[Runtime] Skip shared cache protocol conformance queries we know won't succeed.

The shared cache tables can only point to things within the shared cache, so if the protocol, ObjC class, or type descriptor are outside the shared cache, we know that the lookup will fail and we can skip it.

rdar://90427793

Author: mikeash

stdlib/public/runtime/ProtocolConformance.cpp

@@ -802,6 +802,19 @@ static _dyld_protocol_conformance_result getDyldSharedCacheConformance(
     ConformanceState &C, const ProtocolDescriptor *protocol,
     const ClassMetadata *objcClassMetadata,
     const ContextDescriptor *description, llvm::StringRef foreignTypeIdentity) {
+  // Protocols, classes, and descriptions that aren't in the shared cache will
+  // never be found in the shared cache conformances. Foreign types are
+  // non-unique so those can still be found in the shared cache regardless of
+  // where the we got the identity.
+  if (!C.inSharedCache(protocol) ||
+      (objcClassMetadata && !C.inSharedCache(objcClassMetadata)) ||
+      (description && !C.inSharedCache(description))) {
+    DYLD_CONFORMANCES_LOG("Skipping shared cache lookup, protocol %p, class "
+                          "%p, or description %p is not in shared cache.",
+                          protocol, objcClassMetadata, description);
+    return {_dyld_protocol_conformance_result_kind_not_found, nullptr};
+  }
+
   if (!foreignTypeIdentity.empty()) {
     DYLD_CONFORMANCES_LOG(
         "_dyld_find_foreign_type_protocol_conformance(%p, %.*s, %zu)", protocol,