* gc.c (set_stack_end): new function to obtain stack end address.

  set_stack_end obtains a stack end address by an address of local
  variable in the function.
  (SET_STACK_END, STACK_END): use set_stack_end.  don't use alloca.
  This makes the conservative garbage collector to scan a stack frame
  of the garbage_collect function itself.  This is required because
  callee-save registers may be stored in the frame.
  [ruby-dev:25158]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@7545 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 11 insertions, 10 deletions

diff --git a/gc.c b/gc.c
index 98ff2af246..6489c218a0 100644
--- a/gc.c
+++ b/gc.c
@@ -430,17 +430,18 @@ static unsigned int STACK_LEVEL_MAX = 655300;
 # define STACK_LEVEL_MAX 655300
 #endif
 
-#ifdef C_ALLOCA
-# define SET_STACK_END VALUE stack_end; alloca(0);
-# define STACK_END (&stack_end)
-#else
-# if defined(__GNUC__) && defined(USE_BUILTIN_FRAME_ADDRESS) && !defined(__ia64__)
-#  define  SET_STACK_END    VALUE *stack_end = __builtin_frame_address(0)
-# else
-#  define  SET_STACK_END    VALUE *stack_end = alloca(1)
-# endif
-# define STACK_END (stack_end)
+#ifdef __GNUC__
+__attribute__ ((noinline)) 
 #endif
+static void
+set_stack_end(VALUE **stack_end_p)
+{
+    VALUE stack_end;
+    *stack_end_p = &stack_end;
+}
+#define SET_STACK_END    VALUE *stack_end; set_stack_end(&stack_end)
+#define STACK_END        (stack_end)
+
 #if defined(sparc) || defined(__sparc__)
 # define STACK_LENGTH  (rb_gc_stack_start - STACK_END + 0x80)
 #elif STACK_GROW_DIRECTION < 0