use yaxpeax_arch::Reader;
use yaxpeax_arch::annotation::DescriptionSink;

use crate::protected_mode::Arch;
use crate::protected_mode::OperandSpec;
use crate::protected_mode::DecodeError;
use crate::protected_mode::FieldDescription;
use crate::protected_mode::RegSpec;
use crate::protected_mode::RegisterBank;
use crate::protected_mode::InnerDescription;
use crate::protected_mode::Instruction;
use crate::protected_mode::Opcode;
use crate::protected_mode::read_modrm;
use crate::protected_mode::read_E;
use crate::protected_mode::read_E_xmm;
use crate::protected_mode::read_E_ymm;
use crate::protected_mode::read_imm_unsigned;

#[derive(Debug)]
enum VEXOpcodeMap {
    Map0F,
    Map0F38,
    Map0F3A,
}

#[derive(Debug)]
enum VEXOpcodePrefix {
    None,
    Prefix66,
    PrefixF3,
    PrefixF2,
}

#[allow(non_camel_case_types)]
#[derive(Debug)]
enum VEXOperandCode {
    Nothing,
    VPS_71,
    VPS_72,
    VPS_73,
    VMOVSS_10,
    VMOVSD_10,
    VMOVSD_11,
    VMOVSS_11,
    VMOVLPS_12,
    VMOVHPS_16,
    M_G_xmm,
    G_M_xmm,
    G_U_xmm,
    Gd_U_xmm,
    E_G_xmm_imm8,
    Ud_G_xmm_imm8,
    Ud_G_xyLmm,
    M_G_xyLmm,
    M_G_ymm,
    G_E_ymm,
    G_M_ymm,
    Gd_U_ymm,
    E_xmm_G_ymm_imm8,
    Ev_G_xmm_imm8,
    G_ExyL_V_xyLmm,
    G_E_xmm,
    G_E_xmm_imm8,
    G_E_ymm_imm8,
    G_xmm_E_xmm,
    G_xmm_E_ymm,
    G_ymm_E_xmm,
    G_ymm_M_xmm,
    G_ymm_E_ymm,
    G_V_ymm_E_xmm,
    M_V_G_xmm,
    M_V_G_ymm,
    G_V_xmm_Ed,
    G_V_E_xyLmm,
    G_E_xyLmm,
    E_G_xyLmm,
    G_E_xyLmm_imm8,
    G_V_E_xyLmm_imm8,
    G_V_E_xmm,
    G_V_E_xmm_imm8,
    G_V_E_xmm_xmm4,
    G_V_Ed_xmm,
    G_V_Eq_xmm,
    G_V_E_ymm,
    G_V_E_ymm_imm8,
    G_V_E_ymm_ymm4,
    G_V_xmm_Ev_imm8,
    G_V_M_xmm,
    G_V_M_ymm,
    G_ymm_V_ymm_E_xmm_imm8,
    Ed_G_xmm,
    G_xmm_Ed,
    G_E_V,
    G_V_E,
    G_E_Ib,
    VCVT_Gd_Ed_xmm,
    VCVT_Gd_Eq_xmm,
    BMI1_F3,
    MXCSR,
}

#[inline(always)]
pub(crate) fn three_byte_vex<
    T: Reader<<Arch as yaxpeax_arch::Arch>::Address, <Arch as yaxpeax_arch::Arch>::Word>,
    S: DescriptionSink<FieldDescription>,
>(words: &mut T, vex_byte_one: u8, instruction: &mut Instruction, sink: &mut S) -> Result<(), DecodeError> {
    let vex_start = words.offset() as u32 * 8 - 8;
    let vex_byte_two = words.next().ok().ok_or(DecodeError::ExhaustedInput)?;
    let p = vex_byte_two & 0x03;
    let p = match p {
        0x00 => VEXOpcodePrefix::None,
        0x01 => VEXOpcodePrefix::Prefix66,
        0x02 => VEXOpcodePrefix::PrefixF3,
        0x03 => VEXOpcodePrefix::PrefixF2,
        _ => { unreachable!("p is two bits"); }
    };
    sink.record(
        vex_start + 8,
        vex_start + 9,
        InnerDescription::Misc(match p {
            VEXOpcodePrefix::None => "vex.p indicates no opcode prefix",
            VEXOpcodePrefix::Prefix66 => "vex.p indicates opcode prefix 66",
            VEXOpcodePrefix::PrefixF3 => "vex.p indicates opcode prefix f3",
            VEXOpcodePrefix::PrefixF2 => "vex.p indicates opcode prefix f2",
        })
            .with_id(vex_start)
    );
    let m = vex_byte_one & 0b11111;
    sink.record(
        vex_start + 0,
        vex_start + 4,
        InnerDescription::Misc(match m {
            0b00001 => "vex.mmmmm indicates opcode escape of 0f",
            0b00010 => "vex.mmmmm indicates opcode escape of 0f38",
            0b00011 => "vex.mmmmm indicates opcode escape of 0f3a",
            _ => "vex.mmmmm indicates illegal opcode escape and is invalid",
        })
            .with_id(vex_start)
    );
    let m = match m {
        0b00001 => VEXOpcodeMap::Map0F,
        0b00010 => VEXOpcodeMap::Map0F38,
        0b00011 => VEXOpcodeMap::Map0F3A,
        _ => {
            return Err(DecodeError::InvalidOpcode);
        }
    };
    instruction.regs[3] = RegSpec {
        bank: RegisterBank::X,
        num: ((vex_byte_two >> 3) & 0b1111) ^ 0b1111,
    };
    sink.record(
        vex_start + 11,
        vex_start + 14,
        InnerDescription::RegisterNumber("vvvv", instruction.regs[3].num, instruction.regs[3])
            .with_id(vex_start + 2)
    );

    sink.record(
        vex_start + 7,
        vex_start + 7,
        InnerDescription::Misc(if vex_byte_one & 0b10000000 == 0 {
            "vex.r extends extends rrr by 0b1000"
        } else {
            "vex.r does not alter rrr"
        })
            .with_id(vex_start + 1)
    );
    sink.record(
        vex_start + 6,
        vex_start + 6,
        InnerDescription::Misc(if vex_byte_one & 0b01000000 == 0 {
            "vex.x extends extends index reg (if used) by 0b1000"
        } else {
            "vex.x does not alter index reg"
        })
            .with_id(vex_start + 1)
    );
    sink.record(
        vex_start + 5,
        vex_start + 5,
        InnerDescription::Misc(if vex_byte_one & 0b00100000 == 0 {
            "vex.b extends extends base reg (if used) by 0b1000"
        } else {
            "vex.b does not alter base reg"
        })
            .with_id(vex_start + 1)
    );
    sink.record(
        vex_start + 10,
        vex_start + 10,
        InnerDescription::Misc(if vex_byte_two & 0b100 == 0 {
            "vex.l selects 128-bit vector sizes"
        } else {
            "vex.l selects 256-bit vector sizes"
        })
            .with_id(vex_start + 1)
    );
    sink.record(
        vex_start + 15,
        vex_start + 15,
        InnerDescription::Misc(if vex_byte_two & 0b10000000 != 0 {
            "vex.w selects 64-bit operand size"
        } else {
            "vex.w leaves default operand size"
        })
            .with_id(vex_start + 1)
    );

    instruction.prefixes.vex_from_c4(vex_byte_one, vex_byte_two);

    sink.record(
        vex_start + 23,
        vex_start + 23,
        InnerDescription::Boundary("vex prefix ends/opcode begins")
            .with_id(vex_start + 23)
    );

    read_vex_instruction(m, words, instruction, p, sink)?;
    instruction.regs[3].num &= 0b0111; // ignore bit 4 in 32-bit mode
    Ok(())
}

#[inline(always)]
pub(crate) fn two_byte_vex<
    T: Reader<<Arch as yaxpeax_arch::Arch>::Address, <Arch as yaxpeax_arch::Arch>::Word>,
    S: DescriptionSink<FieldDescription>,
>(words: &mut T, vex_byte: u8, instruction: &mut Instruction, sink: &mut S) -> Result<(), DecodeError> {
    let vex_start = words.offset() as u32 * 8 - 8;
    let p = vex_byte & 0x03;
    let p = match p {
        0x00 => VEXOpcodePrefix::None,
        0x01 => VEXOpcodePrefix::Prefix66,
        0x02 => VEXOpcodePrefix::PrefixF3,
        0x03 => VEXOpcodePrefix::PrefixF2,
        _ => { unreachable!("p is two bits"); }
    };
    instruction.regs[3] = RegSpec {
        bank: RegisterBank::X,
        num: ((vex_byte >> 3) & 0b1111) ^ 0b1111,
    };

    sink.record(
        vex_start + 0,
        vex_start + 1,
        InnerDescription::Misc(match p {
            VEXOpcodePrefix::None => "vex.p indicates no opcode prefix",
            VEXOpcodePrefix::Prefix66 => "vex.p indicates opcode prefix 66",
            VEXOpcodePrefix::PrefixF3 => "vex.p indicates opcode prefix f3",
            VEXOpcodePrefix::PrefixF2 => "vex.p indicates opcode prefix f2",
        })
            .with_id(vex_start)
    );

    sink.record(
        vex_start + 3,
        vex_start + 6,
        InnerDescription::RegisterNumber("vvvv", instruction.regs[3].num, instruction.regs[3])
            .with_id(vex_start + 2)
    );

    sink.record(
        vex_start + 2,
        vex_start + 2,
        InnerDescription::Misc(if vex_byte & 0b100 == 0 {
            "vex.r extends extends rrr by 0b1000"
        } else {
            "vex.r does not alter rrr"
        })
            .with_id(vex_start + 1)
    );
    sink.record(
        vex_start + 7,
        vex_start + 7,
        InnerDescription::Misc(if vex_byte & 0b10000000 != 0 {
            "vex.w selects 64-bit operand size"
        } else {
            "vex.w leaves default operand size"
        })
            .with_id(vex_start + 1)
    );

    instruction.prefixes.vex_from_c5(vex_byte);

    sink.record(
        vex_start + 15,
        vex_start + 15,
        InnerDescription::Boundary("vex prefix ends/opcode begins")
            .with_id(vex_start + 15)
    );

    read_vex_instruction(VEXOpcodeMap::Map0F, words, instruction, p, sink)?;
    instruction.regs[3].num &= 0b0111; // ignore bit 4 in 32-bit mode
    Ok(())
}

