Add a new flag -enable-recompilation-to-ossa-module

Author: meg-gupta

include/swift/AST/SILOptions.h

@@ -188,6 +188,10 @@ class SILOptions {
   /// If this is disabled we do not serialize in OSSA form when optimizing.
   bool EnableOSSAModules = false;
 
+  /// Allow recompilation of a non-OSSA module to an OSSA module when imported
+  /// from another OSSA module.
+  bool EnableRecompilationToOSSAModule = false;
+
   /// If set to true, compile with the SIL Opaque Values enabled.
   bool EnableSILOpaqueValues = false;
 

include/swift/Option/FrontendOptions.td

@@ -1226,6 +1226,9 @@ let Flags = [FrontendOption, NoDriverOption, HelpHidden, ModuleInterfaceOptionIg
             "when optimizing ownership will be lowered before serializing SIL">;
 }
 
+def enable_recompilation_to_ossa_module : Flag<["-"], "enable-recompilation-to-ossa-module">,
+  HelpText<"Allow recompilation of a non-OSSA module to an OSSA module when imported from another OSSA module">;
+
 def enable_sil_opaque_values : Flag<["-"], "enable-sil-opaque-values">,
   HelpText<"Enable SIL Opaque Values">;
 

lib/Frontend/CompilerInvocation.cpp

@@ -2697,6 +2697,8 @@ static bool ParseSILArgs(SILOptions &Opts, ArgList &Args,
 
   Opts.EnableARCOptimizations &= !Args.hasArg(OPT_disable_arc_opts);
   Opts.EnableOSSAModules |= Args.hasArg(OPT_enable_ossa_modules);
+  Opts.EnableRecompilationToOSSAModule |=
+      Args.hasArg(OPT_enable_recompilation_to_ossa_module);
   Opts.EnableOSSAOptimizations &= !Args.hasArg(OPT_disable_ossa_opts);
   Opts.EnableSILOpaqueValues = Args.hasFlag(
       OPT_enable_sil_opaque_values, OPT_disable_sil_opaque_values, false);

lib/Serialization/SerializedModuleLoader.cpp

@@ -1190,8 +1190,8 @@ void swift::serialization::diagnoseSerializedASTLoadFailure(
                        moduleBufferID);
     break;
   case serialization::Status::NotInOSSA:
-    // Diagnose only when explicit build modules is enabled
-    if (Ctx.SerializationOpts.ExplicitModuleBuild) {
+    if (Ctx.SerializationOpts.ExplicitModuleBuild ||
+        !Ctx.SILOpts.EnableRecompilationToOSSAModule) {
       Ctx.Diags.diagnose(diagLoc,
                          diag::serialization_non_ossa_module_incompatible,
                          ModuleName);