tree: 0bbcbfd05aca864a3c4405c387bcd790d3c9b247 [path history] [tgz]
  1. CMakeLists.txt
  3. Makefile
  4. gen/
  6. readme.txt
  7. sample/
  8. test/
  9. xbyak.sln
  10. xbyak/

Xbyak 5.431 ; JIT assembler for x86(IA32), x64(AMD64, x86-64) by C++


This is a header file which enables dynamically to assemble x86(IA32), x64(AMD64, x86-64) mnemonic.


header file only you can use Xbyak's functions at once if xbyak.h is included.

Supported Instructions Sets


Supported OS

  • Windows Xp, Vista, Windows 7(32bit, 64bit)
  • Linux(32bit, 64bit)
  • Intel Mac OSX

Supported Compilers

  • Visual Studio C++ VC2012 or later
  • gcc 4.7 or later
  • clang 3.3
  • cygwin gcc 4.5.3
  • icc 7.2

Note: Xbyak uses and(), or(), xor(), not() functions, so “-fno-operator-names” option is required on gcc. Or define XBYAK_NO_OP_NAMES and use and_(), or_(), xor_(), not_() instead of them. and_(), or_(), xor_(), not_() are always available.


The following files are necessary. Please add the path to your compile directories.

  • xbyak.h
  • xbyak_mnemonic.h


make install

These files are copied into /usr/local/include/xbyak

New Feature

Add support for AVX-512 instruction set.


Make Xbyak::CodeGenerator and make the class method and get the function pointer by calling cgetCode() and casting the return value.

NASM              Xbyak
mov eax, ebx  --> mov(eax, ebx);
inc ecx           inc(ecx);
ret           --> ret();


(ptr|dword|word|byte) [base + index * (1|2|4|8) + displacement]
                      [rip + 32bit disp] ; x64 only

NASM                   Xbyak
mov eax, [ebx+ecx] --> mov (eax, ptr[ebx+ecx]);
test byte [esp], 4 --> test (byte [esp], 4);

How to use Selector(Segment Register)

Note: Segment class is not derived from Operand.

mov eax, [fs:eax] --> putSeg(fs); mov(eax, ptr [eax]);
mov ax, cs        --> mov(ax, cs);

you can use ptr for almost memory access unless you specify the size of memory.

dword, word and byte are member variables, then don't use dword as unsigned int, for example.


vaddps(xmm1, xmm2, xmm3); // xmm1 <- xmm2 + xmm3
vaddps(xmm2, xmm3, ptr [rax]); // use ptr to access memory
vgatherdpd(xmm1, ptr [ebp+123+xmm2*4], xmm3);

Remark The omitted destination syntax as the following ss disabled.

    vaddps(xmm2, xmm3); // xmm2 <- xmm2 + xmm3

define XBYAK_ENABLE_OMITTED_OPERAND if you use it for backward compatibility. But the newer version will not support it.


vaddpd zmm2, zmm5, zmm30                --> vaddpd(zmm2, zmm5, zmm30);
vaddpd xmm30, xmm20, [rax]              --> vaddpd(xmm30, xmm20, ptr [rax]);
vaddps xmm30, xmm20, [rax]              --> vaddps(xmm30, xmm20, ptr [rax]);
vaddpd zmm2{k5}, zmm4, zmm2             --> vaddpd(zmm2 | k5, zmm4, zmm2);
vaddpd zmm2{k5}{z}, zmm4, zmm2          --> vaddpd(zmm2 | k5 | T_z, zmm4, zmm2);
vaddpd zmm2{k5}{z}, zmm4, zmm2,{rd-sae} --> vaddpd(zmm2 | k5 | T_z, zmm4, zmm2 | T_rd_sae);
                                            vaddpd(zmm2 | k5 | T_z | T_rd_sae, zmm4, zmm2); // the position of `|` is arbitrary.
vcmppd k4{k3}, zmm1, zmm2, {sae}, 5     --> vcmppd(k4 | k3, zmm1, zmm2 | T_sae, 5);

