Enable GC safepoint for non-threading build

JuliaLang · May 5, 2016 · ab2f0c1 · ab2f0c1
1 parent c89632e
commit ab2f0c1
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Showing 8 changed files with 45 additions and 56 deletions.
diff --git a/src/ccall.cpp b/src/ccall.cpp
@@ -1243,27 +1243,16 @@ static jl_cgval_t emit_ccall(jl_value_t **args, size_t nargs, jl_codectx_t *ctx)
         assert(!isVa);
         assert(nargt == 0);
         JL_GC_POP();
-#ifdef JULIA_ENABLE_THREADING
 #ifdef LLVM39
         builder.CreateFence(AtomicOrdering::SequentiallyConsistent, SingleThread);
 #else
         builder.CreateFence(SequentiallyConsistent, SingleThread);
 #endif
-        Value *addr;
-        if (imaging_mode) {
-            assert(ctx->signalPage);
-            addr = ctx->signalPage;
-        }
-        else {
-            addr = builder.CreateIntToPtr(
-                ConstantInt::get(T_size, (uintptr_t)jl_gc_signal_page), T_pint8);
-        }
-        builder.CreateLoad(addr, true);
+        builder.CreateLoad(ctx->signalPage, true);
 #ifdef LLVM39
         builder.CreateFence(AtomicOrdering::SequentiallyConsistent, SingleThread);
 #else
         builder.CreateFence(SequentiallyConsistent, SingleThread);
-#endif
 #endif
         return ghostValue(jl_void_type);
     }

diff --git a/src/codegen.cpp b/src/codegen.cpp
@@ -342,9 +342,10 @@ static GlobalVariable *jltls_states_var;
 // Imaging mode only
 static GlobalVariable *jltls_states_func_ptr = NULL;
 static size_t jltls_states_func_idx = 0;
+#endif
+// Imaging mode only (non-imaging mode use pointer directly)
 static GlobalVariable *jl_gc_signal_page_ptr = NULL;
 static size_t jl_gc_signal_page_idx = 0;
-#endif
 
 // important functions
 static Function *jlnew_func;
@@ -576,9 +577,7 @@ typedef struct {
     std::vector<bool> inbounds;
 
     CallInst *ptlsStates;
-#ifdef JULIA_ENABLE_THREADING
     Value *signalPage;
-#endif
 
     llvm::DIBuilder *dbuilder;
     bool debug_enabled;
@@ -3431,12 +3430,14 @@ static void allocate_gc_frame(BasicBlock *b0, jl_codectx_t *ctx)
 {
     // allocate a placeholder gc instruction
     ctx->ptlsStates = builder.CreateCall(prepare_call(jltls_states_func));
-#ifdef JULIA_ENABLE_THREADING
     if (imaging_mode) {
         ctx->signalPage =
             tbaa_decorate(tbaa_const, builder.CreateLoad(prepare_global(jl_gc_signal_page_ptr)));
     }
-#endif
+    else {
+        ctx->signalPage = builder.CreateIntToPtr(
+            ConstantInt::get(T_size, (uintptr_t)jl_gc_signal_page), T_pint8);
+    }
 }
 
 void jl_codegen_finalize_temp_arg(CallInst *ptlsStates, Type *T_pjlvalue,
@@ -5167,12 +5168,14 @@ static void init_julia_llvm_env(Module *m)
             jl_emit_sysimg_slot(m, pfunctype, "jl_get_ptls_states.ptr",
                                 (uintptr_t)jl_get_ptls_states_getter(),
                                 jltls_states_func_idx);
+    }
+#endif
+    if (imaging_mode) {
         jl_gc_signal_page_ptr =
             jl_emit_sysimg_slot(m, T_pint8, "jl_gc_signal_page.ptr",
                                 (uintptr_t)jl_gc_signal_page,
                                 jl_gc_signal_page_idx);
     }
-#endif
 
     std::vector<Type*> args1(0);
     args1.push_back(T_pint8);

