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Merged
merged 7 commits into from
Jan 11, 2025
Merged

-ftime-report: reorganize timers #122225

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586f1fa
[𝘀𝗽𝗿] initial version
MaskRay Jan 9, 2025
97fdcb8
.
MaskRay Jan 9, 2025
dc3ded7
.
MaskRay Jan 9, 2025
1a32599
fix overlap
MaskRay Jan 9, 2025
d7a856d
add yieldTo and add optimizer/machine code generation
MaskRay Jan 10, 2025
41835cb
remove unneeded assert
MaskRay Jan 10, 2025
c9c6310
rebase
MaskRay Jan 11, 2025
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10 changes: 3 additions & 7 deletions clang/include/clang/CodeGen/BackendUtil.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,11 +25,9 @@ class FileSystem;
} // namespace llvm

namespace clang {
class CompilerInstance;
class DiagnosticsEngine;
class HeaderSearchOptions;
class CodeGenOptions;
class TargetOptions;
class LangOptions;
class BackendConsumer;

enum BackendAction {
Expand All @@ -41,10 +39,8 @@ enum BackendAction {
Backend_EmitObj ///< Emit native object files
};

void EmitBackendOutput(DiagnosticsEngine &Diags, const HeaderSearchOptions &,
const CodeGenOptions &CGOpts, const TargetOptions &TOpts,
const LangOptions &LOpts, StringRef TDesc,
llvm::Module *M, BackendAction Action,
void emitBackendOutput(CompilerInstance &CI, StringRef TDesc, llvm::Module *M,
BackendAction Action,
llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
std::unique_ptr<raw_pwrite_stream> OS,
BackendConsumer *BC = nullptr);
Expand Down
4 changes: 3 additions & 1 deletion clang/include/clang/Frontend/CompilerInstance.h
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Expand Up @@ -118,7 +118,7 @@ class CompilerInstance : public ModuleLoader {
std::unique_ptr<Sema> TheSema;

/// The frontend timer group.
std::unique_ptr<llvm::TimerGroup> FrontendTimerGroup;
std::unique_ptr<llvm::TimerGroup> timerGroup;

/// The frontend timer.
std::unique_ptr<llvm::Timer> FrontendTimer;
Expand Down Expand Up @@ -630,6 +630,8 @@ class CompilerInstance : public ModuleLoader {
/// @name Frontend timer
/// @{

llvm::TimerGroup &getTimerGroup() const { return *timerGroup; }

bool hasFrontendTimer() const { return (bool)FrontendTimer; }

llvm::Timer &getFrontendTimer() const {
Expand Down
4 changes: 2 additions & 2 deletions clang/lib/CodeGen/BackendConsumer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -28,8 +28,8 @@ class BackendConsumer : public ASTConsumer {
using LinkModule = CodeGenAction::LinkModule;

virtual void anchor();
CompilerInstance &CI;
DiagnosticsEngine &Diags;
const HeaderSearchOptions &HeaderSearchOpts;
const CodeGenOptions &CodeGenOpts;
const TargetOptions &TargetOpts;
const LangOptions &LangOpts;
Expand Down Expand Up @@ -70,7 +70,7 @@ class BackendConsumer : public ASTConsumer {
llvm::Module *CurLinkModule = nullptr;

public:
BackendConsumer(const CompilerInstance &CI, BackendAction Action,
BackendConsumer(CompilerInstance &CI, BackendAction Action,
IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
llvm::LLVMContext &C, SmallVector<LinkModule, 4> LinkModules,
StringRef InFile, std::unique_ptr<raw_pwrite_stream> OS,
Expand Down
44 changes: 29 additions & 15 deletions clang/lib/CodeGen/BackendUtil.cpp
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Expand Up @@ -16,6 +16,7 @@
#include "clang/Frontend/FrontendDiagnostic.h"
#include "clang/Frontend/Utils.h"
#include "clang/Lex/HeaderSearchOptions.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Analysis/GlobalsModRef.h"
Expand Down Expand Up @@ -137,8 +138,6 @@ class EmitAssemblyHelper {
llvm::Module *TheModule;
IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS;

Timer CodeGenerationTime;

std::unique_ptr<raw_pwrite_stream> OS;

