linker", false);
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return;
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}
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// Handle --version
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if (Args.hasArg(OPT_version) || Args.hasArg(OPT_v)) {
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outs() << getLLDVersion() << "\n";
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return;
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}
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// Parse and evaluate -mllvm options.
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std::vector<const char *> V;
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V.push_back("wasm-ld (LLVM option parsing)");
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for (auto *Arg : Args.filtered(OPT_mllvm))
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V.push_back(Arg->getValue());
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cl::ParseCommandLineOptions(V.size(), V.data());
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errorHandler().ErrorLimit = args::getInteger(Args, OPT_error_limit, 20);
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Config->AllowUndefined = Args.hasArg(OPT_allow_undefined);
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Config->Demangle = Args.hasFlag(OPT_demangle, OPT_no_demangle, true);
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Config->DisableVerify = Args.hasArg(OPT_disable_verify);
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Config->Entry = getEntry(Args, Args.hasArg(OPT_relocatable) ? "" : "_start");
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Config->ExportAll = Args.hasArg(OPT_export_all);
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Config->ExportTable = Args.hasArg(OPT_export_table);
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errorHandler().FatalWarnings =
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Args.hasFlag(OPT_fatal_warnings, OPT_no_fatal_warnings, false);
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Config->ImportMemory = Args.hasArg(OPT_import_memory);
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Config->ImportTable = Args.hasArg(OPT_import_table);
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Config->LTOO = args::getInteger(Args, OPT_lto_O, 2);
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Config->LTOPartitions = args::getInteger(Args, OPT_lto_partitions, 1);
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Config->Optimize = args::getInteger(Args, OPT_O, 0);
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Config->OutputFile = Args.getLastArgValue(OPT_o);
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Config->Relocatable = Args.hasArg(OPT_relocatable);
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Config->GcSections =
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Args.hasFlag(OPT_gc_sections, OPT_no_gc_sections, !Config->Relocatable);
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Config->MergeDataSegments =
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Args.hasFlag(OPT_merge_data_segments, OPT_no_merge_data_segments,
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!Config->Relocatable);
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Config->PrintGcSections =
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Args.hasFlag(OPT_print_gc_sections, OPT_no_print_gc_sections, false);
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Config->SaveTemps = Args.hasArg(OPT_save_temps);
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Config->SearchPaths = args::getStrings(Args, OPT_L);
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Config->StripAll = Args.hasArg(OPT_strip_all);
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Config->StripDebug = Args.hasArg(OPT_strip_debug);
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Config->StackFirst = Args.hasArg(OPT_stack_first);
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Config->ThinLTOCacheDir = Args.getLastArgValue(OPT_thinlto_cache_dir);
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Config->ThinLTOCachePolicy = CHECK(
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parseCachePruningPolicy(Args.getLastArgValue(OPT_thinlto_cache_policy)),
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"--thinlto-cache-policy: invalid cache policy");
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Config->ThinLTOJobs = args::getInteger(Args, OPT_thinlto_jobs, -1u);
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errorHandler().Verbose = Args.hasArg(OPT_verbose);
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ThreadsEnabled = Args.hasFlag(OPT_threads, OPT_no_threads, true);
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Config->InitialMemory = args::getInteger(Args, OPT_initial_memory, 0);
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Config->GlobalBase = args::getInteger(Args, OPT_global_base, 1024);
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Config->MaxMemory = args::getInteger(Args, OPT_max_memory, 0);
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Config->ZStackSize =
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args::getZOptionValue(Args, OPT_z, "stack-size", WasmPageSize);
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Config->CompressRelocTargets = Config->Optimize > 0 && !Config->Relocatable;
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if (Config->LTOO > 3)
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error("invalid optimization level for LTO: " + Twine(Config->LTOO));
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if (Config->LTOPartitions == 0)
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error("--lto-partitions: number of threads must be > 0");
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if (Config->ThinLTOJobs == 0)