#[inline(always)]
fn read_vex_operands<
    T: Reader<<Arch as yaxpeax_arch::Arch>::Address, <Arch as yaxpeax_arch::Arch>::Word>,
    S: DescriptionSink<FieldDescription>,
>(words: &mut T, instruction: &mut Instruction, operand_code: VEXOperandCode, sink: &mut S) -> Result<(), DecodeError> {
//    println!("operand code: {:?}", operand_code);
    match operand_code {
        VEXOperandCode::VPS_71 => {
            let modrm = read_modrm(words)?;
            if modrm & 0xc0 != 0xc0 {
                return Err(DecodeError::InvalidOperand);
            }
            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();

            let bank = if L {
                RegisterBank::Y
            } else {
                RegisterBank::X
            };

            let rrr = (modrm >> 3) & 0b111;

            if rrr == 0b001 && L {
                return Err(DecodeError::InvalidOpcode);
            }

            instruction.opcode = match rrr {
                0b001 => Opcode::VPSLLW,
                0b010 => Opcode::VPSRLW,
                0b100 => Opcode::VPSRAW,
                0b110 => Opcode::VPSLLW,
                _ => {
                    return Err(DecodeError::InvalidOpcode);
                }
            };
            instruction.regs[0] =
                RegSpec::from_parts(modrm & 7, bank);
            instruction.regs[3].bank = bank;
            instruction.operands[0] = OperandSpec::RegVex;
            instruction.operands[1] = OperandSpec::RegRRR;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[2] = OperandSpec::ImmI8;
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::VPS_72 => {
            let modrm = read_modrm(words)?;
            if modrm & 0xc0 != 0xc0 {
                return Err(DecodeError::InvalidOperand);
            }

            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();

            let bank = if L {
                RegisterBank::Y
            } else {
                RegisterBank::X
            };

            match (modrm >> 3) & 0b111 {
                0b010 => {
                    instruction.opcode = Opcode::VPSRLD;
                }
                0b100 => {
                    instruction.opcode = Opcode::VPSRAD;
                }
                0b110 => {
                    instruction.opcode = Opcode::VPSLLD;
                }
                _ => {
                    return Err(DecodeError::InvalidOpcode);
                }
            }
            instruction.regs[0] =
                RegSpec::from_parts(modrm & 7, bank);
            instruction.regs[3].bank = bank;
            instruction.operands[0] = OperandSpec::RegVex;
            instruction.operands[1] = OperandSpec::RegRRR;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[2] = OperandSpec::ImmI8;
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::VPS_73 => {
            let modrm = read_modrm(words)?;
            if modrm & 0xc0 != 0xc0 {
                return Err(DecodeError::InvalidOperand);
            }

            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();

            let bank = if L {
                RegisterBank::Y
            } else {
                RegisterBank::X
            };

            match (modrm >> 3) & 0b111 {
                0b010 => {
                    instruction.opcode = Opcode::VPSRLQ;
                }
                0b011 => {
                    instruction.opcode = Opcode::VPSRLDQ;
                }
                0b110 => {
                    instruction.opcode = Opcode::VPSLLQ;
                }
                0b111 => {
                    instruction.opcode = Opcode::VPSLLDQ;
                }
                _ => {
                    return Err(DecodeError::InvalidOpcode);
                }
            }
            instruction.regs[0] =
                RegSpec::from_parts(modrm & 7, bank);
            instruction.regs[3].bank = bank;
            instruction.operands[0] = OperandSpec::RegVex;
            instruction.operands[1] = OperandSpec::RegRRR;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[2] = OperandSpec::ImmI8;
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::VMOVSS_10 |
        VEXOperandCode::VMOVSD_10 => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            match mem_oper {
                OperandSpec::RegMMM => {
                    instruction.operands[1] = OperandSpec::RegVex;
                    instruction.operands[2] = OperandSpec::RegMMM;
                    instruction.operand_count = 3;
                },
                other => {
                    if instruction.regs[3].num != 0 {
                        return Err(DecodeError::InvalidOperand);
                    }
                    if instruction.opcode == Opcode::VMOVSS {
                        instruction.mem_size = 4;
                    } else {
                        instruction.mem_size = 8;
                    }
                    instruction.operands[1] = other;
                    instruction.operand_count = 2;
                }
            }
            Ok(())
        },
        VEXOperandCode::VMOVSS_11 |
        VEXOperandCode::VMOVSD_11 => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[2] = OperandSpec::RegRRR;
            match mem_oper {
                OperandSpec::RegMMM => {
                    instruction.operands[0] = OperandSpec::RegMMM;
                    instruction.operands[1] = OperandSpec::RegVex;
                    instruction.operand_count = 3;
                },
                other => {
                    if instruction.regs[3].num != 0 {
                        return Err(DecodeError::InvalidOperand);
                    }
                    if instruction.opcode == Opcode::VMOVSS {
                        instruction.mem_size = 4;
                    } else {
                        instruction.mem_size = 8;
                    }
                    instruction.operands[0] = other;
                    instruction.operands[1] = instruction.operands[2];
                    instruction.operand_count = 2;
                }
            }
            Ok(())
        },
        VEXOperandCode::VMOVLPS_12 => {
            let modrm = read_modrm(words)?;
            instruction.opcode = if modrm & 0xc0 == 0xc0 {
                Opcode::VMOVHLPS
            } else {
                instruction.mem_size = 8;
                Opcode::VMOVLPS
            };
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::VMOVHPS_16 => {
            let modrm = read_modrm(words)?;
            instruction.opcode = if modrm & 0xc0 == 0xc0 {
                Opcode::VMOVLHPS
            } else {
                instruction.mem_size = 8;
                Opcode::VMOVHPS
            };
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::Nothing => {
            if instruction.opcode == Opcode::VZEROUPPER || instruction.opcode == Opcode::VZEROALL {
                if instruction.regs[3].num != 0 {
                    return Err(DecodeError::InvalidOperand);
                }
            }
            instruction.operand_count = 0;
            Ok(())
        },
        VEXOperandCode::Ev_G_xmm_imm8 => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E(words, instruction, modrm, RegisterBank::D, sink)?;
            instruction.operands[0] = mem_oper;
            instruction.operands[1] = OperandSpec::RegRRR;
            instruction.operands[2] = OperandSpec::ImmU8;
            if mem_oper != OperandSpec::RegMMM {
                match instruction.opcode {
                    Opcode::VPEXTRB => {
                        instruction.mem_size = 1;
                    }
                    Opcode::VPEXTRW => {
                        instruction.mem_size = 2;
                    }
                    Opcode::VEXTRACTPS |
                    Opcode::VPEXTRD => {
                        instruction.mem_size = 4;
                    }
                    _ => {
                        instruction.mem_size = 8;
                    }
                }
            }
            instruction.operand_count = 3;
            instruction.imm = read_imm_unsigned(words, 1)?;
            Ok(())
        },
        VEXOperandCode::G_xmm_Ed => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E(words, instruction, modrm, RegisterBank::D, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 4;
            }
            instruction.operand_count = 2;
            Ok(())
        }
        VEXOperandCode::Ed_G_xmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E(words, instruction, modrm, RegisterBank::D, sink)?;
            instruction.operands[0] = mem_oper;
            instruction.operands[1] = OperandSpec::RegRRR;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 4;
            }
            instruction.operand_count = 2;
            Ok(())
        }
        VEXOperandCode::VCVT_Gd_Ed_xmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::D);
            let mem_oper = read_E(words, instruction, modrm, RegisterBank::D, sink)?;
            if let OperandSpec::RegMMM = mem_oper {
                instruction.regs[1].bank = RegisterBank::X;
            } else {
                instruction.mem_size = 4;
            }
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.operand_count = 2;
            Ok(())
        }
        VEXOperandCode::VCVT_Gd_Eq_xmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::D);
            let mem_oper = read_E(words, instruction, modrm, RegisterBank::D, sink)?;
            if let OperandSpec::RegMMM = mem_oper {
                instruction.regs[1].bank = RegisterBank::X;
            } else {
                instruction.mem_size = 8;
            }
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.operand_count = 2;
            Ok(())
        }
         VEXOperandCode::M_G_xyLmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            // the name of this bit is `L` in the documentation, so use the same name here.
            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();
            let bank = if L { RegisterBank::Y } else { RegisterBank::X };

            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, bank);
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            if mem_oper == OperandSpec::RegMMM {
                return Err(DecodeError::InvalidOperand);
            }
            if mem_oper != OperandSpec::RegMMM {
                if instruction.opcode == Opcode::VMOVLPD || instruction.opcode == Opcode::VMOVHPD || instruction.opcode == Opcode::VMOVHPS {
                    instruction.mem_size = 8;
                } else {
                    if L {
                        instruction.mem_size = 32;
                    } else {
                        instruction.mem_size = 16;
                    }
                }
            }
            instruction.operands[0] = mem_oper;
            instruction.operands[1] = OperandSpec::RegRRR;
            instruction.operand_count = 2;
            Ok(())
        }
         VEXOperandCode::M_G_xmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            if mem_oper == OperandSpec::RegMMM {
                return Err(DecodeError::InvalidOperand);
            }
            if mem_oper != OperandSpec::RegMMM {
                if instruction.opcode == Opcode::VMOVLPD || instruction.opcode == Opcode::VMOVHPD || instruction.opcode == Opcode::VMOVHPS {
                    instruction.mem_size = 8;
                } else {
                    instruction.mem_size = 16;
                }
            }
            instruction.operands[0] = mem_oper;
            instruction.operands[1] = OperandSpec::RegRRR;
            instruction.operand_count = 2;
            Ok(())
        }
        VEXOperandCode::Ud_G_xyLmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            // the name of this bit is `L` in the documentation, so use the same name here.
            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();
            let bank = if L { RegisterBank::Y } else { RegisterBank::X };

            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::D);
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            if mem_oper != OperandSpec::RegMMM {
                return Err(DecodeError::InvalidOperand);
            }
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.operand_count = 2;
            Ok(())
        }
        VEXOperandCode::Ud_G_xmm_imm8 => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::D);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            if mem_oper != OperandSpec::RegMMM {
                return Err(DecodeError::InvalidOperand);
            }
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[2] = OperandSpec::ImmU8;
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::E_G_xmm_imm8 => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = mem_oper;
            instruction.operands[1] = OperandSpec::RegRRR;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[2] = OperandSpec::ImmU8;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 16;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::E_xmm_G_ymm_imm8 => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::Y);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = mem_oper;
            instruction.operands[1] = OperandSpec::RegRRR;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[2] = OperandSpec::ImmU8;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 16;
            }
            instruction.operand_count = 3;
            Ok(())
        }

