Use thread private key to avoid weak linkage

We use one bit of the third reserved swift private tls key.

Also move the functionality into a separate static archive that is
always linked dependent on deployment target.

Author: aschwaighofer

cmake/modules/SwiftSource.cmake

@@ -269,6 +269,7 @@ function(_compile_swift_files
   # into the new runtime.
   if (SWIFTFILE_IS_STDLIB OR SWIFTFILE_IS_SDK_OVERLAY)
     list(APPEND swift_flags "-runtime-compatibility-version" "none")
+    list(APPEND swift_flags "-disable-autolinking-runtime-compatibility-dynamic-replacements")
   endif()
 
   if (SWIFTFILE_IS_STDLIB_CORE OR SWIFTFILE_IS_SDK_OVERLAY)

include/swift/AST/IRGenOptions.h

@@ -228,6 +228,7 @@ class IRGenOptions {
 
   /// Pull in runtime compatibility shim libraries by autolinking.
   Optional<llvm::VersionTuple> AutolinkRuntimeCompatibilityLibraryVersion;
+  Optional<llvm::VersionTuple> AutolinkRuntimeCompatibilityDynamicReplacementLibraryVersion;
 
   IRGenOptions()
       : DWARFVersion(2), OutputKind(IRGenOutputKind::LLVMAssembly),

include/swift/Option/Options.td

@@ -904,4 +904,10 @@ def disable_autolinking_runtime_compatibility : Flag<["-"], "disable-autolinking
   Flags<[FrontendOption]>,
   HelpText<"Do not use autolinking for runtime compatibility libraries">;
 
+def disable_autolinking_runtime_compatibility_dynamic_replacements
+    : Flag<[ "-" ],
+    "disable-autolinking-runtime-compatibility-dynamic-replacements">,
+      Flags<[ FrontendOption ]>,
+      HelpText<"Do not use autolinking for runtime compatibility libraries">;
+
 include "FrontendOptions.td"

lib/Driver/ToolChains.cpp

@@ -446,6 +446,12 @@ ToolChain::constructInvocation(const CompileJobAction &job,
     Arguments.push_back(arg->getValue());
   }
 
+  if (context.Args.hasArg(options::
+          OPT_disable_autolinking_runtime_compatibility_dynamic_replacements)) {
+    Arguments.push_back(
+        "-disable-autolinking-runtime-compatibility-dynamic-replacements");
+  }
+
   return II;
 }
 

lib/Frontend/CompilerInvocation.cpp

@@ -1178,6 +1178,11 @@ static bool ParseIRGenArgs(IRGenOptions &Opts, ArgList &Args,
                                                     runtimeCompatibilityVersion;
   }
 
+  if (!Args.hasArg(options::
+          OPT_disable_autolinking_runtime_compatibility_dynamic_replacements)) {
+    Opts.AutolinkRuntimeCompatibilityDynamicReplacementLibraryVersion =
+        getSwiftRuntimeCompatibilityVersionForTarget(Triple);
+  }
   return false;
 }
 

lib/IRGen/GenDecl.cpp

@@ -468,6 +468,15 @@ void IRGenModule::emitSourceFile(SourceFile &SF) {
                                          /*forceLoad*/ true));
       }
     }
+
+    if (auto compatibilityVersion =
+            IRGen.Opts.AutolinkRuntimeCompatibilityDynamicReplacementLibraryVersion) {
+      if (*compatibilityVersion <= llvm::VersionTuple(5, 0)) {
+        this->addLinkLibrary(LinkLibrary("swiftCompatibilityDynamicReplacements",
+                                         LibraryKind::Library,
+                                         /*forceLoad*/ true));
+      }
+    }
   }
 }
 

stdlib/public/CMakeLists.txt

@@ -62,6 +62,7 @@ if(SWIFT_BUILD_STDLIB)
   add_subdirectory(core)
   add_subdirectory(SwiftOnoneSupport)
   add_subdirectory(Compatibility50)
+  add_subdirectory(CompatibilityDynamicReplacements)
 endif()
 
