[LLD][COFF] Add support for `--time-trace` (#68236)

This adds support for generating Chrome-tracing .json profile traces in
the LLD COFF driver.

Also add the necessary time scopes, so that the profile trace shows in
great detail which tasks are executed.

As an example, this is what we see when linking a Unreal Engine
executable:

![image](https://github.com/llvm/llvm-project/assets/37383324/b2e26eb4-9d37-4cf9-b002-48b604e7dcb7)

1 files changed, 17 insertions, 9 deletions

diff --git a/llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp b/llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
index cd30b56..06e379c 100644
--- a/llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
+++ b/llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
@@ -25,6 +25,7 @@
 #include "llvm/Support/BinaryStreamWriter.h"
 #include "llvm/Support/CRC.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/TimeProfiler.h"
 #include "llvm/Support/xxhash.h"
 
 #include <ctime>
@@ -129,6 +130,7 @@ void PDBFileBuilder::addInjectedSource(StringRef Name,
 }
 
 Error PDBFileBuilder::finalizeMsfLayout() {
+  llvm::TimeTraceScope timeScope("MSF layout");
 
   if (Ipi && Ipi->getRecordCount() > 0) {
     // In theory newer PDBs always have an ID stream, but by saying that we're
@@ -254,6 +256,7 @@ void PDBFileBuilder::commitInjectedSources(WritableBinaryStream &MsfBuffer,
   if (InjectedSourceTable.empty())
     return;
 
+  llvm::TimeTraceScope timeScope("Commit injected sources");
   commitSrcHeaderBlock(MsfBuffer, Layout);
 
   for (const auto &IS : InjectedSources) {
@@ -290,15 +293,18 @@ Error PDBFileBuilder::commit(StringRef Filename, codeview::GUID *Guid) {
   if (auto EC = Strings.commit(NSWriter))
     return EC;
 
-  for (const auto &NSE : NamedStreamData) {
-    if (NSE.second.empty())
-      continue;
-
-    auto NS = WritableMappedBlockStream::createIndexedStream(
-        Layout, Buffer, NSE.first, Allocator);
-    BinaryStreamWriter NSW(*NS);
-    if (auto EC = NSW.writeBytes(arrayRefFromStringRef(NSE.second)))
-      return EC;
+  {
+    llvm::TimeTraceScope timeScope("Named stream data");
+    for (const auto &NSE : NamedStreamData) {
+      if (NSE.second.empty())
+        continue;
+
+      auto NS = WritableMappedBlockStream::createIndexedStream(
+          Layout, Buffer, NSE.first, Allocator);
+      BinaryStreamWriter NSW(*NS);
+      if (auto EC = NSW.writeBytes(arrayRefFromStringRef(NSE.second)))
+        return EC;
+    }
   }
 
   if (Info) {
@@ -338,6 +344,8 @@ Error PDBFileBuilder::commit(StringRef Filename, codeview::GUID *Guid) {
   // Set the build id at the very end, after every other byte of the PDB
   // has been written.
   if (Info->hashPDBContentsToGUID()) {
+    llvm::TimeTraceScope timeScope("Compute build ID");
+
     // Compute a hash of all sections of the output file.
     uint64_t Digest =
         xxh3_64bits({Buffer.getBufferStart(), Buffer.getBufferEnd()});