--- a/hotspot/src/cpu/x86/vm/assembler_x86.cpp	Wed Oct 19 00:16:02 2016 +0000
+++ b/hotspot/src/cpu/x86/vm/assembler_x86.cpp	Tue Oct 18 19:08:24 2016 -0700
@@ -2461,6 +2461,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(AVX_128bit, /* rex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ true);
   attributes.set_address_attributes(/* tuple_type */ EVEX_FVM, /* input_size_in_bits */ EVEX_NObit);
+  attributes.reset_is_clear_context();
   simd_prefix(src, xnoreg, dst, VEX_SIMD_F3, VEX_OPCODE_0F, &attributes);
   emit_int8(0x7F);
   emit_operand(src, dst);
@@ -2490,6 +2491,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(AVX_256bit, /* vex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ true);
   attributes.set_address_attributes(/* tuple_type */ EVEX_FVM, /* input_size_in_bits */ EVEX_NObit);
+  attributes.reset_is_clear_context();
   // swap src<->dst for encoding
   assert(src != xnoreg, "sanity");
   vex_prefix(dst, 0, src->encoding(), VEX_SIMD_F3, VEX_OPCODE_0F, &attributes);
@@ -2590,6 +2592,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(vector_len, /* vex_w */ true, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ true);
   attributes.set_address_attributes(/* tuple_type */ EVEX_FVM, /* input_size_in_bits */ EVEX_NObit);
+  attributes.reset_is_clear_context();
   attributes.set_embedded_opmask_register_specifier(mask);
   attributes.set_is_evex_instruction();
   vex_prefix(dst, 0, src->encoding(), VEX_SIMD_F2, VEX_OPCODE_0F, &attributes);
@@ -2623,6 +2626,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(vector_len, /* vex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ true);
   attributes.set_address_attributes(/* tuple_type */ EVEX_FVM, /* input_size_in_bits */ EVEX_NObit);
+  attributes.reset_is_clear_context();
   attributes.set_is_evex_instruction();
   vex_prefix(dst, 0, src->encoding(), VEX_SIMD_F3, VEX_OPCODE_0F, &attributes);
   emit_int8(0x7F);
@@ -2655,6 +2659,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(vector_len, /* vex_w */ true, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ true);
   attributes.set_address_attributes(/* tuple_type */ EVEX_FVM, /* input_size_in_bits */ EVEX_NObit);
+  attributes.reset_is_clear_context();
   attributes.set_is_evex_instruction();
   vex_prefix(dst, 0, src->encoding(), VEX_SIMD_F3, VEX_OPCODE_0F, &attributes);
   emit_int8(0x7F);
@@ -2794,6 +2799,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(AVX_128bit, /* rex_w */ VM_Version::supports_evex(), /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ false);
   attributes.set_address_attributes(/* tuple_type */ EVEX_T1S, /* input_size_in_bits */ EVEX_64bit);
+  attributes.reset_is_clear_context();
   attributes.set_rex_vex_w_reverted();
   simd_prefix(src, xnoreg, dst, VEX_SIMD_F2, VEX_OPCODE_0F, &attributes);
   emit_int8(0x11);
@@ -2823,6 +2829,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(AVX_128bit, /* rex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ false);
   attributes.set_address_attributes(/* tuple_type */ EVEX_T1S, /* input_size_in_bits */ EVEX_32bit);
+  attributes.reset_is_clear_context();
   simd_prefix(src, xnoreg, dst, VEX_SIMD_F3, VEX_OPCODE_0F, &attributes);
   emit_int8(0x11);
   emit_operand(src, dst);
@@ -3362,6 +3369,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(vector_len, /* rex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ false);
   attributes.set_address_attributes(/* tuple_type */ EVEX_FVM, /* input_size_in_bits */ EVEX_NObit);
+  attributes.reset_is_clear_context();