vaddpd xmm1, xmm2, [rax+256]            --> vaddpd(xmm1, xmm2, ptr [rax+256]);
vaddpd xmm1, xmm2, [rax+256]{1to2}      --> vaddpd(xmm1, xmm2, ptr_b [rax+256]);
vaddpd ymm1, ymm2, [rax+256]{1to4}      --> vaddpd(ymm1, ymm2, ptr_b [rax+256]);
vaddpd zmm1, zmm2, [rax+256]{1to8}      --> vaddpd(zmm1, zmm2, ptr_b [rax+256]);
vaddps zmm1, zmm2, [rax+rcx*8+8]{1to16} --> vaddps(zmm1, zmm2, ptr_b [rax+rcx*8+8]);
vmovsd [rax]{k1}, xmm4                  --> vmovsd(ptr [rax] | k1, xmm4);

vcvtpd2dq xmm16, oword [eax+33]         --> vcvtpd2dq(xmm16, xword [eax+33]); // use xword for m128 instead of oword
                                            vcvtpd2dq(xmm16, ptr [eax+33]); // default xword
vcvtpd2dq xmm21, [eax+32]{1to2}         --> vcvtpd2dq(xmm21, ptr_b [eax+32]);
vcvtpd2dq xmm0, yword [eax+33]          --> vcvtpd2dq(xmm0, yword [eax+33]); // use yword for m256
vcvtpd2dq xmm19, [eax+32]{1to4}         --> vcvtpd2dq(xmm19, yword_b [eax+32]); // use yword_b to broadcast

vfpclassps k5{k3}, zword [rax+64], 5    --> vfpclassps(k5|k3, zword [rax+64], 5); // specify m512
vfpclasspd k5{k3}, [rax+64]{1to2}, 5    --> vfpclasspd(k5|k3, xword_b [rax+64], 5); // broadcast 64-bit to 128-bit
vfpclassps k5{k3}, [rax+64]{1to4}, 5    --> vfpclassps(k5|k3, xword_b [rax+64], 5); // broadcast 32-bit to 128-bit


  • k1, ..., k7 are new opmask registers.
  • use | T_z, | T_sae, | T_rn_sae, | T_rd_sae, | T_ru_sae, | T_rz_sae instead of ,{z}, ,{sae}, ,{rn-sae}, ,{rd-sae}, ,{ru-sae}, ,{rz-sae} respectively.
  • k4 | k3 is different from k3 | k4.
  • use ptr_b for broadcast {1toX}. X is automatically determined.
  • specify xword/yword/zword(_b) for m128/m256/m512 if necessary.


  jmp ("L1");

  jmp ("L2");
  a few mnemonics(8-bit displacement jmp)

  jmp ("L3", T_NEAR);
  a lot of mnemonics(32-bit displacement jmp)

Call hasUndefinedLabel() to verify your code has no undefined label. you can use a label for immediate value of mov like as mov (eax, “L2”);

1. support @@, @f, @b like MASM

L("@@"); // <A>
  jmp("@b"); // jmp to <A>
  jmp("@f"); // jmp to <B>
L("@@"); // <B>
  jmp("@b"); // jmp to <B>
  mov(eax, "@b");
  jmp(eax); // jmp to <B>

2. localization of label by calling inLocalLabel(), outLocallabel().

labels begining of period between inLocalLabel() and outLocalLabel() are dealed with local label. inLocalLabel() and outLocalLabel() can be nested.

void func1()
  L(".lp"); // <A> ; local label
    jmp(".lp"); // jmpt to <A>
  L("aaa"); // global label

void func2()
  L(".lp"); // <B> ; local label
    jmp(".lp"); // jmp to <B>

Label class

L() and jxx() functions support a new Label class.

  Label label1, label2;

Moreover, assignL(dstLabel, srcLabel) method binds dstLabel with srcLabel.

  Label label1, label2;
  assignL(label2, label1); // label2 <= label1

The above jmp opecode jumps label1.

  • Restriction:
  • srcLabel must be used in L().
  • dstLabel must not be used in L().

Label::getAddress() returns the address specified by the label instance and 0 if not specified.

