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//===-- llvm-mca.cpp - Machine Code Analyzer -------------------*- C++ -* -===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This utility is a simple driver that allows static performance analysis on
// machine code similarly to how IACA (Intel Architecture Code Analyzer) works.
// llvm-mca [options] <file-name>
// -march <type>
// -mcpu <cpu>
// -o <file>
// The target defaults to the host target.
// The cpu defaults to the 'native' host cpu.
// The output defaults to standard output.
#include "CodeRegion.h"
#include "Context.h"
#include "DispatchStatistics.h"
#include "FetchStage.h"
#include "InstructionInfoView.h"
#include "InstructionTables.h"
#include "Pipeline.h"
#include "PipelinePrinter.h"
#include "RegisterFileStatistics.h"
#include "ResourcePressureView.h"
#include "RetireControlUnitStatistics.h"
#include "SchedulerStatistics.h"
#include "SummaryView.h"
#include "TimelineView.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCParser/MCTargetAsmParser.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/InitLLVM.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Support/WithColor.h"
using namespace llvm;
static cl::OptionCategory ToolOptions("Tool Options");
static cl::OptionCategory ViewOptions("View Options");
static cl::opt<std::string> InputFilename(cl::Positional,
cl::desc("<input file>"),
cl::cat(ToolOptions), cl::init("-"));
static cl::opt<std::string> OutputFilename("o", cl::desc("Output filename"),
cl::init("-"), cl::cat(ToolOptions),
static cl::opt<std::string>
ArchName("march", cl::desc("Target arch to assemble for, "
"see -version for available targets"),
static cl::opt<std::string>
TripleName("mtriple", cl::desc("Target triple to assemble for, "
"see -version for available targets"),
static cl::opt<std::string>
cl::desc("Target a specific cpu type (-mcpu=help for details)"),
cl::value_desc("cpu-name"), cl::cat(ToolOptions), cl::init("native"));
static cl::opt<int>
cl::desc("Syntax variant to use for output printing"),
cl::cat(ToolOptions), cl::init(-1));
static cl::opt<unsigned> Iterations("iterations",
cl::desc("Number of iterations to run"),
cl::cat(ToolOptions), cl::init(0));
static cl::opt<unsigned>
DispatchWidth("dispatch", cl::desc("Override the processor dispatch width"),
cl::cat(ToolOptions), cl::init(0));
static cl::opt<unsigned>
cl::desc("Maximum number of physical registers which can "
"be used for register mappings"),
cl::cat(ToolOptions), cl::init(0));
static cl::opt<bool>
cl::desc("Print register file statistics"),
cl::cat(ViewOptions), cl::init(false));
static cl::opt<bool> PrintDispatchStats("dispatch-stats",
cl::desc("Print dispatch statistics"),
cl::cat(ViewOptions), cl::init(false));
static cl::opt<bool>
PrintSummaryView("summary-view", cl::Hidden,
cl::desc("Print summary view (enabled by default)"),
cl::cat(ViewOptions), cl::init(true));
static cl::opt<bool> PrintSchedulerStats("scheduler-stats",
cl::desc("Print scheduler statistics"),
cl::cat(ViewOptions), cl::init(false));
static cl::opt<bool>
cl::desc("Print retire control unit statistics"),
cl::cat(ViewOptions), cl::init(false));
static cl::opt<bool> PrintResourcePressureView(
cl::desc("Print the resource pressure view (enabled by default)"),
cl::cat(ViewOptions), cl::init(true));
static cl::opt<bool> PrintTimelineView("timeline",
cl::desc("Print the timeline view"),
cl::cat(ViewOptions), cl::init(false));
static cl::opt<unsigned> TimelineMaxIterations(
cl::desc("Maximum number of iterations to print in timeline view"),
cl::cat(ViewOptions), cl::init(0));
static cl::opt<unsigned> TimelineMaxCycles(
"Maximum number of cycles in the timeline view. Defaults to 80 cycles"),
cl::cat(ViewOptions), cl::init(80));
static cl::opt<bool>
cl::desc("If set, assume that loads and stores do not alias"),
cl::cat(ToolOptions), cl::init(true));
static cl::opt<unsigned>
cl::desc("Size of the load queue (unbound by default)"),
cl::cat(ToolOptions), cl::init(0));
static cl::opt<unsigned>
cl::desc("Size of the store queue (unbound by default)"),
cl::cat(ToolOptions), cl::init(0));
static cl::opt<bool>
cl::desc("Print instruction tables"),
cl::cat(ToolOptions), cl::init(false));
static cl::opt<bool> PrintInstructionInfoView(
cl::desc("Print the instruction info view (enabled by default)"),
cl::cat(ViewOptions), cl::init(true));
static cl::opt<bool> EnableAllStats("all-stats",
cl::desc("Print all hardware statistics"),
cl::cat(ViewOptions), cl::init(false));
static cl::opt<bool>
cl::desc("Print all views including hardware statistics"),
cl::cat(ViewOptions), cl::init(false));
namespace {
const Target *getTarget(const char *ProgName) {
TripleName = Triple::normalize(TripleName);
if (TripleName.empty())
TripleName = Triple::normalize(sys::getDefaultTargetTriple());
Triple TheTriple(TripleName);
// Get the target specific parser.
