rex_bits
reg = (ctxt->b & 7) | (ctxt->rex_bits & REX_B ? 8 : 0);
ctxt->modrm_reg = (ctxt->rex_bits & REX_R ? 8 : 0);
index_reg = (ctxt->rex_bits & REX_X ? 8 : 0);
base_reg = (ctxt->rex_bits & REX_B ? 8 : 0);
if (ctxt->rex_bits & REX_W)
ctxt->rex_bits = (vex_2nd & 0xE0) >> 5; /* RXB */
ctxt->rex_bits |= (vex_3rd & 0x80) >> 4; /* w */
if (ctxt->rex_bits && ctxt->mode != X86EMUL_MODE_PROT64)
ctxt->rex_bits = ctxt->b & 0xf;
ctxt->rex_bits = 0;
if (ctxt->rex_bits & REX_W)
ctxt->rex_bits = 0;
u8 rex_bits;