GC_stack_range_for iOS 32/64-bit code refactoring (Darwin/arm)

* darwin_stop_world.c (kCFCoreFoundationVersionNumber_iOS_8_0): Move
definition out of GC_stack_range_for.
* darwin_stop_world.c (GC_stack_range_for): Refine comment and abort
message; eliminate code duplication regarding thread_get_state call.

diff --git a/darwin_stop_world.c b/darwin_stop_world.c
index 5754899..b4799d9 100644 (file)
--- a/darwin_stop_world.c
+++ b/darwin_stop_world.c
@@ -122,6 +122,10 @@ GC_API void GC_CALL GC_use_threads_discovery(void)
 # endif
 }
 
+#ifndef kCFCoreFoundationVersionNumber_iOS_8_0
+# define kCFCoreFoundationVersionNumber_iOS_8_0 1140.1
+#endif
+
 /* Evaluates the stack range for a given thread.  Returns the lower     */
 /* bound and sets *phi to the upper one.                                */
 STATIC ptr_t GC_stack_range_for(ptr_t *phi, thread_act_t thread, GC_thread p,
@@ -146,45 +150,41 @@ STATIC ptr_t GC_stack_range_for(ptr_t *phi, thread_act_t thread, GC_thread p,
     /* everywhere.  Hence we use our own version.  Alternatively,   */
     /* we could use THREAD_STATE_MAX (but seems to be not optimal). */
     kern_return_t kern_result;
-    mach_msg_type_number_t thread_state_count = GC_MACH_THREAD_STATE_COUNT;
     GC_THREAD_STATE_T state;
 
 #   if defined(ARM32) && defined(ARM_THREAD_STATE32)
-#     ifndef kCFCoreFoundationVersionNumber_iOS_8_0
-#       define kCFCoreFoundationVersionNumber_iOS_8_0 1140.1
-#     endif
-      /* Use ARM_UNIFIED_THREAD_STATE on iOS7 64-bit and up and iOS8  */
-      /* 32-bit and up. iOS7 was the first iOS with 64-bit support so */
-      /* if we run on a 64-bit CPU we know we're on iOS7 or higher.   */
+      /* Use ARM_UNIFIED_THREAD_STATE on iOS8+ 32-bit targets and on    */
+      /* 64-bit H/W (iOS7+ 32-bit mode).                                */
       size_t size;
       static cpu_type_t cputype = 0;
+
       if (cputype == 0) {
         sysctlbyname("hw.cputype", &cputype, &size, NULL, 0);
       }
-      if (cputype == CPU_TYPE_ARM64 || kCFCoreFoundationVersionNumber >= kCFCoreFoundationVersionNumber_iOS_8_0) {
+      if (cputype == CPU_TYPE_ARM64
+          || kCFCoreFoundationVersionNumber
+             >= kCFCoreFoundationVersionNumber_iOS_8_0) {
         arm_unified_thread_state_t unified_state;
-        mach_msg_type_number_t unified_thread_state_count = ARM_UNIFIED_THREAD_STATE_COUNT;
+        mach_msg_type_number_t unified_thread_state_count
+                                        = ARM_UNIFIED_THREAD_STATE_COUNT;
+
         kern_result = thread_get_state(thread, ARM_UNIFIED_THREAD_STATE,
                                        (natural_t *)&unified_state,
                                        &unified_thread_state_count);
         if (unified_state.ash.flavor != ARM_THREAD_STATE32) {
-          // Sanity check. The flavor in the header should always be ARM_THREAD_STATE32
-          ABORT("unified_state.ash.flavor != ARM_THREAD_STATE32");
+          ABORT("unified_state flavor should be ARM_THREAD_STATE32");
         }
         state = unified_state.ts_32;
-        thread_state_count = unified_state.ash.count;
-      } else {
-        kern_result = thread_get_state(thread, ARM_THREAD_STATE,
-                               (natural_t *)&state,
-                               &thread_state_count);
-      }
-#   else
-
-    /* Get the thread state (registers, etc) */
-    kern_result = thread_get_state(thread, GC_MACH_THREAD_STATE,
-                                   (natural_t *)&state,
-                                   &thread_state_count);
+      } else
 #   endif
+    /* else */ {
+      mach_msg_type_number_t thread_state_count = GC_MACH_THREAD_STATE_COUNT;
+
+      /* Get the thread state (registers, etc) */
+      kern_result = thread_get_state(thread, GC_MACH_THREAD_STATE,
+                                     (natural_t *)&state,
+                                     &thread_state_count);
+    }
 #   ifdef DEBUG_THREADS
       GC_log_printf("thread_get_state returns value = %d\n", kern_result);
 #   endif