llvm/tools/llvm-link/llvm-link.cpp

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//===- llvm-link.cpp - Low-level LLVM linker ------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This utility may be invoked in the following manner:
// llvm-link a.bc b.bc c.bc -o x.bc
//
//===----------------------------------------------------------------------===//
#include "llvm/Linker/Linker.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/IR/AutoUpgrade.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/FunctionInfo.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/IRReader/IRReader.h"
#include "llvm/Object/FunctionIndexObjectFile.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/PrettyStackTrace.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/SystemUtils.h"
#include "llvm/Support/ToolOutputFile.h"
#include <memory>
using namespace llvm;
static cl::list<std::string>
InputFilenames(cl::Positional, cl::OneOrMore,
cl::desc("<input bitcode files>"));
static cl::list<std::string> OverridingInputs(
"override", cl::ZeroOrMore, cl::value_desc("filename"),
cl::desc(
"input bitcode file which can override previously defined symbol(s)"));
// Option to simulate function importing for testing. This enables using
// llvm-link to simulate ThinLTO backend processes.
static cl::list<std::string> Imports(
"import", cl::ZeroOrMore, cl::value_desc("function:filename"),
cl::desc("Pair of function name and filename, where function should be "
"imported from bitcode in filename"));
// Option to support testing of function importing. The function index
// must be specified in the case were we request imports via the -import
// option, as well as when compiling any module with functions that may be
// exported (imported by a different llvm-link -import invocation), to ensure
// consistent promotion and renaming of locals.
static cl::opt<std::string> FunctionIndex("functionindex",
cl::desc("Function index filename"),
cl::init(""),
cl::value_desc("filename"));
static cl::opt<std::string>
OutputFilename("o", cl::desc("Override output filename"), cl::init("-"),
cl::value_desc("filename"));
static cl::opt<bool>
Internalize("internalize", cl::desc("Internalize linked symbols"));
static cl::opt<bool>
OnlyNeeded("only-needed", cl::desc("Link only needed symbols"));
static cl::opt<bool>
Force("f", cl::desc("Enable binary output on terminals"));
static cl::opt<bool>
OutputAssembly("S",
cl::desc("Write output as LLVM assembly"), cl::Hidden);
static cl::opt<bool>
Verbose("v", cl::desc("Print information about actions taken"));
static cl::opt<bool>
DumpAsm("d", cl::desc("Print assembly as linked"), cl::Hidden);
static cl::opt<bool>
SuppressWarnings("suppress-warnings", cl::desc("Suppress all linking warnings"),
cl::init(false));
static cl::opt<bool> PreserveBitcodeUseListOrder(
"preserve-bc-uselistorder",
cl::desc("Preserve use-list order when writing LLVM bitcode."),
cl::init(true), cl::Hidden);
static cl::opt<bool> PreserveAssemblyUseListOrder(
"preserve-ll-uselistorder",
cl::desc("Preserve use-list order when writing LLVM assembly."),
cl::init(false), cl::Hidden);
// Read the specified bitcode file in and return it. This routine searches the
// link path for the specified file to try to find it...
//
static std::unique_ptr<Module> loadFile(const char *argv0,
const std::string &FN,
LLVMContext &Context,
bool MaterializeMetadata = true) {
SMDiagnostic Err;
if (Verbose) errs() << "Loading '" << FN << "'\n";
std::unique_ptr<Module> Result =
getLazyIRFileModule(FN, Err, Context, !MaterializeMetadata);
if (!Result)
Err.print(argv0, errs());
if (MaterializeMetadata) {
Result->materializeMetadata();
UpgradeDebugInfo(*Result);
}
return Result;
}
static void diagnosticHandler(const DiagnosticInfo &DI) {
unsigned Severity = DI.getSeverity();
switch (Severity) {
case DS_Error:
errs() << "ERROR: ";
break;
case DS_Warning:
if (SuppressWarnings)
return;
errs() << "WARNING: ";
break;
case DS_Remark:
case DS_Note:
llvm_unreachable("Only expecting warnings and errors");
}
DiagnosticPrinterRawOStream DP(errs());
DI.print(DP);
errs() << '\n';
}
static void diagnosticHandlerWithContext(const DiagnosticInfo &DI, void *C) {
diagnosticHandler(DI);
}
/// Import any functions requested via the -import option.
static bool importFunctions(const char *argv0, LLVMContext &Context,
Linker &L) {
StringMap<std::unique_ptr<DenseMap<unsigned, MDNode *>>>
ModuleToTempMDValsMap;
for (const auto &Import : Imports) {
// Identify the requested function and its bitcode source file.
size_t Idx = Import.find(':');
if (Idx == std::string::npos) {
errs() << "Import parameter bad format: " << Import << "\n";
return false;
}
std::string FunctionName = Import.substr(0, Idx);
std::string FileName = Import.substr(Idx + 1, std::string::npos);
// Load the specified source module.
std::unique_ptr<Module> M = loadFile(argv0, FileName, Context, false);
if (!M.get()) {
errs() << argv0 << ": error loading file '" << FileName << "'\n";
return false;
}
if (verifyModule(*M, &errs())) {
errs() << argv0 << ": " << FileName
<< ": error: input module is broken!\n";
return false;
}
Function *F = M->getFunction(FunctionName);
if (!F) {
errs() << "Ignoring import request for non-existent function "
<< FunctionName << " from " << FileName << "\n";
continue;
}
// We cannot import weak_any functions without possibly affecting the
// order they are seen and selected by the linker, changing program
// semantics.