// not AutoGrow mode
Label  label;
assert(label.getAddress() == 0);
assert(label.getAddress() == getCurr());


Label label;
mov(eax, ptr [rip + label]); // eax = 4

int x;
  mov(eax, ptr[rip + &x]); // throw exception if the difference between &x and current position is larger than 2GiB

Code size

The default max code size is 4096 bytes. Please set it in constructor of CodeGenerator() if you want to use large size.

class Quantize : public Xbyak::CodeGenerator {
    : CodeGenerator(8192)

use user allocated memory

You can make jit code on prepaired memory.

class Sample : public Xbyak::CodeGenerator {
    Sample(void *userPtr, size_t size)
        : Xbyak::CodeGenerator(size, userPtr)

const size_t codeSize = 1024;
uint8 buf[codeSize + 16];

// get 16-byte aligned address
uint8 *p = Xbyak::CodeArray::getAlignedAddress(buf);

// append executable attribute to the memory
Xbyak::CodeArray::protect(p, codeSize, true);

// construct your jit code on the memory
Sample s(p, codeSize);

See sample/test0.cpp


Under AutoGrow mode, Xbyak extends memory automatically if necessary. Call ready() before calling getCode() to calc address of jmp.

    struct Code : Xbyak::CodeGenerator {
        : Xbyak::CodeGenerator(<default memory size>, Xbyak::AutoGrow)
    Code c;
    c.ready(); // Don't forget to call this function

Don't use the address returned by getCurr() before calling ready(). It may be invalid address. RESTRICTION : rip addressing is not supported in AutoGrow


  • XBYAK32 is defined on 32bit.
  • XBYAK64 is defined on 64bit.
  • XBYAK64_WIN is defined on 64bit Windows(VC)
  • XBYAK64_GCC is defined on 64bit gcc, cygwin
  • define XBYAK_NO_OP_NAMES on gcc without -fno-operator-names
  • define XBYAK_ENABLE_OMITTED_OPERAND if you use omitted destination such as vaddps(xmm2, xmm3);(duplicated in the future)
  • define XBYAK_UNDEF_JNL if Bessel function jnl is defined as macro


  • test0.cpp ; tiny sample of Xbyak(x86, x64)
  • quantize.cpp ; JIT optimized quantization by fast division(x86 only)
  • calc.cpp ; assemble and estimate a given polynomial(x86, x64)
  • bf.cpp ; JIT brainfuck(x86, x64)


modified new BSD License

The files under test/cybozu/ are copied from cybozulib(, which is licensed by BSD-3-Clause and are used for only tests. The header files under xbyak/ are independent of cybozulib.