Triple TargetTriple;
Expand Down Expand Up @@ -211,7 +210,6 @@ class EmitAssemblyHelper {
IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS)
: Diags(_Diags), HSOpts(HeaderSearchOpts), CodeGenOpts(CGOpts),
TargetOpts(TOpts), LangOpts(LOpts), TheModule(M), VFS(std::move(VFS)),
CodeGenerationTime("codegen", "Code Generation Time"),
TargetTriple(TheModule->getTargetTriple()) {}

~EmitAssemblyHelper() {
Expand All @@ -222,8 +220,8 @@ class EmitAssemblyHelper {
std::unique_ptr<TargetMachine> TM;

// Emit output using the new pass manager for the optimization pipeline.
void EmitAssembly(BackendAction Action, std::unique_ptr<raw_pwrite_stream> OS,
BackendConsumer *BC);
void emitAssembly(const CompilerInstance &CI, BackendAction Action,
std::unique_ptr<raw_pwrite_stream> OS, BackendConsumer *BC);
};
} // namespace

Expand Down Expand Up @@ -1212,10 +1210,10 @@ void EmitAssemblyHelper::RunCodegenPipeline(
}
}

void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
void EmitAssemblyHelper::emitAssembly(const CompilerInstance &CI,
BackendAction Action,
std::unique_ptr<raw_pwrite_stream> OS,
BackendConsumer *BC) {
TimeRegion Region(CodeGenOpts.TimePasses ? &CodeGenerationTime : nullptr);
setCommandLineOpts(CodeGenOpts);

bool RequiresCodeGen = actionRequiresCodeGen(Action);
Expand Down Expand Up @@ -1346,14 +1344,30 @@ static void runThinLTOBackend(
}
}

void clang::EmitBackendOutput(
DiagnosticsEngine &Diags, const HeaderSearchOptions &HeaderOpts,
const CodeGenOptions &CGOpts, const clang::TargetOptions &TOpts,
const LangOptions &LOpts, StringRef TDesc, llvm::Module *M,
BackendAction Action, IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
std::unique_ptr<raw_pwrite_stream> OS, BackendConsumer *BC) {

void clang::emitBackendOutput(CompilerInstance &CI, StringRef TDesc,
llvm::Module *M, BackendAction Action,
IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
std::unique_ptr<raw_pwrite_stream> OS,
BackendConsumer *BC) {
llvm::TimeTraceScope TimeScope("Backend");
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@cachemeifyoucan cachemeifyoucan Jan 9, 2025

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I hope there is a way to unify those two timers, at least the scope of them.

DiagnosticsEngine &Diags = CI.getDiagnostics();
const auto &HeaderOpts = CI.getHeaderSearchOpts();
const auto &CGOpts = CI.getCodeGenOpts();
const auto &TOpts = CI.getTargetOpts();
const auto &LOpts = CI.getLangOpts();

Timer timer;
if (CGOpts.TimePasses) {
CI.getFrontendTimer().stopTimer();
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@cachemeifyoucan cachemeifyoucan Jan 9, 2025

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This stopTimer() is a bit suspicious. Where is the start timer? There are assertions to make sure that start/stop is balanced. I also believe you can enter this function without ever doing frontend?

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@MaskRay MaskRay Jan 9, 2025 •
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"Clang front-end" has a TimeRegion in clang/lib/Frontend/FrontendAction.cpp.

This PR repurposes the "Clang front-end timer" (which included backend time) to remove the backend part. If we don't stop "Clang front-end" here, "Clang front-end" and "Backend" in the same group would double count the time... After this PR, "Clang front-end" is more like preprocessing, lexing, parsing, and semantic analysis.

I recalled another complaint https://aras-p.info/blog/2019/01/12/Investigating-compile-times-and-Clang-ftime-report/

“Clang front-end time report” seems to be time for “everything”, not just the frontend (Clang frontend, LLVM backend, and whatever else it did).

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@cachemeifyoucan cachemeifyoucan Jan 9, 2025

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I see. I like the proposed time breakdown. This deserves a release note I think?

timer.init("backend", "Backend", CI.getTimerGroup());
timer.startTimer();
}
auto _ = llvm::make_scope_exit([&] {
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@cachemeifyoucan cachemeifyoucan Jan 9, 2025

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Just use llvm::TimeRegion?

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@MaskRay MaskRay Jan 9, 2025

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emitBackendOutput is a subset of clang/lib/Frontend/FrontendAction.cpp:1074 llvm::TimeRegion Timer(CI.getFrontendTimer()). We have to start getFrontendTimer() after Backend stops (required by TimeRegion).

