path: root/src/cpu/x86/vm/vm_version_x86.cpp

/*
 * Copyright (c) 1997, 2012, 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.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "assembler_x86.inline.hpp"
#include "memory/resourceArea.hpp"
#include "runtime/java.hpp"
#include "runtime/stubCodeGenerator.hpp"
#include "vm_version_x86.hpp"
#ifdef TARGET_OS_FAMILY_linux
# include "os_linux.inline.hpp"
#endif
#ifdef TARGET_OS_FAMILY_solaris
# include "os_solaris.inline.hpp"
#endif
#ifdef TARGET_OS_FAMILY_windows
# include "os_windows.inline.hpp"
#endif
#ifdef TARGET_OS_FAMILY_bsd
# include "os_bsd.inline.hpp"
#endif


int VM_Version::_cpu;
int VM_Version::_model;
int VM_Version::_stepping;
int VM_Version::_cpuFeatures;
const char*           VM_Version::_features_str = "";
VM_Version::CpuidInfo VM_Version::_cpuid_info   = { 0, };

static BufferBlob* stub_blob;
static const int stub_size = 550;

extern "C" {
  typedef void (*getPsrInfo_stub_t)(void*);
}
static getPsrInfo_stub_t getPsrInfo_stub = NULL;


class VM_Version_StubGenerator: public StubCodeGenerator {
 public:

  VM_Version_StubGenerator(CodeBuffer *c) : StubCodeGenerator(c) {}

  address generate_getPsrInfo() {
    // Flags to test CPU type.
    const uint32_t HS_EFL_AC           = 0x40000;
    const uint32_t HS_EFL_ID           = 0x200000;
    // Values for when we don't have a CPUID instruction.
    const int      CPU_FAMILY_SHIFT = 8;
    const uint32_t CPU_FAMILY_386   = (3 << CPU_FAMILY_SHIFT);
    const uint32_t CPU_FAMILY_486   = (4 << CPU_FAMILY_SHIFT);

    Label detect_486, cpu486, detect_586, std_cpuid1, std_cpuid4;
    Label sef_cpuid, ext_cpuid, ext_cpuid1, ext_cpuid5, ext_cpuid7, done;

    StubCodeMark mark(this, "VM_Version", "getPsrInfo_stub");
#   define __ _masm->

    address start = __ pc();

    //
    // void getPsrInfo(VM_Version::CpuidInfo* cpuid_info);
    //
    // LP64: rcx and rdx are first and second argument registers on windows

    __ push(rbp);
#ifdef _LP64
    __ mov(rbp, c_rarg0); // cpuid_info address
#else
    __ movptr(rbp, Address(rsp, 8)); // cpuid_info address
#endif
    __ push(rbx);
    __ push(rsi);
    __ pushf();          // preserve rbx, and flags
    __ pop(rax);
    __ push(rax);
    __ mov(rcx, rax);
    //
    // if we are unable to change the AC flag, we have a 386
    //
    __ xorl(rax, HS_EFL_AC);
    __ push(rax);
    __ popf();
    __ pushf();
    __ pop(rax);
    __ cmpptr(rax, rcx);
    __ jccb(Assembler::notEqual, detect_486);

    __ movl(rax, CPU_FAMILY_386);
    __ movl(Address(rbp, in_bytes(VM_Version::std_cpuid1_offset())), rax);
    __ jmp(done);

    //
    // If we are unable to change the ID flag, we have a 486 which does
    // not support the "cpuid" instruction.
    //
    __ bind(detect_486);
    __ mov(rax, rcx);
    __ xorl(rax, HS_EFL_ID);
    __ push(rax);
    __ popf();
    __ pushf();
    __ pop(rax);
    __ cmpptr(rcx, rax);
    __ jccb(Assembler::notEqual, detect_586);

    __ bind(cpu486);
    __ movl(rax, CPU_FAMILY_486);
    __ movl(Address(rbp, in_bytes(VM_Version::std_cpuid1_offset())), rax);
    __ jmp(done);

    //
    // At this point, we have a chip which supports the "cpuid" instruction
    //
    __ bind(detect_586);
    __ xorl(rax, rax);
    __ cpuid();
    __ orl(rax, rax);
    __ jcc(Assembler::equal, cpu486);   // if cpuid doesn't support an input
                                        // value of at least 1, we give up and
                                        // assume a 486
    __ lea(rsi, Address(rbp, in_bytes(VM_Version::std_cpuid0_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rbx);
    __ movl(Address(rsi, 8), rcx);
    __ movl(Address(rsi,12), rdx);