  • 2017/Jul/09 ver 5.431 fix hasRex() (no affect) (thanks to drillsar)
  • 2017/May/14 ver 5.43 fix CodeGenerator::resetSize() (thanks to gibbed)
  • 2017/May/13 ver 5.42 add movs{b,w,d,q}
  • 2017/Jan/26 ver 5.41 add prefetchwt1 and support for scale == 0(thanks to rsdubtso)
  • 2016/Dec/14 ver 5.40 add Label::getAddress() method to get the pointer specified by the label
  • 2016/Dec/09 ver 5.34 fix handling of negative offsets when encoding disp8N(thanks to rsdubtso)
  • 2016/Dec/08 ver 5.33 fix encoding of vpbroadcast{b,w,d,q}, vpinsr{b,w}, vpextr{b,w} for disp8N
  • 2016/Dec/01 ver 5.32 rename __xgetbv() to _xgetbv() to support clang for Visual Studio(thanks to freiro)
  • 2016/Nov/27 ver 5.31 rename AVX512_4VNNI to AVX512_4VNNIW
  • 2016/Nov/27 ver 5.30 add AVX512_4VNNI, AVX512_4FMAPS instructions(thanks to rsdubtso)
  • 2016/Nov/26 ver 5.20 add detection of AVX512_4VNNI and AVX512_4FMAPS(thanks to rsdubtso)
  • 2016/Nov/20 ver 5.11 lost vptest for ymm(thanks to gregory38)
  • 2016/Nov/20 ver 5.10 add addressing [rip+&var]
  • 2016/Sep/29 ver 5.03 fix detection ERR_INVALID_OPMASK_WITH_MEMORY(thanks to PVS-Studio)
  • 2016/Aug/15 ver 5.02 xbyak does not include xbyak_bin2hex.h
  • 2016/Aug/15 ver 5.011 fix detection of version of gcc 5.4
  • 2016/Aug/03 ver 5.01 disable omitted operand
  • 2016/Jun/24 ver 5.00 support avx-512 instruction set
  • 2016/Jun/13 avx-512 add mask instructions
  • 2016/May/05 ver 4.91 add detection of AVX-512 to Xbyak::util::Cpu
  • 2016/Mar/14 ver 4.901 comment to ready() function(thanks to skmp)
  • 2016/Feb/04 ver 4.90 add jcc(const void *addr);
  • 2016/Jan/30 ver 4.89 vpblendvb supports ymm reg(thanks to John Funnell)
  • 2016/Jan/24 ver 4.88 lea, cmov supports 16-bit register(thanks to whyisthisfieldhere)
  • 2015/Oct/05 ver 4.87 support segment selectors
  • 2015/Aug/18 ver 4.86 fix [rip + label] addressing with immediate value(thanks to whyisthisfieldhere)
  • 2015/Aug/10 ver 4.85 Address::operator==() is not correct(thanks to inolen)
  • 2015/Jun/22 ver 4.84 call() support variadic template if available(thanks to randomstuff)
  • 2015/Jun/16 ver 4.83 support movbe(thanks to benvanik)
  • 2015/May/24 ver 4.82 support detection of F16C
  • 2015/Apr/25 ver 4.81 fix the condition to throw exception for setSize(thanks to whyisthisfieldhere)
  • 2015/Apr/22 ver 4.80 rip supports label(thanks to whyisthisfieldhere)
  • 2015/Jar/28 ver 4.71 support adcx, adox, cmpxchg, rdseed, stac
  • 2014/Oct/14 ver 4.70 support MmapAllocator
  • 2014/Jun/13 ver 4.62 disable warning of VC2014
  • 2014/May/30 ver 4.61 support bt, bts, btr, btc
  • 2014/May/28 ver 4.60 support vcvtph2ps, vcvtps2ph
  • 2014/Apr/11 ver 4.52 add detection of rdrand
  • 2014/Mar/25 ver 4.51 remove state information of unreferenced labels
  • 2014/Mar/16 ver 4.50 support new Label
  • 2014/Mar/05 ver 4.40 fix wrong detection of BMI/enhanced rep on VirtualBox
  • 2013/Dec/03 ver 4.30 support Reg::cvt8(), cvt16(), cvt32(), cvt64()
  • 2013/Oct/16 ver 4.21 label support std::string
  • 2013/Jul/30 ver 4.20 [break backward compatibility] split Reg32e class into RegExp(base+index*scale+disp) and Reg32e(means Reg32 or Reg64)
  • 2013/Jul/04 ver 4.10 [break backward compatibility] change the type of Xbyak::Error from enum to a class
  • 2013/Jun/21 ver 4.02 add putL(LABEL) function to put the address of the label
  • 2013/Jun/21 ver 4.01 vpsllw, vpslld, vpsllq, vpsraw, vpsrad, vpsrlw, vpsrld, vpsrlq support (ymm, ymm, xmm). support vpbroadcastb, vpbroadcastw, vpbroadcastd, vpbroadcastq(thanks to Gabest).
  • 2013/May/30 ver 4.00 support AVX2, VEX-encoded GPR-instructions
  • 2013/Mar/27 ver 3.80 support mov(reg, “label”);