        VEXOperandCode::Gd_U_xmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::D);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            if mem_oper != OperandSpec::RegMMM {
                return Err(DecodeError::InvalidOperand);
            }
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.operand_count = 2;
            Ok(())
        }
        VEXOperandCode::Gd_U_ymm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::D);
            let mem_oper = read_E_ymm(words, instruction, modrm, sink)?;
            if mem_oper != OperandSpec::RegMMM {
                return Err(DecodeError::InvalidOperand);
            }
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.operand_count = 2;
            Ok(())
        }

        op @ VEXOperandCode::G_M_xmm |
        op @ VEXOperandCode::G_U_xmm |
        op @ VEXOperandCode::G_E_xmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            match (op, modrm & 0xc0) {
                (VEXOperandCode::G_U_xmm, 0xc0) => {
                    /* this is the only accepted operand */
                }
                (VEXOperandCode::G_U_xmm, _) |
                (VEXOperandCode::G_M_xmm, 0xc0) => {
                    return Err(DecodeError::InvalidOperand);
                }
                (VEXOperandCode::G_M_xmm, _) | // otherwise it's memory-constrained and a memory operand
                (_, _) => {                    // ... or unconstrained
                    /* and this is always accepted */
                }
            }
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                if [Opcode::VBROADCASTSS, Opcode::VUCOMISS, Opcode::VCOMISS].contains(&instruction.opcode)  {
                    instruction.mem_size = 4;
                } else if [Opcode::VMOVDDUP, Opcode::VUCOMISD, Opcode::VCOMISD, Opcode::VCVTPS2PD, Opcode::VMOVD].contains(&instruction.opcode)  {
                    instruction.mem_size = 8;
                } else {
                    instruction.mem_size = 16;
                };
            }
            instruction.operand_count = 2;
            Ok(())
        }
        VEXOperandCode::G_xmm_E_xmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 16;
            }
            instruction.operand_count = 2;
            Ok(())
        }
        VEXOperandCode::G_xmm_E_ymm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_ymm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 32;
            }
            instruction.operand_count = 2;
            Ok(())
        }
        op @ VEXOperandCode::G_ymm_M_xmm |
        op @ VEXOperandCode::G_ymm_E_xmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            if modrm & 0xc0 == 0xc0 {
                if let VEXOperandCode::G_ymm_M_xmm = op {
                    return Err(DecodeError::InvalidOperand);
                }
            }
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::Y);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                if [Opcode::VBROADCASTSS].contains(&instruction.opcode) {
                    instruction.mem_size = 4;
                } else if [Opcode::VBROADCASTSD].contains(&instruction.opcode) {
                    instruction.mem_size = 8;
                } else {
                    instruction.mem_size = 16;
                }
            }
            instruction.operand_count = 2;
            Ok(())
        }
        VEXOperandCode::G_ymm_E_ymm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::Y);
            let mem_oper = read_E_ymm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 32;
            }
            instruction.operand_count = 2;
            Ok(())
        }

        op @ VEXOperandCode::M_G_ymm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            match (op, modrm & 0xc0) {
                (VEXOperandCode::M_G_ymm, 0xc0) => {
                    return Err(DecodeError::InvalidOperand);
                }
                (VEXOperandCode::M_G_ymm, _) | // otherwise it's memory-constrained and a memory operand
                (_, _) => {                    // ... or unconstrained
                    /* and this is always accepted */
                }
            }
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::Y);
            let mem_oper = read_E_ymm(words, instruction, modrm, sink)?;
            instruction.operands[0] = mem_oper;
            instruction.operands[1] = OperandSpec::RegRRR;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 32;
            }
            instruction.operand_count = 2;
            Ok(())
        }

        op @ VEXOperandCode::G_M_ymm |
        op @ VEXOperandCode::G_E_ymm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            match (op, modrm & 0xc0) {
                (VEXOperandCode::G_M_ymm, 0xc0) => {
                    return Err(DecodeError::InvalidOperand);
                }
                (VEXOperandCode::G_M_ymm, _) | // otherwise it's memory-constrained and a memory operand
                (_, _) => {                    // ... or unconstrained
                    /* and this is always accepted */
                }
            }
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::Y);
            let mem_oper = read_E_ymm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 32;
            }
            instruction.operand_count = 2;
            Ok(())
        }
        op @ VEXOperandCode::G_V_E_ymm |
        op @ VEXOperandCode::G_V_M_ymm => {
            let modrm = read_modrm(words)?;
            if let VEXOperandCode::G_V_M_ymm = op {
                if modrm & 0xc0 == 0xc0 {
                    return Err(DecodeError::InvalidOperand);
                }
            }
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::Y);
            instruction.regs[3].bank = RegisterBank::Y;
            let mem_oper = read_E_ymm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 32;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_V_E_ymm_imm8 => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::Y);
            instruction.regs[3].bank = RegisterBank::Y;
            let mem_oper = read_E_ymm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[3] = OperandSpec::ImmU8;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 32;
            }
            instruction.operand_count = 4;
            Ok(())
        }
        VEXOperandCode::M_V_G_ymm => {
            let modrm = read_modrm(words)?;
            if modrm & 0xc0 == 0xc0 {
                return Err(DecodeError::InvalidOperand);
            }
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::Y);
            instruction.regs[3].bank = RegisterBank::Y;
            let mem_oper = read_E_ymm(words, instruction, modrm, sink)?;
            instruction.operands[0] = mem_oper;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = OperandSpec::RegRRR;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 32;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_V_M_xmm => {
            let modrm = read_modrm(words)?;
            if modrm & 0xc0 == 0xc0 {
                return Err(DecodeError::InvalidOperand);
            }
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                if instruction.opcode == Opcode::VMOVLPD || instruction.opcode == Opcode::VMOVHPD {
                    instruction.mem_size = 8;
                } else {
                    instruction.mem_size = 16;
                }
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::E_G_xyLmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            // the name of this bit is `L` in the documentation, so use the same name here.
            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();
            let bank = if L { RegisterBank::Y } else { RegisterBank::X };

            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, bank);
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            if mem_oper != OperandSpec::RegMMM {
                if instruction.opcode == Opcode::VMOVLPD || instruction.opcode == Opcode::VMOVHPD || instruction.opcode == Opcode::VMOVHPS {
                    instruction.mem_size = 8;
                } else {
                    if L {
                        instruction.mem_size = 32;
                    } else {
                        instruction.mem_size = 16;
                    }
                }
            }
            instruction.operands[0] = mem_oper;
            instruction.operands[1] = OperandSpec::RegRRR;

            instruction.operand_count = 2;
            Ok(())
        }
        VEXOperandCode::G_V_E_xyLmm_imm8 => {
            // the name of this bit is `L` in the documentation, so use the same name here.
            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();
            let bank = if L { RegisterBank::Y } else { RegisterBank::X };

            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, bank);
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            instruction.regs[3].bank = bank;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[3] = OperandSpec::ImmU8;
            if mem_oper != OperandSpec::RegMMM {
                if L {
                    instruction.mem_size = 32;
                } else {
                    instruction.mem_size = 16;
                }
            }
            instruction.operand_count = 4;
            Ok(())
        }
        VEXOperandCode::G_E_xyLmm => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            // the name of this bit is `L` in the documentation, so use the same name here.
            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();
            let bank = if L { RegisterBank::Y } else { RegisterBank::X };

            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, bank);
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                if L {
                    instruction.mem_size = 32;
                } else {
                    instruction.mem_size = 16;
                }

                if instruction.opcode == Opcode::VMOVDDUP && !L {
                    instruction.mem_size = 8;
                } else if [Opcode::VBROADCASTSS, Opcode::VUCOMISS, Opcode::VCOMISS].contains(&instruction.opcode)  {
                    instruction.mem_size = 4;
                } else if [Opcode::VUCOMISD, Opcode::VCOMISD, Opcode::VCVTPS2PD, Opcode::VMOVD].contains(&instruction.opcode)  {
                    instruction.mem_size = 8;
                };
            }
            instruction.operand_count = 2;
            Ok(())
        }
        VEXOperandCode::G_V_E_xyLmm => {
            let modrm = read_modrm(words)?;
            // the name of this bit is `L` in the documentation, so use the same name here.
            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();
            let bank = if L { RegisterBank::Y } else { RegisterBank::X };

            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, bank);
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            instruction.regs[3].bank = bank;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                if [Opcode::VSQRTSS, Opcode::VADDSS, Opcode::VMULSS, Opcode::VSUBSS, Opcode::VMINSS, Opcode::VDIVSS, Opcode::VMAXSS].contains(&instruction.opcode) {
                    instruction.mem_size = 4;
                } else if [Opcode::VSQRTSD, Opcode::VADDSD, Opcode::VMULSD, Opcode::VSUBSD, Opcode::VMINSD, Opcode::VDIVSD, Opcode::VMAXSD].contains(&instruction.opcode) {
                    instruction.mem_size = 8;
                } else {
                    if L {
                        instruction.mem_size = 32;
                    } else {
                        instruction.mem_size = 16;
                    }
                }
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_V_E_xmm => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                if [Opcode::VSQRTSS, Opcode::VADDSS, Opcode::VMULSS, Opcode::VSUBSS, Opcode::VMINSS, Opcode::VDIVSS, Opcode::VMAXSS].contains(&instruction.opcode) {
                    instruction.mem_size = 4;
                } else if [Opcode::VSQRTSD, Opcode::VADDSD, Opcode::VMULSD, Opcode::VSUBSD, Opcode::VMINSD, Opcode::VDIVSD, Opcode::VMAXSD].contains(&instruction.opcode) {
                    instruction.mem_size = 8;
                } else {
                    instruction.mem_size = 16;
                }
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_V_Ed_xmm => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 4;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_V_Eq_xmm => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 8;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_V_xmm_Ed => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E(words, instruction, modrm, RegisterBank::D, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 4;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_V_E_xmm_imm8 => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[3] = OperandSpec::ImmU8;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 16;
            }
            instruction.operand_count = 4;
            Ok(())
        }
        VEXOperandCode::G_ymm_V_ymm_E_xmm_imm8 => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::Y);
            instruction.regs[3].bank = RegisterBank::Y;
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[3] = OperandSpec::ImmU8;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 16;
            }
            instruction.operand_count = 4;
            Ok(())
        }
        VEXOperandCode::M_V_G_xmm => {
            let modrm = read_modrm(words)?;
            if modrm & 0xc0 == 0xc0 {
                return Err(DecodeError::InvalidOperand);
            }

