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llvm-mirror/tools/llvm-lto2/llvm-lto2.cpp
Fangrui Song 2174d3b961 [LTO] Add SelectionKind to IRSymtab and use it in ld.lld/LLVMgold 
In PGO, a C++ external linkage function `foo` has a private counter
`__profc_foo` and a private `__profd_foo` in a `comdat nodeduplicate`.

A `__attribute__((weak))` function `foo` has a weak hidden counter `__profc_foo`
and a private `__profd_foo` in a `comdat nodeduplicate`.

In `ld.lld a.o b.o`, say a.o defines an external linkage `foo` and b.o
defines a weak `foo`. Currently we treat `comdat nodeduplicate` as `comdat any`,
ld.lld will incorrectly consider `b.o:__profc_foo` non-prevailing.  In the worst
case when `b.o:__profd_foo` is retained and `b.o:__profc_foo` isn't, there will
be dangling reference causing an `undefined hidden symbol` error.

Add SelectionKind to `Comdat` in IRSymtab and let linkers ignore nodeduplicate comdat.

Differential Revision: https://reviews.llvm.org/D106228
2021-07-20 13:22:00 -07:00

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//===-- llvm-lto2: test harness for the resolution-based LTO interface ----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This program takes in a list of bitcode files, links them and performs
// link-time optimization according to the provided symbol resolutions using the
// resolution-based LTO interface, and outputs one or more object files.
//
// This program is intended to eventually replace llvm-lto which uses the legacy
// LTO interface.
//
//===----------------------------------------------------------------------===//
#include "llvm/Bitcode/BitcodeReader.h"
#include "llvm/CodeGen/CommandFlags.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/LTO/Caching.h"
#include "llvm/LTO/LTO.h"
#include "llvm/Passes/PassPlugin.h"
#include "llvm/Remarks/HotnessThresholdParser.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/InitLLVM.h"
#include "llvm/Support/PluginLoader.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/Threading.h"
using namespace llvm;
using namespace lto;
static codegen::RegisterCodeGenFlags CGF;
static cl::opt<char>
OptLevel("O", cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
"(default = '-O2')"),
cl::Prefix, cl::ZeroOrMore, cl::init('2'));
static cl::opt<char> CGOptLevel(
"cg-opt-level",
cl::desc("Codegen optimization level (0, 1, 2 or 3, default = '2')"),
cl::init('2'));
static cl::list<std::string> InputFilenames(cl::Positional, cl::OneOrMore,
cl::desc("<input bitcode files>"));
static cl::opt<std::string> OutputFilename("o", cl::Required,
cl::desc("Output filename"),
cl::value_desc("filename"));
static cl::opt<std::string> CacheDir("cache-dir", cl::desc("Cache Directory"),
cl::value_desc("directory"));
static cl::opt<std::string> OptPipeline("opt-pipeline",
cl::desc("Optimizer Pipeline"),
cl::value_desc("pipeline"));
static cl::opt<std::string> AAPipeline("aa-pipeline",
cl::desc("Alias Analysis Pipeline"),
cl::value_desc("aapipeline"));
static cl::opt<bool> SaveTemps("save-temps", cl::desc("Save temporary files"));
static cl::opt<bool>
ThinLTODistributedIndexes("thinlto-distributed-indexes", cl::init(false),
cl::desc("Write out individual index and "
"import files for the "
"distributed backend case"));
// Default to using all available threads in the system, but using only one
// thread per core (no SMT).
// Use -thinlto-threads=all to use hardware_concurrency() instead, which means
// to use all hardware threads or cores in the system.
static cl::opt<std::string> Threads("thinlto-threads");
static cl::list<std::string> SymbolResolutions(
"r",
cl::desc("Specify a symbol resolution: filename,symbolname,resolution\n"
"where \"resolution\" is a sequence (which may be empty) of the\n"
"following characters:\n"
" p - prevailing: the linker has chosen this definition of the\n"
" symbol\n"
" l - local: the definition of this symbol is unpreemptable at\n"
" runtime and is known to be in this linkage unit\n"
" x - externally visible: the definition of this symbol is\n"
" visible outside of the LTO unit\n"
"A resolution for each symbol must be specified."),
cl::ZeroOrMore);
static cl::opt<std::string> OverrideTriple(
"override-triple",
cl::desc("Replace target triples in input files with this triple"));
static cl::opt<std::string> DefaultTriple(
"default-triple",
cl::desc(
"Replace unspecified target triples in input files with this triple"));
static cl::opt<bool> RemarksWithHotness(
"pass-remarks-with-hotness",
cl::desc("With PGO, include profile count in optimization remarks"),
cl::Hidden);
cl::opt<Optional<uint64_t>, false, remarks::HotnessThresholdParser>
RemarksHotnessThreshold(
"pass-remarks-hotness-threshold",
cl::desc("Minimum profile count required for an "
"optimization remark to be output."
