[SIL][PackageCMO] Allow optimizing [serialized_for_pkg] functions during SIL

inlining, generic/closure specialization, and devirtualization optimization passes.

SILFunction::canBeInlinedIntoCaller now exlicitly requires a caller's SerializedKind_t arg.
isAnySerialized() is added as a convenience function that checks if [serialized] or [serialized_for_pkg].

Resolves rdar://128704752

Author: elsh

include/swift/SIL/SILBridgingImpl.h

@@ -718,7 +718,7 @@ bool BridgedFunction::isSerialized() const {
 }
 
 bool BridgedFunction::hasValidLinkageForFragileRef() const {
-  return getFunction()->hasValidLinkageForFragileRef();
+  return getFunction()->hasValidLinkageForFragileRef(swift::SerializedKind_t::IsSerialized);
 }
 
 bool BridgedFunction::needsStackProtection() const {

include/swift/SIL/SILFunction.h

@@ -874,10 +874,8 @@ class SILFunction
   void setLinkage(SILLinkage linkage) { Linkage = unsigned(linkage); }
 
 ///   Checks if this (callee) function body can be inlined into the caller
-///   by comparing their SerializedKind_t values.
+///   by comparing their `SerializedKind_t` values.
 ///
-///   If the \p assumeFragileCaller is true, the caller must be serialized,
-///   in which case the callee needs to be serialized also to be inlined.
 ///   If both callee and caller are `not_serialized`, the callee can be inlined
 ///   into the caller during SIL inlining passes even if it (and the caller)
 ///   might contain private symbols. If this callee is `serialized_for_pkg`,
@@ -894,21 +892,13 @@ class SILFunction
 ///  ```
 ///
 /// \p callerSerializedKind The caller's SerializedKind.
-/// \p assumeFragileCaller True if the call site of this function already
-///                        knows that the caller is serialized.
-  bool canBeInlinedIntoCaller(
-      std::optional<SerializedKind_t> callerSerializedKind = std::nullopt,
-      bool assumeFragileCaller = true) const;
+  bool canBeInlinedIntoCaller(SerializedKind_t callerSerializedKind) const;
 
   /// Returns true if this function can be referenced from a fragile function
   /// body.
   /// \p callerSerializedKind The caller's SerializedKind. Used to be passed to
   ///                         \c canBeInlinedIntoCaller.
-  /// \p assumeFragileCaller Default to true since this function must be called
-  //                         if the caller is [serialized].
-  bool hasValidLinkageForFragileRef(
-      std::optional<SerializedKind_t> callerSerializedKind = std::nullopt,
-      bool assumeFragileCaller = true) const;
+  bool hasValidLinkageForFragileRef(SerializedKind_t callerSerializedKind) const;
 
   /// Get's the effective linkage which is used to derive the llvm linkage.
   /// Usually this is the same as getLinkage(), except in one case: if this
@@ -1165,11 +1155,9 @@ class SILFunction
   bool isSerialized() const {
     return SerializedKind_t(SerializedKind) == IsSerialized;
   }
-  bool isSerializedForPackage() const {
-    return SerializedKind_t(SerializedKind) == IsSerializedForPackage;
-  }
-  bool isNotSerialized() const {
-    return SerializedKind_t(SerializedKind) == IsNotSerialized;
+  bool isAnySerialized() const {
+    return SerializedKind_t(SerializedKind) == IsSerialized ||
+           SerializedKind_t(SerializedKind) == IsSerializedForPackage;
   }
 
   /// Get this function's serialized attribute.