Since we both stop a timer and start a timer, I resort to a make_scope_exit.

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Is it better to relocate the Frontend Timer TimeRegion instead of doing a stop and start here? I am not sure if frontend should count the time after backend (even if it isn't much time).

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@MaskRay MaskRay Jan 10, 2025

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This is difficult.... Parsing and codegen are interleaved in clang.ParseAST calls BackendConsumer::HandleTopLevelDecl and BackendConsumer::HandleTranslationUnit (call stack, which do code generation.

I've introduced yieldTo and changed the timers. Updated the description.

if (!CGOpts.TimePasses)
return;
timer.stopTimer();
CI.getFrontendTimer().startTimer();
});

std::unique_ptr<llvm::Module> EmptyModule;
if (!CGOpts.ThinLTOIndexFile.empty()) {
Expand Down Expand Up @@ -1394,7 +1408,7 @@ void clang::EmitBackendOutput(
}

EmitAssemblyHelper AsmHelper(Diags, HeaderOpts, CGOpts, TOpts, LOpts, M, VFS);
AsmHelper.EmitAssembly(Action, std::move(OS), BC);
AsmHelper.emitAssembly(CI, Action, std::move(OS), BC);

// Verify clang's TargetInfo DataLayout against the LLVM TargetMachine's
// DataLayout.
Expand Down
69 changes: 35 additions & 34 deletions clang/lib/CodeGen/CodeGenAction.cpp
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Expand Up @@ -105,23 +105,26 @@ static void reportOptRecordError(Error E, DiagnosticsEngine &Diags,
});
}

BackendConsumer::BackendConsumer(
const CompilerInstance &CI, BackendAction Action,
IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS, LLVMContext &C,
SmallVector<LinkModule, 4> LinkModules, StringRef InFile,
std::unique_ptr<raw_pwrite_stream> OS, CoverageSourceInfo *CoverageInfo,
llvm::Module *CurLinkModule)
: Diags(CI.getDiagnostics()), HeaderSearchOpts(CI.getHeaderSearchOpts()),
CodeGenOpts(CI.getCodeGenOpts()), TargetOpts(CI.getTargetOpts()),
LangOpts(CI.getLangOpts()), AsmOutStream(std::move(OS)), FS(VFS),
LLVMIRGeneration("irgen", "LLVM IR Generation Time"), Action(Action),
BackendConsumer::BackendConsumer(CompilerInstance &CI, BackendAction Action,
IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
LLVMContext &C,
SmallVector<LinkModule, 4> LinkModules,
StringRef InFile,
std::unique_ptr<raw_pwrite_stream> OS,
CoverageSourceInfo *CoverageInfo,
llvm::Module *CurLinkModule)
: CI(CI), Diags(CI.getDiagnostics()), CodeGenOpts(CI.getCodeGenOpts()),
TargetOpts(CI.getTargetOpts()), LangOpts(CI.getLangOpts()),
AsmOutStream(std::move(OS)), FS(VFS), Action(Action),
Gen(CreateLLVMCodeGen(Diags, InFile, std::move(VFS),
CI.getHeaderSearchOpts(), CI.getPreprocessorOpts(),
CI.getCodeGenOpts(), C, CoverageInfo)),
LinkModules(std::move(LinkModules)), CurLinkModule(CurLinkModule) {
TimerIsEnabled = CodeGenOpts.TimePasses;
llvm::TimePassesIsEnabled = CodeGenOpts.TimePasses;
llvm::TimePassesPerRun = CodeGenOpts.TimePassesPerRun;
if (CodeGenOpts.TimePasses)
LLVMIRGeneration.init("irgen", "LLVM IR Generation", CI.getTimerGroup());
}

llvm::Module* BackendConsumer::getModule() const {
Expand Down Expand Up @@ -160,18 +163,16 @@ bool BackendConsumer::HandleTopLevelDecl(DeclGroupRef D) {
"LLVM IR generation of declaration");

// Recurse.
if (TimerIsEnabled) {
LLVMIRGenerationRefCount += 1;
if (LLVMIRGenerationRefCount == 1)
LLVMIRGeneration.startTimer();
if (TimerIsEnabled && !LLVMIRGenerationRefCount++) {
CI.getFrontendTimer().stopTimer();
LLVMIRGeneration.startTimer();
}

