Fix all address-of-dummy operations by using GC_approx_sp() instead

(previous commit 'd6acbda' has not solved this problem)

* alloc.c (min_bytes_allocd, GC_stopped_mark): Use GC_approx_sp()
instead of "&dummy"; remove 'dummy' local variable.
* dyn_load.c (GC_cond_add_roots): Likewise.
* misc.c (GC_init): Likewise.
* os_dep.c (GC_get_stack_base, GC_get_main_stack_base): Likewise.
* pthread_stop_world.c (GC_suspend_handler_inner,
nacl_pre_syscall_hook, __nacl_suspend_thread_if_needed): Likewise.
* pthread_support.c (GC_thr_init): Likewise.
* ptr_chck.c (GC_on_stack): Likewise.
* win32_threads.c (GC_push_stack_for): Likewise.
* misc.c (GC_clear_stack_inner): Store address of volatile 'dummy'
local array (i.e. 'sp' value) to its first element (and use it in the
comparison of addresses) to prevent any harmful optimizations as C
officially disallows comparisons of pointers to different objects
(e.g., some Mac OS X clang releases might turn a conditional
expression that uses 'dummy' address into a constant); update comment.
* misc.c (GC_call_with_stack_base): Use "&base" instead of "&dummy"
(it is safe to use address of base here); remove dummy variable.
* os_dep.c (currently_updating): Change type from "word" to "int*".
* os_dep.c (async_set_pht_entry_from_index): Remove volatile and casts
for 'update_dummy' local variable.
* tools/setjmp_t.c (main): Define volatile 'sp' local variable, store
its address to it and use it instead of "&dummy"; remove 'dummy' local
variable.

1 files changed, 12 insertions, 11 deletions

diff --git a/ptr_chck.c b/ptr_chck.c
index fd88c162..eb1c4569 100644
--- a/ptr_chck.c
+++ b/ptr_chck.c
@@ -163,17 +163,18 @@ void (GC_CALLBACK *GC_is_visible_print_proc)(void * p) =
 /* Could p be a stack address? */
    STATIC GC_bool GC_on_stack(ptr_t p)
    {
-        volatile int dummy;
-#       ifdef STACK_GROWS_DOWN
-            if ((word)p >= (word)(&dummy) && (word)p < (word)GC_stackbottom) {
-                return(TRUE);
-            }
-#       else
-            if ((word)p <= (word)(&dummy) && (word)p > (word)GC_stackbottom) {
-                return(TRUE);
-            }
-#       endif
-        return(FALSE);
+#    ifdef STACK_GROWS_DOWN
+       if ((word)p >= (word)GC_approx_sp()
+           && (word)p < (word)GC_stackbottom) {
+         return(TRUE);
+       }
+#    else
+       if ((word)p <= (word)GC_approx_sp()
+           && (word)p > (word)GC_stackbottom) {
+         return(TRUE);
+       }
+#    endif
+     return(FALSE);
    }
 #endif