diff --git a/src/dump.c b/src/dump.c
@@ -231,10 +231,10 @@ static int jl_load_sysimg_so(void)
                                                    "jl_ptls_states_getter_idx");
         *sysimg_gvars[tls_getter_idx - 1] =
             (jl_value_t*)jl_get_ptls_states_getter();
+#endif
         size_t signal_page_idx = *(size_t*)jl_dlsym(jl_sysimg_handle,
                                                     "jl_gc_signal_page_idx");
         *sysimg_gvars[signal_page_idx - 1] = (jl_value_t*)jl_gc_signal_page;
-#endif
         const char *cpu_target = (const char*)jl_dlsym(jl_sysimg_handle, "jl_sysimg_cpu_target");
         if (strcmp(cpu_target,jl_options.cpu_target) != 0)
             jl_error("Julia and the system image were compiled for different architectures.\n"

diff --git a/src/gc.c b/src/gc.c
@@ -358,9 +358,29 @@ NOINLINE static uintptr_t gc_get_stack_ptr(void)
 // `jl_running_gc` to one on entering the GC and set it back afterward.
 static volatile uint64_t jl_gc_running = 0;
 
-#ifdef JULIA_ENABLE_THREADING
 JL_DLLEXPORT volatile size_t *jl_gc_signal_page = NULL;
 
+void jl_gc_signal_init(void)
+{
+    // jl_page_size isn't available yet.
+#ifdef _OS_WINDOWS_
+    jl_gc_signal_page = (size_t*)VirtualAlloc(NULL, jl_getpagesize(),
+                                              MEM_COMMIT, PAGE_READONLY);
+#else
+    jl_gc_signal_page = (size_t*)mmap(0, jl_getpagesize(), PROT_READ,
+                                      MAP_NORESERVE | MAP_PRIVATE |
+                                      MAP_ANONYMOUS, -1, 0);
+    if (jl_gc_signal_page == MAP_FAILED)
+        jl_gc_signal_page = NULL;
+#endif
+    if (jl_gc_signal_page == NULL) {
+        jl_printf(JL_STDERR, "could not allocate GC synchronization page\n");
+        gc_debug_critical_error();
+        abort();
+    }
+}
+
+#ifdef JULIA_ENABLE_THREADING
 static void jl_wait_for_gc(void)
 {
     while (jl_gc_running) {
@@ -386,26 +406,6 @@ static void jl_gc_wait_for_the_world(void)
     }
 }
 
-void jl_gc_signal_init(void)
-{
-    // jl_page_size isn't available yet.
-#ifdef _OS_WINDOWS_
-    jl_gc_signal_page = (size_t*)VirtualAlloc(NULL, jl_getpagesize(),
-                                              MEM_COMMIT, PAGE_READONLY);
-#else
-    jl_gc_signal_page = (size_t*)mmap(0, jl_getpagesize(), PROT_READ,
-                                      MAP_NORESERVE | MAP_PRIVATE |
-                                      MAP_ANONYMOUS, -1, 0);
-    if (jl_gc_signal_page == MAP_FAILED)
-        jl_gc_signal_page = NULL;
-#endif
-    if (jl_gc_signal_page == NULL) {
-        jl_printf(JL_STDERR, "could not allocate GC synchronization page\n");
-        gc_debug_critical_error();
-        abort();
-    }
-}
-
 static void jl_gc_signal_begin(void)
 {
 #ifdef __APPLE__

diff --git a/src/init.c b/src/init.c
@@ -533,8 +533,8 @@ void _julia_init(JL_IMAGE_SEARCH rel)
 #ifdef JULIA_ENABLE_THREADING
     // Make sure we finalize the tls callback before starting any threads.
     jl_get_ptls_states_getter();
-    jl_gc_signal_init();
 #endif
+    jl_gc_signal_init();
     libsupport_init();
     jl_io_loop = uv_default_loop(); // this loop will internal events (spawning process etc.),
                                     // best to call this first, since it also initializes libuv

diff --git a/src/jitlayers.cpp b/src/jitlayers.cpp
@@ -812,7 +812,6 @@ static void* jl_emit_and_add_to_shadow(GlobalVariable *gv, void *gvarinit = NULL
 #endif
 }
 