std::string Error;
const Target *TheTarget =
TargetRegistry::lookupTarget(ArchName, TheTriple, Error);
if (!TheTarget) {
errs() << ProgName << ": " << Error;
return nullptr;
// Return the found target.
return TheTarget;
// A comment consumer that parses strings.
// The only valid tokens are strings.
class MCACommentConsumer : public AsmCommentConsumer {
mca::CodeRegions &Regions;
MCACommentConsumer(mca::CodeRegions &R) : Regions(R) {}
void HandleComment(SMLoc Loc, StringRef CommentText) override {
// Skip empty comments.
StringRef Comment(CommentText);
if (Comment.empty())
// Skip spaces and tabs
unsigned Position = Comment.find_first_not_of(" \t");
if (Position >= Comment.size())
// we reached the end of the comment. Bail out.
Comment = Comment.drop_front(Position);
if (Comment.consume_front("LLVM-MCA-END")) {
// Now try to parse string LLVM-MCA-BEGIN
if (!Comment.consume_front("LLVM-MCA-BEGIN"))
// Skip spaces and tabs
Position = Comment.find_first_not_of(" \t");
if (Position < Comment.size())
Comment = Comment.drop_front(Position);
// Use the rest of the string as a descriptor for this code snippet.
Regions.beginRegion(Comment, Loc);
int AssembleInput(const char *ProgName, MCAsmParser &Parser,
const Target *TheTarget, MCSubtargetInfo &STI,
MCInstrInfo &MCII, MCTargetOptions &MCOptions) {
std::unique_ptr<MCTargetAsmParser> TAP(
TheTarget->createMCAsmParser(STI, Parser, MCII, MCOptions));
if (!TAP) {
WithColor::error() << "this target does not support assembly parsing.\n";
return 1;
return Parser.Run(false);
ErrorOr<std::unique_ptr<ToolOutputFile>> getOutputStream() {
if (OutputFilename == "")
OutputFilename = "-";
std::error_code EC;
auto Out =
llvm::make_unique<ToolOutputFile>(OutputFilename, EC, sys::fs::F_None);
if (!EC)
return std::move(Out);
return EC;
class MCStreamerWrapper final : public MCStreamer {
mca::CodeRegions &Regions;
MCStreamerWrapper(MCContext &Context, mca::CodeRegions &R)
: MCStreamer(Context), Regions(R) {}
// We only want to intercept the emission of new instructions.