    __ cmpl(rax, 0xa);                  // Is cpuid(0xB) supported?
    __ jccb(Assembler::belowEqual, std_cpuid4);

    //
    // cpuid(0xB) Processor Topology
    //
    __ movl(rax, 0xb);
    __ xorl(rcx, rcx);   // Threads level
    __ cpuid();

    __ lea(rsi, Address(rbp, in_bytes(VM_Version::tpl_cpuidB0_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rbx);
    __ movl(Address(rsi, 8), rcx);
    __ movl(Address(rsi,12), rdx);

    __ movl(rax, 0xb);
    __ movl(rcx, 1);     // Cores level
    __ cpuid();
    __ push(rax);
    __ andl(rax, 0x1f);  // Determine if valid topology level
    __ orl(rax, rbx);    // eax[4:0] | ebx[0:15] == 0 indicates invalid level
    __ andl(rax, 0xffff);
    __ pop(rax);
    __ jccb(Assembler::equal, std_cpuid4);

    __ lea(rsi, Address(rbp, in_bytes(VM_Version::tpl_cpuidB1_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rbx);
    __ movl(Address(rsi, 8), rcx);
    __ movl(Address(rsi,12), rdx);

    __ movl(rax, 0xb);
    __ movl(rcx, 2);     // Packages level
    __ cpuid();
    __ push(rax);
    __ andl(rax, 0x1f);  // Determine if valid topology level
    __ orl(rax, rbx);    // eax[4:0] | ebx[0:15] == 0 indicates invalid level
    __ andl(rax, 0xffff);
    __ pop(rax);
    __ jccb(Assembler::equal, std_cpuid4);

    __ lea(rsi, Address(rbp, in_bytes(VM_Version::tpl_cpuidB2_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rbx);
    __ movl(Address(rsi, 8), rcx);
    __ movl(Address(rsi,12), rdx);

    //
    // cpuid(0x4) Deterministic cache params
    //
    __ bind(std_cpuid4);
    __ movl(rax, 4);
    __ cmpl(rax, Address(rbp, in_bytes(VM_Version::std_cpuid0_offset()))); // Is cpuid(0x4) supported?
    __ jccb(Assembler::greater, std_cpuid1);

    __ xorl(rcx, rcx);   // L1 cache
    __ cpuid();
    __ push(rax);
    __ andl(rax, 0x1f);  // Determine if valid cache parameters used
    __ orl(rax, rax);    // eax[4:0] == 0 indicates invalid cache
    __ pop(rax);
    __ jccb(Assembler::equal, std_cpuid1);

    __ lea(rsi, Address(rbp, in_bytes(VM_Version::dcp_cpuid4_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rbx);
    __ movl(Address(rsi, 8), rcx);
    __ movl(Address(rsi,12), rdx);

    //
    // Standard cpuid(0x1)
    //
    __ bind(std_cpuid1);
    __ movl(rax, 1);
    __ cpuid();
    __ lea(rsi, Address(rbp, in_bytes(VM_Version::std_cpuid1_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rbx);
    __ movl(Address(rsi, 8), rcx);
    __ movl(Address(rsi,12), rdx);

    //
    // Check if OS has enabled XGETBV instruction to access XCR0
    // (OSXSAVE feature flag) and CPU supports AVX
    //
    __ andl(rcx, 0x18000000);
    __ cmpl(rcx, 0x18000000);
    __ jccb(Assembler::notEqual, sef_cpuid);

    //
    // XCR0, XFEATURE_ENABLED_MASK register
    //
    __ xorl(rcx, rcx);   // zero for XCR0 register
    __ xgetbv();
    __ lea(rsi, Address(rbp, in_bytes(VM_Version::xem_xcr0_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rdx);

    //
    // cpuid(0x7) Structured Extended Features
    //
    __ bind(sef_cpuid);
    __ movl(rax, 7);
    __ cmpl(rax, Address(rbp, in_bytes(VM_Version::std_cpuid0_offset()))); // Is cpuid(0x7) supported?
    __ jccb(Assembler::greater, ext_cpuid);