            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = mem_oper;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = OperandSpec::RegRRR;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 16;
            }
            instruction.operand_count = 3;
            Ok(())
        }

        VEXOperandCode::G_ExyL_V_xyLmm => {
            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();

            let bank = if L && instruction.opcode != Opcode::VGATHERQPS && instruction.opcode != Opcode::VPGATHERQD {
                RegisterBank::Y
            } else {
                RegisterBank::X
            };

            let index_bank = if L {
                RegisterBank::Y
            } else {
                RegisterBank::X
            };

            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, bank);
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            if instruction.opcode == Opcode::VPGATHERDQ {
                instruction.regs[2].bank = RegisterBank::X;
            } else {
                instruction.regs[2].bank = index_bank;
            }
            instruction.regs[3].bank = bank;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.operands[2] = OperandSpec::RegVex;
            if mem_oper != OperandSpec::RegMMM {
                if instruction.opcode == Opcode::VPGATHERDD || instruction.opcode == Opcode::VPGATHERQD || instruction.opcode == Opcode::VGATHERDPS || instruction.opcode == Opcode::VGATHERQPS {
                    instruction.mem_size = 4;
                } else {
                    instruction.mem_size = 8;
                }
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_V_E => {
            let modrm = read_modrm(words)?;
            let bank = RegisterBank::D;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7,bank);
            instruction.regs[3].bank = bank;
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = bank as u8;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_E_V => {
            let modrm = read_modrm(words)?;
            let bank = RegisterBank::D;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7,bank);
            instruction.regs[3].bank = bank;
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.operands[2] = OperandSpec::RegVex;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = bank as u8;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_E_Ib => {
            let modrm = read_modrm(words)?;
            let bank = RegisterBank::D;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7,bank);
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[2] = OperandSpec::ImmI8;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = bank as u8;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::BMI1_F3 => {
            let modrm = read_modrm(words)?;
            instruction.opcode = match (modrm >> 3) & 7 {
                1 => {
                    Opcode::BLSR
                }
                2 => {
                    Opcode::BLSMSK
                }
                3 => {
                    Opcode::BLSI
                }
                _ => {
                    return Err(DecodeError::InvalidOpcode);
                }
            };
            let bank = RegisterBank::D;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7,bank);
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            instruction.operands[0] = OperandSpec::RegVex;
            instruction.operands[1] = mem_oper;
            instruction.operand_count = 2;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = bank as u8;
            }
            instruction.regs[3].bank = bank;
            Ok(())
        }
        VEXOperandCode::MXCSR => {
            let modrm = read_modrm(words)?;
            instruction.opcode = match (modrm >> 3) & 7 {
                2 => {
                    Opcode::VLDMXCSR
                }
                3 => {
                    Opcode::VSTMXCSR
                }
                _ => {
                    return Err(DecodeError::InvalidOpcode);
                }
            };
            let mem_oper = read_E(words, instruction, modrm, RegisterBank::D, sink)?;
            if let OperandSpec::RegMMM = mem_oper {
                return Err(DecodeError::InvalidOperand);
            }
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 4;
            }
            instruction.operands[0] = mem_oper;
            instruction.operand_count = 1;
            Ok(())
        }
        VEXOperandCode::G_E_xyLmm_imm8 => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }

            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();

            let bank = if L {
                RegisterBank::Y
            } else {
                RegisterBank::X
            };

            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, bank);
            let mem_oper = read_E(words, instruction, modrm, bank, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[2] = OperandSpec::ImmU8;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 16;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_E_xmm_imm8 => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }

            #[allow(non_snake_case)]
            let L = instruction.prefixes.vex_unchecked().l();
            if L {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::X);
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[2] = OperandSpec::ImmU8;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 16;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_E_ymm_imm8 => {
            if instruction.regs[3].num != 0 {
                return Err(DecodeError::InvalidOperand);
            }
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7, RegisterBank::Y);
            let mem_oper = read_E_ymm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[2] = OperandSpec::ImmU8;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 32;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_V_E_ymm_ymm4 => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7,RegisterBank::Y);
            instruction.regs[3].bank = RegisterBank::Y;
            let mem_oper = read_E_ymm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)? >> 4;
            instruction.operands[3] = OperandSpec::Reg4;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 32;
            }
            instruction.operand_count = 4;
            Ok(())
        }
        VEXOperandCode::G_V_E_xmm_xmm4 => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7,RegisterBank::X);
            instruction.regs[3].bank = RegisterBank::X;
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)? >> 4;
            instruction.operands[3] = OperandSpec::Reg4;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 16;
            }
            instruction.operand_count = 4;
            Ok(())
        }
        VEXOperandCode::G_V_ymm_E_xmm => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7,RegisterBank::Y);
            instruction.regs[3].bank = RegisterBank::Y;
            let mem_oper = read_E_xmm(words, instruction, modrm, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            if mem_oper != OperandSpec::RegMMM {
                instruction.mem_size = 16;
            }
            instruction.operand_count = 3;
            Ok(())
        }
        VEXOperandCode::G_V_xmm_Ev_imm8 => {
            let modrm = read_modrm(words)?;
            instruction.regs[0] =
                RegSpec::from_parts((modrm >> 3) & 7,RegisterBank::X);
            instruction.regs[3].bank = RegisterBank::X;
            // TODO: but the memory access is word-sized
            let mem_oper = read_E(words, instruction, modrm, RegisterBank::D, sink)?;
            instruction.operands[0] = OperandSpec::RegRRR;
            instruction.operands[1] = OperandSpec::RegVex;
            instruction.operands[2] = mem_oper;
            instruction.imm = read_imm_unsigned(words, 1)?;
            instruction.operands[3] = OperandSpec::ImmI8;
            if mem_oper != OperandSpec::RegMMM {
                match instruction.opcode {
                    Opcode::VPINSRB => {
                        instruction.mem_size = 1;
                    }
                    Opcode::VPINSRW => {
                        instruction.mem_size = 2;
                    }
                    Opcode::VINSERTPS |
                    Opcode::VPINSRD => {
                        instruction.mem_size = 4;
                    }
                    _ => {
                        instruction.mem_size = 8;
                    }
                }
            }
            instruction.operand_count = 4;
            Ok(())
        }

    }
}

#[inline(never)]
fn read_vex_instruction<
    T: Reader<<Arch as yaxpeax_arch::Arch>::Address, <Arch as yaxpeax_arch::Arch>::Word>,
    S: DescriptionSink<FieldDescription>,
>(opcode_map: VEXOpcodeMap, words: &mut T, instruction: &mut Instruction, p: VEXOpcodePrefix, sink: &mut S) -> Result<(), DecodeError> {
    let opcode_start = words.offset() as u32 * 8;
    let opc = words.next().ok().ok_or(DecodeError::ExhaustedInput)?;

    // the name of this bit is `L` in the documentation, so use the same name here.
    #[allow(non_snake_case)]
    let L = instruction.prefixes.vex_unchecked().l();

//    println!("reading vex instruction from opcode prefix {:?}, L: {}, opc: {:#x}, map:{:?}", p, L, opc, opcode_map);
//    println!("w? {}", instruction.prefixes.vex_unchecked().w());

