[SIL] Serialize the markedAsUsed bit in SILFunction

We were dropping this bit during serialization, so we don't know
whether the function was originally marked as "used".

Author: DougGregor

lib/Serialization/DeserializeSIL.cpp

@@ -734,17 +734,17 @@ llvm::Expected<SILFunction *> SILDeserializer::readSILFunctionChecked(
   GenericSignatureID genericSigID;
   unsigned rawLinkage, isTransparent, serializedKind, isThunk,
       isWithoutActuallyEscapingThunk, specialPurpose, inlineStrategy,
-      optimizationMode, perfConstr, subclassScope, hasCReferences, effect,
-      numAttrs, hasQualifiedOwnership, isWeakImported,
+      optimizationMode, perfConstr, subclassScope, hasCReferences,
+      markedAsUsed, effect, numAttrs, hasQualifiedOwnership, isWeakImported,
       LIST_VER_TUPLE_PIECES(available), isDynamic, isExactSelfClass,
       isDistributed, isRuntimeAccessible, forceEnableLexicalLifetimes,
       onlyReferencedByDebugInfo;
   ArrayRef<uint64_t> SemanticsIDs;
   SILFunctionLayout::readRecord(
       scratch, rawLinkage, isTransparent, serializedKind, isThunk,
       isWithoutActuallyEscapingThunk, specialPurpose, inlineStrategy,
-      optimizationMode, perfConstr, subclassScope, hasCReferences, effect,
-      numAttrs, hasQualifiedOwnership, isWeakImported,
+      optimizationMode, perfConstr, subclassScope, hasCReferences, markedAsUsed,
+      effect, numAttrs, hasQualifiedOwnership, isWeakImported,
       LIST_VER_TUPLE_PIECES(available), isDynamic, isExactSelfClass,
       isDistributed, isRuntimeAccessible, forceEnableLexicalLifetimes,
       onlyReferencedByDebugInfo, funcTyID, replacedFunctionID,
@@ -917,6 +917,7 @@ llvm::Expected<SILFunction *> SILDeserializer::readSILFunctionChecked(
     fn->setIsAlwaysWeakImported(isWeakImported);
     fn->setClassSubclassScope(SubclassScope(subclassScope));
     fn->setHasCReferences(bool(hasCReferences));
+    fn->setMarkedAsUsed(bool(markedAsUsed));
 
     llvm::VersionTuple available;
     DECODE_VER_TUPLE(available);
@@ -3967,17 +3968,17 @@ bool SILDeserializer::hasSILFunction(StringRef Name,
   GenericSignatureID genericSigID;
   unsigned rawLinkage, isTransparent, serializedKind, isThunk,
       isWithoutActuallyEscapingThunk, isGlobal, inlineStrategy,
-      optimizationMode, perfConstr, subclassScope, hasCReferences, effect,
-      numSpecAttrs, hasQualifiedOwnership, isWeakImported,
+      optimizationMode, perfConstr, subclassScope, hasCReferences, markedAsUsed,
+      effect, numSpecAttrs, hasQualifiedOwnership, isWeakImported,
       LIST_VER_TUPLE_PIECES(available), isDynamic, isExactSelfClass,
       isDistributed, isRuntimeAccessible, forceEnableLexicalLifetimes,
       onlyReferencedByDebugInfo;
   ArrayRef<uint64_t> SemanticsIDs;
   SILFunctionLayout::readRecord(
       scratch, rawLinkage, isTransparent, serializedKind, isThunk,
       isWithoutActuallyEscapingThunk, isGlobal, inlineStrategy,
-      optimizationMode, perfConstr, subclassScope, hasCReferences, effect,
-      numSpecAttrs, hasQualifiedOwnership, isWeakImported,
+      optimizationMode, perfConstr, subclassScope, hasCReferences, markedAsUsed,
+      effect, numSpecAttrs, hasQualifiedOwnership, isWeakImported,
       LIST_VER_TUPLE_PIECES(available), isDynamic, isExactSelfClass,
       isDistributed, isRuntimeAccessible, forceEnableLexicalLifetimes,
       onlyReferencedByDebugInfo, funcTyID, replacedFunctionID,

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 = 956; // nonisolated(nonsending) isolation was moved
+const uint16_t SWIFTMODULE_VERSION_MINOR = 957; // SILFunction markedAsUsed
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///

lib/Serialization/SILFormat.h

@@ -374,6 +374,7 @@ namespace sil_block {
                      BCFixed<3>,  // perfConstraints
                      BCFixed<2>,  // classSubclassScope
                      BCFixed<1>,  // hasCReferences
+                     BCFixed<1>,  // markedAsUsed
                      BCFixed<3>,  // side effect info.
                      BCVBR<8>,    // number of specialize attributes
                      BCFixed<1>,  // has qualified ownership

lib/Serialization/SerializeSIL.cpp

@@ -561,8 +561,8 @@ void SILSerializer::writeSILFunction(const SILFunction &F, bool DeclOnly) {
       (unsigned)F.getSpecialPurpose(), (unsigned)F.getInlineStrategy(),
       (unsigned)F.getOptimizationMode(), (unsigned)F.getPerfConstraints(),
       (unsigned)F.getClassSubclassScope(), (unsigned)F.hasCReferences(),
-      (unsigned)F.getEffectsKind(), (unsigned)numAttrs,
-      (unsigned)F.hasOwnership(), F.isAlwaysWeakImported(),
+      (unsigned)F.markedAsUsed(), (unsigned)F.getEffectsKind(),
+      (unsigned)numAttrs, (unsigned)F.hasOwnership(), F.isAlwaysWeakImported(),
       LIST_VER_TUPLE_PIECES(available), (unsigned)F.isDynamicallyReplaceable(),
       (unsigned)F.isExactSelfClass(), (unsigned)F.isDistributed(),
       (unsigned)F.isRuntimeAccessible(),

test/embedded/modules-used2.swift

@@ -30,10 +30,10 @@ func foo() {
 import MyModule
 
 // CHECK-SIL:      // main()
-// CHECK-SIL-NEXT: sil @$e8MyModule4mains5Int32VyF : $@convention(thin) () -> Int32 {
+// CHECK-SIL-NEXT: sil [used] @$e8MyModule4mains5Int32VyF : $@convention(thin) () -> Int32 {
 // CHECK-SIL: 	   // main
-// CHECK-SIL-NEXT: sil [thunk] @main : $@convention(c) () -> Int32
+// CHECK-SIL-NEXT: sil [thunk] [used] @main : $@convention(c) () -> Int32
 // CHECK-SIL:      // foo()
-// CHECK-SIL-NEXT: sil @$e8MyModule3fooyyF : $@convention(thin) () -> () {
+// CHECK-SIL-NEXT: sil [used] @$e8MyModule3fooyyF : $@convention(thin) () -> () {
 
 // CHECK: main in a submodule