    __ xorl(rcx, rcx);
    __ cpuid();
    __ lea(rsi, Address(rbp, in_bytes(VM_Version::sef_cpuid7_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rbx);

    //
    // Extended cpuid(0x80000000)
    //
    __ bind(ext_cpuid);
    __ movl(rax, 0x80000000);
    __ cpuid();
    __ cmpl(rax, 0x80000000);     // Is cpuid(0x80000001) supported?
    __ jcc(Assembler::belowEqual, done);
    __ cmpl(rax, 0x80000004);     // Is cpuid(0x80000005) supported?
    __ jccb(Assembler::belowEqual, ext_cpuid1);
    __ cmpl(rax, 0x80000006);     // Is cpuid(0x80000007) supported?
    __ jccb(Assembler::belowEqual, ext_cpuid5);
    __ cmpl(rax, 0x80000007);     // Is cpuid(0x80000008) supported?
    __ jccb(Assembler::belowEqual, ext_cpuid7);
    //
    // Extended cpuid(0x80000008)
    //
    __ movl(rax, 0x80000008);
    __ cpuid();
    __ lea(rsi, Address(rbp, in_bytes(VM_Version::ext_cpuid8_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rbx);
    __ movl(Address(rsi, 8), rcx);
    __ movl(Address(rsi,12), rdx);

    //
    // Extended cpuid(0x80000007)
    //
    __ bind(ext_cpuid7);
    __ movl(rax, 0x80000007);
    __ cpuid();
    __ lea(rsi, Address(rbp, in_bytes(VM_Version::ext_cpuid7_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rbx);
    __ movl(Address(rsi, 8), rcx);
    __ movl(Address(rsi,12), rdx);

    //
    // Extended cpuid(0x80000005)
    //
    __ bind(ext_cpuid5);
    __ movl(rax, 0x80000005);
    __ cpuid();
    __ lea(rsi, Address(rbp, in_bytes(VM_Version::ext_cpuid5_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rbx);
    __ movl(Address(rsi, 8), rcx);
    __ movl(Address(rsi,12), rdx);

    //
    // Extended cpuid(0x80000001)
    //
    __ bind(ext_cpuid1);
    __ movl(rax, 0x80000001);
    __ cpuid();
    __ lea(rsi, Address(rbp, in_bytes(VM_Version::ext_cpuid1_offset())));
    __ movl(Address(rsi, 0), rax);
    __ movl(Address(rsi, 4), rbx);
    __ movl(Address(rsi, 8), rcx);
    __ movl(Address(rsi,12), rdx);

    //
    // return
    //
    __ bind(done);
    __ popf();
    __ pop(rsi);
    __ pop(rbx);
    __ pop(rbp);
    __ ret(0);

#   undef __

    return start;
  };
};


void VM_Version::get_processor_features() {

  _cpu = 4; // 486 by default
  _model = 0;
  _stepping = 0;
  _cpuFeatures = 0;
  _logical_processors_per_package = 1;

  if (!Use486InstrsOnly) {
    // Get raw processor info
    getPsrInfo_stub(&_cpuid_info);
    assert_is_initialized();
    _cpu = extended_cpu_family();
    _model = extended_cpu_model();
    _stepping = cpu_stepping();

    if (cpu_family() > 4) { // it supports CPUID
      _cpuFeatures = feature_flags();
      // Logical processors are only available on P4s and above,
      // and only if hyperthreading is available.
      _logical_processors_per_package = logical_processor_count();
    }
  }

  _supports_cx8 = supports_cmpxchg8();

#ifdef _LP64
  // OS should support SSE for x64 and hardware should support at least SSE2.
  if (!VM_Version::supports_sse2()) {
    vm_exit_during_initialization("Unknown x64 processor: SSE2 not supported");
  }
  // in 64 bit the use of SSE2 is the minimum
  if (UseSSE < 2) UseSSE = 2;
#endif

#ifdef AMD64
  // flush_icache_stub have to be generated first.
  // That is why Icache line size is hard coded in ICache class,
  // see icache_x86.hpp. It is also the reason why we can't use
  // clflush instruction in 32-bit VM since it could be running
  // on CPU which does not support it.
  //
  // The only thing we can do is to verify that flushed
  // ICache::line_size has correct value.
  guarantee(_cpuid_info.std_cpuid1_edx.bits.clflush != 0, "clflush is not supported");
  // clflush_size is size in quadwords (8 bytes).
  guarantee(_cpuid_info.std_cpuid1_ebx.bits.clflush_size == 8, "such clflush size is not supported");
#endif