Gen->HandleTopLevelDecl(D);

if (TimerIsEnabled) {
LLVMIRGenerationRefCount -= 1;
if (LLVMIRGenerationRefCount == 0)
LLVMIRGeneration.stopTimer();
if (TimerIsEnabled && !--LLVMIRGenerationRefCount) {
LLVMIRGeneration.stopTimer();
CI.getFrontendTimer().startTimer();
}

return true;
Expand All @@ -181,13 +182,17 @@ void BackendConsumer::HandleInlineFunctionDefinition(FunctionDecl *D) {
PrettyStackTraceDecl CrashInfo(D, SourceLocation(),
Context->getSourceManager(),
"LLVM IR generation of inline function");
if (TimerIsEnabled)
if (TimerIsEnabled) {
CI.getFrontendTimer().stopTimer();
LLVMIRGeneration.startTimer();
}

Gen->HandleInlineFunctionDefinition(D);

if (TimerIsEnabled)
if (TimerIsEnabled) {
LLVMIRGeneration.stopTimer();
CI.getFrontendTimer().startTimer();
}
}

void BackendConsumer::HandleInterestingDecl(DeclGroupRef D) {
Expand Down Expand Up @@ -237,18 +242,16 @@ void BackendConsumer::HandleTranslationUnit(ASTContext &C) {
{
llvm::TimeTraceScope TimeScope("Frontend");
PrettyStackTraceString CrashInfo("Per-file LLVM IR generation");
if (TimerIsEnabled) {
LLVMIRGenerationRefCount += 1;
if (LLVMIRGenerationRefCount == 1)
LLVMIRGeneration.startTimer();
if (TimerIsEnabled && !LLVMIRGenerationRefCount++) {
CI.getFrontendTimer().stopTimer();
LLVMIRGeneration.startTimer();
}

Gen->HandleTranslationUnit(C);

if (TimerIsEnabled) {
LLVMIRGenerationRefCount -= 1;
if (LLVMIRGenerationRefCount == 0)
LLVMIRGeneration.stopTimer();
if (TimerIsEnabled && !--LLVMIRGenerationRefCount) {
LLVMIRGeneration.stopTimer();
CI.getFrontendTimer().startTimer();
}

IRGenFinished = true;
Expand Down Expand Up @@ -321,8 +324,7 @@ void BackendConsumer::HandleTranslationUnit(ASTContext &C) {

EmbedBitcode(getModule(), CodeGenOpts, llvm::MemoryBufferRef());

EmitBackendOutput(Diags, HeaderSearchOpts, CodeGenOpts, TargetOpts, LangOpts,
C.getTargetInfo().getDataLayoutString(), getModule(),
emitBackendOutput(CI, C.getTargetInfo().getDataLayoutString(), getModule(),
Action, FS, std::move(AsmOutStream), this);

Ctx.setDiagnosticHandler(std::move(OldDiagnosticHandler));
Expand Down Expand Up @@ -1183,10 +1185,9 @@ void CodeGenAction::ExecuteAction() {
std::unique_ptr<llvm::ToolOutputFile> OptRecordFile =
std::move(*OptRecordFileOrErr);

EmitBackendOutput(
Diagnostics, CI.getHeaderSearchOpts(), CodeGenOpts, TargetOpts,
CI.getLangOpts(), CI.getTarget().getDataLayoutString(), TheModule.get(),
BA, CI.getFileManager().getVirtualFileSystemPtr(), std::move(OS));
emitBackendOutput(CI, CI.getTarget().getDataLayoutString(), TheModule.get(),
BA, CI.getFileManager().getVirtualFileSystemPtr(),
std::move(OS));
if (OptRecordFile)
OptRecordFile->keep();
}
Expand Down
15 changes: 7 additions & 8 deletions clang/lib/CodeGen/ObjectFilePCHContainerWriter.cpp
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Expand Up @@ -37,6 +37,7 @@ using namespace clang;

