Add a SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC flag to allow/disallow uses of Darwin libmalloc APIs (malloc_default_zone, malloc_zone_malloc, etc.)

include/swift/Runtime/Concurrent.h

@@ -639,7 +639,7 @@ struct ConcurrentReadableHashMap {
   /// Otherwise, just return the passed-in size, which is always valid even if
   /// not necessarily optimal.
   static size_t goodSize(size_t size) {
-#if defined(__APPLE__) && defined(__MACH__)
+#if defined(__APPLE__) && defined(__MACH__) && SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC
     return malloc_good_size(size);
 #else
     return size;

stdlib/CMakeLists.txt

@@ -75,6 +75,10 @@ option(SWIFT_RUNTIME_MACHO_NO_DYLD
        "Build stdlib assuming the runtime environment uses Mach-O but does not support dynamic modules."
        FALSE)
 
+option(SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC
+  "Build stdlib assuming the Darwin build of stdlib can use extended libmalloc APIs"
+  )
+
 option(SWIFT_STDLIB_SINGLE_THREADED_RUNTIME
        "Build the standard libraries assuming that they will be used in an environment with only a single thread."
        FALSE)

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -320,6 +320,12 @@ function(_add_target_variant_c_compile_flags)
     list(APPEND result "-DSWIFT_RUNTIME_MACHO_NO_DYLD")
   endif()
 
+  if(SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC)
+    list(APPEND result "-DSWIFT_STDLIB_HAS_DARWIN_LIBMALLOC=1")
+  else()
+    list(APPEND result "-DSWIFT_STDLIB_HAS_DARWIN_LIBMALLOC=0")
+  endif()
+
   if(SWIFT_STDLIB_SINGLE_THREADED_RUNTIME)
     list(APPEND result "-DSWIFT_STDLIB_SINGLE_THREADED_RUNTIME")
   endif()

stdlib/public/runtime/Heap.cpp

@@ -21,7 +21,7 @@
 #include "../SwiftShims/RuntimeShims.h"
 #include <algorithm>
 #include <stdlib.h>
-#if defined(__APPLE__)
+#if defined(__APPLE__) && SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC
 #include "swift/Basic/Lazy.h"
 #include <malloc/malloc.h>
 #endif
@@ -61,7 +61,7 @@ using namespace swift;
 static_assert(_swift_MinAllocationAlignment > MALLOC_ALIGN_MASK,
               "Swift's default alignment must exceed platform malloc mask.");
 
-#if defined(__APPLE__)
+#if defined(__APPLE__) && SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC
 static inline malloc_zone_t *DEFAULT_ZONE() {
   static malloc_zone_t *z = SWIFT_LAZY_CONSTANT(malloc_default_zone());
   return z;
@@ -88,7 +88,7 @@ void *swift::swift_slowAlloc(size_t size, size_t alignMask) {
   void *p;
   // This check also forces "default" alignment to use AlignedAlloc.
   if (alignMask <= MALLOC_ALIGN_MASK) {
-#if defined(__APPLE__)
+#if defined(__APPLE__) && SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC
     p = malloc_zone_malloc(DEFAULT_ZONE(), size);
 #else
     p = malloc(size);
@@ -121,7 +121,7 @@ void *swift::swift_slowAlloc(size_t size, size_t alignMask) {
 //   consistent with allocation with the same alignment.
 void swift::swift_slowDealloc(void *ptr, size_t bytes, size_t alignMask) {
   if (alignMask <= MALLOC_ALIGN_MASK) {
-#if defined(__APPLE__)
+#if defined(__APPLE__) && SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC
     malloc_zone_free(DEFAULT_ZONE(), ptr);
 #else
     free(ptr);

utils/build-presets.ini

@@ -2431,6 +2431,7 @@ build-swift-static-stdlib=1
 swift-objc-interop=0
 swift-enable-compatibility-overrides=0
 swift-runtime-macho-no-dyld=1
+swift-stdlib-has-darwin-libmalloc=0
 swift-stdlib-single-threaded-runtime=1
 swift-stdlib-os-versioning=0
 extra-cmake-options=

utils/build-script-impl

@@ -203,6 +203,7 @@ KNOWN_SETTINGS=(
     swift-stdlib-single-threaded-runtime          "0"               "whether to build stdlib as a single-threaded runtime only"
     swift-stdlib-os-versioning                    "1"               "whether to build stdlib with availability based on OS versions (Darwin only)"
     swift-stdlib-stable-abi                       ""                "should stdlib be built with stable ABI, if not set defaults to true on Darwin, false otherwise"
+    swift-stdlib-has-darwin-libmalloc             "1"               "whether the Darwin build of stdlib can use extended libmalloc APIs"
     swift-disable-dead-stripping                  "0"               "turns off Darwin-specific dead stripping for Swift host tools"
     common-swift-flags                            ""                "Flags used for Swift targets other than the stdlib, like the corelibs"
 
@@ -1961,6 +1962,7 @@ for host in "${ALL_HOSTS[@]}"; do
                     -DSWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS:BOOL=$(true_false "${SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS}")
                     -DSWIFT_RUNTIME_MACHO_NO_DYLD:BOOL=$(true_false "${SWIFT_RUNTIME_MACHO_NO_DYLD}")
                     -DSWIFT_STDLIB_OS_VERSIONING:BOOL=$(true_false "${SWIFT_STDLIB_OS_VERSIONING}")
+                    -DSWIFT_STDLIB_HAS_DARWIN_LIBMALLOC:BOOL=$(true_false "${SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC}")
                     -DSWIFT_NATIVE_LLVM_TOOLS_PATH:STRING="${native_llvm_tools_path}"
                     -DSWIFT_NATIVE_CLANG_TOOLS_PATH:STRING="${native_clang_tools_path}"
                     -DSWIFT_NATIVE_SWIFT_TOOLS_PATH:STRING="${native_swift_tools_path}"