  // If the OS doesn't support SSE, we can't use this feature even if the HW does
  if (!os::supports_sse())
    _cpuFeatures &= ~(CPU_SSE|CPU_SSE2|CPU_SSE3|CPU_SSSE3|CPU_SSE4A|CPU_SSE4_1|CPU_SSE4_2);

  if (UseSSE < 4) {
    _cpuFeatures &= ~CPU_SSE4_1;
    _cpuFeatures &= ~CPU_SSE4_2;
  }

  if (UseSSE < 3) {
    _cpuFeatures &= ~CPU_SSE3;
    _cpuFeatures &= ~CPU_SSSE3;
    _cpuFeatures &= ~CPU_SSE4A;
  }

  if (UseSSE < 2)
    _cpuFeatures &= ~CPU_SSE2;

  if (UseSSE < 1)
    _cpuFeatures &= ~CPU_SSE;

  if (UseAVX < 2)
    _cpuFeatures &= ~CPU_AVX2;

  if (UseAVX < 1)
    _cpuFeatures &= ~CPU_AVX;

  if (logical_processors_per_package() == 1) {
    // HT processor could be installed on a system which doesn't support HT.
    _cpuFeatures &= ~CPU_HT;
  }

  char buf[256];
  jio_snprintf(buf, sizeof(buf), "(%u cores per cpu, %u threads per core) family %d model %d stepping %d%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
               cores_per_cpu(), threads_per_core(),
               cpu_family(), _model, _stepping,
               (supports_cmov() ? ", cmov" : ""),
               (supports_cmpxchg8() ? ", cx8" : ""),
               (supports_fxsr() ? ", fxsr" : ""),
               (supports_mmx()  ? ", mmx"  : ""),
               (supports_sse()  ? ", sse"  : ""),
               (supports_sse2() ? ", sse2" : ""),
               (supports_sse3() ? ", sse3" : ""),
               (supports_ssse3()? ", ssse3": ""),
               (supports_sse4_1() ? ", sse4.1" : ""),
               (supports_sse4_2() ? ", sse4.2" : ""),
               (supports_popcnt() ? ", popcnt" : ""),
               (supports_avx()    ? ", avx" : ""),
               (supports_avx2()   ? ", avx2" : ""),
               (supports_mmx_ext() ? ", mmxext" : ""),
               (supports_3dnow_prefetch() ? ", 3dnowpref" : ""),
               (supports_lzcnt()   ? ", lzcnt": ""),
               (supports_sse4a()   ? ", sse4a": ""),
               (supports_ht() ? ", ht": ""),
               (supports_tsc() ? ", tsc": ""),
               (supports_tscinv_bit() ? ", tscinvbit": ""),
               (supports_tscinv() ? ", tscinv": ""));
  _features_str = strdup(buf);

  // UseSSE is set to the smaller of what hardware supports and what
  // the command line requires.  I.e., you cannot set UseSSE to 2 on
  // older Pentiums which do not support it.
  if (UseSSE > 4) UseSSE=4;
  if (UseSSE < 0) UseSSE=0;
  if (!supports_sse4_1()) // Drop to 3 if no SSE4 support
    UseSSE = MIN2((intx)3,UseSSE);
  if (!supports_sse3()) // Drop to 2 if no SSE3 support
    UseSSE = MIN2((intx)2,UseSSE);
  if (!supports_sse2()) // Drop to 1 if no SSE2 support
    UseSSE = MIN2((intx)1,UseSSE);
  if (!supports_sse ()) // Drop to 0 if no SSE  support
    UseSSE = 0;

  if (UseAVX > 2) UseAVX=2;
  if (UseAVX < 0) UseAVX=0;
  if (!supports_avx2()) // Drop to 1 if no AVX2 support
    UseAVX = MIN2((intx)1,UseAVX);
  if (!supports_avx ()) // Drop to 0 if no AVX  support
    UseAVX = 0;

