D Programming Language
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# Inline Assembler

D, being a systems programming language, provides an inline assembler. The inline assembler is standardized for D implementations across the same CPU family, for example, the Intel Pentium inline assembler for a Win32 D compiler will be syntax compatible with the inline assembler for Linux running on an Intel Pentium.

Implementations of D on different architectures, however, are free to innovate upon the memory model, function call/return conventions, argument passing conventions, etc.

This document describes the x86 and x86_64 implementations of the inline assembler. The inline assembler platform support that a compiler provides is indicated by the D_InlineAsm_X86 and D_InlineAsm_X86_64 version identifiers, respectively.

    AsmInstruction:
        Identifier : AsmInstruction
        align IntegerExpression
        even
        naked
        db Operands
        ds Operands
        di Operands
        dl Operands
        df Operands
        dd Operands
        de Operands
        Opcode
        Opcode Operands

    Operands:
        Operand
        Operand , Operands

## Labels

Assembler instructions can be labeled just like other statements. They can be the target of goto statements. For example:

    void *pc;
    asm
    {
        call L1          ;
      L1:                ;
        pop  EBX         ;
        mov  pc[EBP],EBX ; // pc now points to code at L1
    }

## align IntegerExpression

    IntegerExpression:
        IntegerLiteral
        Identifier

Causes the assembler to emit NOP instructions to align the next assembler instruction on an IntegerExpression boundary. IntegerExpression must evaluate at compile time to an integer that is a power of 2.

Aligning the start of a loop body can sometimes have a dramatic effect on the execution speed.

## even

Causes the assembler to emit NOP instructions to align the next assembler instruction on an even boundary.

## naked

Causes the compiler to not generate the function prolog and epilog sequences. This means such is the responsibility of inline assembly programmer, and is normally used when the entire function is to be written in assembler.

## db, ds, di, dl, df, dd, de

These pseudo ops are for inserting raw data directly into the code. db is for bytes, ds is for 16 bit words, di is for 32 bit words, dl is for 64 bit words, df is for 32 bit floats, dd is for 64 bit doubles, and de is for 80 bit extended reals. Each can have multiple operands. If an operand is a string literal, it is as if there were length operands, where length is the number of characters in the string. One character is used per operand. For example:

    asm
    {
        db 5,6,0x83;   // insert bytes 0x05, 0x06, and 0x83 into code
        ds 0x1234;     // insert bytes 0x34, 0x12
        di 0x1234;     // insert bytes 0x34, 0x12, 0x00, 0x00
        dl 0x1234;     // insert bytes 0x34, 0x12, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
        df 1.234;      // insert float 1.234
        dd 1.234;      // insert double 1.234
        de 1.234;      // insert real 1.234
        db "abc";      // insert bytes 0x61, 0x62, and 0x63
        ds "abc";      // insert bytes 0x61, 0x00, 0x62, 0x00, 0x63, 0x00
    }

## Opcodes

A list of supported opcodes is at the end.

The following registers are supported. Register names are always in upper case.

    Register:
        AL AH AX EAX
        BL BH BX EBX
        CL CH CX ECX
        DL DH DX EDX
        BP EBP
        SP ESP
        DI EDI
        SI ESI
        ES CS SS DS GS FS
        CR0 CR2 CR3 CR4
        DR0 DR1 DR2 DR3 DR6 DR7
        TR3 TR4 TR5 TR6 TR7
        ST
        ST(0) ST(1) ST(2) ST(3) ST(4) ST(5) ST(6) ST(7)
        MM0  MM1  MM2  MM3  MM4  MM5  MM6  MM7
        XMM0 XMM1 XMM2 XMM3 XMM4 XMM5 XMM6 XMM7

x86_64 adds these additional registers.