    // several combinations simply have no instructions. check for those first.
    let (opcode, operand_code) = match opcode_map {
        VEXOpcodeMap::Map0F => {
            match p {
                VEXOpcodePrefix::None => {
                    match opc {
                        0x10 => (Opcode::VMOVUPS, VEXOperandCode::G_E_xyLmm),
                        0x11 => (Opcode::VMOVUPS, VEXOperandCode::E_G_xyLmm),
                        0x12 => (Opcode::Invalid, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::VMOVLPS_12
                        }),
                        0x13 => (Opcode::VMOVLPS, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::M_G_xmm
                        }),
                        0x14 => (Opcode::VUNPCKLPS, VEXOperandCode::G_V_E_xyLmm),
                        0x15 => (Opcode::VUNPCKHPS, VEXOperandCode::G_V_E_xyLmm),
                        0x16 => (Opcode::Invalid, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::VMOVHPS_16
                        }),
                        0x17 => (Opcode::VMOVHPS, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::M_G_xmm
                        }),
                        0x28 => (Opcode::VMOVAPS, VEXOperandCode::G_E_xyLmm),
                        0x29 => (Opcode::VMOVAPS, VEXOperandCode::E_G_xyLmm),
                        0x2B => (Opcode::VMOVNTPS, if L {
                            VEXOperandCode::M_G_ymm
                        } else {
                            VEXOperandCode::M_G_xmm
                        }),
                        0x2e => (Opcode::VUCOMISS, VEXOperandCode::G_E_xmm),
                        0x2f => (Opcode::VCOMISS, VEXOperandCode::G_E_xmm),
                        0x50 => (Opcode::VMOVMSKPS, VEXOperandCode::Ud_G_xyLmm),
                        0x51 => (Opcode::VSQRTPS, VEXOperandCode::G_E_xyLmm),
                        0x52 => (Opcode::VRSQRTPS, VEXOperandCode::G_E_xyLmm),
                        0x53 => (Opcode::VRCPPS, VEXOperandCode::G_E_xyLmm),
                        0x54 => (Opcode::VANDPS, VEXOperandCode::G_V_E_xyLmm),
                        0x55 => (Opcode::VANDNPS, VEXOperandCode::G_V_E_xyLmm),
                        0x56 => (Opcode::VORPS, VEXOperandCode::G_V_E_xyLmm),
                        0x57 => (Opcode::VXORPS, VEXOperandCode::G_V_E_xyLmm),
                        0x58 => (Opcode::VADDPS, VEXOperandCode::G_V_E_xyLmm),
                        0x59 => (Opcode::VMULPS, VEXOperandCode::G_V_E_xyLmm),
                        0x5A => (Opcode::VCVTPS2PD, if L {
                            VEXOperandCode::G_ymm_E_xmm
                        } else {
                            VEXOperandCode::G_E_xmm
                        }),
                        0x5B => (Opcode::VCVTDQ2PS, VEXOperandCode::G_E_xyLmm),
                        0x5C => (Opcode::VSUBPS, VEXOperandCode::G_V_E_xyLmm),
                        0x5D => (Opcode::VMINPS, VEXOperandCode::G_V_E_xyLmm),
                        0x5E => (Opcode::VDIVPS, VEXOperandCode::G_V_E_xyLmm),
                        0x5F => (Opcode::VMAXPS, VEXOperandCode::G_V_E_xyLmm),
                        0x77 => if L {
                            (Opcode::VZEROALL, VEXOperandCode::Nothing)
                        } else {
                            (Opcode::VZEROUPPER, VEXOperandCode::Nothing)
                        },
                        0xAE => (Opcode::Invalid, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::MXCSR
                        }),
                        0xC2 => (Opcode::VCMPPS, VEXOperandCode::G_V_E_xyLmm_imm8),
                        0xC6 => (Opcode::VSHUFPS, VEXOperandCode::G_V_E_xyLmm_imm8),
                        _ => {
                            return Err(DecodeError::InvalidOpcode);
                        }
                    }
                },
                VEXOpcodePrefix::Prefix66 => {
                    match opc {
//                        0x0a => (Opcode::VROUNDSS, VEXOperandCode::G_V_E_xmm_imm8),
//                        0x0b => (Opcode::VROUNDSD, VEXOperandCode::G_V_E_xmm_imm8),
                        0x10 => (Opcode::VMOVUPD, VEXOperandCode::G_E_xyLmm),
                        0x11 => (Opcode::VMOVUPD, VEXOperandCode::G_E_xyLmm),
                        0x12 => (Opcode::VMOVLPD, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::G_V_M_xmm
                        }),
                        0x13 => (Opcode::VMOVLPD, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::M_G_xmm
                        }),
                        0x14 => (Opcode::VUNPCKLPD, VEXOperandCode::G_V_E_xyLmm),
                        0x15 => (Opcode::VUNPCKHPD, VEXOperandCode::G_V_E_xyLmm),
                        0x16 => (Opcode::VMOVHPD, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::G_V_M_xmm
                        }),
                        0x17 => (Opcode::VMOVHPD, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::M_G_xmm
                        }),
                        0x28 => (Opcode::VMOVAPD, VEXOperandCode::G_E_xyLmm),
                        0x29 => (Opcode::VMOVAPD, VEXOperandCode::E_G_xyLmm),
                        0x2B => (Opcode::VMOVNTPD, VEXOperandCode::M_G_xyLmm),
                        0x2e => (Opcode::VUCOMISD, VEXOperandCode::G_E_xmm),
                        0x2f => (Opcode::VCOMISD, VEXOperandCode::G_E_xmm),
                        0x50 => (Opcode::VMOVMSKPD, if L {
                            VEXOperandCode::Gd_U_ymm
                        } else {
                            VEXOperandCode::Gd_U_xmm
                        }),
                        0x51 => (Opcode::VSQRTPD, VEXOperandCode::G_E_xyLmm),
                        0x54 => (Opcode::VANDPD, VEXOperandCode::G_V_E_xyLmm),
                        0x55 => (Opcode::VANDNPD, VEXOperandCode::G_V_E_xyLmm),
                        0x56 => (Opcode::VORPD, VEXOperandCode::G_V_E_xyLmm),
                        0x57 => (Opcode::VXORPD, VEXOperandCode::G_V_E_xyLmm),
                        0x58 => (Opcode::VADDPD, VEXOperandCode::G_V_E_xyLmm),
                        0x59 => (Opcode::VMULPD, VEXOperandCode::G_V_E_xyLmm),
                        0x5A => (Opcode::VCVTPD2PS, if L {
                            VEXOperandCode::G_xmm_E_ymm
                        } else {
                            VEXOperandCode::G_xmm_E_xmm
                        }),
                        0x5B => (Opcode::VCVTPS2DQ, VEXOperandCode::G_E_xyLmm),
                        0x5C => (Opcode::VSUBPD, VEXOperandCode::G_V_E_xyLmm),
                        0x5D => (Opcode::VMINPD, VEXOperandCode::G_V_E_xyLmm),
                        0x5E => (Opcode::VDIVPD, VEXOperandCode::G_V_E_xyLmm),
                        0x5F => (Opcode::VMAXPD, VEXOperandCode::G_V_E_xyLmm),
                        0x60 => (Opcode::VPUNPCKLBW, VEXOperandCode::G_V_E_xyLmm),
                        0x61 => (Opcode::VPUNPCKLWD, VEXOperandCode::G_V_E_xyLmm),
                        0x62 => (Opcode::VPUNPCKLDQ, VEXOperandCode::G_V_E_xyLmm),
                        0x63 => (Opcode::VPACKSSWB, VEXOperandCode::G_V_E_xyLmm),
                        0x64 => (Opcode::VPCMPGTB, VEXOperandCode::G_V_E_xyLmm),
                        0x65 => (Opcode::VPCMPGTW, VEXOperandCode::G_V_E_xyLmm),
                        0x66 => (Opcode::VPCMPGTD, VEXOperandCode::G_V_E_xyLmm),
                        0x67 => (Opcode::VPACKUSWB, VEXOperandCode::G_V_E_xyLmm),
                        0x68 => (Opcode::VPUNPCKHBW, VEXOperandCode::G_V_E_xyLmm),
                        0x69 => (Opcode::VPUNPCKHWD, VEXOperandCode::G_V_E_xyLmm),
                        0x6A => (Opcode::VPUNPCKHDQ, VEXOperandCode::G_V_E_xyLmm),
                        0x6B => (Opcode::VPACKSSDW, VEXOperandCode::G_V_E_xyLmm),
                        0x6C => (Opcode::VPUNPCKLQDQ, VEXOperandCode::G_V_E_xyLmm),
                        0x6D => (Opcode::VPUNPCKHQDQ, VEXOperandCode::G_V_E_xyLmm),
                        0x6E => {
                            (Opcode::VMOVD, if L {
                                return Err(DecodeError::InvalidOpcode);
                            } else {
                                VEXOperandCode::G_xmm_Ed
                            })
                        },
                        0x6F => (Opcode::VMOVDQA, VEXOperandCode::G_E_xyLmm),
                        0x70 => (Opcode::VPSHUFD, VEXOperandCode::G_E_xyLmm_imm8),
                        0x71 => (Opcode::Invalid, VEXOperandCode::VPS_71),
                        0x72 => (Opcode::Invalid, VEXOperandCode::VPS_72),
                        0x73 => (Opcode::Invalid, VEXOperandCode::VPS_73),
                        0x74 => (Opcode::VPCMPEQB, VEXOperandCode::G_V_E_xyLmm),
                        0x75 => (Opcode::VPCMPEQW, VEXOperandCode::G_V_E_xyLmm),
                        0x76 => (Opcode::VPCMPEQD, VEXOperandCode::G_V_E_xyLmm),
                        0x7C => (Opcode::VHADDPD, VEXOperandCode::G_V_E_xyLmm),
                        0x7D => (Opcode::VHSUBPD, VEXOperandCode::G_V_E_xyLmm),
                        0x7E => {
                            (Opcode::VMOVD, if L {
                                return Err(DecodeError::InvalidOpcode);
                            } else {
                                VEXOperandCode::Ed_G_xmm
                            })
                        }
                        0x7F => (Opcode::VMOVDQA, VEXOperandCode::E_G_xyLmm),
                        0xC2 => (Opcode::VCMPPD, VEXOperandCode::G_V_E_xyLmm_imm8),
                        0xC4 => (Opcode::VPINSRW, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::G_V_xmm_Ev_imm8
                        }),
                        0xC5 => (Opcode::VPEXTRW, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::Ud_G_xmm_imm8
                        }),
                        0xC6 => (Opcode::VSHUFPD, VEXOperandCode::G_V_E_xyLmm_imm8),
                        0xD0 => (Opcode::VADDSUBPD, VEXOperandCode::G_V_E_xyLmm),
                        0xD1 => (Opcode::VPSRLW, if L {
                            VEXOperandCode::G_V_ymm_E_xmm
                        } else {
                            VEXOperandCode::G_V_E_xmm
                        }),
                        0xD2 => (Opcode::VPSRLD, if L {
                            VEXOperandCode::G_V_ymm_E_xmm
                        } else {
                            VEXOperandCode::G_V_E_xmm
                        }),
                        0xD3 => (Opcode::VPSRLQ, if L {
                            VEXOperandCode::G_V_ymm_E_xmm
                        } else {
                            VEXOperandCode::G_V_E_xmm
                        }),
                        0xD4 => (Opcode::VPADDQ, VEXOperandCode::G_V_E_xyLmm),
                        0xD5 => (Opcode::VPMULLW, VEXOperandCode::G_V_E_xyLmm),
                        0xD6 => (Opcode::VMOVD, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::G_E_xmm
                        }),
                        0xD7 => (Opcode::VPMOVMSKB, VEXOperandCode::Ud_G_xyLmm),
                        0xD8 => (Opcode::VPSUBUSB, VEXOperandCode::G_V_E_xyLmm),
                        0xD9 => (Opcode::VPSUBUSW, VEXOperandCode::G_V_E_xyLmm),
                        0xDA => (Opcode::VPMINUB, VEXOperandCode::G_V_E_xyLmm),
                        0xDB => (Opcode::VPAND, VEXOperandCode::G_V_E_xyLmm),
                        0xDC => (Opcode::VPADDUSB, VEXOperandCode::G_V_E_xyLmm),
                        0xDD => (Opcode::VPADDUSW, VEXOperandCode::G_V_E_xyLmm),
                        0xDE => (Opcode::VPMAXUB, VEXOperandCode::G_V_E_xyLmm),
                        0xDF => (Opcode::VPANDN, VEXOperandCode::G_V_E_xyLmm),
                        0xE0 => (Opcode::VPAVGB, VEXOperandCode::G_V_E_xyLmm),
                        0xE1 => (Opcode::VPSRAW, if L {
                            VEXOperandCode::G_V_ymm_E_xmm
                        } else {
