--- old/src/cpu/x86/vm/x86_64.ad	2016-03-01 15:42:51.578537397 +0300
+++ new/src/cpu/x86/vm/x86_64.ad	2016-03-01 15:42:51.522537694 +0300
@@ -1637,9 +1637,6 @@
 // The ecx parameter to rep stosq for the ClearArray node is in words.
 const bool Matcher::init_array_count_is_in_bytes = false;
 
-// Threshold size for cleararray.
-const int Matcher::init_array_short_size = 8 * BytesPerLong;
-
 // No additional cost for CMOVL.
 const int Matcher::long_cmove_cost() { return 0; }
 
@@ -10460,14 +10457,29 @@
 instruct rep_stos(rcx_RegL cnt, rdi_RegP base, rax_RegI zero, Universe dummy,
                   rFlagsReg cr)
 %{
-  predicate(!UseFastStosb);
+  predicate(!UseFastStosb && !((ClearArrayNode*)n)->is_large());
+  match(Set dummy (ClearArray cnt base));
+  effect(USE_KILL cnt, USE_KILL base, KILL zero, KILL cr);
+
+  format %{ "xorq    rax, rax\t# ClearArray:\n\t"
+            "rep     stosq\t# Store rax to *rdi++ while rcx--" %}
+  ins_encode %{
+    __ clear_mem($base$$Register, $cnt$$Register, $zero$$Register, false);
+  %}
+  ins_pipe(pipe_slow);
+%}
+
+instruct rep_stos_large(rcx_RegL cnt, rdi_RegP base, rax_RegI zero, Universe dummy,
+                  rFlagsReg cr)
+%{
+  predicate(!UseFastStosb && ((ClearArrayNode*)n)->is_large());
   match(Set dummy (ClearArray cnt base));
   effect(USE_KILL cnt, USE_KILL base, KILL zero, KILL cr);
 
   format %{ "xorq    rax, rax\t# ClearArray:\n\t"
             "rep     stosq\t# Store rax to *rdi++ while rcx--" %}
   ins_encode %{
-    __ clear_mem($base$$Register, $cnt$$Register, $zero$$Register);
+    __ clear_mem($base$$Register, $cnt$$Register, $zero$$Register, true);
   %}
   ins_pipe(pipe_slow);
 %}
@@ -10475,14 +10487,29 @@
 instruct rep_fast_stosb(rcx_RegL cnt, rdi_RegP base, rax_RegI zero, Universe dummy,
                         rFlagsReg cr)
 %{
-  predicate(UseFastStosb);
+  predicate(UseFastStosb && !((ClearArrayNode*)n)->is_large());
+  match(Set dummy (ClearArray cnt base));
+  effect(USE_KILL cnt, USE_KILL base, KILL zero, KILL cr);
+  format %{ "xorq    rax, rax\t# ClearArray:\n\t"
+            "shlq    rcx,3\t# Convert doublewords to bytes\n\t"
+            "rep     stosb\t# Store rax to *rdi++ while rcx--" %}
+  ins_encode %{
+    __ clear_mem($base$$Register, $cnt$$Register, $zero$$Register, false);
+  %}
+  ins_pipe( pipe_slow );
+%}
+
+instruct rep_fast_stosb_large(rcx_RegL cnt, rdi_RegP base, rax_RegI zero, Universe dummy,
+                        rFlagsReg cr)
+%{
+  predicate(UseFastStosb && ((ClearArrayNode*)n)->is_large());
   match(Set dummy (ClearArray cnt base));
   effect(USE_KILL cnt, USE_KILL base, KILL zero, KILL cr);
   format %{ "xorq    rax, rax\t# ClearArray:\n\t"
             "shlq    rcx,3\t# Convert doublewords to bytes\n\t"
             "rep     stosb\t# Store rax to *rdi++ while rcx--" %}
   ins_encode %{
-    __ clear_mem($base$$Register, $cnt$$Register, $zero$$Register);
+    __ clear_mem($base$$Register, $cnt$$Register, $zero$$Register, true);
   %}
   ins_pipe( pipe_slow );
 %}