    Register64:
        RAX  RBX  RCX  RDX
        BPL  RBP
        SPL  RSP
        DIL  RDI
        SIL  RSI
        R8B  R8W  R8D  R8
        R9B  R9W  R9D  R9
        R10B R10W R10D R10
        R11B R11W R11D R11
        R12B R12W R12D R12
        R13B R13W R13D R13
        R14B R14W R14D R14
        R15B R15W R15D R15
        XMM8 XMM9 XMM10 XMM11 XMM12 XMM13 XMM14 XMM15
        YMM0 YMM1 YMM2  YMM3  YMM4  YMM5  YMM6  YMM7
        YMM8 YMM9 YMM10 YMM11 YMM12 YMM13 YMM14 YMM15

### Special Cases

lock, rep, repe, repne, repnz, repz
  These prefix instructions do not appear in the same statement as the instructions they prefix; they appear in their own statement. For example:

      asm
      {
          rep   ;
          movsb ;
      }

pause
  This opcode is not supported by the assembler, instead use

      asm
      {
          rep  ;
          nop  ;
      }

  which produces the same result.
floating point ops
  Use the two operand form of the instruction format;

      fdiv ST(1);     // wrong
      fmul ST;        // wrong
      fdiv ST,ST(1);  // right
      fmul ST,ST(0);  // right

## Operands

    Operand:
        AsmExp

    AsmExp:
        AsmLogOrExp
        AsmLogOrExp ? AsmExp : AsmExp

    AsmLogOrExp:
        AsmLogAndExp
        AsmLogAndExp || AsmLogAndExp

    AsmLogAndExp:
        AsmOrExp
        AsmOrExp && AsmOrExp

    AsmOrExp:
        AsmXorExp
        AsmXorExp | AsmXorExp

    AsmXorExp:
        AsmAndExp
        AsmAndExp ^ AsmAndExp

    AsmAndExp:
        AsmEqualExp
        AsmEqualExp & AsmEqualExp

    AsmEqualExp:
        AsmRelExp
        AsmRelExp == AsmRelExp
        AsmRelExp != AsmRelExp

    AsmRelExp:
        AsmShiftExp
        AsmShiftExp < AsmShiftExp
        AsmShiftExp <= AsmShiftExp
        AsmShiftExp > AsmShiftExp
        AsmShiftExp >= AsmShiftExp

    AsmShiftExp:
        AsmAddExp
        AsmAddExp << AsmAddExp
        AsmAddExp >> AsmAddExp
        AsmAddExp >>> AsmAddExp

    AsmAddExp:
        AsmMulExp
        AsmMulExp + AsmMulExp
        AsmMulExp - AsmMulExp

    AsmMulExp:
        AsmBrExp
        AsmBrExp * AsmBrExp
        AsmBrExp / AsmBrExp
        AsmBrExp % AsmBrExp

    AsmBrExp:
        AsmUnaExp
        AsmBrExp [ AsmExp ]

    AsmUnaExp:
        AsmTypePrefix AsmExp
        offsetof AsmExp
        seg AsmExp
        + AsmUnaExp
        - AsmUnaExp
        ! AsmUnaExp
        ~ AsmUnaExp
        AsmPrimaryExp

    AsmPrimaryExp:
        IntegerLiteral
        FloatLiteral
        __LOCAL_SIZE
        $
        Register
        Register : AsmExp
        Register64
        Register64 : AsmExp
        DotIdentifier
        this

    DotIdentifier:
        Identifier
        Identifier . DotIdentifier

The operand syntax more or less follows the Intel CPU documentation conventions. In particular, the convention is that for two operand instructions the source is the right operand and the destination is the left operand. The syntax differs from that of Intel's in order to be compatible with the D language tokenizer and to simplify parsing.

The seg means load the segment number that the symbol is in. This is not relevant for flat model code. Instead, do a move from the relevant segment register.

### Operand Types

    AsmTypePrefix:
        near ptr
        far ptr
        byte ptr
        short ptr
        int ptr
        word ptr
        dword ptr
        qword ptr
        float ptr
        double ptr
        real ptr

In cases where the operand size is ambiguous, as in:

    add [EAX],3     ;

it can be disambiguated by using an AsmTypePrefix:

    add  byte ptr [EAX],3 ;
    add  int ptr [EAX],7  ;

far ptr is not relevant for flat model code.