 if(SWIFT_BUILD_STDLIB OR SWIFT_BUILD_REMOTE_MIRROR)

stdlib/public/Compatibility50/CMakeLists.txt

@@ -3,7 +3,6 @@ set(swift_runtime_linker_flags ${SWIFT_RUNTIME_CORE_LINK_FLAGS})
 
 add_swift_target_library(swiftCompatibility50 TARGET_LIBRARY STATIC INSTALL_WITH_SHARED
   ProtocolConformance.cpp
-  DynamicReplaceable.cpp
   Overrides.cpp
   C_COMPILE_FLAGS ${swift_runtime_library_compile_flags}
   LINK_FLAGS ${swift_runtime_linker_flags}

stdlib/public/CompatibilityDynamicReplacements/CMakeLists.txt

@@ -0,0 +1,11 @@
+set(swift_runtime_compile_flags ${SWIFT_RUNTIME_CORE_CXX_FLAGS})
+set(swift_runtime_linker_flags ${SWIFT_RUNTIME_CORE_LINK_FLAGS})
+
+add_swift_target_library(swiftCompatibilityDynamicReplacements TARGET_LIBRARY STATIC INSTALL_WITH_SHARED
+  DynamicReplaceable.cpp
+  C_COMPILE_FLAGS ${swift_runtime_library_compile_flags}
+  LINK_FLAGS ${swift_runtime_linker_flags}
+  TARGET_SDKS ${SWIFT_APPLE_PLATFORMS}
+  INSTALL_IN_COMPONENT compiler)
+
+

stdlib/public/Compatibility50/DynamicReplaceable.cpp renamed to stdlib/public/CompatibilityDynamicReplacements/DynamicReplaceable.cpp

@@ -17,29 +17,12 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "Overrides.h"
 #include "swift/Runtime/Once.h"
 #include "swift/Runtime/Exclusivity.h"
 #include "../runtime/ThreadLocalStorage.h"
 
 using namespace swift;
 
-// The thread-local key must be weak so that it is shared between different
-// binaries (e.g. shared libraries).
-__attribute__((weak)) __swift_thread_key_t _swift_dr_key;
-__attribute__((weak)) swift_once_t _swift_dr_Predicate;
-
-static void createSwiftThreadKey(void *) {
-  int result = SWIFT_THREAD_KEY_CREATE(&_swift_dr_key, nullptr);
-  if (result != 0)
-    abort();
-}
-
-static __swift_thread_key_t &getTLSKey() {
-  swift_once(&_swift_dr_Predicate, createSwiftThreadKey, nullptr);
-  return _swift_dr_key;
-}
-
 __attribute__((visibility("hidden"), weak))
 extern "C" char *swift_getFunctionReplacement50(char **ReplFnPtr, char *CurrFn) {
   // Call the current implementation if it is available.
@@ -52,9 +35,11 @@ extern "C" char *swift_getFunctionReplacement50(char **ReplFnPtr, char *CurrFn)
   if (RawReplFn == CurrFn)
     return nullptr;
 
-  __swift_thread_key_t key = getTLSKey();
-  if ((intptr_t)SWIFT_THREAD_GETSPECIFIC(key) != 0) {
-    SWIFT_THREAD_SETSPECIFIC(key, (void *)0);
+  auto origKey = (uintptr_t)SWIFT_THREAD_GETSPECIFIC(SWIFT_RUNTIME2_TLS_KEY);
+  if ((origKey & 0x1) != 0) {
+    auto mask = ((uintptr_t)-1) < 1;
+    auto resetKey = origKey & mask;
+    SWIFT_THREAD_SETSPECIFIC(SWIFT_RUNTIME2_TLS_KEY, (void *)resetKey);
     return nullptr;
   }
   return ReplFn;
@@ -67,6 +52,13 @@ extern "C" char *swift_getOrigOfReplaceable50(char **OrigFnPtr) {
     return swift_getOrigOfReplaceable(OrigFnPtr);
 