   attributes.set_embedded_opmask_register_specifier(mask);
   attributes.set_is_evex_instruction();
   int dst_enc = kdst->encoding();
@@ -3384,6 +3392,7 @@
   assert(is_vector_masking(), "");
   assert(VM_Version::supports_avx512vlbw(), "");
   InstructionAttr attributes(vector_len, /* rex_w */ true, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ false);
+  attributes.reset_is_clear_context();
   attributes.set_embedded_opmask_register_specifier(mask);
   attributes.set_is_evex_instruction();
   int encode = vex_prefix_and_encode(kdst->encoding(), nds->encoding(), src->encoding(), VEX_SIMD_66, VEX_OPCODE_0F_3A, &attributes);
@@ -3423,6 +3432,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(vector_len, /* vex_w */ false, /* legacy_mode */ false, /* no_reg_mask */ false, /* uses_vl */ false);
   attributes.set_address_attributes(/* tuple_type */ EVEX_FVM, /* input_size_in_bits */ EVEX_NObit);
+  attributes.reset_is_clear_context();
   attributes.set_embedded_opmask_register_specifier(mask);
   attributes.set_is_evex_instruction();
   vex_prefix(src, nds->encoding(), kdst->encoding(), VEX_SIMD_66, VEX_OPCODE_0F, &attributes);
@@ -3493,6 +3503,7 @@
   assert(VM_Version::supports_evex(), "");
   InstructionAttr attributes(vector_len, /* rex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ true);
   attributes.set_is_evex_instruction();
+  attributes.reset_is_clear_context();
   int encode = vex_prefix_and_encode(kdst->encoding(), nds->encoding(), src->encoding(), VEX_SIMD_66, VEX_OPCODE_0F, &attributes);
   emit_int8(0x76);
   emit_int8((unsigned char)(0xC0 | encode));
@@ -3503,6 +3514,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(vector_len, /* rex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ true);
   attributes.set_address_attributes(/* tuple_type */ EVEX_FV, /* input_size_in_bits */ EVEX_32bit);
+  attributes.reset_is_clear_context();
   attributes.set_is_evex_instruction();
   int dst_enc = kdst->encoding();
   vex_prefix(src, nds->encoding(), dst_enc, VEX_SIMD_66, VEX_OPCODE_0F, &attributes);
@@ -3532,6 +3544,7 @@
 void Assembler::evpcmpeqq(KRegister kdst, XMMRegister nds, XMMRegister src, int vector_len) {
   assert(VM_Version::supports_evex(), "");
   InstructionAttr attributes(vector_len, /* rex_w */ true, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ true);
+  attributes.reset_is_clear_context();
   attributes.set_is_evex_instruction();
   int encode = vex_prefix_and_encode(kdst->encoding(), nds->encoding(), src->encoding(), VEX_SIMD_66, VEX_OPCODE_0F_38, &attributes);
   emit_int8(0x29);
@@ -3543,6 +3556,7 @@
   assert(VM_Version::supports_evex(), "");
   InstructionMark im(this);
   InstructionAttr attributes(vector_len, /* rex_w */ true, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ true);
+  attributes.reset_is_clear_context();
   attributes.set_is_evex_instruction();
   attributes.set_address_attributes(/* tuple_type */ EVEX_FV, /* input_size_in_bits */ EVEX_64bit);
   int dst_enc = kdst->encoding();
@@ -3763,6 +3777,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(vector_len, /* rex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ false);
   attributes.set_address_attributes(/* tuple_type */ EVEX_HVM, /* input_size_in_bits */ EVEX_NObit);
+  attributes.reset_is_clear_context();
   attributes.set_embedded_opmask_register_specifier(mask);
   attributes.set_is_evex_instruction();
   vex_prefix(dst, 0, src->encoding(), VEX_SIMD_F3, VEX_OPCODE_0F_38, &attributes);