#ifdef COMPILER2
  if (UseFPUForSpilling) {
    if (UseSSE < 2) {
      // Only supported with SSE2+
      FLAG_SET_DEFAULT(UseFPUForSpilling, false);
    }
  }
  if (MaxVectorSize > 0) {
    if (!is_power_of_2(MaxVectorSize)) {
      warning("MaxVectorSize must be a power of 2");
      FLAG_SET_DEFAULT(MaxVectorSize, 32);
    }
    if (MaxVectorSize > 32) {
      FLAG_SET_DEFAULT(MaxVectorSize, 32);
    }
    if (MaxVectorSize > 16 && UseAVX == 0) {
      // Only supported with AVX+
      FLAG_SET_DEFAULT(MaxVectorSize, 16);
    }
    if (UseSSE < 2) {
      // Only supported with SSE2+
      FLAG_SET_DEFAULT(MaxVectorSize, 0);
    }
  }
#endif

  // On new cpus instructions which update whole XMM register should be used
  // to prevent partial register stall due to dependencies on high half.
  //
  // UseXmmLoadAndClearUpper == true  --> movsd(xmm, mem)
  // UseXmmLoadAndClearUpper == false --> movlpd(xmm, mem)
  // UseXmmRegToRegMoveAll == true  --> movaps(xmm, xmm), movapd(xmm, xmm).
  // UseXmmRegToRegMoveAll == false --> movss(xmm, xmm),  movsd(xmm, xmm).

  if( is_amd() ) { // AMD cpus specific settings
    if( supports_sse2() && FLAG_IS_DEFAULT(UseAddressNop) ) {
      // Use it on new AMD cpus starting from Opteron.
      UseAddressNop = true;
    }
    if( supports_sse2() && FLAG_IS_DEFAULT(UseNewLongLShift) ) {
      // Use it on new AMD cpus starting from Opteron.
      UseNewLongLShift = true;
    }
    if( FLAG_IS_DEFAULT(UseXmmLoadAndClearUpper) ) {
      if( supports_sse4a() ) {
        UseXmmLoadAndClearUpper = true; // use movsd only on '10h' Opteron
      } else {
        UseXmmLoadAndClearUpper = false;
      }
    }
    if( FLAG_IS_DEFAULT(UseXmmRegToRegMoveAll) ) {
      if( supports_sse4a() ) {
        UseXmmRegToRegMoveAll = true; // use movaps, movapd only on '10h'
      } else {
        UseXmmRegToRegMoveAll = false;
      }
    }
    if( FLAG_IS_DEFAULT(UseXmmI2F) ) {
      if( supports_sse4a() ) {
        UseXmmI2F = true;
      } else {
        UseXmmI2F = false;
      }
    }
    if( FLAG_IS_DEFAULT(UseXmmI2D) ) {
      if( supports_sse4a() ) {
        UseXmmI2D = true;
      } else {
        UseXmmI2D = false;
      }
    }
    if( FLAG_IS_DEFAULT(UseSSE42Intrinsics) ) {
      if( supports_sse4_2() && UseSSE >= 4 ) {
        UseSSE42Intrinsics = true;
      }
    }

    // Use count leading zeros count instruction if available.
    if (supports_lzcnt()) {
      if (FLAG_IS_DEFAULT(UseCountLeadingZerosInstruction)) {
        UseCountLeadingZerosInstruction = true;
      }
    }

    // some defaults for AMD family 15h
    if ( cpu_family() == 0x15 ) {
      // On family 15h processors default is no sw prefetch
      if (FLAG_IS_DEFAULT(AllocatePrefetchStyle)) {
        AllocatePrefetchStyle = 0;
      }
      // Also, if some other prefetch style is specified, default instruction type is PREFETCHW
      if (FLAG_IS_DEFAULT(AllocatePrefetchInstr)) {
        AllocatePrefetchInstr = 3;
      }
      // On family 15h processors use XMM and UnalignedLoadStores for Array Copy
      if( supports_sse2() && FLAG_IS_DEFAULT(UseXMMForArrayCopy) ) {
        UseXMMForArrayCopy = true;
      }
      if( FLAG_IS_DEFAULT(UseUnalignedLoadStores) && UseXMMForArrayCopy ) {
        UseUnalignedLoadStores = true;
      }
    }

