Use thread_local on iOS

Using thread_local on iOS requires iOS 9 or greater. Chrome for iOS
now requires 13, Skia sets the minimum to 11 for test builds, and
Flutter actively does not support 8 or earlier. Dropping support for
iOS 8 in practice and moving to iOS 9 makes it possible to use
thread_local without reservations on iOS.

Change-Id: Ib80cbe24e8154be650f343643281384c17356242
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/447497
Reviewed-by: Heather Miller <hcm@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>

include/private/SkSLDefines.h

@@ -13,13 +13,6 @@
 #include "include/core/SkTypes.h"
 #include "include/private/SkTArray.h"
 
-#if defined(SK_BUILD_FOR_IOS) && \
-        (!defined(__IPHONE_9_0) || __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_9_0)
-#define SKSL_USE_THREAD_LOCAL 0
-#else
-#define SKSL_USE_THREAD_LOCAL 1
-#endif
-
 using SKSL_INT = int64_t;
 using SKSL_FLOAT = float;
 

modules/skottie/src/SkottieTool.cpp

@@ -336,14 +336,6 @@ int main(int argc, char** argv) {
         i = frame_count - 1 - i;
 
         const auto start = std::chrono::steady_clock::now();
-#if defined(SK_BUILD_FOR_IOS)
-        // iOS doesn't support thread_local on versions less than 9.0.
-        auto anim = skottie::Animation::Builder()
-                            .setResourceProvider(rp)
-                            .setPrecompInterceptor(precomp_interceptor)
-                            .make(static_cast<const char*>(data->data()), data->size());
-        auto sink = MakeSink(FLAGS_format[0], scale_matrix);
-#else
         thread_local static auto* anim =
                 skottie::Animation::Builder()
                     .setResourceProvider(rp)
@@ -351,7 +343,6 @@ int main(int argc, char** argv) {
                     .make(static_cast<const char*>(data->data()), data->size())
                     .release();
         thread_local static auto* sink = MakeSink(FLAGS_format[0], scale_matrix).release();
-#endif
 
         if (sink && anim) {
             anim->seekFrame(frame0 + i * fps_scale);

src/core/SkStrikeCache.cpp

@@ -21,12 +21,10 @@
 bool gSkUseThreadLocalStrikeCaches_IAcknowledgeThisIsIncrediblyExperimental = false;
 
 SkStrikeCache* SkStrikeCache::GlobalStrikeCache() {
-#if !defined(SK_BUILD_FOR_IOS)
     if (gSkUseThreadLocalStrikeCaches_IAcknowledgeThisIsIncrediblyExperimental) {
         static thread_local auto* cache = new SkStrikeCache;
         return cache;
     }
-#endif
     static auto* cache = new SkStrikeCache;
     return cache;
 }

src/core/SkVMBlitter.cpp

@@ -579,14 +579,14 @@ SkVMBlitter::~SkVMBlitter() {
 }
 
 SkLRUCache<SkVMBlitter::Key, skvm::Program>* SkVMBlitter::TryAcquireProgramCache() {
-#if 1 && defined(SKVM_JIT)
+#if defined(SKVM_JIT)
     thread_local static SkLRUCache<Key, skvm::Program> cache{64};
     return &cache;
 #else
-    // iOS in particular does not support thread_local until iOS 9.0.
-        // On the other hand, we'll never be able to JIT there anyway.
-        // It's probably fine to not cache any interpreted programs, anywhere.
-        return nullptr;
+    // iOS now supports thread_local since iOS 9.
+    // On the other hand, we'll never be able to JIT there anyway.
+    // It's probably fine to not cache any interpreted programs, anywhere.
+    return nullptr;
 #endif
 }
 

src/gpu/ops/AtlasTextOp.cpp

@@ -33,7 +33,6 @@
 namespace skgpu::v1 {
 
 // If we have thread local, then cache memory for a single AtlasTextOp.
-#if defined(GR_HAS_THREAD_LOCAL)
 static thread_local void* gCache = nullptr;
 void* AtlasTextOp::operator new(size_t s) {
     if (gCache != nullptr) {
@@ -55,7 +54,6 @@ void AtlasTextOp::ClearCache() {
     ::operator delete(gCache);
     gCache = nullptr;
 }
-#endif
 
 AtlasTextOp::AtlasTextOp(MaskType maskType,
                          bool needsTransform,

src/gpu/ops/AtlasTextOp.h

@@ -12,11 +12,6 @@
 #include "src/gpu/ops/GrMeshDrawOp.h"
 #include "src/gpu/text/GrTextBlob.h"
 
