add time traces for AST serialization

[Trass3r]

Summary

Fills gaps in the time trace when precompiled headers are created/loaded.

[Trass3r]

rebased

[jansvoboda11]

This looks good to me in principle. It would be nice to have a simple test that shows what kind of output we get. Can you add that?

[Trass3r]

It looks like this:

There is a generic test for the TimeTraceScope functionality.
Other than that there's only this one I found in https://reviews.llvm.org/D135658#change-sRvmpoTP4Jas.

[jansvoboda11]

Thanks, LGTM.

[Trass3r]

Thanks, could you also commit it? I don't have the rights.

[jansvoboda11]

In D135657#3865581, @Trass3r wrote:

Thanks, could you also commit it? I don't have the rights.

Sure. What name and email do you want me to associate with the commit?

[Trass3r]

This comment was removed by Trass3r.

clang/lib/Serialization/ASTReader.cpp

 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/SaveAndRestore.h"
+#include "llvm/Support/TimeProfiler.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/VersionTuple.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
 #include <cstdio>
static bool SkipCursorToBlock(BitstreamCursor &Cursor, unsigned BlockID) {
   }
 }
 
 ASTReader::ASTReadResult ASTReader::ReadAST(StringRef FileName,
                                             ModuleKind Type,
                                             SourceLocation ImportLoc,
                                             unsigned ClientLoadCapabilities,
                                             SmallVectorImpl<ImportedSubmodule> *Imported) {
+  llvm::TimeTraceScope scope("ReadAST", FileName);
+
   llvm::SaveAndRestore<SourceLocation>
     SetCurImportLocRAII(CurrentImportLoc, ImportLoc);
   llvm::SaveAndRestore<Optional<ModuleKind>> SetCurModuleKindRAII(
       CurrentDeserializingModuleKind, Type);
 
   // Defer any pending actions until we get to the end of reading the AST file.
   Deserializing AnASTFile(this);
 

clang/lib/Serialization/ASTWriter.cpp

 #include "llvm/Support/EndianStream.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/OnDiskHashTable.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/SHA1.h"
+#include "llvm/Support/TimeProfiler.h"
 #include "llvm/Support/VersionTuple.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
 #include <cstdlib>
 #include <cstring>
 #include <ctime>

 time_t ASTWriter::getTimestampForOutput(const FileEntry *E) const {
   return IncludeTimestamps ? E->getModificationTime() : 0;
 }
 
 ASTFileSignature ASTWriter::WriteAST(Sema &SemaRef, StringRef OutputFile,
                                      Module *WritingModule, StringRef isysroot,
                                      bool hasErrors,
                                      bool ShouldCacheASTInMemory) {
+  llvm::TimeTraceScope scope("WriteAST", OutputFile);
   WritingAST = true;
 
   ASTHasCompilerErrors = hasErrors;
 
   // Emit the file header.
   Stream.Emit((unsigned)'C', 8);
   Stream.Emit((unsigned)'P', 8);
   Stream.Emit((unsigned)'C', 8);