Merge pull request swiftlang#20592 from DougGregor/runtime-get-assoc-typeconformance-override

Author: swift-ci

stdlib/public/runtime/CompatibilityOverride.def

@@ -44,6 +44,7 @@
 #  define OVERRIDE_FOREIGN OVERRIDE
 #  define OVERRIDE_PROTOCOLCONFORMANCE OVERRIDE
 #  define OVERRIDE_KEYPATH OVERRIDE
+#  define OVERRIDE_WITNESSTABLE OVERRIDE
 #else
 #  ifndef OVERRIDE_METADATALOOKUP
 #    define OVERRIDE_METADATALOOKUP(...)
@@ -63,6 +64,9 @@
 #  ifndef OVERRIDE_KEYPATH
 #    define OVERRIDE_KEYPATH(...)
 #  endif
+#  ifndef OVERRIDE_WITNESSTABLE
+#    define OVERRIDE_WITNESSTABLE(...)
+#  endif
 #endif
 
 OVERRIDE_METADATALOOKUP(getTypeByMangledName, const Metadata *,
@@ -140,6 +144,22 @@ OVERRIDE_KEYPATH(getKeyPath, const HeapObject *, , swift::,
                  (const void *pattern, const void *arguments),
                  (pattern, arguments))
 
+OVERRIDE_WITNESSTABLE(getAssociatedTypeWitnessSlow, MetadataResponse,
+                      SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL, swift::,
+                      (MetadataRequest request, WitnessTable *wtable,
+                       const Metadata *conformingType,
+                       const ProtocolRequirement *reqBase,
+                       const ProtocolRequirement *assocType),
+                      (request, wtable, conformingType, reqBase, assocType))
+
+OVERRIDE_WITNESSTABLE(getAssociatedConformanceWitnessSlow, const WitnessTable *,
+                      SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL, swift::,
+                      (WitnessTable *wtable, const Metadata *conformingType,
+                       const Metadata *assocType,
+                       const ProtocolRequirement *reqBase,
+                       const ProtocolRequirement *assocConformance),
+                      (wtable, conformingType, assocType, reqBase,
+                               assocConformance))
 #if SWIFT_OBJC_INTEROP
 
 OVERRIDE_OBJC(dynamicCastObjCClass, const void *, , swift::,
@@ -183,3 +203,4 @@ OVERRIDE_FOREIGN(dynamicCastForeignClassUnconditional, const void *, , swift::,
 #undef OVERRIDE_FOREIGN
 #undef OVERRIDE_PROTOCOLCONFORMANCE
 #undef OVERRIDE_KEYPATH
+#undef OVERRIDE_WITNESSTABLE

stdlib/public/runtime/Metadata.cpp

@@ -4053,13 +4053,13 @@ static StringRef findAssociatedTypeName(const ProtocolDescriptor *protocol,
   return StringRef();
 }
 
-MetadataResponse
-swift::swift_getAssociatedTypeWitness(MetadataRequest request,
+static MetadataResponse
+swift_getAssociatedTypeWitnessSlowImpl(
+                                      MetadataRequest request,
                                       WitnessTable *wtable,
                                       const Metadata *conformingType,
                                       const ProtocolRequirement *reqBase,
                                       const ProtocolRequirement *assocType) {
-
 #ifndef NDEBUG
   {
     const ProtocolConformanceDescriptor *conformance = wtable->Description;
@@ -4077,7 +4077,7 @@ swift::swift_getAssociatedTypeWitness(MetadataRequest request,
   unsigned witnessIndex = assocType - reqBase;
   auto witness = ((const void* const *)wtable)[witnessIndex];
   if (LLVM_LIKELY((uintptr_t(witness) &
-         ProtocolRequirementFlags::AssociatedTypeMangledNameBit) == 0)) {
+        ProtocolRequirementFlags::AssociatedTypeMangledNameBit) == 0)) {
     // Cached metadata pointers are always complete.
     return MetadataResponse{(const Metadata *)witness, MetadataState::Complete};
   }
@@ -4158,7 +4158,26 @@ swift::swift_getAssociatedTypeWitness(MetadataRequest request,
   return response;
 }
 
-const WitnessTable *swift::swift_getAssociatedConformanceWitness(
+MetadataResponse
+swift::swift_getAssociatedTypeWitness(MetadataRequest request,
+                                      WitnessTable *wtable,
+                                      const Metadata *conformingType,
+                                      const ProtocolRequirement *reqBase,
+                                      const ProtocolRequirement *assocType) {
+  // If the low bit of the witness is clear, it's already a metadata pointer.
+  unsigned witnessIndex = assocType - reqBase;
+  auto witness = ((const void* const *)wtable)[witnessIndex];
+  if (LLVM_LIKELY((uintptr_t(witness) &
+        ProtocolRequirementFlags::AssociatedTypeMangledNameBit) == 0)) {
+    // Cached metadata pointers are always complete.
+    return MetadataResponse{(const Metadata *)witness, MetadataState::Complete};
+  }
+
+  return swift_getAssociatedTypeWitnessSlow(request, wtable, conformingType,
+                                            reqBase, assocType);
+}
+
+static const WitnessTable *swift_getAssociatedConformanceWitnessSlowImpl(
                                   WitnessTable *wtable,
                                   const Metadata *conformingType,
                                   const Metadata *assocType,
@@ -4177,7 +4196,7 @@ const WitnessTable *swift::swift_getAssociatedConformanceWitness(
   }
 #endif
 