   char *OrigFn = *OrigFnPtr;
-  SWIFT_THREAD_SETSPECIFIC(getTLSKey(), (void *)-1);
+  auto origKey = (uintptr_t)SWIFT_THREAD_GETSPECIFIC(SWIFT_RUNTIME2_TLS_KEY);
+  auto newKey = origKey | 0x1;
+  SWIFT_THREAD_SETSPECIFIC(SWIFT_RUNTIME2_TLS_KEY, (void *)newKey);
   return OrigFn;
 }
+
+// Allow this library to get force-loaded by autolinking
+__attribute__((weak, visibility("hidden")))
+extern "C"
+char _swift_FORCE_LOAD_$_swiftCompatibilityDynamicReplacements = 0;

stdlib/public/runtime/ThreadLocalStorage.h

@@ -53,9 +53,14 @@ extern "C" int pthread_key_init_np(int key, void (*destructor)(void *));
 # ifndef __PTK_FRAMEWORK_SWIFT_KEY1
 #  define __PTK_FRAMEWORK_SWIFT_KEY1 101
 # endif
+# ifndef __PTK_FRAMEWORK_SWIFT_KEY2
+#  define __PTK_FRAMEWORK_SWIFT_KEY2 102
+# endif
+
 
 # define SWIFT_RUNTIME_TLS_KEY __PTK_FRAMEWORK_SWIFT_KEY0
 # define SWIFT_STDLIB_TLS_KEY __PTK_FRAMEWORK_SWIFT_KEY1
+# define SWIFT_RUNTIME2_TLS_KEY __PTK_FRAMEWORK_SWIFT_KEY2
 
 #endif
 

test/IRGen/autolink-runtime-compatibility.swift

@@ -1,14 +1,14 @@
 // REQUIRES: OS=macosx
 
 // Doesn't autolink compatibility library because autolinking is disabled
-// RUN: %target-swift-frontend -target x86_64-apple-macosx10.9 -disable-autolinking-runtime-compatibility -emit-ir -parse-stdlib %s | %FileCheck -check-prefix=NO-FORCE-LOAD %s
-// RUN: %target-swift-frontend -runtime-compatibility-version 5.0 -disable-autolinking-runtime-compatibility -emit-ir -parse-stdlib %s | %FileCheck -check-prefix=NO-FORCE-LOAD %s
+// RUN: %target-swift-frontend -disable-autolinking-runtime-compatibility-dynamic-replacements -target x86_64-apple-macosx10.9 -disable-autolinking-runtime-compatibility -emit-ir -parse-stdlib %s | %FileCheck -check-prefix=NO-FORCE-LOAD %s
+// RUN: %target-swift-frontend -disable-autolinking-runtime-compatibility-dynamic-replacements -runtime-compatibility-version 5.0 -disable-autolinking-runtime-compatibility -emit-ir -parse-stdlib %s | %FileCheck -check-prefix=NO-FORCE-LOAD %s
 
 // Doesn't autolink compatibility library because runtime compatibility library is disabled
-// RUN: %target-swift-frontend -runtime-compatibility-version none -emit-ir -parse-stdlib %s | %FileCheck -check-prefix=NO-FORCE-LOAD %s
+// RUN: %target-swift-frontend -disable-autolinking-runtime-compatibility-dynamic-replacements -runtime-compatibility-version none -emit-ir -parse-stdlib %s | %FileCheck -check-prefix=NO-FORCE-LOAD %s
 
 // Doesn't autolink compatibility library because target OS doesn't need it
-// RUN: %target-swift-frontend -target x86_64-apple-macosx10.24 -emit-ir -parse-stdlib %s | %FileCheck -check-prefix=NO-FORCE-LOAD %s
+// RUN: %target-swift-frontend -disable-autolinking-runtime-compatibility-dynamic-replacements -target x86_64-apple-macosx10.24 -emit-ir -parse-stdlib %s | %FileCheck -check-prefix=NO-FORCE-LOAD %s
 
