Add a new frontend option -sil-serialize-witness-tables to force serialization of SIL witness tables

This option is supposed to be used only for compiling overlays. User code should never be compiled with this option.

Author: swiftix

include/swift/AST/SILOptions.h

@@ -150,6 +150,12 @@ class SILOptions {
   /// \see ResilienceStrategy::Fragile
   bool SILSerializeAll = false;
 
+  /// If set, SIL witness tables will be serialized.
+  ///
+  /// It is supposed to be used only for compiling overlays.
+  /// User code should never be compiled with this flag set.
+  bool SILSerializeWitnessTables = false;
+
   SILOptions() : Sanitize(SanitizerKind::None) {}
 
   /// Return a hash code of any components from these options that should

include/swift/Option/FrontendOptions.td

@@ -366,6 +366,9 @@ def sil_link_all : Flag<["-"], "sil-link-all">,
 def sil_serialize_all : Flag<["-"], "sil-serialize-all">,
   HelpText<"Serialize all generated SIL">;
 
+def sil_serialize_witness_tables : Flag<["-"], "sil-serialize-witness-tables">,
+  HelpText<"Serialize eligible SIL witness tables">;
+
 def sil_verify_all : Flag<["-"], "sil-verify-all">,
   HelpText<"Verify SIL after each transform">;
 

lib/Frontend/CompilerInvocation.cpp

@@ -1329,6 +1329,9 @@ static bool ParseSILArgs(SILOptions &Opts, ArgList &Args,
     Opts.MergePartialModules = true;
 
   Opts.SILSerializeAll |= Args.hasArg(OPT_sil_serialize_all);
+  Opts.SILSerializeWitnessTables |=
+    Args.hasArg(OPT_sil_serialize_witness_tables);
+
   // Parse the optimization level.
   if (const Arg *A = Args.getLastArg(OPT_O_Group)) {
     if (A->getOption().matches(OPT_Onone)) {

stdlib/CMakeLists.txt

@@ -93,11 +93,14 @@ add_custom_target(swift-test-stdlib ALL
 
 if(SWIFT_STDLIB_ENABLE_RESILIENCE)
   set(STDLIB_SIL_SERIALIZE_ALL)
+  set(STDLIB_SIL_SERIALIZE_WITNESS_TABLES)
 else()
   if(SWIFT_STDLIB_SIL_SERIALIZE_ALL)
     set(STDLIB_SIL_SERIALIZE_ALL "-Xfrontend" "-sil-serialize-all")
+    set(STDLIB_SIL_SERIALIZE_WITNESS_TABLES "-Xfrontend" "-sil-serialize-witness-tables")
   else()
     set(STDLIB_SIL_SERIALIZE_ALL)
+    set(STDLIB_SIL_SERIALIZE_WITNESS_TABLES)
   endif()
 endif()
 

stdlib/public/SDK/CMakeLists.txt

@@ -8,6 +8,8 @@ if(SWIFT_BUILD_STATIC_SDK_OVERLAY)
   list(APPEND SWIFT_SDK_OVERLAY_LIBRARY_BUILD_TYPES STATIC)
 endif()
 
+list(APPEND SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS "${STDLIB_SIL_SERIALIZE_WITNESS_TABLES}")
+
 set(all_overlays "Accelerate;AppKit;ARKit;AssetsLibrary;AVFoundation;CallKit;CloudKit;Contacts;CoreAudio;CoreData;CoreFoundation;CoreGraphics;CoreImage;CoreLocation;CoreMedia;CryptoTokenKit;Dispatch;Foundation;GameplayKit;GLKit;HomeKit;IOKit;Intents;MapKit;ObjectiveC;OpenCL;os;Photos;QuartzCore;SafariServices;SceneKit;simd;SpriteKit;UIKit;WatchKit;XCTest;XPC")
 
 if(DEFINED SWIFT_OVERLAY_TARGETS)