[Runtime] Add option to remove override point for retain/release.

mikeash · mikeash · commit 66068502325b · 2023-10-31T15:26:01.000-04:00
Add a `SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE` CMake option. When set to true, swift_retain/release and the other functions in InstrumentsSupport.h can be overridden by setting the appropriate global function pointer, as is already the case. When set to false, those function pointers are removed and the functions always go into the default implementation.

Set `SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE` to false when building the minimal stdlib, and set it to true otherwise by default.

rdar://115987924
diff --git a/include/swift/Runtime/InstrumentsSupport.h b/include/swift/Runtime/InstrumentsSupport.h
@@ -23,6 +23,8 @@
 
 namespace swift {
 
+#ifdef SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE
+
 // liboainject patches the function pointers and calls the functions below.
 SWIFT_RUNTIME_EXPORT
 HeapObject *(*SWIFT_RT_DECLARE_ENTRY _swift_allocObject)(
@@ -60,6 +62,8 @@ size_t _swift_indexToSize(size_t idx);
 SWIFT_RUNTIME_EXPORT
 void _swift_zone_init(void);
 
+#endif // SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE
+
 }
 
 #endif
diff --git a/stdlib/cmake/modules/AddSwiftStdlib.cmake b/stdlib/cmake/modules/AddSwiftStdlib.cmake
@@ -449,6 +449,10 @@ function(_add_target_variant_c_compile_flags)
     list(APPEND result "-DSWIFT_STDLIB_USE_RELATIVE_PROTOCOL_WITNESS_TABLES")
   endif()
 
+  if(SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE)
+    list(APPEND result "-DSWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE")
+  endif()
+
   list(APPEND result ${SWIFT_STDLIB_EXTRA_C_COMPILE_FLAGS})
 
   set("${CFLAGS_RESULT_VAR_NAME}" "${result}" PARENT_SCOPE)
diff --git a/stdlib/cmake/modules/StdlibOptions.cmake b/stdlib/cmake/modules/StdlibOptions.cmake
@@ -264,6 +264,10 @@ option(SWIFT_STDLIB_INSTALL_PARENT_MODULE_FOR_SHIMS
        "Install a parent module map for Swift shims."
        ${SWIFT_STDLIB_INSTALL_PARENT_MODULE_FOR_SHIMS_default})
 
+option(SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE
+       "Allow retain/release functions to be overridden by indirecting through function pointers."
+       TRUE)
+
 set(SWIFT_RUNTIME_FIXED_BACKTRACER_PATH "" CACHE STRING
   "If set, provides a fixed path to the swift-backtrace binary.  This
    will disable dynamic determination of the path and will also disable
diff --git a/stdlib/cmake/modules/SwiftSource.cmake b/stdlib/cmake/modules/SwiftSource.cmake
@@ -341,6 +341,10 @@ function(_add_target_variant_swift_compile_flags
     list(APPEND result "-D" "SWIFT_STDLIB_TASK_TO_THREAD_MODEL_CONCURRENCY")
   endif()
 
+  if(SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE)
+    list(APPEND result "-D" "SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE")
+  endif()
+
   string(TOUPPER "${SWIFT_SDK_${sdk}_THREADING_PACKAGE}" _threading_package)
   list(APPEND result "-D" "SWIFT_THREADING_${_threading_package}")
 
diff --git a/stdlib/public/runtime/HeapObject.cpp b/stdlib/public/runtime/HeapObject.cpp
@@ -107,6 +107,9 @@ static void _swift_release_n_(HeapObject *object, uint32_t n)
   asm("__swift_release_n_");
 static HeapObject *_swift_tryRetain_(HeapObject *object)
   asm("__swift_tryRetain_");
+
+#ifdef SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE
+
 #define CALL_IMPL(name, args) do { \
     void *fptr; \
     memcpy(&fptr, (void *)&_ ## name, sizeof(fptr)); \
@@ -117,6 +120,14 @@ static HeapObject *_swift_tryRetain_(HeapObject *object)
     return _ ## name ## _ args; \
 } while(0)
 
