diff --git a/ChangeLog b/ChangeLog
index 6cd6a2919c..280f16b4c1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+Wed Jun 22 19:47:03 2011  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* cont.c (cont_capture): add volatile.
+	  On clang -O, it is needed to avoid the optimization.
+	  With this and llvm/clang's recent fix, clang 3.0 can
+	  build ruby-trunk with -O option.
+
+	* cont.c (cont_capture): use for-loop.
+
+	* array.c (rb_ary_each): add volatile and use it.
+
+	* vm_insnhelper.c (vm_call_cfunc): ditto.
+
 Wed Jun 22 18:20:46 2011  Hiroshi Nakamura  <nahi@ruby-lang.org>
 
 	* ext/openssl/ossl_ssl.c (ossl_sslctx_session_remove_cb):
diff --git a/array.c b/array.c
index 5fb0c64cb3..82ae7efdb4 100644
--- a/array.c
+++ b/array.c
@@ -1468,9 +1468,10 @@ rb_ary_insert(int argc, VALUE *argv, VALUE ary)
  */
 
 VALUE
-rb_ary_each(VALUE ary)
+rb_ary_each(VALUE array)
 {
     long i;
+    volatile VALUE ary = array;
 
     RETURN_ENUMERATOR(ary, 0, 0);
     for (i=0; i<RARRAY_LEN(ary); i++) {
diff --git a/cont.c b/cont.c
index f5e6698751..cdbe5909c5 100644
--- a/cont.c
+++ b/cont.c
@@ -437,7 +437,7 @@ cont_capture(volatile int *stat)
     cont_save_machine_stack(th, cont);
 
     if (ruby_setjmp(cont->jmpbuf)) {
-	VALUE value;
+	volatile VALUE value;
 
 	value = cont->value;
 	if (cont->argc == -1) rb_exc_raise(value);
@@ -654,9 +654,10 @@ cont_restore_1(rb_context_t *cont)
     }
 #endif
     if (cont->machine_stack_src) {
+	size_t i;
 	FLUSH_REGISTER_WINDOWS;
-	MEMCPY(cont->machine_stack_src, cont->machine_stack,
-	       VALUE, cont->machine_stack_size);
+	for (i = 0; i < cont->machine_stack_size; i++)
+	    cont->machine_stack_src[i] = cont->machine_stack[i];
     }
 
 #ifdef __ia64
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 376c6aa15a..bd03c69395 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -386,11 +386,11 @@ call_cfunc(VALUE (*func)(), VALUE recv,
 }
 
 static inline VALUE
-vm_call_cfunc(rb_thread_t *th, rb_control_frame_t *reg_cfp,
+vm_call_cfunc(rb_thread_t *th, volatile rb_control_frame_t *reg_cfp,
 	      int num, VALUE recv, const rb_block_t *blockptr,
 	      const rb_method_entry_t *me)
 {
-    VALUE val = 0;
+    volatile VALUE val = 0;
     const rb_method_definition_t *def = me->def;
     rb_control_frame_t *cfp;