Merge pull request #17120 from JuliaLang/yyc/threads/mac

Optimize TLS access on mac and windows

Author: vtjnash

src/julia_threads.h

@@ -366,7 +366,9 @@ STATIC_INLINE int8_t jl_gc_state_set(jl_tls_states_t *ptls,
 }
 #else // ifndef JULIA_ENABLE_THREADING
 typedef jl_tls_states_t *(*jl_get_ptls_states_func)(void);
+#if !defined(_OS_DARWIN_) && !defined(_OS_WINDOWS_)
 JL_DLLEXPORT void jl_set_ptls_states_getter(jl_get_ptls_states_func f);
+#endif
 // Make sure jl_gc_state() is always a rvalue
 #define jl_gc_state(ptls) ((int8_t)ptls->gc_state)
 STATIC_INLINE int8_t jl_gc_state_set(jl_tls_states_t *ptls,

src/threading.c

@@ -30,14 +30,82 @@ extern "C" {
 #include "threading.h"
 
 #ifdef JULIA_ENABLE_THREADING
+#  if defined(_OS_DARWIN_)
+// Mac doesn't seem to have static TLS model so the runtime TLS getter
+// registration will only add overhead to TLS access. The `__thread` variables
+// are emulated with `pthread_key_t` so it is actually faster to use it directly.
+static pthread_key_t jl_tls_key;
+
+__attribute__((constructor)) void jl_mac_init_tls(void)
+{
+    pthread_key_create(&jl_tls_key, NULL);
+}
+
+JL_DLLEXPORT JL_CONST_FUNC jl_tls_states_t *(jl_get_ptls_states)(void)
+{
+    void *ptls = pthread_getspecific(jl_tls_key);
+    if (__unlikely(!ptls)) {
+        ptls = calloc(1, sizeof(jl_tls_states_t));
+        pthread_setspecific(jl_tls_key, ptls);
+    }
+    return (jl_tls_states_t*)ptls;
+}
+
+// This is only used after the tls is already initialized on the thread
+static JL_CONST_FUNC jl_tls_states_t *jl_get_ptls_states_fast(void)
+{
+    return (jl_tls_states_t*)pthread_getspecific(jl_tls_key);
+}
+
+jl_get_ptls_states_func jl_get_ptls_states_getter(void)
+{
+    // for codegen
+    return &jl_get_ptls_states_fast;
+}
+#  elif defined(_OS_WINDOWS_)
+// Apparently windows doesn't have a static TLS model (or one that can be
+// reliably used from a shared library) either..... Use `TLSAlloc` instead.
+
+static DWORD jl_tls_key;
+
+// Put this here for now. We can move this out later if we find more use for it.
+BOOLEAN WINAPI DllMain(IN HINSTANCE hDllHandle, IN DWORD nReason,
+                       IN LPVOID Reserved)
+{
+    switch (nReason) {
+    case DLL_PROCESS_ATTACH:
+        jl_tls_key = TlsAlloc();
+        assert(jl_tls_key != TLS_OUT_OF_INDEXES);
+        // Fall through
+    case DLL_THREAD_ATTACH:
+        TlsSetValue(jl_tls_key, calloc(1, sizeof(jl_tls_states_t)));
+        break;
+    case DLL_THREAD_DETACH:
+        free(TlsGetValue(jl_tls_key));
+        TlsSetValue(jl_tls_key, NULL);
+        break;
+    case DLL_PROCESS_DETACH:
+        free(TlsGetValue(jl_tls_key));
+        TlsFree(jl_tls_key);
+        break;
+    }
+}
+
+JL_DLLEXPORT JL_CONST_FUNC jl_tls_states_t *(jl_get_ptls_states)(void)
+{
+    return TlsGetValue(jl_tls_key);
+}
+
+jl_get_ptls_states_func jl_get_ptls_states_getter(void)
+{
+    // for codegen
+    return &jl_get_ptls_states;
+}
+#  else
 // fallback provided for embedding
 static JL_CONST_FUNC jl_tls_states_t *jl_get_ptls_states_fallback(void)
 {
-#  if !defined(_COMPILER_MICROSOFT_)
     static __thread jl_tls_states_t tls_states;
-#  else
-    static __declspec(thread) jl_tls_states_t tls_states;
-#  endif
     return &tls_states;
 }
 static jl_tls_states_t *jl_get_ptls_states_init(void);
@@ -78,6 +146,7 @@ jl_get_ptls_states_func jl_get_ptls_states_getter(void)
     // for codegen
     return jl_tls_states_cb;
 }
+#  endif
 #else
 JL_DLLEXPORT jl_tls_states_t jl_tls_states;
 JL_DLLEXPORT JL_CONST_FUNC jl_tls_states_t *(jl_get_ptls_states)(void)

ui/repl.c

@@ -34,14 +34,10 @@
 extern "C" {
 #endif
 
-#ifdef JULIA_ENABLE_THREADING
+#if defined(JULIA_ENABLE_THREADING) && !defined(_OS_DARWIN_) && !defined(_OS_WINDOWS_)
 static JL_CONST_FUNC jl_tls_states_t *jl_get_ptls_states_static(void)
 {
-#  if !defined(_COMPILER_MICROSOFT_)
     static __attribute__((tls_model("local-exec"))) __thread jl_tls_states_t tls_states;
-#  else
-    static __declspec(thread) jl_tls_states_t tls_states;
-#  endif
     return &tls_states;
 }
 #endif
@@ -660,7 +656,7 @@ int wmain(int argc, wchar_t *argv[], wchar_t *envp[])
         argv[i] = (wchar_t*)arg;
     }
 #endif
-#ifdef JULIA_ENABLE_THREADING
+#if defined(JULIA_ENABLE_THREADING) && !defined(_OS_DARWIN_) && !defined(_OS_WINDOWS_)
     // We need to make sure this function is called before any reference to
     // TLS variables. Since the compiler is free to move calls to
     // `jl_get_ptls_states()` around, we should avoid referencing TLS