virtual void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
bool /* unused */) override {
Regions.addInstruction(llvm::make_unique<const MCInst>(Inst));
bool EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override {
return true;
void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) override {}
void EmitZerofill(MCSection *Section, MCSymbol *Symbol = nullptr,
uint64_t Size = 0, unsigned ByteAlignment = 0,
SMLoc Loc = SMLoc()) override {}
void EmitGPRel32Value(const MCExpr *Value) override {}
void BeginCOFFSymbolDef(const MCSymbol *Symbol) override {}
void EmitCOFFSymbolStorageClass(int StorageClass) override {}
void EmitCOFFSymbolType(int Type) override {}
void EndCOFFSymbolDef() override {}
const std::vector<std::unique_ptr<const MCInst>> &
GetInstructionSequence(unsigned Index) const {
return Regions.getInstructionSequence(Index);
} // end of anonymous namespace
static void processOptionImpl(cl::opt<bool> &O, const cl::opt<bool> &Default) {
if (!O.getNumOccurrences() || O.getPosition() < Default.getPosition())
O = Default.getValue();
static void processViewOptions() {
if (!EnableAllViews.getNumOccurrences() &&
if (EnableAllViews.getNumOccurrences()) {
processOptionImpl(PrintSummaryView, EnableAllViews);
processOptionImpl(PrintResourcePressureView, EnableAllViews);
processOptionImpl(PrintTimelineView, EnableAllViews);
processOptionImpl(PrintInstructionInfoView, EnableAllViews);
const cl::opt<bool> &Default =
EnableAllViews.getPosition() < EnableAllStats.getPosition()
? EnableAllStats
: EnableAllViews;
processOptionImpl(PrintSummaryView, Default);
processOptionImpl(PrintRegisterFileStats, Default);
processOptionImpl(PrintDispatchStats, Default);
processOptionImpl(PrintSchedulerStats, Default);
processOptionImpl(PrintRetireStats, Default);
int main(int argc, char **argv) {
InitLLVM X(argc, argv);
// Initialize targets and assembly parsers.
// Enable printing of available targets when flag --version is specified.
cl::HideUnrelatedOptions({&ToolOptions, &ViewOptions});
// Parse flags and initialize target options.
cl::ParseCommandLineOptions(argc, argv,
"llvm machine code performance analyzer.\n");
MCTargetOptions MCOptions;
MCOptions.PreserveAsmComments = false;
// Get the target from the triple. If a triple is not specified, then select
// the default triple for the host. If the triple doesn't correspond to any
// registered target, then exit with an error message.
const char *ProgName = argv[0];
const Target *TheTarget = getTarget(ProgName);
if (!TheTarget)
return 1;
// GetTarget() may replaced TripleName with a default triple.
// For safety, reconstruct the Triple object.
Triple TheTriple(TripleName);
ErrorOr<std::unique_ptr<MemoryBuffer>> BufferPtr =
if (std::error_code EC = BufferPtr.getError()) {
WithColor::error() << InputFilename << ": " << EC.message() << '\n';
return 1;
// Apply overrides to llvm-mca specific options.
SourceMgr SrcMgr;
// Tell SrcMgr about this buffer, which is what the parser will pick up.
SrcMgr.AddNewSourceBuffer(std::move(*BufferPtr), SMLoc());
std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(TripleName));
assert(MRI && "Unable to create target register info!");
std::unique_ptr<MCAsmInfo> MAI(TheTarget->createMCAsmInfo(*MRI, TripleName));
assert(MAI && "Unable to create target asm info!");
MCObjectFileInfo MOFI;
MCContext Ctx(MAI.get(), MRI.get(), &MOFI, &SrcMgr);
MOFI.InitMCObjectFileInfo(TheTriple, /* PIC= */ false, Ctx);
std::unique_ptr<buffer_ostream> BOS;
mca::CodeRegions Regions(SrcMgr);
MCStreamerWrapper Str(Ctx, Regions);
std::unique_ptr<MCInstrInfo> MCII(TheTarget->createMCInstrInfo());
std::unique_ptr<MCInstrAnalysis> MCIA(
if (!"native"))
MCPU = llvm::sys::getHostCPUName();
std::unique_ptr<MCSubtargetInfo> STI(
TheTarget->createMCSubtargetInfo(TripleName, MCPU, /* FeaturesStr */ ""));
if (!STI->isCPUStringValid(MCPU))
return 1;
if (!PrintInstructionTables && !STI->getSchedModel().isOutOfOrder()) {
WithColor::error() << "please specify an out-of-order cpu. '" << MCPU
<< "' is an in-order cpu.\n";
return 1;
if (!STI->getSchedModel().hasInstrSchedModel()) {
<< "unable to find instruction-level scheduling information for"
<< " target triple '" << TheTriple.normalize() << "' and cpu '" << MCPU
<< "'.\n";
if (STI->getSchedModel().InstrItineraries)
<< "cpu '" << MCPU << "' provides itineraries. However, "
<< "instruction itineraries are currently unsupported.\n";
return 1;
std::unique_ptr<MCAsmParser> P(createMCAsmParser(SrcMgr, Ctx, Str, *MAI));
MCAsmLexer &Lexer = P->getLexer();
MCACommentConsumer CC(Regions);
if (AssembleInput(ProgName, *P, TheTarget, *STI, *MCII, MCOptions))
return 1;
if (Regions.empty()) {
WithColor::error() << "no assembly instructions found.\n";
return 1;
// Now initialize the output file.