### Struct/Union/Class Member Offsets

To access members of an aggregate, given a pointer to the aggregate is in a register, use the .offsetof property of the qualified name of the member:

    struct Foo { int a,b,c; }
    int bar(Foo *f)
    {
        asm
        {
            mov EBX,f                   ;
            mov EAX,Foo.b.offsetof[EBX] ;
        }
    }
    void main()
    {
        Foo f = Foo(0, 2, 0);
        assert(bar(&f) == 2);
    }

Alternatively, inside the scope of an aggregate, only the member name is needed:

    struct Foo   // or class
    {
        int a,b,c;
        int bar()
        {
            asm
            {
                mov EBX, this   ;
                mov EAX, b[EBX] ;
            }
        }
    }
    void main()
    {
        Foo f = Foo(0, 2, 0);
        assert(f.bar() == 2);
    }

### Stack Variables

Stack variables (variables local to a function and allocated on the stack) are accessed via the name of the variable indexed by EBP:

    int foo(int x)
    {
        asm
        {
            mov EAX,x[EBP] ; // loads value of parameter x into EAX
            mov EAX,x      ; // does the same thing
        }
    }

If the [EBP] is omitted, it is assumed for local variables. If naked is used, this no longer holds.

### Special Symbols

$
  Represents the program counter of the start of the next instruction. So,

      jmp  $  ;

  branches to the instruction following the jmp instruction. The $ can only appear as the target of a jmp or call instruction.
__LOCAL_SIZE
  This gets replaced by the number of local bytes in the local stack frame. It is most handy when the naked is invoked and a custom stack frame is programmed.