#ifdef COMPILER2
    if (MaxVectorSize > 16) {
      // Limit vectors size to 16 bytes on current AMD cpus.
      FLAG_SET_DEFAULT(MaxVectorSize, 16);
    }
#endif // COMPILER2
  }

  if( is_intel() ) { // Intel cpus specific settings
    if( FLAG_IS_DEFAULT(UseStoreImmI16) ) {
      UseStoreImmI16 = false; // don't use it on Intel cpus
    }
    if( cpu_family() == 6 || cpu_family() == 15 ) {
      if( FLAG_IS_DEFAULT(UseAddressNop) ) {
        // Use it on all Intel cpus starting from PentiumPro
        UseAddressNop = true;
      }
    }
    if( FLAG_IS_DEFAULT(UseXmmLoadAndClearUpper) ) {
      UseXmmLoadAndClearUpper = true; // use movsd on all Intel cpus
    }
    if( FLAG_IS_DEFAULT(UseXmmRegToRegMoveAll) ) {
      if( supports_sse3() ) {
        UseXmmRegToRegMoveAll = true; // use movaps, movapd on new Intel cpus
      } else {
        UseXmmRegToRegMoveAll = false;
      }
    }
    if( cpu_family() == 6 && supports_sse3() ) { // New Intel cpus
#ifdef COMPILER2
      if( FLAG_IS_DEFAULT(MaxLoopPad) ) {
        // For new Intel cpus do the next optimization:
        // don't align the beginning of a loop if there are enough instructions
        // left (NumberOfLoopInstrToAlign defined in c2_globals.hpp)
        // in current fetch line (OptoLoopAlignment) or the padding
        // is big (> MaxLoopPad).
        // Set MaxLoopPad to 11 for new Intel cpus to reduce number of
        // generated NOP instructions. 11 is the largest size of one
        // address NOP instruction '0F 1F' (see Assembler::nop(i)).
        MaxLoopPad = 11;
      }
#endif // COMPILER2
      if( FLAG_IS_DEFAULT(UseXMMForArrayCopy) ) {
        UseXMMForArrayCopy = true; // use SSE2 movq on new Intel cpus
      }
      if( supports_sse4_2() && supports_ht() ) { // Newest Intel cpus
        if( FLAG_IS_DEFAULT(UseUnalignedLoadStores) && UseXMMForArrayCopy ) {
          UseUnalignedLoadStores = true; // use movdqu on newest Intel cpus
        }
      }
      if( supports_sse4_2() && UseSSE >= 4 ) {
        if( FLAG_IS_DEFAULT(UseSSE42Intrinsics)) {
          UseSSE42Intrinsics = true;
        }
      }
    }
  }

  // Use population count instruction if available.
  if (supports_popcnt()) {
    if (FLAG_IS_DEFAULT(UsePopCountInstruction)) {
      UsePopCountInstruction = true;
    }
  } else if (UsePopCountInstruction) {
    warning("POPCNT instruction is not available on this CPU");
    FLAG_SET_DEFAULT(UsePopCountInstruction, false);
  }

  assert(0 <= ReadPrefetchInstr && ReadPrefetchInstr <= 3, "invalid value");
  assert(0 <= AllocatePrefetchInstr && AllocatePrefetchInstr <= 3, "invalid value");

  // set valid Prefetch instruction
  if( ReadPrefetchInstr < 0 ) ReadPrefetchInstr = 0;
  if( ReadPrefetchInstr > 3 ) ReadPrefetchInstr = 3;
  if( ReadPrefetchInstr == 3 && !supports_3dnow_prefetch() ) ReadPrefetchInstr = 0;
  if( !supports_sse() && supports_3dnow_prefetch() ) ReadPrefetchInstr = 3;

  if( AllocatePrefetchInstr < 0 ) AllocatePrefetchInstr = 0;
  if( AllocatePrefetchInstr > 3 ) AllocatePrefetchInstr = 3;
  if( AllocatePrefetchInstr == 3 && !supports_3dnow_prefetch() ) AllocatePrefetchInstr=0;
  if( !supports_sse() && supports_3dnow_prefetch() ) AllocatePrefetchInstr = 3;

