During Package CMO, SIL cloning happens during which

SILOptions::EnableSerializePackage info is lost.

SILVerifier needs this info to determine whether resilience
can be bypassed for decls serialized in a resiliently
built module when Package CMO optimization enabled.

This PR adds SerializePackageEnabled bit to Module format
and uses that in SILVerifier.

Resolves rdar://126157356

Author: elsh

include/swift/AST/Decl.h

@@ -697,7 +697,7 @@ class alignas(1 << DeclAlignInBits) Decl : public ASTAllocated<Decl> {
     HasAnyUnavailableDuringLoweringValues : 1
   );
 
-  SWIFT_INLINE_BITFIELD(ModuleDecl, TypeDecl, 1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1,
+  SWIFT_INLINE_BITFIELD(ModuleDecl, TypeDecl, 1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1,
     /// If the module is compiled as static library.
     StaticLibrary : 1,
 
@@ -756,7 +756,10 @@ class alignas(1 << DeclAlignInBits) Decl : public ASTAllocated<Decl> {
     HasCxxInteroperability : 1,
 
     /// Whether this module has been built with -experimental-allow-non-resilient-access.
-    AllowNonResilientAccess : 1
+    AllowNonResilientAccess : 1,
+
+    /// Whether this module has been built with -experimental-package-cmo.
+    SerializePackageEnabled : 1
   );
 
   SWIFT_INLINE_BITFIELD(PrecedenceGroupDecl, Decl, 1+2,

include/swift/AST/Module.h

@@ -721,6 +721,16 @@ class ModuleDecl
     Bits.ModuleDecl.AllowNonResilientAccess = flag;
   }
 
+  /// Returns true if -experimental-package-cmo was passed, which
+  /// enables serialization of package, public, and inlinable decls in a
+  /// package. This requires -experimental-allow-non-resilient-access.
+  bool serializePackageEnabled() const {
+    return Bits.ModuleDecl.SerializePackageEnabled;
+  }
+  void setSerializePackageEnabled(bool flag = true) {
+    Bits.ModuleDecl.SerializePackageEnabled = flag;
+  }
+
   /// Returns true if this module is a non-Swift module that was imported into
   /// Swift.
   ///

include/swift/Serialization/Validation.h

@@ -141,6 +141,7 @@ class ExtendedValidationInfo {
     unsigned IsConcurrencyChecked : 1;
     unsigned HasCxxInteroperability : 1;
     unsigned AllowNonResilientAccess: 1;
+    unsigned SerializePackageEnabled: 1;
   } Bits;
 public:
   ExtendedValidationInfo() : Bits() {}
@@ -209,6 +210,10 @@ class ExtendedValidationInfo {
   void setAllowNonResilientAccess(bool val) {
     Bits.AllowNonResilientAccess = val;
   }
+  bool serializePackageEnabled() const { return Bits.SerializePackageEnabled; }
+  void setSerializePackageEnabled(bool val) {
+    Bits.SerializePackageEnabled = val;
+  }
   bool isAllowModuleWithCompilerErrorsEnabled() {
     return Bits.IsAllowModuleWithCompilerErrorsEnabled;
   }

lib/AST/Module.cpp

@@ -723,6 +723,7 @@ ModuleDecl::ModuleDecl(Identifier name, ASTContext &ctx,
   Bits.ModuleDecl.ObjCNameLookupCachePopulated = 0;
   Bits.ModuleDecl.HasCxxInteroperability = 0;
   Bits.ModuleDecl.AllowNonResilientAccess = 0;
+  Bits.ModuleDecl.SerializePackageEnabled = 0;
 }
 
 void ModuleDecl::setIsSystemModule(bool flag) {

lib/Frontend/Frontend.cpp

@@ -1382,6 +1382,8 @@ ModuleDecl *CompilerInstance::getMainModule() const {
       MainModule->setHasCxxInteroperability();
     if (Invocation.getLangOptions().AllowNonResilientAccess)
       MainModule->setAllowNonResilientAccess();
+    if (Invocation.getSILOptions().EnableSerializePackage)
+      MainModule->setSerializePackageEnabled();
 
