[BOLT][NFC] Pre-disasm metadata rewriters

bolt/include/bolt/Rewrite/MetadataManager.h

@@ -31,6 +31,10 @@ class MetadataManager {
   /// Run initializers after sections are discovered.
   void runSectionInitializers();
 
+  /// Execute metadata initializers when functions are discovered but not yet
+  /// disassembled.
+  void runInitializersPreDisasm();
+
   /// Execute initialization of rewriters while functions are disassembled, but
   /// CFG is not yet built.
   void runInitializersPreCFG();

bolt/include/bolt/Rewrite/MetadataRewriter.h

@@ -49,6 +49,10 @@ class MetadataRewriter {
   /// but before functions are discovered.
   virtual Error sectionInitializer() { return Error::success(); }
 
+  /// Run initialization after the functions are identified but not yet
+  /// disassembled.
+  virtual Error preDisasmInitializer() { return Error::success(); }
+
   /// Interface for modifying/annotating functions in the binary based on the
   /// contents of the section. Functions are in pre-cfg state.
   virtual Error preCFGInitializer() { return Error::success(); }

bolt/include/bolt/Rewrite/RewriteInstance.h

@@ -181,6 +181,9 @@ class RewriteInstance {
   /// Process metadata in sections before functions are discovered.
   void processSectionMetadata();
 
+  /// Process metadata in special sections before functions are disassembled.
+  void processMetadataPreDisasm();
+
   /// Process metadata in special sections before CFG is built for functions.
   void processMetadataPreCFG();
 

bolt/lib/Rewrite/MetadataManager.cpp

@@ -32,6 +32,18 @@ void MetadataManager::runSectionInitializers() {
   }
 }
 
+void MetadataManager::runInitializersPreDisasm() {
+  for (auto &Rewriter : Rewriters) {
+    LLVM_DEBUG(dbgs() << "BOLT-DEBUG: invoking " << Rewriter->getName()
+                      << " after reading sections\n");
+    if (Error E = Rewriter->preDisasmInitializer()) {
+      errs() << "BOLT-ERROR: while running " << Rewriter->getName()
+             << " in pre-disasm state: " << toString(std::move(E)) << '\n';
+      exit(1);
+    }
+  }
+}
+
 void MetadataManager::runInitializersPreCFG() {
   for (auto &Rewriter : Rewriters) {
     LLVM_DEBUG(dbgs() << "BOLT-DEBUG: invoking " << Rewriter->getName()

bolt/lib/Rewrite/RewriteInstance.cpp

@@ -694,7 +694,7 @@ Error RewriteInstance::run() {
 
   selectFunctionsToProcess();
 
-  readDebugInfo();
+  processMetadataPreDisasm();
 
   disassembleFunctions();
 
@@ -3237,6 +3237,14 @@ void RewriteInstance::processSectionMetadata() {
   MetadataManager.runSectionInitializers();
 }
 
+void RewriteInstance::processMetadataPreDisasm() {
+  NamedRegionTimer T("processmetadata-predisasm", "process metadata pre-disasm",
+                     TimerGroupName, TimerGroupDesc, opts::TimeRewrite);
+  MetadataManager.runInitializersPreDisasm();
+
+  readDebugInfo();
+}
+
 void RewriteInstance::processMetadataPreCFG() {
   NamedRegionTimer T("processmetadata-precfg", "process metadata pre-CFG",
                      TimerGroupName, TimerGroupDesc, opts::TimeRewrite);