*** old/src/cpu/x86/vm/nativeInst_x86.hpp	Fri Mar 25 19:58:41 2011
--- new/src/cpu/x86/vm/nativeInst_x86.hpp	Fri Mar 25 19:58:41 2011

*** 1,7 ****
--- 1,7 ----
  /*
!  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.

*** 517,527 ****
--- 517,531 ----
  
  // Simple test vs memory
  class NativeTstRegMem: public NativeInstruction {
   public:
    enum Intel_specific_constants {
!     instruction_code_memXregl   = 0x85
!     instruction_rex_prefix_mask = 0xF0,
+     instruction_rex_prefix      = Assembler::REX,
+     instruction_code_memXregl   = 0x85,
+     modrm_mask                  = 0x38, // select reg from the ModRM byte 
+     modrm_reg                   = 0x00  // rax               
    };
  };
  
  inline bool NativeInstruction::is_illegal()      { return (short)int_at(0) == (short)NativeIllegalInstruction::instruction_code; }
  inline bool NativeInstruction::is_call()         { return ubyte_at(0) == NativeCall::instruction_code; }

*** 531,547 ****
--- 535,564 ----
                                                            ubyte_at(0) == 0xEB; /* short jump */ }
  inline bool NativeInstruction::is_cond_jump()    { return (int_at(0) & 0xF0FF) == 0x800F /* long jump */ ||
                                                            (ubyte_at(0) & 0xF0) == 0x70;  /* short jump */ }
  inline bool NativeInstruction::is_safepoint_poll() {
  #ifdef AMD64
!   if ( ubyte_at(0) == NativeTstRegMem::instruction_code_memXregl &&
         ubyte_at(1) == 0x05 ) { // 00 rax 101
!   if (Assembler::is_polling_page_far()) {
+     // two cases, depending on the choice of the base register in the address.
+     if (((ubyte_at(0) & NativeTstRegMem::instruction_rex_prefix_mask) == NativeTstRegMem::instruction_rex_prefix && 
+          ubyte_at(1) == NativeTstRegMem::instruction_code_memXregl &&
+          (ubyte_at(2) & NativeTstRegMem::modrm_mask) == NativeTstRegMem::modrm_reg) || 
+         ubyte_at(0) == NativeTstRegMem::instruction_code_memXregl &&
+         (ubyte_at(1) & NativeTstRegMem::modrm_mask) == NativeTstRegMem::modrm_reg) { 
+       return true;
+     } else {
+       return false;
+     }
+   } else {
+     if (ubyte_at(0) == NativeTstRegMem::instruction_code_memXregl &&
+         ubyte_at(1) == 0x05) { // 00 rax 101
        address fault = addr_at(6) + int_at(2);
        return os::is_poll_address(fault);
      } else {
        return false;
      }
+   }
  #else
    return ( ubyte_at(0) == NativeMovRegMem::instruction_code_mem2reg ||
             ubyte_at(0) == NativeTstRegMem::instruction_code_memXregl ) &&
             (ubyte_at(1)&0xC7) == 0x05 && /* Mod R/M == disp32 */
             (os::is_poll_address((address)int_at(2)));