  // Allocation prefetch settings
  intx cache_line_size = prefetch_data_size();
  if( cache_line_size > AllocatePrefetchStepSize )
    AllocatePrefetchStepSize = cache_line_size;

  assert(AllocatePrefetchLines > 0, "invalid value");
  if( AllocatePrefetchLines < 1 )     // set valid value in product VM
    AllocatePrefetchLines = 3;
  assert(AllocateInstancePrefetchLines > 0, "invalid value");
  if( AllocateInstancePrefetchLines < 1 ) // set valid value in product VM
    AllocateInstancePrefetchLines = 1;

  AllocatePrefetchDistance = allocate_prefetch_distance();
  AllocatePrefetchStyle    = allocate_prefetch_style();

  if( is_intel() && cpu_family() == 6 && supports_sse3() ) {
    if( AllocatePrefetchStyle == 2 ) { // watermark prefetching on Core
#ifdef _LP64
      AllocatePrefetchDistance = 384;
#else
      AllocatePrefetchDistance = 320;
#endif
    }
    if( supports_sse4_2() && supports_ht() ) { // Nehalem based cpus
      AllocatePrefetchDistance = 192;
      AllocatePrefetchLines = 4;
#ifdef COMPILER2
      if (AggressiveOpts && FLAG_IS_DEFAULT(UseFPUForSpilling)) {
        FLAG_SET_DEFAULT(UseFPUForSpilling, true);
      }
#endif
    }
  }
  assert(AllocatePrefetchDistance % AllocatePrefetchStepSize == 0, "invalid value");

#ifdef _LP64
  // Prefetch settings
  PrefetchCopyIntervalInBytes = prefetch_copy_interval_in_bytes();
  PrefetchScanIntervalInBytes = prefetch_scan_interval_in_bytes();
  PrefetchFieldsAhead         = prefetch_fields_ahead();
#endif

#ifndef PRODUCT
  if (PrintMiscellaneous && Verbose) {
    tty->print_cr("Logical CPUs per core: %u",
                  logical_processors_per_package());
    tty->print("UseSSE=%d",UseSSE);
    if (UseAVX > 0) {
      tty->print("  UseAVX=%d",UseAVX);
    }
    tty->cr();
    tty->print("Allocation");
    if (AllocatePrefetchStyle <= 0 || UseSSE == 0 && !supports_3dnow_prefetch()) {
      tty->print_cr(": no prefetching");
    } else {
      tty->print(" prefetching: ");
      if (UseSSE == 0 && supports_3dnow_prefetch()) {
        tty->print("PREFETCHW");
      } else if (UseSSE >= 1) {
        if (AllocatePrefetchInstr == 0) {
          tty->print("PREFETCHNTA");
        } else if (AllocatePrefetchInstr == 1) {
          tty->print("PREFETCHT0");
        } else if (AllocatePrefetchInstr == 2) {
          tty->print("PREFETCHT2");
        } else if (AllocatePrefetchInstr == 3) {
          tty->print("PREFETCHW");
        }
      }
      if (AllocatePrefetchLines > 1) {
        tty->print_cr(" at distance %d, %d lines of %d bytes", AllocatePrefetchDistance, AllocatePrefetchLines, AllocatePrefetchStepSize);
      } else {
        tty->print_cr(" at distance %d, one line of %d bytes", AllocatePrefetchDistance, AllocatePrefetchStepSize);
      }
    }

    if (PrefetchCopyIntervalInBytes > 0) {
      tty->print_cr("PrefetchCopyIntervalInBytes %d", PrefetchCopyIntervalInBytes);
    }
    if (PrefetchScanIntervalInBytes > 0) {
      tty->print_cr("PrefetchScanIntervalInBytes %d", PrefetchScanIntervalInBytes);
    }
    if (PrefetchFieldsAhead > 0) {
      tty->print_cr("PrefetchFieldsAhead %d", PrefetchFieldsAhead);
    }
  }
#endif // !PRODUCT
}

void VM_Version::initialize() {
  ResourceMark rm;
  // Making this stub must be FIRST use of assembler

  stub_blob = BufferBlob::create("getPsrInfo_stub", stub_size);
  if (stub_blob == NULL) {
    vm_exit_during_initialization("Unable to allocate getPsrInfo_stub");
  }
  CodeBuffer c(stub_blob);
  VM_Version_StubGenerator g(&c);
  getPsrInfo_stub = CAST_TO_FN_PTR(getPsrInfo_stub_t,
                                   g.generate_getPsrInfo());

  get_processor_features();
}