Implement FindTopOfStack(0) for ARM and AArch64 (Darwin)

(part of commit 9379c66 from Unity-Technologies/bdwgc)

Issue #173 (bdwgc).

* darwin_stop_world.c [!DARWIN_DONT_PARSE_STACK && (ARM32 || AARCH64)]
(GC_FindTopOfStack): Set proper frame value (using asm instruction)
if stack_start is zero (instead of ABORT).

diff --git a/darwin_stop_world.c b/darwin_stop_world.c
index aef58c2..062eb21 100644 (file)
--- a/darwin_stop_world.c
+++ b/darwin_stop_world.c
@@ -64,6 +64,14 @@ GC_INNER ptr_t GC_FindTopOfStack(unsigned long stack_start)
 #     else
         __asm__ __volatile__ ("ld %0,0(r1)" : "=r" (frame));
 #     endif
+#   elif defined(ARM32)
+        volatile ptr_t sp_reg;
+        __asm__ __volatile__ ("mov %0, r7\n" : "=r" (sp_reg));
+        frame = (StackFrame *)sp_reg;
+#   elif defined(AARCH64)
+        volatile ptr_t sp_reg;
+        __asm__ __volatile__ ("mov %0, x29\n" : "=r" (sp_reg));
+        frame = (StackFrame *)sp_reg;
 #   else
       ABORT("GC_FindTopOfStack(0) is not implemented");
 #   endif