x86lmao.md

unfinished :p

SSE instructions (OP refers to the opcodes in the table below):

  ___ss 32 x 1  F3 0F OP ...
  ___sd 64 x 1  F2 0F OP ...
  ___ps 32 x 4     0F OP ...
  ___pd 64 x 2  66 0F OP ...

simple example:

    addss xmm0, xmm1     F3 0F 58 C1
    addsd xmm0, xmm1     F2 0F 58 C1
    addps xmm0, xmm1        0F 58 C1
    addpd xmm0, xmm1     66 0F 58 C1

Opcode list:

  mov   0x10
  add   0x58
  mul   0x59
  sub   0x5C
  div   0x5E
  cmp   0xC2
  ucomi 0x2E
  cvt   0x5A
  sqrt  0x51
  rsqrt 0x52
  and   0x54
  or    0x56
  xor   0x57

Exceptions:

for the mov it doesn't refer to the standard integer mov on x86, instead it means the movss,movsd,movups,movupd (the unaligned variants) and the bottom bit acts as a "direction flag" which will flip which side has the memory operand:

direction set:

            you'll notice that the 1s bit is set for storing
                                 VV
    movups [rsp + 8], xmm0    0F 11 44 24 10
    movups xmm0, [rsp + 8]    0F 10 44 24 10

Oddities:

bitwise operations seem really dumb here because the type info is useless and there's just extra instructions for example andps, andpd are literally the same... except they're not?