include/swift/SIL/SILGlobalVariable.h

@@ -154,11 +154,10 @@ class SILGlobalVariable
   /// Check if this global variable is [serialized]. This does not check
   /// if it's [serialized_for_package].
   bool isSerialized() const;
-  /// Check if this global variable is [serialized_for_package].
-  bool isSerializedForPackage() const;
-  /// Checks whether this global var is neither [serialized] nor
-  /// [serialized_for_package].
-  bool isNotSerialized() const;
+
+  /// Check if this global variable is [serialized] or [serialized_for_package].
+  bool isAnySerialized() const;
+
   /// Get this global variable's serialized attribute.
   SerializedKind_t getSerializedKind() const;
   void setSerializedKind(SerializedKind_t isSerialized);

include/swift/SIL/SILMoveOnlyDeinit.h

@@ -66,8 +66,9 @@ class SILMoveOnlyDeinit final : public SILAllocated<SILMoveOnlyDeinit> {
     return funcImpl;
   }
 
-  bool isNotSerialized() const {
-    return SerializedKind_t(serialized) == IsNotSerialized;
+  bool isAnySerialized() const {
+    return SerializedKind_t(serialized) == IsSerialized ||
+           SerializedKind_t(serialized) == IsSerializedForPackage;
   }
   SerializedKind_t getSerializedKind() const {
     return SerializedKind_t(serialized);

include/swift/SIL/SILProperty.h

@@ -53,7 +53,10 @@ class SILProperty : public llvm::ilist_node<SILProperty>,
                              AbstractStorageDecl *Decl,
                              std::optional<KeyPathPatternComponent> Component);
 
-  bool isNotSerialized() const { return SerializedKind_t(Serialized) == IsNotSerialized; }
+  bool isAnySerialized() const {
+    return SerializedKind_t(Serialized) == IsSerialized ||
+           SerializedKind_t(Serialized) == IsSerializedForPackage;
+  }
   SerializedKind_t getSerializedKind() const {
     return SerializedKind_t(Serialized);
   }

include/swift/SIL/SILVTable.h

@@ -158,11 +158,10 @@ class SILVTable final : public SILAllocated<SILVTable>,
   bool isSerialized() const {
     return SerializedKind_t(SerializedKind) == IsSerialized;
   }
-  bool isSerializedForPackage() const {
-    return SerializedKind_t(SerializedKind) == IsSerializedForPackage;
-  }
-  bool isNotSerialized() const {
-    return SerializedKind_t(SerializedKind) == IsNotSerialized;
+
+  bool isAnySerialized() const {
+    return SerializedKind_t(SerializedKind) == IsSerialized ||
+           SerializedKind_t(SerializedKind) == IsSerializedForPackage;
   }
 
   SerializedKind_t getSerializedKind() const {

include/swift/SIL/SILWitnessTable.h

@@ -255,12 +255,12 @@ class SILWitnessTable : public llvm::ilist_node<SILWitnessTable>,
   bool isSerialized() const {
     return SerializedKind_t(SerializedKind) == IsSerialized;
   }
-  bool isSerializedForPackage() const {
-    return SerializedKind_t(SerializedKind) == IsSerializedForPackage;
-  }
-  bool isNotSerialized() const {
-    return SerializedKind_t(SerializedKind) == IsNotSerialized;
+
+  bool isAnySerialized() const {
+    return SerializedKind_t(SerializedKind) == IsSerialized ||
+           SerializedKind_t(SerializedKind) == IsSerializedForPackage;
   }
+
   SerializedKind_t getSerializedKind() const {
     return SerializedKind_t(SerializedKind);
   }

lib/SIL/IR/Linker.cpp

@@ -87,7 +87,7 @@ void SILLinkerVisitor::deserializeAndPushToWorklist(SILFunction *F) {
     return;
   }
 
-  assert(F->isNotSerialized() == Mod.isSerialized() &&
+  assert(!F->isAnySerialized() == Mod.isSerialized() &&
          "the de-serializer did set the wrong serialized flag");
 