" Use 'auto' to apply the threshold from profile summary."),
cl::value_desc("uint or 'auto'"), cl::init(0), cl::Hidden);
static cl::opt<std::string>
RemarksFilename("pass-remarks-output",
cl::desc("Output filename for pass remarks"),
cl::value_desc("filename"));
static cl::opt<std::string>
RemarksPasses("pass-remarks-filter",
cl::desc("Only record optimization remarks from passes whose "
"names match the given regular expression"),
cl::value_desc("regex"));
static cl::opt<std::string> RemarksFormat(
"pass-remarks-format",
cl::desc("The format used for serializing remarks (default: YAML)"),
cl::value_desc("format"), cl::init("yaml"));
static cl::opt<std::string>
SamplePGOFile("lto-sample-profile-file",
cl::desc("Specify a SamplePGO profile file"));
static cl::opt<std::string>
CSPGOFile("lto-cspgo-profile-file",
cl::desc("Specify a context sensitive PGO profile file"));
static cl::opt<bool>
RunCSIRInstr("lto-cspgo-gen",
cl::desc("Run PGO context sensitive IR instrumentation"),
cl::init(false), cl::Hidden);
static cl::opt<bool>
UseNewPM("use-new-pm",
cl::desc("Run LTO passes using the new pass manager"),
cl::init(LLVM_ENABLE_NEW_PASS_MANAGER), cl::Hidden);
static cl::opt<bool>
DebugPassManager("debug-pass-manager", cl::init(false), cl::Hidden,
cl::desc("Print pass management debugging information"));
static cl::opt<std::string>
StatsFile("stats-file", cl::desc("Filename to write statistics to"));
static cl::list<std::string>
PassPlugins("load-pass-plugin",
cl::desc("Load passes from plugin library"));
static cl::opt<bool> EnableFreestanding(
"lto-freestanding",
cl::desc("Enable Freestanding (disable builtins / TLI) during LTO"),
cl::init(false), cl::Hidden);
static void check(Error E, std::string Msg) {
if (!E)
return;
handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
errs() << "llvm-lto2: " << Msg << ": " << EIB.message().c_str() << '\n';
});
exit(1);
}
template <typename T> static T check(Expected<T> E, std::string Msg) {
if (E)
return std::move(*E);
check(E.takeError(), Msg);
return T();
}
static void check(std::error_code EC, std::string Msg) {
check(errorCodeToError(EC), Msg);
}
template <typename T> static T check(ErrorOr<T> E, std::string Msg) {
if (E)
return std::move(*E);
check(E.getError(), Msg);
return T();
}
static int usage() {
errs() << "Available subcommands: dump-symtab run\n";
return 1;
}
static int run(int argc, char **argv) {
cl::ParseCommandLineOptions(argc, argv, "Resolution-based LTO test harness");
// FIXME: Workaround PR30396 which means that a symbol can appear
// more than once if it is defined in module-level assembly and
// has a GV declaration. We allow (file, symbol) pairs to have multiple
// resolutions and apply them in the order observed.
std::map<std::pair<std::string, std::string>, std::list<SymbolResolution>>
CommandLineResolutions;
for (std::string R : SymbolResolutions) {
StringRef Rest = R;
StringRef FileName, SymbolName;
std::tie(FileName, Rest) = Rest.split(',');
if (Rest.empty()) {
llvm::errs() << "invalid resolution: " << R << '\n';
return 1;
}
std::tie(SymbolName, Rest) = Rest.split(',');
SymbolResolution Res;
for (char C : Rest) {
if (C == 'p')
Res.Prevailing = true;
else if (C == 'l')
Res.FinalDefinitionInLinkageUnit = true;
else if (C == 'x')
Res.VisibleToRegularObj = true;
else if (C == 'r')
Res.LinkerRedefined = true;
else {
llvm::errs() << "invalid character " << C << " in resolution: " << R
<< '\n';
return 1;
}
}
CommandLineResolutions[{std::string(FileName), std::string(SymbolName)}]
.push_back(Res);
}
std::vector<std::unique_ptr<MemoryBuffer>> MBs;
Config Conf;
Conf.DiagHandler = [](const DiagnosticInfo &DI) {
DiagnosticPrinterRawOStream DP(errs());
DI.print(DP);
errs() << '\n';
if (DI.getSeverity() == DS_Error)
exit(1);
};
Conf.CPU = codegen::getMCPU();
Conf.Options = codegen::InitTargetOptionsFromCodeGenFlags(Triple());
Conf.MAttrs = codegen::getMAttrs();
if (auto RM = codegen::getExplicitRelocModel())
Conf.RelocModel = RM.getValue();
Conf.CodeModel = codegen::getExplicitCodeModel();
Conf.DebugPassManager = DebugPassManager;
if (SaveTemps)
check(Conf.addSaveTemps(OutputFilename + "."),
"Config::addSaveTemps failed");
// Optimization remarks.