namespace {
class PCHContainerGenerator : public ASTConsumer {
CompilerInstance &CI;
DiagnosticsEngine &Diags;
const std::string MainFileName;
const std::string OutputFileName;
Expand Down Expand Up @@ -139,7 +140,7 @@ class PCHContainerGenerator : public ASTConsumer {
const std::string &OutputFileName,
std::unique_ptr<raw_pwrite_stream> OS,
std::shared_ptr<PCHBuffer> Buffer)
: Diags(CI.getDiagnostics()), MainFileName(MainFileName),
: CI(CI), Diags(CI.getDiagnostics()), MainFileName(MainFileName),
OutputFileName(OutputFileName), Ctx(nullptr),
MMap(CI.getPreprocessor().getHeaderSearchInfo().getModuleMap()),
FS(&CI.getVirtualFileSystem()),
Expand Down Expand Up @@ -317,19 +318,17 @@ class PCHContainerGenerator : public ASTConsumer {
LLVM_DEBUG({
// Print the IR for the PCH container to the debug output.
llvm::SmallString<0> Buffer;
clang::EmitBackendOutput(
Diags, HeaderSearchOpts, CodeGenOpts, TargetOpts, LangOpts,
Ctx.getTargetInfo().getDataLayoutString(), M.get(),
clang::emitBackendOutput(
CI, Ctx.getTargetInfo().getDataLayoutString(), M.get(),
BackendAction::Backend_EmitLL, FS,
std::make_unique<llvm::raw_svector_ostream>(Buffer));
llvm::dbgs() << Buffer;
});

// Use the LLVM backend to emit the pch container.
clang::EmitBackendOutput(Diags, HeaderSearchOpts, CodeGenOpts, TargetOpts,
LangOpts,
Ctx.getTargetInfo().getDataLayoutString(), M.get(),
BackendAction::Backend_EmitObj, FS, std::move(OS));
clang::emitBackendOutput(CI, Ctx.getTargetInfo().getDataLayoutString(),
M.get(), BackendAction::Backend_EmitObj, FS,
std::move(OS));

// Free the memory for the temporary buffer.
llvm::SmallVector<char, 0> Empty;
Expand Down
23 changes: 10 additions & 13 deletions clang/lib/Frontend/CompilerInstance.cpp
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Expand Up @@ -722,11 +722,9 @@ void CompilerInstance::createCodeCompletionConsumer() {
}

void CompilerInstance::createFrontendTimer() {
FrontendTimerGroup.reset(
new llvm::TimerGroup("frontend", "Clang front-end time report"));
timerGroup.reset(new llvm::TimerGroup("clang", "Clang time report"));
FrontendTimer.reset(
new llvm::Timer("frontend", "Clang front-end timer",
*FrontendTimerGroup));
new llvm::Timer("frontend", "Clang front-end", *timerGroup));
}

CodeCompleteConsumer *
Expand Down Expand Up @@ -1726,10 +1724,9 @@ void CompilerInstance::createASTReader() {
const FrontendOptions &FEOpts = getFrontendOpts();
std::unique_ptr<llvm::Timer> ReadTimer;

if (FrontendTimerGroup)
if (timerGroup)
ReadTimer = std::make_unique<llvm::Timer>("reading_modules",
"Reading modules",
*FrontendTimerGroup);
"Reading modules", *timerGroup);
TheASTReader = new ASTReader(
getPreprocessor(), getModuleCache(), &getASTContext(),
getPCHContainerReader(), getFrontendOpts().ModuleFileExtensions,
Expand Down Expand Up @@ -1758,10 +1755,10 @@ void CompilerInstance::createASTReader() {
bool CompilerInstance::loadModuleFile(
StringRef FileName, serialization::ModuleFile *&LoadedModuleFile) {
llvm::Timer Timer;
if (FrontendTimerGroup)
if (timerGroup)
Timer.init("preloading." + FileName.str(), "Preloading " + FileName.str(),
*FrontendTimerGroup);
llvm::TimeRegion TimeLoading(FrontendTimerGroup ? &Timer : nullptr);
*timerGroup);
llvm::TimeRegion TimeLoading(timerGroup ? &Timer : nullptr);

// If we don't already have an ASTReader, create one now.
if (!TheASTReader)
Expand Down Expand Up @@ -1892,10 +1889,10 @@ ModuleLoadResult CompilerInstance::findOrCompileModuleAndReadAST(

// Time how long it takes to load the module.
llvm::Timer Timer;
if (FrontendTimerGroup)
if (timerGroup)
Timer.init("loading." + ModuleFilename, "Loading " + ModuleFilename,
*FrontendTimerGroup);
llvm::TimeRegion TimeLoading(FrontendTimerGroup ? &Timer : nullptr);
*timerGroup);
llvm::TimeRegion TimeLoading(timerGroup ? &Timer : nullptr);
llvm::TimeTraceScope TimeScope("Module Load", ModuleName);

// Try to load the module file. If we are not trying to load from the
Expand Down
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