+#else
+
+// If retain/release etc. aren't overridable, just call the real implementation.
+#define CALL_IMPL(name, args) \
+    return _ ## name ## _ args;
+
+#endif
+
 #if SWIFT_STDLIB_HAS_MALLOC_TYPE
 static malloc_type_summary_t
 computeMallocTypeSummary(const HeapMetadata *heapMetadata) {
@@ -212,6 +223,35 @@ static malloc_type_id_t getMallocTypeId(const HeapMetadata *heapMetadata) {
 }
 #endif // SWIFT_STDLIB_HAS_MALLOC_TYPE
 
+#ifdef SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE
+
+SWIFT_RUNTIME_EXPORT
+HeapObject *(*SWIFT_RT_DECLARE_ENTRY _swift_allocObject)(
+    HeapMetadata const *metadata, size_t requiredSize,
+    size_t requiredAlignmentMask) = _swift_allocObject_;
+
+SWIFT_RUNTIME_EXPORT
+HeapObject *(*SWIFT_RT_DECLARE_ENTRY _swift_retain)(HeapObject *object) =
+    _swift_retain_;
+
+SWIFT_RUNTIME_EXPORT
+HeapObject *(*SWIFT_RT_DECLARE_ENTRY _swift_retain_n)(
+    HeapObject *object, uint32_t n) = _swift_retain_n_;
+
+SWIFT_RUNTIME_EXPORT
+void (*SWIFT_RT_DECLARE_ENTRY _swift_release)(HeapObject *object) =
+    _swift_release_;
+
+SWIFT_RUNTIME_EXPORT
+void (*SWIFT_RT_DECLARE_ENTRY _swift_release_n)(HeapObject *object,
+                                                uint32_t n) = _swift_release_n_;
+
+SWIFT_RUNTIME_EXPORT
+HeapObject *(*SWIFT_RT_DECLARE_ENTRY _swift_tryRetain)(HeapObject *object) =
+    _swift_tryRetain_;
+
+#endif // SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE
+
 static HeapObject *_swift_allocObject_(HeapMetadata const *metadata,
                                        size_t requiredSize,
                                        size_t requiredAlignmentMask) {
@@ -243,11 +283,6 @@ HeapObject *swift::swift_allocObject(HeapMetadata const *metadata,
   CALL_IMPL(swift_allocObject, (metadata, requiredSize, requiredAlignmentMask));
 }
 
-SWIFT_RUNTIME_EXPORT
-HeapObject *(*SWIFT_RT_DECLARE_ENTRY _swift_allocObject)(
-    HeapMetadata const *metadata, size_t requiredSize,
-    size_t requiredAlignmentMask) = _swift_allocObject_;
-
 HeapObject *
 swift::swift_initStackObject(HeapMetadata const *metadata,
                              HeapObject *object) {
@@ -465,10 +500,6 @@ HeapObject *swift::swift_retain(HeapObject *object) {
 
 CUSTOM_RR_ENTRYPOINTS_DEFINE_ENTRYPOINTS(swift_retain)
 
-SWIFT_RUNTIME_EXPORT
-HeapObject *(*SWIFT_RT_DECLARE_ENTRY _swift_retain)(HeapObject *object) =
-    _swift_retain_;
-
 HeapObject *swift::swift_nonatomic_retain(HeapObject *object) {
   SWIFT_RT_TRACK_INVOCATION(object, swift_nonatomic_retain);
   if (isValidPointerForNativeRetain(object))
@@ -492,10 +523,6 @@ HeapObject *swift::swift_retain_n(HeapObject *object, uint32_t n) {
 #endif
 }
 
-SWIFT_RUNTIME_EXPORT
-HeapObject *(*SWIFT_RT_DECLARE_ENTRY _swift_retain_n)(
-    HeapObject *object, uint32_t n) = _swift_retain_n_;
-
 HeapObject *swift::swift_nonatomic_retain_n(HeapObject *object, uint32_t n) {
   SWIFT_RT_TRACK_INVOCATION(object, swift_nonatomic_retain_n);
   if (isValidPointerForNativeRetain(object))
@@ -520,10 +547,6 @@ void swift::swift_release(HeapObject *object) {
 