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error("--thinlto-jobs: number of threads must be > 0");
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if (auto *Arg = Args.getLastArg(OPT_allow_undefined_file))
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readImportFile(Arg->getValue());
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if (!Args.hasArg(OPT_INPUT)) {
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error("no input files");
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return;
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}
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if (Config->OutputFile.empty())
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error("no output file specified");
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if (Config->ImportTable && Config->ExportTable)
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error("--import-table and --export-table may not be used together");
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if (Config->Relocatable) {
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if (!Config->Entry.empty())
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error("entry point specified for relocatable output file");
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if (Config->GcSections)
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error("-r and --gc-sections may not be used together");
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if (Args.hasArg(OPT_undefined))
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error("-r -and --undefined may not be used together");
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}
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Symbol *EntrySym = nullptr;
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if (!Config->Relocatable) {
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llvm::wasm::WasmGlobal Global;
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Global.Type = {WASM_TYPE_I32, true};
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Global.InitExpr.Value.Int32 = 0;
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Global.InitExpr.Opcode = WASM_OPCODE_I32_CONST;
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Global.SymbolName = "__stack_pointer";
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InputGlobal *StackPointer = make<InputGlobal>(Global, nullptr);
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StackPointer->Live = true;
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static WasmSignature NullSignature = {{}, WASM_TYPE_NORESULT};
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// Add synthetic symbols before any others
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WasmSym::CallCtors = Symtab->addSyntheticFunction(
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"__wasm_call_ctors", WASM_SYMBOL_VISIBILITY_HIDDEN,
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make<SyntheticFunction>(NullSignature, "__wasm_call_ctors"));
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// TODO(sbc): Remove WASM_SYMBOL_VISIBILITY_HIDDEN when the mutable global
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// spec proposal is implemented in all major browsers.
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// See: https://github.com/WebAssembly/mutable-global
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WasmSym::StackPointer = Symtab->addSyntheticGlobal(
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"__stack_pointer", WASM_SYMBOL_VISIBILITY_HIDDEN, StackPointer);
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WasmSym::HeapBase = Symtab->addSyntheticDataSymbol("__heap_base", 0);
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WasmSym::DsoHandle = Symtab->addSyntheticDataSymbol(
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"__dso_handle", WASM_SYMBOL_VISIBILITY_HIDDEN);
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WasmSym::DataEnd = Symtab->addSyntheticDataSymbol("__data_end", 0);
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}
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createFiles(Args);
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if (errorCount())
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return;
|
|
|
|
// Add all files to the symbol table. This will add almost all
|
|
// symbols that we need to the symbol table.
|
|
for (InputFile *F : Files)
|
|
Symtab->addFile(F);
|
|
if (errorCount())
|
|
return;
|
|
|
|
// Handle the `--undefined <sym>` options.
|
|
for (auto *Arg : Args.filtered(OPT_undefined))
|
|
handleUndefined(Arg->getValue());
|
|
|
|
// Handle the `--export <sym>` options
|
|
// This works like --undefined but also exports the symbol if its found
|
|
for (auto *Arg : Args.filtered(OPT_export)) {
|
|
Symbol *Sym = handleUndefined(Arg->getValue());
|
|
if (Sym && Sym->isDefined())
|
|
Sym->ForceExport = true;
|
|
else if (!Config->AllowUndefined)
|
|
error(Twine("symbol exported via --export not found: ") +
|
|
Arg->getValue());
|
|
}
|
|
|
|
if (!Config->Relocatable) {
|
|
// Add synthetic dummies for weak undefined functions.
|
|
handleWeakUndefines();
|
|
|
|
if (!Config->Entry.empty()) {
|
|
EntrySym = handleUndefined(Config->Entry);
|
|
if (!EntrySym)
|
|
error("entry symbol not defined (pass --no-entry to supress): " +
|
|
Config->Entry);
|
|
}
|
|
|
|
// Make sure we have resolved all symbols.
|
|
if (!Config->AllowUndefined)
|
|
Symtab->reportRemainingUndefines();
|
|
}
|
|
|
|
if (errorCount())
|
|
return;
|
|
|
|
// Do link-time optimization if given files are LLVM bitcode files.
|
|
// This compiles bitcode files into real object files.
|
|
Symtab->addCombinedLTOObject();
|
|
if (errorCount())
|
|
return;
|
|
|
|
if (EntrySym)
|
|
EntrySym->setHidden(false);
|
|
|
|
if (errorCount())
|
|
return;
|
|
|
|
// Do size optimizations: garbage collection
|
|
markLive();
|
|
|
|
// Write the result to the file.
|
|
writeResult();
|
|
}
|