-#ifdef JULIA_ENABLE_THREADING // only used in the threading build
 // Emit a slot in the system image to be filled at sysimg init time.
 // Returns the global var. Fill `idx` with 1-base index in the sysimg gv.
 // Use as an optimization for runtime constant addresses to have one less
@@ -840,7 +839,6 @@ static GlobalVariable *jl_emit_sysimg_slot(Module *m, Type *typ, const char *nam
     idx = jl_sysimg_gvars.size();
     return gv;
 }
-#endif
 
 static void* jl_get_global(GlobalVariable *gv)
 {
@@ -915,13 +913,13 @@ static void jl_gen_llvm_globaldata(llvm::Module *mod, ValueToValueMapTy &VMap,
                                  GlobalVariable::ExternalLinkage,
                                  ConstantInt::get(T_size, jltls_states_func_idx),
                                  "jl_ptls_states_getter_idx"));
+#endif
     addComdat(new GlobalVariable(*mod,
                                  T_size,
                                  true,
                                  GlobalVariable::ExternalLinkage,
                                  ConstantInt::get(T_size, jl_gc_signal_page_idx),
                                  "jl_gc_signal_page_idx"));
-#endif
 
     Constant *feature_string = ConstantDataArray::getString(jl_LLVMContext, jl_options.cpu_target);
     addComdat(new GlobalVariable(*mod,

diff --git a/src/julia_internal.h b/src/julia_internal.h
@@ -266,9 +266,9 @@ void jl_set_base_ctx(char *__stk);
 void jl_init_threading(void);
 void jl_start_threads(void);
 void jl_shutdown_threading(void);
+void jl_gc_signal_init(void);
 #ifdef JULIA_ENABLE_THREADING
 jl_get_ptls_states_func jl_get_ptls_states_getter(void);
-void jl_gc_signal_init(void);
 void jl_gc_signal_wait(void);
 #endif
 

diff --git a/src/julia_threads.h b/src/julia_threads.h
@@ -285,11 +285,20 @@ JL_DLLEXPORT void (jl_cpu_wake)(void);
 
 // Accessing the tls variables, gc safepoint and gc states
 JL_DLLEXPORT JL_CONST_FUNC jl_tls_states_t *(jl_get_ptls_states)(void);
+JL_DLLEXPORT extern volatile size_t *jl_gc_signal_page;
+// This triggers a SegFault when we are in GC
+// Assign it to a variable to make sure the compiler emit the load
+// and to avoid Clang warning for -Wunused-volatile-lvalue
+#define jl_gc_safepoint() do {                          \
+        jl_signal_fence();                              \
+        size_t safepoint_load = *jl_gc_signal_page;     \
+        jl_signal_fence();                              \
+        (void)safepoint_load;                           \
+    } while (0)
 #ifndef JULIA_ENABLE_THREADING
 extern JL_DLLEXPORT jl_tls_states_t jl_tls_states;
 #define jl_get_ptls_states() (&jl_tls_states)
 #define jl_gc_state() ((int8_t)0)
-#define jl_gc_safepoint() do {} while (0)
 STATIC_INLINE int8_t jl_gc_state_set(int8_t state, int8_t old_state)
 {
     (void)state;
@@ -300,16 +309,6 @@ typedef jl_tls_states_t *(*jl_get_ptls_states_func)(void);
 JL_DLLEXPORT void jl_set_ptls_states_getter(jl_get_ptls_states_func f);
 // Make sure jl_gc_state() is always a rvalue
 #define jl_gc_state() ((int8_t)(jl_get_ptls_states()->gc_state))
-JL_DLLEXPORT extern volatile size_t *jl_gc_signal_page;
-// This triggers a SegFault when we are in GC
-// Assign it to a variable to make sure the compiler emit the load
-// and to avoid Clang warning for -Wunused-volatile-lvalue
-#define jl_gc_safepoint() do {                          \
-        jl_signal_fence();                              \
-        size_t safepoint_load = *jl_gc_signal_page;     \
-        jl_signal_fence();                              \
-        (void)safepoint_load;                           \
-    } while (0)
 STATIC_INLINE int8_t jl_gc_state_set(int8_t state, int8_t old_state)
 {
     jl_get_ptls_states()->gc_state = state;