 CUSTOM_RR_ENTRYPOINTS_DEFINE_ENTRYPOINTS(swift_release)
 
-SWIFT_RUNTIME_EXPORT
-void (*SWIFT_RT_DECLARE_ENTRY _swift_release)(HeapObject *object) =
-    _swift_release_;
-
 void swift::swift_nonatomic_release(HeapObject *object) {
   SWIFT_RT_TRACK_INVOCATION(object, swift_nonatomic_release);
   if (isValidPointerForNativeRetain(object))
@@ -545,10 +568,6 @@ void swift::swift_release_n(HeapObject *object, uint32_t n) {
 #endif
 }
 
-SWIFT_RUNTIME_EXPORT
-void (*SWIFT_RT_DECLARE_ENTRY _swift_release_n)(HeapObject *object,
-                                                uint32_t n) = _swift_release_n_;
-
 void swift::swift_nonatomic_release_n(HeapObject *object, uint32_t n) {
   SWIFT_RT_TRACK_INVOCATION(object, swift_nonatomic_release_n);
   if (isValidPointerForNativeRetain(object))
@@ -706,10 +725,6 @@ HeapObject *swift::swift_tryRetain(HeapObject *object) {
   CALL_IMPL(swift_tryRetain, (object));
 }
 
-SWIFT_RUNTIME_EXPORT
-HeapObject *(*SWIFT_RT_DECLARE_ENTRY _swift_tryRetain)(HeapObject *object) =
-    _swift_tryRetain_;
-
 bool swift::swift_isDeallocating(HeapObject *object) {
   if (!isValidPointerForNativeRetain(object))
     return false;
diff --git a/utils/build-presets.ini b/utils/build-presets.ini
@@ -2638,6 +2638,7 @@ build-swift-stdlib-unicode-data=0
 build-swift-stdlib-static-print=1
 darwin-crash-reporter-client=0
 swift-stdlib-use-relative-protocol-witness-tables=1
+swift-stdlib-overridable-retain-release=0
 
 [preset: stdlib_S_standalone_minimal_macho_x86_64,build]
 mixin-preset=
diff --git a/utils/build-script-impl b/utils/build-script-impl
@@ -245,6 +245,7 @@ KNOWN_SETTINGS=(
     swift-earlyswiftsyntax                        "0"               "use the early SwiftSyntax"
     swift-enable-backtracing                      "1"               "whether to build the backtracing support"
     swift-runtime-fixed-backtracer-path           ""                "if set, use a fixed path for the backtracer"
+    swift-stdlib-overridable-retain-release       "1"               "whether to allow retain/release functions to be overridden by indirecting through function pointers"
 
     ## FREESTANDING Stdlib Options
     swift-freestanding-flavor                     ""                "when building the FREESTANDING stdlib, which build style to use (options: apple, linux)"
@@ -1876,6 +1877,7 @@ for host in "${ALL_HOSTS[@]}"; do
                     -DLIBDISPATCH_CMAKE_BUILD_TYPE:STRING="${LIBDISPATCH_BUILD_TYPE}"
                     -DSWIFT_PATH_TO_SWIFT_SYNTAX_SOURCE:PATH="${SWIFT_SYNTAX_SOURCE_DIR}"
                     -DSWIFT_ENABLE_BACKTRACING:BOOL=$(true_false "${SWIFT_ENABLE_BACKTRACING}")
+                    -DSWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE:BOOL=$(true_false "${SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE}")
                     "${swift_cmake_options[@]}"
                 )
 
diff --git a/utils/swift_build_support/swift_build_support/products/minimalstdlib.py b/utils/swift_build_support/swift_build_support/products/minimalstdlib.py
@@ -167,6 +167,8 @@ def build(self, host_target):
         self.cmake_options.define(
             'SWIFT_STDLIB_USE_RELATIVE_PROTOCOL_WITNESS_TABLES:BOOL', 'TRUE')
         self.cmake_options.define('SWIFT_THREADING_PACKAGE:STRING', 'none')
+        self.cmake_options.define(
+            'SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE:BOOL', 'FALSE')
 
         # Build!
         self.build_with_cmake(["swift-stdlib-freestanding"], build_variant, [],