                            VEXOperandCode::G_V_E_xmm
                        }),
                        0xE2 => (Opcode::VPSRAD, if L {
                            VEXOperandCode::G_V_ymm_E_xmm
                        } else {
                            VEXOperandCode::G_V_E_xmm
                        }),
                        0xE3 => (Opcode::VPAVGW, VEXOperandCode::G_V_E_xyLmm),
                        0xE4 => (Opcode::VPMULHUW, VEXOperandCode::G_V_E_xyLmm),
                        0xE5 => (Opcode::VPMULHW, VEXOperandCode::G_V_E_xyLmm),
                        0xE6 => (Opcode::VCVTTPD2DQ, if L {
                            VEXOperandCode::G_xmm_E_ymm
                        } else {
                            VEXOperandCode::G_E_xmm
                        }),
                        0xE7 => (Opcode::VMOVNTDQ, VEXOperandCode::M_G_xyLmm),
                        0xE8 => (Opcode::VPSUBSB, VEXOperandCode::G_V_E_xyLmm),
                        0xE9 => (Opcode::VPSUBSW, VEXOperandCode::G_V_E_xyLmm),
                        0xEA => (Opcode::VPMINSW, VEXOperandCode::G_V_E_xyLmm),
                        0xEB => (Opcode::VPOR, VEXOperandCode::G_V_E_xyLmm),
                        0xEC => (Opcode::VPADDSB, VEXOperandCode::G_V_E_xyLmm),
                        0xED => (Opcode::VPADDSW, VEXOperandCode::G_V_E_xyLmm),
                        0xEE => (Opcode::VPMAXSW, VEXOperandCode::G_V_E_xyLmm),
                        0xEF => (Opcode::VPXOR, VEXOperandCode::G_V_E_xyLmm),
                        0xF1 => (Opcode::VPSLLW, if L {
                            VEXOperandCode::G_V_ymm_E_xmm
                        } else {
                            VEXOperandCode::G_V_E_xmm
                        }),
                        0xF2 => (Opcode::VPSLLD, if L {
                            VEXOperandCode::G_V_ymm_E_xmm
                        } else {
                            VEXOperandCode::G_V_E_xmm
                        }),
                        0xF3 => (Opcode::VPSLLQ, if L {
                            VEXOperandCode::G_V_ymm_E_xmm
                        } else {
                            VEXOperandCode::G_V_E_xmm
                        }),
                        0xF4 => (Opcode::VPMULUDQ, VEXOperandCode::G_V_E_xyLmm),
                        0xF5 => (Opcode::VPMADDWD, VEXOperandCode::G_V_E_xyLmm),
                        0xF6 => (Opcode::VPSADBW, VEXOperandCode::G_V_E_xyLmm),
                        0xF7 => (Opcode::VMASKMOVDQU, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::G_U_xmm
                        }),
                        0xF8 => (Opcode::VPSUBB, VEXOperandCode::G_V_E_xyLmm),
                        0xF9 => (Opcode::VPSUBW, VEXOperandCode::G_V_E_xyLmm),
                        0xFA => (Opcode::VPSUBD, VEXOperandCode::G_V_E_xyLmm),
                        0xFB => (Opcode::VPSUBQ, VEXOperandCode::G_V_E_xyLmm),
                        0xFC => (Opcode::VPADDB, VEXOperandCode::G_V_E_xyLmm),
                        0xFD => (Opcode::VPADDW, VEXOperandCode::G_V_E_xyLmm),
                        0xFE => (Opcode::VPADDD, VEXOperandCode::G_V_E_xyLmm),
                        _ => {
                            return Err(DecodeError::InvalidOpcode);
                        }
                    }
                }
                VEXOpcodePrefix::PrefixF2 => {
                    match opc {
                        0x10 => (Opcode::VMOVSD, VEXOperandCode::VMOVSD_10),
                        0x11 => (Opcode::VMOVSD, VEXOperandCode::VMOVSD_11),
                        0x12 => (Opcode::VMOVDDUP, VEXOperandCode::G_E_xyLmm),
                        0x2a => (Opcode::VCVTSI2SD, {
                            VEXOperandCode::G_V_xmm_Ed // 32-bit last operand
                        }),
                        0x2c => (Opcode::VCVTTSD2SI, {
                            VEXOperandCode::VCVT_Gd_Eq_xmm
                        }),
                        0x2d => (Opcode::VCVTSD2SI, {
                            VEXOperandCode::VCVT_Gd_Eq_xmm
                        }),
                        0x51 => (Opcode::VSQRTSD, VEXOperandCode::G_V_E_xmm),
                        0x58 => (Opcode::VADDSD, VEXOperandCode::G_V_E_xmm),
                        0x59 => (Opcode::VMULSD, VEXOperandCode::G_V_E_xmm),
                        0x5a => (Opcode::VCVTSD2SS, VEXOperandCode::G_V_Eq_xmm),
                        0x5c => (Opcode::VSUBSD, VEXOperandCode::G_V_E_xmm),
                        0x5d => (Opcode::VMINSD, VEXOperandCode::G_V_E_xmm),
                        0x5e => (Opcode::VDIVSD, VEXOperandCode::G_V_E_xmm),
                        0x5f => (Opcode::VMAXSD, VEXOperandCode::G_V_E_xmm),
                        0x70 => (Opcode::VPSHUFLW, VEXOperandCode::G_E_xyLmm_imm8),
                        0x7c => (Opcode::VHADDPS, VEXOperandCode::G_V_E_xyLmm),
                        0x7d => (Opcode::VHSUBPS, VEXOperandCode::G_V_E_xyLmm),
                        0xc2 => (Opcode::VCMPSD, VEXOperandCode::G_V_E_xmm_imm8),
                        0xd0 => (Opcode::VADDSUBPS, VEXOperandCode::G_V_E_xyLmm),
                        0xe6 => (Opcode::VCVTPD2DQ, if L {
                            VEXOperandCode::G_xmm_E_ymm
                        } else {
                            VEXOperandCode::G_xmm_E_xmm
                        }),
                        0xf0 => (Opcode::VLDDQU, if L {
                            VEXOperandCode::G_M_ymm
                        } else {
                            VEXOperandCode::G_M_xmm
                        }),
                        _ => {
                            return Err(DecodeError::InvalidOpcode);
                        }
                    }
                }
                VEXOpcodePrefix::PrefixF3 => {
                    match opc {
                        0x10 => (Opcode::VMOVSS, VEXOperandCode::VMOVSS_10),
                        0x11 => (Opcode::VMOVSS, VEXOperandCode::VMOVSS_11),
                        0x12 => (Opcode::VMOVSLDUP, if L { VEXOperandCode::G_E_ymm } else { VEXOperandCode::G_E_xmm }),
                        0x16 => (Opcode::VMOVSHDUP, if L { VEXOperandCode::G_E_ymm } else { VEXOperandCode::G_E_xmm }),
                        0x2a => (Opcode::VCVTSI2SS, {
                            VEXOperandCode::G_V_xmm_Ed
                        }),
                        0x2c => (Opcode::VCVTTSS2SI, {
                            VEXOperandCode::VCVT_Gd_Ed_xmm
                        }),
                        0x2d => (Opcode::VCVTSS2SI, {
                            VEXOperandCode::VCVT_Gd_Ed_xmm
                        }),
                        0x51 => (Opcode::VSQRTSS, VEXOperandCode::G_V_E_xmm),
                        0x52 => (Opcode::VRSQRTSS, VEXOperandCode::G_V_E_xmm),
                        0x53 => (Opcode::VRCPSS, VEXOperandCode::G_V_E_xmm),
                        0x58 => (Opcode::VADDSS, VEXOperandCode::G_V_E_xmm),
                        0x59 => (Opcode::VMULSS, VEXOperandCode::G_V_E_xmm),
                        0x5a => (Opcode::VCVTSS2SD, VEXOperandCode::G_V_Ed_xmm),
                        0x5b => (Opcode::VCVTTPS2DQ, if L { VEXOperandCode::G_ymm_E_ymm } else { VEXOperandCode::G_xmm_E_xmm }),
                        0x5c => (Opcode::VSUBSS, VEXOperandCode::G_V_E_xmm),
                        0x5d => (Opcode::VMINSS, VEXOperandCode::G_V_E_xmm),
                        0x5e => (Opcode::VDIVSS, VEXOperandCode::G_V_E_xmm),
                        0x5f => (Opcode::VMAXSS, VEXOperandCode::G_V_E_xmm),
                        0x6f => (Opcode::VMOVDQU, if L { VEXOperandCode::G_E_ymm } else { VEXOperandCode::G_E_xmm }),
                        0x70 => (Opcode::VPSHUFHW, VEXOperandCode::G_E_xyLmm_imm8),
                        0x7e => (Opcode::VMOVD, if L { return Err(DecodeError::InvalidOpcode); } else { VEXOperandCode::G_E_xmm }),
                        0x7f => (Opcode::VMOVDQU, VEXOperandCode::E_G_xyLmm),
                        0xc2 => (Opcode::VCMPSS, VEXOperandCode::G_V_E_xmm_imm8),
                        0xe6 => (Opcode::VCVTDQ2PD, if L { VEXOperandCode::G_ymm_E_xmm } else { VEXOperandCode::G_xmm_E_xmm }),
                        _ => {
                            return Err(DecodeError::InvalidOpcode);
                        }
                    }
                }
            }
        }
        VEXOpcodeMap::Map0F38 => {
            // TODO: verify rejecting invalid W bit
            if let VEXOpcodePrefix::Prefix66 = p {
                // possibly valid!
                match opc {
                    0x00 => (Opcode::VPSHUFB, VEXOperandCode::G_V_E_xyLmm),
                    0x01 => (Opcode::VPHADDW, VEXOperandCode::G_V_E_xyLmm),
                    0x02 => (Opcode::VPHADDD, VEXOperandCode::G_V_E_xyLmm),
                    0x03 => (Opcode::VPHADDSW, VEXOperandCode::G_V_E_xyLmm),
                    0x04 => (Opcode::VPMADDUBSW, VEXOperandCode::G_V_E_xyLmm),
                    0x05 => (Opcode::VPHSUBW, VEXOperandCode::G_V_E_xyLmm),
                    0x06 => (Opcode::VPHSUBD, VEXOperandCode::G_V_E_xyLmm),
                    0x07 => (Opcode::VPHSUBSW, VEXOperandCode::G_V_E_xyLmm),
                    0x08 => (Opcode::VPSIGNB, VEXOperandCode::G_V_E_xyLmm),
                    0x09 => (Opcode::VPSIGNW, VEXOperandCode::G_V_E_xyLmm),
                    0x0A => (Opcode::VPSIGND, VEXOperandCode::G_V_E_xyLmm),
                    0x0B => (Opcode::VPMULHRSW, VEXOperandCode::G_V_E_xyLmm),
                    0x0C => (Opcode::VPERMILPS, VEXOperandCode::G_V_E_xyLmm),
                    0x0D => (Opcode::VPERMILPD, VEXOperandCode::G_V_E_xyLmm),
                    0x0E => (Opcode::VTESTPS, VEXOperandCode::G_E_xyLmm),
                    0x0F => (Opcode::VTESTPD, VEXOperandCode::G_E_xyLmm),
                    0x13 => (Opcode::VCVTPH2PS, VEXOperandCode::G_E_xyLmm),
                    0x16 => (Opcode::VPERMPS, if L {
                        if instruction.prefixes.vex_unchecked().w() {
                            return Err(DecodeError::InvalidOpcode);
                        }
                        VEXOperandCode::G_V_E_ymm
                    } else {
                        return Err(DecodeError::InvalidOpcode);
                    }),
                    0x17 => (Opcode::VPTEST, VEXOperandCode::G_E_xyLmm),
                    0x18 => if instruction.prefixes.vex_unchecked().w() {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        (Opcode::VBROADCASTSS, if L {
                            VEXOperandCode::G_ymm_E_xmm
                        } else {
                            VEXOperandCode::G_E_xmm
                        })
                    },
                    0x19 => if instruction.prefixes.vex_unchecked().w() {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        (Opcode::VBROADCASTSD, if L {
                            VEXOperandCode::G_ymm_E_xmm
                        } else {
                            VEXOperandCode::G_E_xmm
                        })
                    }
                    0x1A => (Opcode::VBROADCASTF128, if L {
                        VEXOperandCode::G_ymm_M_xmm
                    } else {
                        return Err(DecodeError::InvalidOpcode);
                    }),
                    0x1C => (Opcode::VPABSB, VEXOperandCode::G_E_xyLmm),
                    0x1D => (Opcode::VPABSW, VEXOperandCode::G_E_xyLmm),
                    0x1E => (Opcode::VPABSD, VEXOperandCode::G_E_xyLmm),
                    0x20 => (Opcode::VPMOVSXBW, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x21 => (Opcode::VPMOVSXBD, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x22 => (Opcode::VPMOVSXBQ, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x23 => (Opcode::VPMOVSXWD, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x24 => (Opcode::VPMOVSXWQ, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x25 => (Opcode::VPMOVSXDQ, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x28 => (Opcode::VPMULDQ, VEXOperandCode::G_V_E_xyLmm),