@@ -6208,6 +6223,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(vector_len, /* vex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ false);
   attributes.set_address_attributes(/* tuple_type */ EVEX_T4, /* input_size_in_bits */ EVEX_32bit);
+  attributes.reset_is_clear_context();
   vex_prefix(dst, 0, src->encoding(), VEX_SIMD_66, VEX_OPCODE_0F_3A, &attributes);
   emit_int8(0x39);
   emit_operand(src, dst);
@@ -6238,6 +6254,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(AVX_512bit, /* vex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ false);
   attributes.set_address_attributes(/* tuple_type */ EVEX_T4, /* input_size_in_bits */ EVEX_32bit);
+  attributes.reset_is_clear_context();
   vex_prefix(dst, 0, src->encoding(), VEX_SIMD_66, VEX_OPCODE_0F_3A, &attributes);
   emit_int8(0x39);
   emit_operand(src, dst);
@@ -6298,6 +6315,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(vector_len, /* vex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ false);
   attributes.set_address_attributes(/* tuple_type */ EVEX_T4, /* input_size_in_bits */ EVEX_32bit);
+  attributes.reset_is_clear_context();
   vex_prefix(dst, 0, src->encoding(), VEX_SIMD_66, VEX_OPCODE_0F_3A, &attributes);
   emit_int8(0x19);
   emit_operand(src, dst);
@@ -6328,6 +6346,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(AVX_512bit, /* vex_w */ false, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ false);
   attributes.set_address_attributes(/* tuple_type */ EVEX_T4, /* input_size_in_bits */ EVEX_32bit);
+  attributes.reset_is_clear_context();
   vex_prefix(dst, 0, src->encoding(), VEX_SIMD_66, VEX_OPCODE_0F_3A, &attributes);
   emit_int8(0x19);
   emit_operand(src, dst);
@@ -6371,6 +6390,7 @@
   InstructionMark im(this);
   InstructionAttr attributes(AVX_512bit, /* vex_w */ true, /* legacy_mode */ false, /* no_mask_reg */ false, /* uses_vl */ false);
   attributes.set_address_attributes(/* tuple_type */ EVEX_T4,/* input_size_in_bits */  EVEX_64bit);
+  attributes.reset_is_clear_context();
   vex_prefix(dst, 0, src->encoding(), VEX_SIMD_66, VEX_OPCODE_0F_3A, &attributes);
   emit_int8(0x1B);
   emit_operand(src, dst);
@@ -7181,7 +7201,9 @@
   // fourth EVEX.L'L for vector length : 0 is 128, 1 is 256, 2 is 512, currently we do not support 1024
   byte4 |= ((_attributes->get_vector_len())& 0x3) << 5;
   // last is EVEX.z for zero/merge actions
-  byte4 |= (_attributes->is_clear_context() ? EVEX_Z : 0);
+  if (_attributes->is_no_reg_mask() == false) {
+    byte4 |= (_attributes->is_clear_context() ? EVEX_Z : 0);
+  }
   emit_int8(byte4);
 }
 

--- a/hotspot/src/cpu/x86/vm/assembler_x86.hpp	Wed Oct 19 00:16:02 2016 +0000
+++ b/hotspot/src/cpu/x86/vm/assembler_x86.hpp	Tue Oct 18 19:08:24 2016 -0700
@@ -2139,7 +2139,7 @@
       _input_size_in_bits(Assembler::EVEX_NObit),
       _is_evex_instruction(false),
       _evex_encoding(0),
-      _is_clear_context(false),
+      _is_clear_context(true),
       _is_extended_context(false),
       _current_assembler(NULL),
       _embedded_opmask_register_specifier(1) { // hard code k1, it will be initialized for now
@@ -2205,7 +2205,7 @@
   void set_evex_encoding(int value) { _evex_encoding = value; }
 
   // Set the Evex.Z field to be used to clear all non directed XMM/YMM/ZMM components
-  void set_is_clear_context(void) { _is_clear_context = true; }
+  void reset_is_clear_context(void) { _is_clear_context = false; }
 
   // Map back to current asembler so that we can manage object level assocation
   void set_current_assembler(Assembler *current_assembler) { _current_assembler = current_assembler; }