[BOLT] Add metadata pre-emit finalization interface (#79925)

Some metadata needs to be updated/finalized before the binary context is
emitted into the binary. Add the interface and use it for Linux ORC
update invocation.

Author: maksfb

bolt/include/bolt/Rewrite/MetadataManager.h

@@ -36,6 +36,9 @@ class MetadataManager {
   /// Execute metadata initializers after CFG was constructed for functions.
   void runInitializersPostCFG();
 
+  /// Run finalization step of rewriters before the binary is emitted.
+  void runFinalizersPreEmit();
+
   /// Run finalization step of rewriters after code has been emitted.
   void runFinalizersAfterEmit();
 };

bolt/include/bolt/Rewrite/MetadataRewriter.h

@@ -52,6 +52,9 @@ class MetadataRewriter {
   /// Run the rewriter once the functions are in CFG state.
   virtual Error postCFGInitializer() { return Error::success(); }
 
+  /// Run the pass before the binary is emitted.
+  virtual Error preEmitFinalizer() { return Error::success(); }
+
   /// Finalize section contents based on the new context after the new code is
   /// emitted.
   virtual Error postEmitFinalizer() { return Error::success(); }

bolt/include/bolt/Rewrite/RewriteInstance.h

@@ -183,6 +183,9 @@ class RewriteInstance {
   /// Process metadata in special sections after CFG is built for functions.
   void processMetadataPostCFG();
 
+  /// Make changes to metadata before the binary is emitted.
+  void finalizeMetadataPreEmit();
+
   /// Update debug and other auxiliary information in the file.
   void updateMetadata();
 

bolt/lib/Rewrite/LinuxKernelRewriter.cpp

@@ -163,14 +163,18 @@ class LinuxKernelRewriter final : public MetadataRewriter {
     return Error::success();
   }
 
-  Error postEmitFinalizer() override {
-    updateLKMarkers();
-
+  Error preEmitFinalizer() override {
     if (Error E = rewriteORCTables())
       return E;
 
     return Error::success();
   }
+
+  Error postEmitFinalizer() override {
+    updateLKMarkers();
+
+    return Error::success();
+  }
 };
 
 Error LinuxKernelRewriter::markInstructions() {

bolt/lib/Rewrite/MetadataManager.cpp

@@ -44,6 +44,18 @@ void MetadataManager::runInitializersPostCFG() {
   }
 }
 
+void MetadataManager::runFinalizersPreEmit() {
+  for (auto &Rewriter : Rewriters) {
+    LLVM_DEBUG(dbgs() << "BOLT-DEBUG: invoking " << Rewriter->getName()
+                      << " before emitting binary context\n");
+    if (Error E = Rewriter->preEmitFinalizer()) {
+      errs() << "BOLT-ERROR: while running " << Rewriter->getName()
+             << " before emit: " << toString(std::move(E)) << '\n';
+      exit(1);
+    }
+  }
+}
+
 void MetadataManager::runFinalizersAfterEmit() {
   for (auto &Rewriter : Rewriters) {
     LLVM_DEBUG(dbgs() << "BOLT-DEBUG: invoking " << Rewriter->getName()

bolt/lib/Rewrite/RewriteInstance.cpp

@@ -742,6 +742,8 @@ Error RewriteInstance::run() {
 
   runOptimizationPasses();
 
+  finalizeMetadataPreEmit();
+
   emitAndLink();
 
   updateMetadata();
@@ -3416,6 +3418,10 @@ void RewriteInstance::emitAndLink() {
   }
 }
 
+void RewriteInstance::finalizeMetadataPreEmit() {
+  MetadataManager.runFinalizersPreEmit();
+}
+
 void RewriteInstance::updateMetadata() {
   MetadataManager.runFinalizersAfterEmit();