auto OF = getOutputStream();
if (std::error_code EC = OF.getError()) {
WithColor::error() << EC.message() << '\n';
return 1;
unsigned AssemblerDialect = P->getAssemblerDialect();
if (OutputAsmVariant >= 0)
AssemblerDialect = static_cast<unsigned>(OutputAsmVariant);
std::unique_ptr<MCInstPrinter> IP(TheTarget->createMCInstPrinter(
Triple(TripleName), AssemblerDialect, *MAI, *MCII, *MRI));
if (!IP) {
<< "unable to create instruction printer for target triple '"
<< TheTriple.normalize() << "' with assembly variant "
<< AssemblerDialect << ".\n";
return 1;
std::unique_ptr<llvm::ToolOutputFile> TOF = std::move(*OF);
const MCSchedModel &SM = STI->getSchedModel();
unsigned Width = SM.IssueWidth;
if (DispatchWidth)
Width = DispatchWidth;
// Create an instruction builder.
mca::InstrBuilder IB(*STI, *MCII, *MRI, *MCIA, *IP);
// Create a context to control ownership of the pipeline hardware.
mca::Context MCA(*MRI, *STI);
mca::PipelineOptions PO(Width, RegisterFileSize, LoadQueueSize,
StoreQueueSize, AssumeNoAlias);
// Number each region in the sequence.
unsigned RegionIdx = 0;
for (const std::unique_ptr<mca::CodeRegion> &Region : Regions) {
// Skip empty code regions.
if (Region->empty())
// Don't print the header of this region if it is the default region, and
// it doesn't have an end location.
if (Region->startLoc().isValid() || Region->endLoc().isValid()) {
TOF->os() << "\n[" << RegionIdx++ << "] Code Region";
StringRef Desc = Region->getDescription();
if (!Desc.empty())
TOF->os() << " - " << Desc;
TOF->os() << "\n\n";
mca::SourceMgr S(Region->getInstructions(),
PrintInstructionTables ? 1 : Iterations);
if (PrintInstructionTables) {
// Create a pipeline, stages, and a printer.
auto P = llvm::make_unique<mca::Pipeline>();
P->appendStage(llvm::make_unique<mca::FetchStage>(IB, S));
P->appendStage(llvm::make_unique<mca::InstructionTables>(SM, IB));
mca::PipelinePrinter Printer(*P);
// Create the views for this pipeline, execute, and emit a report.
if (PrintInstructionInfoView) {
llvm::make_unique<mca::InstructionInfoView>(*STI, *MCII, S, *IP));
llvm::make_unique<mca::ResourcePressureView>(*STI, *IP, S));
// Create a basic pipeline simulating an out-of-order backend.
auto P = MCA.createDefaultPipeline(PO, IB, S);
mca::PipelinePrinter Printer(*P);
if (PrintSummaryView)
Printer.addView(llvm::make_unique<mca::SummaryView>(SM, S, Width));
if (PrintInstructionInfoView)
llvm::make_unique<mca::InstructionInfoView>(*STI, *MCII, S, *IP));
if (PrintDispatchStats)
if (PrintSchedulerStats)
if (PrintRetireStats)
if (PrintRegisterFileStats)
if (PrintResourcePressureView)
llvm::make_unique<mca::ResourcePressureView>(*STI, *IP, S));
if (PrintTimelineView) {
*STI, *IP, S, TimelineMaxIterations, TimelineMaxCycles));
// Clear the InstrBuilder internal state in preparation for another round.
return 0;