-#if !defined(SK_BUILD_FOR_IOS) || \
-            (defined(__IPHONE_9_0) && __IPHONE_OS_VERSION_MIN_REQUIRED > __IPHONE_9_0)
-    #define GR_HAS_THREAD_LOCAL
-#endif
-
 class GrRecordingContext;
 
 namespace skgpu::v1 {
@@ -33,13 +28,9 @@ public:
         }
     }
 
-#if defined(GR_HAS_THREAD_LOCAL)
     void* operator new(size_t s);
     void operator delete(void* b) noexcept;
     static void ClearCache();
-#else
-    static void ClearCache() {}
-#endif
 
     static const int kVerticesPerGlyph = GrAtlasSubRun::kVerticesPerGlyph;
     static const int kIndicesPerGlyph = 6;

src/sksl/SkSLPool.cpp

@@ -13,8 +13,6 @@
 
 namespace SkSL {
 
-#if SKSL_USE_THREAD_LOCAL
-
 static thread_local MemoryPool* sMemPool = nullptr;
 
 static MemoryPool* get_thread_local_memory_pool() {
@@ -25,32 +23,6 @@ static void set_thread_local_memory_pool(MemoryPool* memPool) {
     sMemPool = memPool;
 }
 
-#else
-
-#include <pthread.h>
-
-static pthread_key_t get_pthread_key() {
-    static pthread_key_t sKey = []{
-        pthread_key_t key;
-        int result = pthread_key_create(&key, /*destructor=*/nullptr);
-        if (result != 0) {
-            SK_ABORT("pthread_key_create failure: %d", result);
-        }
-        return key;
-    }();
-    return sKey;
-}
-
-static MemoryPool* get_thread_local_memory_pool() {
-    return static_cast<MemoryPool*>(pthread_getspecific(get_pthread_key()));
-}
-
-static void set_thread_local_memory_pool(MemoryPool* poolData) {
-    pthread_setspecific(get_pthread_key(), poolData);
-}
-
-#endif // SKSL_USE_THREAD_LOCAL
-
 Pool::~Pool() {
     if (get_thread_local_memory_pool() == fMemPool.get()) {
         SkDEBUGFAIL("SkSL pool is being destroyed while it is still attached to the thread");

src/sksl/dsl/priv/DSLWriter.cpp

@@ -25,10 +25,6 @@
 #include "src/sksl/ir/SkSLPrefixExpression.h"
 #include "src/sksl/ir/SkSLSwitchStatement.h"
 
-#if !SKSL_USE_THREAD_LOCAL
-#include <pthread.h>
-#endif // !SKSL_USE_THREAD_LOCAL
-
 namespace SkSL {
 
 namespace dsl {
@@ -326,8 +322,6 @@ void DSLWriter::ReportErrors(PositionInfo pos) {
     GetErrorReporter().reportPendingErrors(pos);
 }
 
-#if SKSL_USE_THREAD_LOCAL
-
 thread_local DSLWriter* instance = nullptr;
 
 bool DSLWriter::IsActive() {
@@ -345,40 +339,6 @@ void DSLWriter::SetInstance(std::unique_ptr<DSLWriter> newInstance) {
     instance = newInstance.release();
 }
 
-#else
-
-static void destroy_dslwriter(void* dslWriter) {
-    delete static_cast<DSLWriter*>(dslWriter);
-}
-
-static pthread_key_t get_pthread_key() {
-    static pthread_key_t sKey = []{
-        pthread_key_t key;
-        int result = pthread_key_create(&key, destroy_dslwriter);
-        if (result != 0) {
-            SK_ABORT("pthread_key_create failure: %d", result);
-        }
-        return key;
-    }();
-    return sKey;
-}
-
-bool DSLWriter::IsActive() {
-    return pthread_getspecific(get_pthread_key()) != nullptr;
-}
-
-DSLWriter& DSLWriter::Instance() {
-    DSLWriter* instance = static_cast<DSLWriter*>(pthread_getspecific(get_pthread_key()));
-    SkASSERTF(instance, "dsl::Start() has not been called");
-    return *instance;
-}
-
-void DSLWriter::SetInstance(std::unique_ptr<DSLWriter> instance) {
-    delete static_cast<DSLWriter*>(pthread_getspecific(get_pthread_key()));
-    pthread_setspecific(get_pthread_key(), instance.release());
-}
-#endif
-
 } // namespace dsl
 
 } // namespace SkSL