-  // Call the access function.
+  // Retrieve the witness.
   unsigned witnessIndex = assocConformance - reqBase;
   auto witness = ((const void* const *)wtable)[witnessIndex];
   // Fast path: we've already resolved this to a witness table, so return it.
@@ -4222,6 +4241,26 @@ const WitnessTable *swift::swift_getAssociatedConformanceWitness(
   swift_runtime_unreachable("Invalid mangled associate conformance");
 }
 
+const WitnessTable *swift::swift_getAssociatedConformanceWitness(
+                                  WitnessTable *wtable,
+                                  const Metadata *conformingType,
+                                  const Metadata *assocType,
+                                  const ProtocolRequirement *reqBase,
+                                  const ProtocolRequirement *assocConformance) {
+  // Retrieve the witness.
+  unsigned witnessIndex = assocConformance - reqBase;
+  auto witness = ((const void* const *)wtable)[witnessIndex];
+  // Fast path: we've already resolved this to a witness table, so return it.
+  if (LLVM_LIKELY((uintptr_t(witness) &
+         ProtocolRequirementFlags::AssociatedTypeMangledNameBit) == 0)) {
+    return static_cast<const WitnessTable *>(witness);
+  }
+
+  return swift_getAssociatedConformanceWitnessSlow(wtable, conformingType,
+                                                   assocType, reqBase,
+                                                   assocConformance);
+}
+
 /***************************************************************************/
 /*** Recursive metadata dependencies ***************************************/
 /***************************************************************************/
@@ -4842,4 +4881,5 @@ const HeapObject *swift_getKeyPathImpl(const void *pattern,
                                        const void *arguments);
 
 #define OVERRIDE_KEYPATH COMPATIBILITY_OVERRIDE
+#define OVERRIDE_WITNESSTABLE COMPATIBILITY_OVERRIDE
 #include "CompatibilityOverride.def"

stdlib/public/runtime/Private.h

@@ -457,6 +457,40 @@ class TypeInfo {
   const Metadata *findConformingSuperclass(
                              const Metadata *type,
                              const ProtocolConformanceDescriptor *conformance);
+
+  /// Retrieve an associated type witness from the given witness table.
+  ///
+  /// \param wtable The witness table.
+  /// \param conformingType Metadata for the conforming type.
+  /// \param reqBase "Base" requirement used to compute the witness index
+  /// \param assocType Associated type descriptor.
+  ///
+  /// \returns metadata for the associated type witness.
+  SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
+  MetadataResponse swift_getAssociatedTypeWitnessSlow(
+                                        MetadataRequest request,
+                                        WitnessTable *wtable,
+                                        const Metadata *conformingType,
+                                        const ProtocolRequirement *reqBase,
+                                        const ProtocolRequirement *assocType);
+
+  /// Retrieve an associated conformance witness table from the given witness
+  /// table.
+  ///
+  /// \param wtable The witness table.
+  /// \param conformingType Metadata for the conforming type.
+  /// \param assocType Metadata for the associated type.
+  /// \param reqBase "Base" requirement used to compute the witness index
+  /// \param assocConformance Associated conformance descriptor.
+  ///
+  /// \returns corresponding witness table.
+  SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
+  const WitnessTable *swift_getAssociatedConformanceWitnessSlow(
+                                  WitnessTable *wtable,
+                                  const Metadata *conformingType,
+                                  const Metadata *assocType,
+                                  const ProtocolRequirement *reqBase,
+                                  const ProtocolRequirement *assocConformance);
 } // end namespace swift
 
 #endif /* SWIFT_RUNTIME_PRIVATE_H */

unittests/runtime/CompatibilityOverride.cpp

@@ -24,14 +24,25 @@ using namespace swift;
 bool EnableOverride;
 bool Ran;
 
+namespace  {
+  template<typename T>
+  T getEmptyValue() {
+    return (T)0;
+  }
+
+  template<>
+  MetadataResponse getEmptyValue<MetadataResponse>() {
+    return MetadataResponse{nullptr, MetadataState::Complete};
+  }
+}
 
 #define OVERRIDE(name, ret, attrs, namespace, typedArgs, namedArgs) \
   static ret name ## Override(COMPATIBILITY_UNPAREN typedArgs,      \
                           Original_ ## name originalImpl) {         \
     if (!EnableOverride)                                            \
       return originalImpl namedArgs;                                \
     Ran = true;                                                     \
-    return (ret)0;                                                  \
+    return getEmptyValue<ret>();                                    \
   }
 #include "../../stdlib/public/runtime/CompatibilityOverride.def"
 
@@ -164,4 +175,20 @@ TEST_F(CompatibilityOverrideTest, test_swift_conformsToProtocol) {
   ASSERT_EQ(Result, nullptr);  
 }
 
+TEST_F(CompatibilityOverrideTest, test_swift_getAssociatedTypeWitnessSlow) {
+  auto Result = swift_getAssociatedTypeWitnessSlow(MetadataState::Complete,
+                                                   nullptr, nullptr,
+                                                   nullptr, nullptr);
+  ASSERT_EQ(Result.Value, nullptr);
+  ASSERT_EQ(Result.State, MetadataState::Complete);
+}
+
+TEST_F(CompatibilityOverrideTest,
+       test_swift_getAssociatedConformanceWitnessSlow) {
+  auto Result = swift_getAssociatedConformanceWitnessSlow(
+                                                   nullptr, nullptr, nullptr,
+                                                   nullptr, nullptr);
+  ASSERT_EQ(Result, nullptr);
+}
+
 #endif