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

[Reid Kleckner via llvm-commits]

================
@@ -650,46 +664,52 @@ void Writer::writePEChecksum() {
 
 // The main function of the writer.
 void Writer::run() {
-  ScopedTimer t1(ctx.codeLayoutTimer);
-
-  createImportTables();
-  createSections();
-  appendImportThunks();
-  // Import thunks must be added before the Control Flow Guard tables are added.
-  createMiscChunks();
-  createExportTable();
-  mergeSections();
-  removeUnusedSections();
-  finalizeAddresses();
-  removeEmptySections();
-  assignOutputSectionIndices();
-  setSectionPermissions();
-  createSymbolAndStringTable();
-
-  if (fileSize > UINT32_MAX)
-    fatal("image size (" + Twine(fileSize) + ") " +
-        "exceeds maximum allowable size (" + Twine(UINT32_MAX) + ")");
-
-  openFile(ctx.config.outputFile);
-  if (ctx.config.is64()) {
-    writeHeader<pe32plus_header>();
-  } else {
-    writeHeader<pe32_header>();
-  }
-  writeSections();
-  checkLoadConfig();
-  sortExceptionTable();
-
-  // Fix up the alignment in the TLS Directory's characteristic field,
-  // if a specific alignment value is needed
-  if (tlsAlignment)
-    fixTlsAlignment();
+  {
+    llvm::TimeTraceScope timeScope("Write PE");
+    ScopedTimer t1(ctx.codeLayoutTimer);
+
+    createImportTables();
+    createSections();
+    appendImportThunks();
+    // Import thunks must be added before the Control Flow Guard tables are
+    // added.
+    createMiscChunks();
+    createExportTable();
+    mergeSections();
+    removeUnusedSections();
+    finalizeAddresses();
+    removeEmptySections();
+    assignOutputSectionIndices();
+    setSectionPermissions();
+    createSymbolAndStringTable();
+
+    if (fileSize > UINT32_MAX)
+      fatal("image size (" + Twine(fileSize) + ") " +
+            "exceeds maximum allowable size (" + Twine(UINT32_MAX) + ")");
+
+    openFile(ctx.config.outputFile);
+    if (ctx.config.is64()) {
+      writeHeader<pe32plus_header>();
+    } else {
+      writeHeader<pe32_header>();
+    }
+    writeSections();
+    checkLoadConfig();
+    sortExceptionTable();
 
-  t1.stop();
+    // Fix up the alignment in the TLS Directory's characteristic field,
+    // if a specific alignment value is needed
+    if (tlsAlignment)
+      fixTlsAlignment();
+  }
 
   if (!ctx.config.pdbPath.empty() && ctx.config.debug) {
     assert(buildId);
     createPDB(ctx, sectionTable, buildId->buildId);
+
+    // Manually end this profile point to measure ~PDBLinker().
+    if (getTimeTraceProfilerInstance() != nullptr)
----------------
rnk wrote:

Please move this into `createPDB` by creating an extra scope where the PDBLinker is created, so that the explicit begin / end calls can appear immediately one after another so this detail doesn't leak out of `createPDB`.

https://github.com/llvm/llvm-project/pull/68236