                    0x29 => (Opcode::VPCMPEQQ, VEXOperandCode::G_V_E_xyLmm),
                    0x2A => (Opcode::VMOVNTDQA, if L {
                        VEXOperandCode::G_M_ymm
                    } else {
                        VEXOperandCode::G_M_xmm
                    }),
                    0x2B => (Opcode::VPACKUSDW, VEXOperandCode::G_V_E_xyLmm),
                    0x2C => (Opcode::VMASKMOVPS, if L {
                        VEXOperandCode::G_V_M_ymm
                    } else {
                        VEXOperandCode::G_V_M_xmm
                    }),
                    0x2D => (Opcode::VMASKMOVPD, if L {
                        VEXOperandCode::G_V_M_ymm
                    } else {
                        VEXOperandCode::G_V_M_xmm
                    }),
                    0x2E => (Opcode::VMASKMOVPS, if L {
                        VEXOperandCode::M_V_G_ymm
                    } else {
                        VEXOperandCode::M_V_G_xmm
                    }),
                    0x2F => (Opcode::VMASKMOVPD, if L {
                        VEXOperandCode::M_V_G_ymm
                    } else {
                        VEXOperandCode::M_V_G_xmm
                    }),
                    0x30 => (Opcode::VPMOVZXBW, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x31 => (Opcode::VPMOVZXBD, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x32 => (Opcode::VPMOVZXBQ, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x33 => (Opcode::VPMOVZXWD, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x34 => (Opcode::VPMOVZXWQ, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x35 => (Opcode::VPMOVZXDQ, if L {
                        VEXOperandCode::G_ymm_E_xmm
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x36 => (Opcode::VPERMD, if L {
                        VEXOperandCode::G_V_E_ymm
                    } else {
                        return Err(DecodeError::InvalidOpcode);
                    }),
                    0x37 => (Opcode::VPCMPGTQ, VEXOperandCode::G_V_E_xyLmm),
                    0x38 => (Opcode::VPMINSB, VEXOperandCode::G_V_E_xyLmm),
                    0x39 => (Opcode::VPMINSD, VEXOperandCode::G_V_E_xyLmm),
                    0x3A => (Opcode::VPMINUW, VEXOperandCode::G_V_E_xyLmm),
                    0x3B => (Opcode::VPMINUD, VEXOperandCode::G_V_E_xyLmm),
                    0x3C => (Opcode::VPMAXSB, VEXOperandCode::G_V_E_xyLmm),
                    0x3D => (Opcode::VPMAXSD, VEXOperandCode::G_V_E_xyLmm),
                    0x3E => (Opcode::VPMAXUW, VEXOperandCode::G_V_E_xyLmm),
                    0x3F => (Opcode::VPMAXUD, VEXOperandCode::G_V_E_xyLmm),
                    0x40 => (Opcode::VPMULLD, VEXOperandCode::G_V_E_xyLmm),
                    0x41 => (Opcode::VPHMINPOSUW, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0x45 => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VPSRLVQ, VEXOperandCode::G_V_E_xyLmm)
                    } else {
                        (Opcode::VPSRLVD, VEXOperandCode::G_V_E_xyLmm)
                    },
                    0x46 => (Opcode::VPSRAVD, if L {
                        if instruction.prefixes.vex_unchecked().w() {
                            return Err(DecodeError::InvalidOpcode);
                        }
                        VEXOperandCode::G_V_E_ymm
                    } else {
                        if instruction.prefixes.vex_unchecked().w() {
                            return Err(DecodeError::InvalidOpcode);
                        }
                        VEXOperandCode::G_V_E_xmm
                    }),
                    0x47 => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VPSLLVQ, VEXOperandCode::G_V_E_xyLmm)
                    } else {
                        (Opcode::VPSLLVD, VEXOperandCode::G_V_E_xyLmm)
                    },
                    0x58 => (Opcode::VPBROADCASTD, VEXOperandCode::G_E_xyLmm),
                    0x59 => (Opcode::VPBROADCASTQ, VEXOperandCode::G_E_xyLmm),
                    0x5A => (Opcode::VBROADCASTI128, if L {
                        if instruction.prefixes.vex_unchecked().w() {
                            return Err(DecodeError::InvalidOpcode);
                        }
                        VEXOperandCode::G_ymm_M_xmm
                    } else {
                        return Err(DecodeError::InvalidOpcode);
                    }),
                    0x78 => (Opcode::VPBROADCASTB, if L {
                        VEXOperandCode::G_E_ymm
                    } else {
                        VEXOperandCode::G_E_ymm
                    }),
                    0x79 => (Opcode::VPBROADCASTW, if L {
                        VEXOperandCode::G_E_ymm
                    } else {
                        VEXOperandCode::G_E_ymm
                    }),
                    0x8C => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VPMASKMOVQ, if L {
                                VEXOperandCode::G_V_M_ymm
                            } else {
                                VEXOperandCode::G_V_M_xmm
                            })
                        } else {
                            (Opcode::VPMASKMOVD, if L {
                                VEXOperandCode::G_V_M_ymm
                            } else {
                                VEXOperandCode::G_V_M_xmm
                            })
                        }
                    },
                    0x8E => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VPMASKMOVQ, if L {
                                VEXOperandCode::M_V_G_ymm
                            } else {
                                VEXOperandCode::M_V_G_xmm
                            })
                        } else {
                            (Opcode::VPMASKMOVD, if L {
                                VEXOperandCode::M_V_G_ymm
                            } else {
                                VEXOperandCode::M_V_G_xmm
                            })
                        }
                    },
                    0x90 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VPGATHERDQ, VEXOperandCode::G_ExyL_V_xyLmm)
                        } else {
                            (Opcode::VPGATHERDD, VEXOperandCode::G_ExyL_V_xyLmm)
                        }
                    },
                    0x91 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VPGATHERQQ, VEXOperandCode::G_ExyL_V_xyLmm)
                        } else {
                            (Opcode::VPGATHERQD, VEXOperandCode::G_ExyL_V_xyLmm)
                        }
                    },
                    0x92 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VGATHERDPD, VEXOperandCode::G_ExyL_V_xyLmm)
                        } else {
                            (Opcode::VGATHERDPS, VEXOperandCode::G_ExyL_V_xyLmm)
                        }
                    },
                    0x93 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VGATHERQPD, VEXOperandCode::G_ExyL_V_xyLmm)
                        } else {
                            (Opcode::VGATHERQPS, VEXOperandCode::G_ExyL_V_xyLmm)
                        }
                    },
                    0x96 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMADDSUB132PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMADDSUB132PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0x97 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMSUBADD132PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMSUBADD132PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0x98 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMADD132PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMADD132PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0x99 => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFMADD132SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFMADD132SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0x9A => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMSUB132PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMSUB132PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0x9B => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFMSUB132SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFMSUB132SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0x9C => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFNMADD132PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFNMADD132PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0x9D => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFNMADD132SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFNMADD132SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0x9E => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFNMSUB132PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFNMSUB132PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0x9F => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFNMSUB132SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFNMSUB132SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0xA6 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMADDSUB213PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMADDSUB213PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xA7 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMSUBADD213PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMSUBADD213PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xA8 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMADD213PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMADD213PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xA9 => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFMADD231SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFMADD231SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0xAA => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMSUB213PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMSUB213PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xAB => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFMSUB231SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFMSUB231SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0xAC => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFNMADD213PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFNMADD213PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xAD => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFNMADD213SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFNMADD213SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0xAE => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFNMSUB213PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFNMSUB213PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xAF => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFNMSUB213SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFNMSUB213SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0xB6 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMADDSUB231PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMADDSUB231PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xB7 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMSUBADD231PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMSUBADD231PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xB8 => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMADD231PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMADD231PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xB9 => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFMADD231SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFMADD231SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0xBA => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFMSUB231PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFMSUB231PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xBB => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFMSUB231SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFMSUB231SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0xBC => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFNMADD231PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFNMADD231PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xBD => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFNMADD231SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFNMADD231SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0xBE => {