  • 2013/Mar/13 ver 3.76 add cqo(), jcxz(), jecxz(), jrcxz()
  • 2013/Jan/15 ver 3.75 add setSize() to modify generated code
  • 2013/Jan/12 ver 3.74 add CodeGenerator::reset() ; add Allocator::useProtect()
  • 2013/Jan/06 ver 3.73 use unordered_map if possible
  • 2012/Dec/04 ver 3.72 eax, ebx, ... are member variables of CodeGenerator(revert), Xbyak::util::eax, ... are static const.
  • 2012/Nov/17 ver 3.71 and_(), or_(), xor_(), not_() are available if XBYAK_NO_OP_NAMES is not defined.
  • 2012/Nov/17 change eax, ebx, ptr and so on in CodeGenerator as static member and alias of them are defined in Xbyak::util.
  • 2012/Nov/09 ver 3.70 XBYAK_NO_OP_NAMES macro is added to use and_() instead of and() (thanks to Mattias)
  • 2012/Nov/01 ver 3.62 add fwait/fnwait/finit/fninit
  • 2012/Nov/01 ver 3.61 add fldcw/fstcw
  • 2012/May/03 ver 3.60 change interface of Allocator
  • 2012/Mar/23 ver 3.51 fix userPtr mode
  • 2012/Mar/19 ver 3.50 support AutoGrow mode
  • 2011/Nov/09 ver 3.05 fix bit property of rip addresing / support movsxd
  • 2011/Aug/15 ver 3.04 fix dealing with imm8 such as add(dword [ebp-8], 0xda); (thanks to lolcat)
  • 2011/Jun/16 ver 3.03 fix __GNUC_PREREQ macro for Mac gcc(thanks to t_teruya)
  • 2011/Apr/28 ver 3.02 do not use xgetbv on Mac gcc
  • 2011/May/24 ver 3.01 fix typo of OSXSAVE
  • 2011/May/23 ver 3.00 add vcmpeqps and so on
  • 2011/Feb/16 ver 2.994 beta add vmovq for 32-bit mode(I forgot it)
  • 2011/Feb/16 ver 2.993 beta remove cvtReg to avoid thread unsafe
  • 2011/Feb/10 ver 2.992 beta support one argument syntax for fadd like nasm
  • 2011/Feb/07 ver 2.991 beta fix pextrw reg, xmm, imm(Thanks to Gabest)
  • 2011/Feb/04 ver 2.99 beta support AVX
  • 2010/Dec/08 ver 2.31 fix ptr [rip + 32bit offset], support rdtscp
  • 2010/Oct/19 ver 2.30 support pclmulqdq, aesdec, aesdeclast, aesenc, aesenclast, aesimc, aeskeygenassist
  • 2010/Jun/07 ver 2.29 fix call()
  • 2010/Jun/17 ver 2.28 move some member functions to public
  • 2010/Jun/01 ver 2.27 support encoding of mov(reg64, imm) like yasm(not nasm)
  • 2010/May/24 ver 2.26 fix sub(rsp, 1000)
  • 2010/Apr/26 ver 2.25 add jc/jnc(I forgot to implement them...)
  • 2010/Apr/16 ver 2.24 change the prototype of rewrite() method
  • 2010/Apr/15 ver 2.23 fix align() and xbyak_util.h for Mac
  • 2010/Feb/16 ver 2.22 fix inLocalLabel()/outLocalLabel()
  • 2009/Dec/09 ver 2.21 support cygwin(gcc 4.3.2)
  • 2009/Nov/28 support a part of FPU
  • 2009/Jun/25 fix mov(qword[rax], imm); (thanks to Martin)
  • 2009/Mar/10 fix redundant REX.W prefix on jmp/call reg64
  • 2009/Feb/24 add movq reg64, mmx/xmm; movq mmx/xmm, reg64
  • 2009/Feb/13 movd(xmm7, dword[eax]) drops 0x66 prefix (thanks to Gabest)
  • 2008/Dec/30 fix call in short relative address(thanks to kato san)
  • 2008/Sep/18 support @@, @f, @b and localization of label(thanks to nobu-q san)
  • 2008/Sep/18 support (ptr[rip + 32bit offset]) (thanks to Dango-Chu san)
  • 2008/Jun/03 fix align(). mov(ptr[eax],1) throws ERR_MEM_SIZE_IS_NOT_SPECIFIED.
  • 2008/Jun/02 support memory interface allocated by user
  • 2008/May/26 fix protect() to avoid invalid setting(thanks to shinichiro_h san)
  • 2008/Apr/30 add cmpxchg16b, cdqe
  • 2008/Apr/29 support x64
  • 2008/Apr/14 code refactoring
  • 2008/Mar/12 add bsr/bsf
  • 2008/Feb/14 fix output of sub eax, 1234 (thanks to Robert)
  • 2007/Nov/5 support lock, xadd, xchg
  • 2007/Nov/2 support SSSE3/SSE4 (thanks to Dango-Chu san)
  • 2007/Feb/4 fix the bug that exception doesn't occur under the condition which the offset of jmp mnemonic without T_NEAR is over 127.
  • 2007/Jan/21 fix the bug to create address like [disp] select smaller representation for mov (eax|ax|al, [disp])
  • 2007/Jan/4 first version