Conf.RemarksFilename = RemarksFilename;
Conf.RemarksPasses = RemarksPasses;
Conf.RemarksWithHotness = RemarksWithHotness;
Conf.RemarksHotnessThreshold = RemarksHotnessThreshold;
Conf.RemarksFormat = RemarksFormat;
Conf.SampleProfile = SamplePGOFile;
Conf.CSIRProfile = CSPGOFile;
Conf.RunCSIRInstr = RunCSIRInstr;
// Run a custom pipeline, if asked for.
Conf.OptPipeline = OptPipeline;
Conf.AAPipeline = AAPipeline;
Conf.OptLevel = OptLevel - '0';
Conf.UseNewPM = UseNewPM;
Conf.Freestanding = EnableFreestanding;
for (auto &PluginFN : PassPlugins)
Conf.PassPlugins.push_back(PluginFN);
switch (CGOptLevel) {
case '0':
Conf.CGOptLevel = CodeGenOpt::None;
break;
case '1':
Conf.CGOptLevel = CodeGenOpt::Less;
break;
case '2':
Conf.CGOptLevel = CodeGenOpt::Default;
break;
case '3':
Conf.CGOptLevel = CodeGenOpt::Aggressive;
break;
default:
llvm::errs() << "invalid cg optimization level: " << CGOptLevel << '\n';
return 1;
}
if (auto FT = codegen::getExplicitFileType())
Conf.CGFileType = FT.getValue();
Conf.OverrideTriple = OverrideTriple;
Conf.DefaultTriple = DefaultTriple;
Conf.StatsFile = StatsFile;
Conf.PTO.LoopVectorization = Conf.OptLevel > 1;
Conf.PTO.SLPVectorization = Conf.OptLevel > 1;
ThinBackend Backend;
if (ThinLTODistributedIndexes)
Backend = createWriteIndexesThinBackend(/* OldPrefix */ "",
/* NewPrefix */ "",
/* ShouldEmitImportsFiles */ true,
/* LinkedObjectsFile */ nullptr,
/* OnWrite */ {});
else
Backend = createInProcessThinBackend(
llvm::heavyweight_hardware_concurrency(Threads));
LTO Lto(std::move(Conf), std::move(Backend));
bool HasErrors = false;
for (std::string F : InputFilenames) {
std::unique_ptr<MemoryBuffer> MB = check(MemoryBuffer::getFile(F), F);
std::unique_ptr<InputFile> Input =
check(InputFile::create(MB->getMemBufferRef()), F);
std::vector<SymbolResolution> Res;
for (const InputFile::Symbol &Sym : Input->symbols()) {
auto I = CommandLineResolutions.find({F, std::string(Sym.getName())});
// If it isn't found, look for ".", which would have been added
// (followed by a hash) when the symbol was promoted during module
// splitting if it was defined in one part and used in the other.
// Try looking up the symbol name before the suffix.