                        if instruction.prefixes.vex_unchecked().w() {
                            (Opcode::VFNMSUB231PD, VEXOperandCode::G_V_E_xyLmm)
                        } else {
                            (Opcode::VFNMSUB231PS, VEXOperandCode::G_V_E_xyLmm)
                        }
                    },
                    0xBF => if instruction.prefixes.vex_unchecked().w() {
                        (Opcode::VFNMSUB231SD, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    } else {
                        (Opcode::VFNMSUB231SS, VEXOperandCode::G_V_E_xmm /* 64bit */)
                    },
                    0xDB => (Opcode::VAESIMC, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_E_xmm
                    }),
                    0xDC => (Opcode::VAESENC, VEXOperandCode::G_V_E_xyLmm),
                    0xDD => (Opcode::VAESENCLAST, VEXOperandCode::G_V_E_xyLmm),
                    0xDE => (Opcode::VAESDEC, VEXOperandCode::G_V_E_xyLmm),
                    0xDF => (Opcode::VAESDECLAST, VEXOperandCode::G_V_E_xyLmm),
                    0xF7 => (Opcode::SHLX, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_E_V
                    }),
                    _ => {
                        return Err(DecodeError::InvalidOpcode);
                    }
                }
            } else if let VEXOpcodePrefix::PrefixF2 = p {
                match opc {
                    0xF5 => (Opcode::PDEP, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_V_E
                    }),
                    0xF6 => (Opcode::MULX, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_V_E
                    }),
                    0xF7 => (Opcode::SHRX, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_E_V
                    }),
                    _ => {
                        return Err(DecodeError::InvalidOpcode);
                    }
                }
            } else if let VEXOpcodePrefix::PrefixF3 = p {
                match opc {
                    0xF5 => (Opcode::PEXT, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_V_E
                    }),
                    0xF7 => (Opcode::SARX, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_E_V
                    }),
                    _ => {
                        return Err(DecodeError::InvalidOpcode);
                    }
                }
            } else {
                match opc {
                    0xF2 => (Opcode::ANDN, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_V_E
                    }),
                    0xF3 => (Opcode::Invalid, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::BMI1_F3
                    }),
                    0xF5 => (Opcode::BZHI, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_E_V
                    }),
                    0xF7 => (Opcode::BEXTR, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_E_V
                    }),
                    _ => {
                        return Err(DecodeError::InvalidOpcode);
                    }
                }
            }
        }
        VEXOpcodeMap::Map0F3A => {
            if let VEXOpcodePrefix::Prefix66 = p {
                // possibly valid!
                match opc {
                    0x00 => (Opcode::VPERMQ, if L {
                        if !instruction.prefixes.vex_unchecked().w() {
                            return Err(DecodeError::InvalidOpcode);
                        }
                        VEXOperandCode::G_E_ymm_imm8
                    } else {
                        return Err(DecodeError::InvalidOpcode);
                    }),
                    0x01 => (Opcode::VPERMPD, if L {
                        if !instruction.prefixes.vex_unchecked().w() {
                            return Err(DecodeError::InvalidOpcode);
                        }
                        VEXOperandCode::G_E_ymm_imm8
                    } else {
                        return Err(DecodeError::InvalidOpcode);
                    }),
                    0x02 => (Opcode::VPBLENDD, if instruction.prefixes.vex_unchecked().w() {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_V_E_xyLmm_imm8
                    }),
                    0x04 => (Opcode::VPERMILPS, VEXOperandCode::G_E_xyLmm_imm8),
                    0x05 => (Opcode::VPERMILPD, VEXOperandCode::G_E_xyLmm_imm8),
                    0x06 => (Opcode::VPERM2F128, if L {
                        if instruction.prefixes.vex_unchecked().w() {
                            return Err(DecodeError::InvalidOpcode);
                        }
                        VEXOperandCode::G_V_E_ymm_imm8
                    } else {
                        return Err(DecodeError::InvalidOpcode);
                    }),
                    0x08 => (Opcode::VROUNDPS, VEXOperandCode::G_E_xyLmm_imm8),
                    0x09 => (Opcode::VROUNDPD, VEXOperandCode::G_E_xyLmm_imm8),
                    0x0A => (Opcode::VROUNDSS, VEXOperandCode::G_V_E_xmm_imm8),
                    0x0B => (Opcode::VROUNDSD, VEXOperandCode::G_V_E_xmm_imm8),
                    0x0C => (Opcode::VBLENDPS, VEXOperandCode::G_V_E_xyLmm_imm8),
                    0x0D => (Opcode::VBLENDPD, VEXOperandCode::G_V_E_xyLmm_imm8),
                    0x0E => (Opcode::VPBLENDW, VEXOperandCode::G_V_E_xyLmm_imm8),
                    0x0F => (Opcode::VPALIGNR, VEXOperandCode::G_V_E_xyLmm_imm8),
                    0x14 => (Opcode::VPEXTRB, if L || instruction.prefixes.vex_unchecked().w() {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::Ev_G_xmm_imm8
                    }),
                    0x15 => (Opcode::VPEXTRW, if L || instruction.prefixes.vex_unchecked().w() {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::Ev_G_xmm_imm8
                    }),
                    0x16 => {
                        (Opcode::VPEXTRD, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            // varies on W
                            VEXOperandCode::Ev_G_xmm_imm8
                        })
                    },
                    0x17 => (Opcode::VEXTRACTPS, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::Ev_G_xmm_imm8
                    }),
                    0x18 => if instruction.prefixes.vex_unchecked().w() {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        (Opcode::VINSERTF128, if L {
                            VEXOperandCode::G_ymm_V_ymm_E_xmm_imm8
                        } else {
                            return Err(DecodeError::InvalidOpcode);
                        })
                    },
                    0x19 => if instruction.prefixes.vex_unchecked().w() {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        (Opcode::VEXTRACTF128, if L {
                            VEXOperandCode::E_xmm_G_ymm_imm8
                        } else {
                            return Err(DecodeError::InvalidOpcode);
                        })
                    },
                    0x1D => (Opcode::VCVTPS2PH, if L {
                        VEXOperandCode::E_xmm_G_ymm_imm8
                    } else {
                        VEXOperandCode::E_G_xmm_imm8
                    }),
                    0x20 => (Opcode::VPINSRB, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_V_xmm_Ev_imm8
                    }),
                    0x21 => (Opcode::VINSERTPS, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_V_E_xmm_imm8
                    }),
                    0x22 => {
                        (Opcode::VPINSRD, if L {
                            return Err(DecodeError::InvalidOpcode);
                        } else {
                            VEXOperandCode::G_V_xmm_Ev_imm8
                        })
                    },
                    0x38 => (Opcode::VINSERTI128, if L {
                        VEXOperandCode::G_ymm_V_ymm_E_xmm_imm8
                    } else {
                        return Err(DecodeError::InvalidOpcode);
                    }),
                    0x39 => (Opcode::VEXTRACTI128, if L {
                        VEXOperandCode::E_xmm_G_ymm_imm8
                    } else {
                        return Err(DecodeError::InvalidOpcode);
                    }),
                    0x40 => (Opcode::VDPPS, VEXOperandCode::G_V_E_xyLmm_imm8),
                    0x41 => (Opcode::VDPPD, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_V_E_xmm_imm8
                    }),
                    0x42 => (Opcode::VMPSADBW, VEXOperandCode::G_V_E_xyLmm_imm8),
                    0x44 => (Opcode::VPCLMULQDQ, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_V_E_xmm_imm8
                    }),
                    0x46 => (Opcode::VPERM2I128, if L {
                        if instruction.prefixes.vex_unchecked().w() {
                            return Err(DecodeError::InvalidOpcode);
                        }
                        VEXOperandCode::G_V_E_ymm_imm8
                    } else {
                        return Err(DecodeError::InvalidOpcode);
                    }),
                    0x4A => (Opcode::VBLENDVPS, if L {
                        VEXOperandCode::G_V_E_ymm_ymm4
                    } else {
                        VEXOperandCode::G_V_E_xmm_xmm4
                    }),
                    0x4B => (Opcode::VBLENDVPD, if L {
                        VEXOperandCode::G_V_E_ymm_ymm4
                    } else {
                        VEXOperandCode::G_V_E_xmm_xmm4
                    }),
                    0x4C => if instruction.prefixes.vex_unchecked().w() {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        (Opcode::VPBLENDVB, if L {
                            VEXOperandCode::G_V_E_ymm_ymm4
                        } else {
                            VEXOperandCode::G_V_E_xmm_xmm4
                        })
                    },
                    0x60 => (Opcode::VPCMPESTRM, VEXOperandCode::G_E_xmm_imm8),
                    0x61 => (Opcode::VPCMPESTRI, VEXOperandCode::G_E_xmm_imm8),
                    0x62 => (Opcode::VPCMPISTRM, VEXOperandCode::G_E_xmm_imm8),
                    0x63 => (Opcode::VPCMPISTRI, VEXOperandCode::G_E_xmm_imm8),
                    0xDF => (Opcode::VAESKEYGENASSIST, VEXOperandCode::G_E_xmm_imm8),
                    _ => {
                        return Err(DecodeError::InvalidOpcode);
                    }
                }
            } else if let VEXOpcodePrefix::PrefixF2 = p {
                match opc {
                    0xF0 => (Opcode::RORX, if L {
                        return Err(DecodeError::InvalidOpcode);
                    } else {
                        VEXOperandCode::G_E_Ib
                    }),
                    _ => {
                        return Err(DecodeError::InvalidOpcode);
                    }
                }
            } else {
                // the only VEX* 0f3a instructions have an implied 66 prefix.
                return Err(DecodeError::InvalidOpcode);
            }
        }
    };
    instruction.opcode = opcode;

    sink.record(
        opcode_start,
        opcode_start + 7,
        InnerDescription::Opcode(instruction.opcode)
            .with_id(opcode_start)
    );
    sink.record(
        opcode_start + 7,
        opcode_start + 7,
        InnerDescription::Boundary("vex opcode ends/operands begin")
            .with_id(opcode_start + 7)
    );

    read_vex_operands(words, instruction, operand_code, sink)
}