## Opcodes Supported

Opcodes
aaa | aad | aam | aas | adc
add | addpd | addps | addsd | addss
and | andnpd | andnps | andpd | andps
arpl | bound | bsf | bsr | bswap
bt | btc | btr | bts | call
cbw | cdq | clc | cld | clflush
cli | clts | cmc | cmova | cmovae
cmovb | cmovbe | cmovc | cmove | cmovg
cmovge | cmovl | cmovle | cmovna | cmovnae
cmovnb | cmovnbe | cmovnc | cmovne | cmovng
cmovnge | cmovnl | cmovnle | cmovno | cmovnp
cmovns | cmovnz | cmovo | cmovp | cmovpe
cmovpo | cmovs | cmovz | cmp | cmppd
cmpps | cmps | cmpsb | cmpsd | cmpss
cmpsw | cmpxch8b | cmpxchg | comisd | comiss
cpuid | cvtdq2pd | cvtdq2ps | cvtpd2dq | cvtpd2pi
cvtpd2ps | cvtpi2pd | cvtpi2ps | cvtps2dq | cvtps2pd
cvtps2pi | cvtsd2si | cvtsd2ss | cvtsi2sd | cvtsi2ss
cvtss2sd | cvtss2si | cvttpd2dq | cvttpd2pi | cvttps2dq
cvttps2pi | cvttsd2si | cvttss2si | cwd | cwde
da | daa | das | db | dd
de | dec | df | di | div
divpd | divps | divsd | divss | dl
dq | ds | dt | dw | emms
enter | f2xm1 | fabs | fadd | faddp
fbld | fbstp | fchs | fclex | fcmovb
fcmovbe | fcmove | fcmovnb | fcmovnbe | fcmovne
fcmovnu | fcmovu | fcom | fcomi | fcomip
fcomp | fcompp | fcos | fdecstp | fdisi
fdiv | fdivp | fdivr | fdivrp | feni
ffree | fiadd | ficom | ficomp | fidiv
fidivr | fild | fimul | fincstp | finit
fist | fistp | fisub | fisubr | fld
fld1 | fldcw | fldenv | fldl2e | fldl2t
fldlg2 | fldln2 | fldpi | fldz | fmul
fmulp | fnclex | fndisi | fneni | fninit
fnop | fnsave | fnstcw | fnstenv | fnstsw
fpatan | fprem | fprem1 | fptan | frndint
frstor | fsave | fscale | fsetpm | fsin
fsincos | fsqrt | fst | fstcw | fstenv
fstp | fstsw | fsub | fsubp | fsubr
fsubrp | ftst | fucom | fucomi | fucomip
fucomp | fucompp | fwait | fxam | fxch
fxrstor | fxsave | fxtract | fyl2x | fyl2xp1
hlt | idiv | imul | in | inc
ins | insb | insd | insw | int
into | invd | invlpg | iret | iretd
ja | jae | jb | jbe | jc
jcxz | je | jecxz | jg | jge
jl | jle | jmp | jna | jnae
jnb | jnbe | jnc | jne | jng
jnge | jnl | jnle | jno | jnp
jns | jnz | jo | jp | jpe
jpo | js | jz | lahf | lar
ldmxcsr | lds | lea | leave | les
lfence | lfs | lgdt | lgs | lidt
lldt | lmsw | lock | lods | lodsb
lodsd | lodsw | loop | loope | loopne
loopnz | loopz | lsl | lss | ltr
maskmovdqu | maskmovq | maxpd | maxps | maxsd
maxss | mfence | minpd | minps | minsd
minss | mov | movapd | movaps | movd
movdq2q | movdqa | movdqu | movhlps | movhpd
movhps | movlhps | movlpd | movlps | movmskpd
movmskps | movntdq | movnti | movntpd | movntps
movntq | movq | movq2dq | movs | movsb
movsd | movss | movsw | movsx | movupd
movups | movzx | mul | mulpd | mulps
mulsd | mulss | neg | nop | not
or | orpd | orps | out | outs
outsb | outsd | outsw | packssdw | packsswb
packuswb | paddb | paddd | paddq | paddsb
paddsw | paddusb | paddusw | paddw | pand
pandn | pavgb | pavgw | pcmpeqb | pcmpeqd
pcmpeqw | pcmpgtb | pcmpgtd | pcmpgtw | pextrw
pinsrw | pmaddwd | pmaxsw | pmaxub | pminsw
pminub | pmovmskb | pmulhuw | pmulhw | pmullw
pmuludq | pop | popa | popad | popf
popfd | por | prefetchnta | prefetcht0 | prefetcht1
prefetcht2 | psadbw | pshufd | pshufhw | pshuflw
pshufw | pslld | pslldq | psllq | psllw
psrad | psraw | psrld | psrldq | psrlq
psrlw | psubb | psubd | psubq | psubsb
psubsw | psubusb | psubusw | psubw | punpckhbw
punpckhdq | punpckhqdq | punpckhwd | punpcklbw | punpckldq
punpcklqdq | punpcklwd | push | pusha | pushad
pushf | pushfd | pxor | rcl | rcpps
rcpss | rcr | rdmsr | rdpmc | rdtsc
rep | repe | repne | repnz | repz
ret | retf | rol | ror | rsm
rsqrtps | rsqrtss | sahf | sal | sar
sbb | scas | scasb | scasd | scasw
seta | setae | setb | setbe | setc
sete | setg | setge | setl | setle
setna | setnae | setnb | setnbe | setnc
setne | setng | setnge | setnl | setnle
setno | setnp | setns | setnz | seto
setp | setpe | setpo | sets | setz
sfence | sgdt | shl | shld | shr
shrd | shufpd | shufps | sidt | sldt
smsw | sqrtpd | sqrtps | sqrtsd | sqrtss
stc | std | sti | stmxcsr | stos
stosb | stosd | stosw | str | sub
subpd | subps | subsd | subss | sysenter
sysexit | test | ucomisd | ucomiss | ud2
unpckhpd | unpckhps | unpcklpd | unpcklps | verr
verw | wait | wbinvd | wrmsr | xadd
xchg | xlat | xlatb | xor | xorpd
xorps |  |  |  |

### Pentium 4 (Prescott) Opcodes Supported

Pentium 4 Opcodes
addsubpd | addsubps | fisttp | haddpd | haddps
hsubpd | hsubps | lddqu | monitor | movddup
movshdup | movsldup | mwait |  |

### AMD Opcodes Supported

AMD Opcodes
pavgusb | pf2id | pfacc | pfadd | pfcmpeq
pfcmpge | pfcmpgt | pfmax | pfmin | pfmul
pfnacc | pfpnacc | pfrcp | pfrcpit1 | pfrcpit2
pfrsqit1 | pfrsqrt | pfsub | pfsubr | pi2fd
pmulhrw | pswapd |  |  |

### SIMD

SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2 and AVX are supported.

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