if (I == CommandLineResolutions.end()) {
auto SplitName = Sym.getName().rsplit(".");
I = CommandLineResolutions.find({F, std::string(SplitName.first)});
}
if (I == CommandLineResolutions.end()) {
llvm::errs() << argv[0] << ": missing symbol resolution for " << F
<< ',' << Sym.getName() << '\n';
HasErrors = true;
} else {
Res.push_back(I->second.front());
I->second.pop_front();
if (I->second.empty())
CommandLineResolutions.erase(I);
}
}
if (HasErrors)
continue;
MBs.push_back(std::move(MB));
check(Lto.add(std::move(Input), Res), F);
}
if (!CommandLineResolutions.empty()) {
HasErrors = true;
for (auto UnusedRes : CommandLineResolutions)
llvm::errs() << argv[0] << ": unused symbol resolution for "
<< UnusedRes.first.first << ',' << UnusedRes.first.second
<< '\n';
}
if (HasErrors)
return 1;
auto AddStream =
[&](size_t Task) -> std::unique_ptr<lto::NativeObjectStream> {
std::string Path = OutputFilename + "." + utostr(Task);
std::error_code EC;
auto S = std::make_unique<raw_fd_ostream>(Path, EC, sys::fs::OF_None);
check(EC, Path);
return std::make_unique<lto::NativeObjectStream>(std::move(S));
};
auto AddBuffer = [&](size_t Task, std::unique_ptr<MemoryBuffer> MB) {
*AddStream(Task)->OS << MB->getBuffer();
};
NativeObjectCache Cache;
if (!CacheDir.empty())
Cache = check(localCache(CacheDir, AddBuffer), "failed to create cache");
check(Lto.run(AddStream, Cache), "LTO::run failed");
return 0;
}
static int dumpSymtab(int argc, char **argv) {
for (StringRef F : make_range(argv + 1, argv + argc)) {
std::unique_ptr<MemoryBuffer> MB =
check(MemoryBuffer::getFile(F), std::string(F));
BitcodeFileContents BFC =
check(getBitcodeFileContents(*MB), std::string(F));
if (BFC.Symtab.size() >= sizeof(irsymtab::storage::Header)) {
auto *Hdr = reinterpret_cast<const irsymtab::storage::Header *>(
BFC.Symtab.data());
outs() << "version: " << Hdr->Version << '\n';
if (Hdr->Version == irsymtab::storage::Header::kCurrentVersion)
outs() << "producer: " << Hdr->Producer.get(BFC.StrtabForSymtab)
<< '\n';
}
std::unique_ptr<InputFile> Input =
check(InputFile::create(MB->getMemBufferRef()), std::string(F));
outs() << "target triple: " << Input->getTargetTriple() << '\n';
Triple TT(Input->getTargetTriple());
outs() << "source filename: " << Input->getSourceFileName() << '\n';
if (TT.isOSBinFormatCOFF())
outs() << "linker opts: " << Input->getCOFFLinkerOpts() << '\n';
if (TT.isOSBinFormatELF()) {
outs() << "dependent libraries:";
for (auto L : Input->getDependentLibraries())
outs() << " \"" << L << "\"";
outs() << '\n';
}
ArrayRef<std::pair<StringRef, Comdat::SelectionKind>> ComdatTable =
Input->getComdatTable();
for (const InputFile::Symbol &Sym : Input->symbols()) {
switch (Sym.getVisibility()) {
case GlobalValue::HiddenVisibility:
outs() << 'H';
break;
case GlobalValue::ProtectedVisibility:
outs() << 'P';
break;
case GlobalValue::DefaultVisibility:
outs() << 'D';
break;
}
auto PrintBool = [&](char C, bool B) { outs() << (B ? C : '-'); };
PrintBool('U', Sym.isUndefined());
PrintBool('C', Sym.isCommon());
PrintBool('W', Sym.isWeak());
PrintBool('I', Sym.isIndirect());
PrintBool('O', Sym.canBeOmittedFromSymbolTable());
PrintBool('T', Sym.isTLS());
PrintBool('X', Sym.isExecutable());
outs() << ' ' << Sym.getName() << '\n';
if (Sym.isCommon())
outs() << " size " << Sym.getCommonSize() << " align "
<< Sym.getCommonAlignment() << '\n';
int Comdat = Sym.getComdatIndex();
if (Comdat != -1) {
outs() << " comdat ";
switch (ComdatTable[Comdat].second) {
case Comdat::Any:
outs() << "any";
break;
case Comdat::ExactMatch:
outs() << "exactmatch";
break;
case Comdat::Largest:
outs() << "largest";
break;
case Comdat::NoDeduplicate:
outs() << "nodeduplicate";
break;
case Comdat::SameSize:
outs() << "samesize";
break;
}
outs() << ' ' << ComdatTable[Comdat].first << '\n';
}
if (TT.isOSBinFormatCOFF() && Sym.isWeak() && Sym.isIndirect())
outs() << " fallback " << Sym.getCOFFWeakExternalFallback() << '\n';
if (!Sym.getSectionName().empty())
outs() << " section " << Sym.getSectionName() << "\n";
}
outs() << '\n';
}
return 0;
}
int main(int argc, char **argv) {
InitLLVM X(argc, argv);
InitializeAllTargets();
InitializeAllTargetMCs();
InitializeAllAsmPrinters();
InitializeAllAsmParsers();
// FIXME: This should use llvm::cl subcommands, but it isn't currently
// possible to pass an argument not associated with a subcommand to a
// subcommand (e.g. -use-new-pm).
if (argc < 2)
return usage();
StringRef Subcommand = argv[1];
// Ensure that argv[0] is correct after adjusting argv/argc.
argv[1] = argv[0];
if (Subcommand == "dump-symtab")
return dumpSymtab(argc - 1, argv + 1);
if (Subcommand == "run")
return run(argc - 1, argv + 1);
return usage();
}
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