 // Autolinks because compatibility library was explicitly asked for
 // RUN: %target-swift-frontend -runtime-compatibility-version 5.0 -emit-ir -parse-stdlib %s | %FileCheck -check-prefix=FORCE-LOAD %s

test/IRGen/unused.sil

@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -runtime-compatibility-version none -primary-file %s -emit-ir | %FileCheck -check-prefix CHECK -check-prefix NEGATIVE -check-prefix CHECK-%target-object-format %s
+// RUN: %target-swift-frontend -disable-autolinking-runtime-compatibility-dynamic-replacements -runtime-compatibility-version none -primary-file %s -emit-ir | %FileCheck -check-prefix CHECK -check-prefix NEGATIVE -check-prefix CHECK-%target-object-format %s
 
 // REQUIRES: CPU=x86_64
 

test/Serialization/autolinking.swift

@@ -1,12 +1,12 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend -emit-module -parse-stdlib -o %t -module-name someModule -module-link-name module %S/../Inputs/empty.swift
-// RUN: %target-swift-frontend -runtime-compatibility-version none -emit-ir -lmagic %s -I %t > %t/out.txt
+// RUN: %target-swift-frontend -disable-autolinking-runtime-compatibility-dynamic-replacements -runtime-compatibility-version none -emit-ir -lmagic %s -I %t > %t/out.txt
 // RUN: %FileCheck %s < %t/out.txt
 // RUN: %FileCheck -check-prefix=NO-FORCE-LOAD %s < %t/out.txt
 
 // RUN: %empty-directory(%t/someModule.framework/Modules/someModule.swiftmodule)
 // RUN: mv %t/someModule.swiftmodule %t/someModule.framework/Modules/someModule.swiftmodule/%target-swiftmodule-name
-// RUN: %target-swift-frontend -runtime-compatibility-version none -emit-ir -lmagic %s -F %t > %t/framework.txt
+// RUN: %target-swift-frontend -disable-autolinking-runtime-compatibility-dynamic-replacements -runtime-compatibility-version none -emit-ir -lmagic %s -F %t > %t/framework.txt
 // RUN: %FileCheck -check-prefix=FRAMEWORK %s < %t/framework.txt
 // RUN: %FileCheck -check-prefix=NO-FORCE-LOAD %s < %t/framework.txt
 
@@ -15,7 +15,7 @@
 // RUN: %FileCheck %s < %t/force-load.txt
 // RUN: %FileCheck -check-prefix FORCE-LOAD-CLIENT -check-prefix FORCE-LOAD-CLIENT-%target-object-format %s < %t/force-load.txt
 
-// RUN: %target-swift-frontend -runtime-compatibility-version none -emit-ir -parse-stdlib -module-name someModule -module-link-name module %S/../Inputs/empty.swift | %FileCheck --check-prefix=NO-FORCE-LOAD %s
+// RUN: %target-swift-frontend -disable-autolinking-runtime-compatibility-dynamic-replacements -runtime-compatibility-version none -emit-ir -parse-stdlib -module-name someModule -module-link-name module %S/../Inputs/empty.swift | %FileCheck --check-prefix=NO-FORCE-LOAD %s
 // RUN: %target-swift-frontend -runtime-compatibility-version none -emit-ir -parse-stdlib -module-name someModule -module-link-name module %S/../Inputs/empty.swift -autolink-force-load | %FileCheck --check-prefix=FORCE-LOAD %s
 // RUN: %target-swift-frontend -runtime-compatibility-version none -emit-ir -parse-stdlib -module-name someModule -module-link-name 0module %S/../Inputs/empty.swift -autolink-force-load | %FileCheck --check-prefix=FORCE-LOAD-HEX %s