if (F->hasWeakAnyLinkage()) {
errs() << "Ignoring import request for weak-any function " << FunctionName
<< " from " << FileName << "\n";
continue;
}
if (Verbose)
errs() << "Importing " << FunctionName << " from " << FileName << "\n";
std::unique_ptr<FunctionInfoIndex> Index;
if (!FunctionIndex.empty()) {
ErrorOr<std::unique_ptr<FunctionInfoIndex>> IndexOrErr =
llvm::getFunctionIndexForFile(FunctionIndex, diagnosticHandler);
std::error_code EC = IndexOrErr.getError();
if (EC) {
errs() << EC.message() << '\n';
return false;
}
Index = std::move(IndexOrErr.get());
}
// Save the mapping of value ids to temporary metadata created when
// importing this function. If we have already imported from this module,
// add new temporary metadata to the existing mapping.
auto &TempMDVals = ModuleToTempMDValsMap[FileName];
if (!TempMDVals)
TempMDVals = llvm::make_unique<DenseMap<unsigned, MDNode *>>();
// Link in the specified function.
DenseSet<const GlobalValue *> FunctionsToImport;
FunctionsToImport.insert(F);
if (L.linkInModule(std::move(M), Linker::Flags::None, Index.get(),
&FunctionsToImport, TempMDVals.get()))
return false;
}
// Now link in metadata for all modules from which we imported functions.
for (StringMapEntry<std::unique_ptr<DenseMap<unsigned, MDNode *>>> &SME :
ModuleToTempMDValsMap) {
// Load the specified source module.
std::unique_ptr<Module> M = loadFile(argv0, SME.getKey(), Context, true);
if (!M.get()) {
errs() << argv0 << ": error loading file '" << SME.getKey() << "'\n";
return false;
}
if (verifyModule(*M, &errs())) {
errs() << argv0 << ": " << SME.getKey()
<< ": error: input module is broken!\n";
return false;
}
// Link in all necessary metadata from this module.
if (L.linkInMetadata(*M, SME.getValue().get()))
return false;
}
return true;
}
static bool linkFiles(const char *argv0, LLVMContext &Context, Linker &L,
const cl::list<std::string> &Files,
unsigned Flags) {
// Filter out flags that don't apply to the first file we load.
unsigned ApplicableFlags = Flags & Linker::Flags::OverrideFromSrc;
for (const auto &File : Files) {
std::unique_ptr<Module> M = loadFile(argv0, File, Context);
if (!M.get()) {
errs() << argv0 << ": error loading file '" << File << "'\n";
return false;
}
if (verifyModule(*M, &errs())) {
errs() << argv0 << ": " << File << ": error: input module is broken!\n";
return false;
}
// If a function index is supplied, load it so linkInModule can treat
// local functions/variables as exported and promote if necessary.
std::unique_ptr<FunctionInfoIndex> Index;
if (!FunctionIndex.empty()) {
ErrorOr<std::unique_ptr<FunctionInfoIndex>> IndexOrErr =
llvm::getFunctionIndexForFile(FunctionIndex, diagnosticHandler);
std::error_code EC = IndexOrErr.getError();
if (EC) {
errs() << EC.message() << '\n';
return false;
}
Index = std::move(IndexOrErr.get());
}
if (Verbose)
errs() << "Linking in '" << File << "'\n";
if (L.linkInModule(std::move(M), ApplicableFlags, Index.get()))
return false;
// All linker flags apply to linking of subsequent files.
ApplicableFlags = Flags;
}
return true;
}
int main(int argc, char **argv) {
// Print a stack trace if we signal out.
sys::PrintStackTraceOnErrorSignal();
PrettyStackTraceProgram X(argc, argv);
LLVMContext &Context = getGlobalContext();
Context.setDiagnosticHandler(diagnosticHandlerWithContext, nullptr, true);
llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
cl::ParseCommandLineOptions(argc, argv, "llvm linker\n");
auto Composite = make_unique<Module>("llvm-link", Context);
Linker L(*Composite);
unsigned Flags = Linker::Flags::None;
if (Internalize)
Flags |= Linker::Flags::InternalizeLinkedSymbols;
if (OnlyNeeded)
Flags |= Linker::Flags::LinkOnlyNeeded;
// First add all the regular input files
if (!linkFiles(argv[0], Context, L, InputFilenames, Flags))
return 1;
// Next the -override ones.
if (!linkFiles(argv[0], Context, L, OverridingInputs,
Flags | Linker::Flags::OverrideFromSrc))
return 1;
// Import any functions requested via -import
if (!importFunctions(argv[0], Context, L))
return 1;
if (DumpAsm) errs() << "Here's the assembly:\n" << *Composite;
std::error_code EC;
tool_output_file Out(OutputFilename, EC, sys::fs::F_None);
if (EC) {
errs() << EC.message() << '\n';
return 1;
}
if (verifyModule(*Composite, &errs())) {
errs() << argv[0] << ": error: linked module is broken!\n";
return 1;
}
if (Verbose) errs() << "Writing bitcode...\n";
if (OutputAssembly) {
Composite->print(Out.os(), nullptr, PreserveAssemblyUseListOrder);
} else if (Force || !CheckBitcodeOutputToConsole(Out.os(), true))
WriteBitcodeToFile(Composite.get(), Out.os(), PreserveBitcodeUseListOrder);
// Declare success.
Out.keep();
return 0;
}