   F->setBare(IsBare);
@@ -186,8 +186,8 @@ void SILLinkerVisitor::linkInVTable(ClassDecl *D) {
   // for processing.
   for (auto &entry : Vtbl->getEntries()) {
     SILFunction *impl = entry.getImplementation();
-    if (!Vtbl->isSerialized() ||
-        impl->hasValidLinkageForFragileRef()) {
+    if (!Vtbl->isAnySerialized() ||
+        impl->hasValidLinkageForFragileRef(Vtbl->getSerializedKind())) {
       // Deserialize and recursively walk any vtable entries that do not have
       // bodies yet.
       maybeAddFunctionToWorklist(impl, 

lib/SIL/IR/SILDeclRef.cpp

@@ -875,7 +875,6 @@ SerializedKind_t SILDeclRef::getSerializedKind() const {
   }
 
   // Anything else that is not public is not serializable.
-  // pcmo TODO: should check if package-cmo is enabled?
   if (d->getEffectiveAccess() < AccessLevel::Public)
     return IsNotSerialized;
 

lib/SIL/IR/SILFunction.cpp

@@ -920,8 +920,6 @@ bool SILFunction::hasName(const char *Name) const {
  Checks if this (callee) function body can be inlined into the caller
  by comparing their SerializedKind_t values. 
  
- If the \p assumeFragileCaller is true, the caller must be serialized,
- in which case the callee needs to be serialized also to be inlined.
  If both callee and caller are not_serialized, the callee can be inlined
  into the caller during SIL inlining passes even if it (and the caller)
  might contain private symbols. If this callee is serialized_for_pkg, it
@@ -934,22 +932,13 @@ Callee  serialized_for_pkg  |      ok        |       ok           |    no
         serialized          |      ok        |       ok           |    ok
 
 */
-bool SILFunction::canBeInlinedIntoCaller(
-      std::optional<SerializedKind_t> callerSerializedKind,
-      bool assumeFragileCaller) const {
-  // If the \p assumeFragileCaller is true, the caller must
-  // be serialized, so return true only if the callee is also
-  // serialized.
-  if (assumeFragileCaller)
-    return isSerialized();
-                                           
+bool SILFunction::canBeInlinedIntoCaller(SerializedKind_t callerSerializedKind) const {
   switch (getSerializedKind()) {
     // If both callee and caller are not_serialized, the callee
     // can be inlined into the caller during SIL inlining passes
     // even if it (and the caller) might contain private symbols.
     case IsNotSerialized:
-      return callerSerializedKind.has_value() &&
-             callerSerializedKind.value() == IsNotSerialized;
+      return callerSerializedKind == IsNotSerialized;
 
     // If Package-CMO is enabled, we serialize package, public,
     // and @usableFromInline decls as [serialized_for_package].
@@ -962,8 +951,7 @@ bool SILFunction::canBeInlinedIntoCaller(
     // for this callee's body to be inlined into the caller.
     // It can however be referenced by [serialized] caller.
     case IsSerializedForPackage:
-      return callerSerializedKind.has_value() &&
-             callerSerializedKind.value() != IsSerialized;
+      return callerSerializedKind != IsSerialized;
     case IsSerialized:
       return true;
   }
@@ -972,16 +960,18 @@ bool SILFunction::canBeInlinedIntoCaller(
 
 /// Returns true if this function can be referenced from a fragile function
 /// body.
-bool SILFunction::hasValidLinkageForFragileRef(
-       std::optional<SerializedKind_t> callerSerializedKind,
-       bool assumeFragileCaller) const {
+bool SILFunction::hasValidLinkageForFragileRef(SerializedKind_t callerSerializedKind) const {
   // Fragile functions can reference 'static inline' functions imported
   // from C.
   if (hasForeignBody())
     return true;
 
+  // The call site of this function must have checked that
+  // caller.isAnySerialized() is true, as indicated by the
+  // function name itself (contains 'ForFragileRef').
+  assert(callerSerializedKind != IsNotSerialized);
   // If we can inline it, we can reference it.
-  if (canBeInlinedIntoCaller(callerSerializedKind, assumeFragileCaller))
+  if (canBeInlinedIntoCaller(callerSerializedKind))
     return true;
 
   // If the containing module has been serialized already, we no longer