     // Register the main module with the AST context.
     Context->addLoadedModule(MainModule);

lib/SIL/Verifier/SILVerifier.cpp

@@ -153,13 +153,28 @@ static bool isArchetypeValidInFunction(ArchetypeType *A, const SILFunction *F) {
 
 namespace {
 
-/// When resilience is bypassed, direct access is legal, but the decls are still
-/// resilient.
+/// When resilience is bypassed for debugging or package serialization is enabled,
+/// direct access is legal, but the decls are still resilient.
 template <typename DeclType>
 bool checkResilience(DeclType *D, ModuleDecl *M,
                      ResilienceExpansion expansion) {
-  return !D->getModuleContext()->getBypassResilience() &&
-         D->isResilient(M, expansion);
+  auto refDeclModule = D->getModuleContext();
+  // Explicitly bypassed for debugging with `bypass-resilience-checks`
+  if (refDeclModule->getBypassResilience())
+    return false;
+
+  // If package serialization is enabled with `experimental-package-cmo`,
+  // decls can be serialized in a resiliently built module. In such case,
+  // a direct access should be allowed.
+  auto packageSerialized = expansion == ResilienceExpansion::Minimal &&
+                           refDeclModule->isResilient() &&
+                           refDeclModule->allowNonResilientAccess() &&
+                           refDeclModule->serializePackageEnabled() &&
+                           refDeclModule->inSamePackage(M);
+  if (packageSerialized)
+    return false;
+
+  return D->isResilient(M, expansion);
 }
 
 bool checkTypeABIAccessible(SILFunction const &F, SILType ty) {

lib/Serialization/ModuleFile.h

@@ -659,6 +659,11 @@ class ModuleFile
     return Core->Bits.AllowNonResilientAccess;
   }
 
+  /// Whether this module was built with -experimental-package-cmo.
+  bool serializePackageEnabled() const {
+    return Core->Bits.SerializePackageEnabled;
+  }
+
   /// Whether this module is compiled with implicit dynamic.
   bool isImplicitDynamicEnabled() const {
     return Core->Bits.IsImplicitDynamicEnabled;

lib/Serialization/ModuleFileSharedCore.cpp

@@ -200,6 +200,9 @@ static bool readOptionsBlock(llvm::BitstreamCursor &cursor,
     case options_block::ALLOW_NON_RESILIENT_ACCESS:
       extendedInfo.setAllowNonResilientAccess(true);
       break;
+    case options_block::SERIALIZE_PACKAGE_ENABLED:
+      extendedInfo.setSerializePackageEnabled(true);
+      break;
     default:
       // Unknown options record, possibly for use by a future version of the
       // module format.
@@ -1448,6 +1451,7 @@ ModuleFileSharedCore::ModuleFileSharedCore(
       Bits.IsConcurrencyChecked = extInfo.isConcurrencyChecked();
       Bits.HasCxxInteroperability = extInfo.hasCxxInteroperability();
       Bits.AllowNonResilientAccess = extInfo.allowNonResilientAccess();
+      Bits.SerializePackageEnabled = extInfo.serializePackageEnabled();
       MiscVersion = info.miscVersion;
       ModuleABIName = extInfo.getModuleABIName();
       ModulePackageName = extInfo.getModulePackageName();

lib/Serialization/ModuleFileSharedCore.h

@@ -391,6 +391,9 @@ class ModuleFileSharedCore {
     /// Whether this module is built with -experimental-allow-non-resilient-access.
     unsigned AllowNonResilientAccess : 1;
 
+    /// Whether this module is built with -experimental-package-cmo.
+    unsigned SerializePackageEnabled : 1;
+
     // Explicitly pad out to the next word boundary.
     unsigned : 3;
   } Bits = {};

lib/Serialization/ModuleFormat.h

@@ -58,7 +58,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 869; // @implementation
+const uint16_t SWIFTMODULE_VERSION_MINOR = 870; // SerializePackageEnabled
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///
@@ -941,6 +941,7 @@ namespace options_block {
     PLUGIN_SEARCH_OPTION,
     HAS_CXX_INTEROPERABILITY_ENABLED,
     ALLOW_NON_RESILIENT_ACCESS,
+    SERIALIZE_PACKAGE_ENABLED,
   };
 
   using SDKPathLayout = BCRecordLayout<
@@ -1027,6 +1028,10 @@ namespace options_block {
   using AllowNonResilientAccess = BCRecordLayout<
     ALLOW_NON_RESILIENT_ACCESS
   >;
+
+  using SerializePackageEnabled = BCRecordLayout<
+    SERIALIZE_PACKAGE_ENABLED
+  >;
 }
 
 /// The record types within the input block.