/*
 * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */


package org.graalvm.compiler.asm.amd64;

import static jdk.vm.ci.amd64.AMD64.MASK;
import static jdk.vm.ci.amd64.AMD64.XMM;
import static jdk.vm.ci.amd64.AMD64.r12;
import static jdk.vm.ci.amd64.AMD64.r13;
import static jdk.vm.ci.amd64.AMD64.rbp;
import static jdk.vm.ci.amd64.AMD64.rsp;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.EVEXPrefixConfig.B0;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.EVEXPrefixConfig.B1;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.EVEXPrefixConfig.Z0;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.EVEXPrefixConfig.Z1;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.L128;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.L256;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.L512;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.LZ;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.M_0F;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.M_0F38;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.M_0F3A;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.P_;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.P_66;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.P_F2;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.P_F3;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.W0;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.W1;
import static org.graalvm.compiler.asm.amd64.AMD64BaseAssembler.VEXPrefixConfig.WIG;
import static org.graalvm.compiler.core.common.NumUtil.isByte;

import org.graalvm.compiler.asm.Assembler;
import org.graalvm.compiler.asm.amd64.AMD64Address.Scale;
import org.graalvm.compiler.asm.amd64.AVXKind.AVXSize;
import org.graalvm.compiler.debug.GraalError;

import jdk.vm.ci.amd64.AMD64;
import jdk.vm.ci.amd64.AMD64.CPUFeature;
import jdk.vm.ci.amd64.AMD64Kind;
import jdk.vm.ci.code.Register;
import jdk.vm.ci.code.Register.RegisterCategory;
import jdk.vm.ci.code.TargetDescription;
import jdk.vm.ci.meta.PlatformKind;

This class implements an assembler that can encode most X86 instructions.
/**
 * This class implements an assembler that can encode most X86 instructions.
 */
public abstract class AMD64BaseAssembler extends Assembler {

    private final SIMDEncoder simdEncoder;

    
Constructs an assembler for the AMD64 architecture.
/**
     * Constructs an assembler for the AMD64 architecture.
     */
    public AMD64BaseAssembler(TargetDescription target) {
        super(target);

        if (supports(CPUFeature.AVX)) {
            simdEncoder = new VEXEncoderImpl();
        } else {
            simdEncoder = new SSEEncoderImpl();
        }
    }

    
The x86 operand sizes.
/**
     * The x86 operand sizes.
     */
    public enum OperandSize {
        BYTE(1, AMD64Kind.BYTE) {
            @Override
            protected void emitImmediate(AMD64BaseAssembler asm, int imm) {
                assert imm == (byte) imm;
                asm.emitByte(imm);
            }

            @Override
            protected int immediateSize() {
                return 1;
            }
        },

        WORD(2, AMD64Kind.WORD, 0x66) {
            @Override
            protected void emitImmediate(AMD64BaseAssembler asm, int imm) {
                assert imm == (short) imm;
                asm.emitShort(imm);
            }

            @Override
            protected int immediateSize() {
                return 2;
            }
        },

        DWORD(4, AMD64Kind.DWORD) {
            @Override
            protected void emitImmediate(AMD64BaseAssembler asm, int imm) {
                asm.emitInt(imm);
            }

            @Override
            protected int immediateSize() {
                return 4;
            }
        },

        QWORD(8, AMD64Kind.QWORD) {
            @Override
            protected void emitImmediate(AMD64BaseAssembler asm, int imm) {
                asm.emitInt(imm);
            }

            @Override
            protected int immediateSize() {
                return 4;
            }
        },

        SS(4, AMD64Kind.SINGLE, 0xF3, true),

        SD(8, AMD64Kind.DOUBLE, 0xF2, true),

        PS(16, AMD64Kind.V128_SINGLE, true),

        PD(16, AMD64Kind.V128_DOUBLE, 0x66, true);

        private final int sizePrefix;
        private final int bytes;
        private final boolean xmm;
        private final AMD64Kind kind;

        OperandSize(int bytes, AMD64Kind kind) {
            this(bytes, kind, 0);
        }

        OperandSize(int bytes, AMD64Kind kind, int sizePrefix) {
            this(bytes, kind, sizePrefix, false);
        }

        OperandSize(int bytes, AMD64Kind kind, boolean xmm) {
            this(bytes, kind, 0, xmm);
        }

        OperandSize(int bytes, AMD64Kind kind, int sizePrefix, boolean xmm) {
            this.sizePrefix = sizePrefix;
            this.bytes = bytes;
            this.kind = kind;
            this.xmm = xmm;
        }

        public int getSizePrefix() {
            return sizePrefix;
        }

        public int getBytes() {
            return bytes;
        }

        public boolean isXmmType() {
            return xmm;
        }

        public AMD64Kind getKind() {
            return kind;
        }

        public static OperandSize get(PlatformKind kind) {
            for (OperandSize operandSize : OperandSize.values()) {
                if (operandSize.kind.equals(kind)) {
                    return operandSize;
                }
            }
            throw GraalError.shouldNotReachHere("Unexpected kind: " + kind.toString());
        }

        
Emit an immediate of this size. Note that immediate QWORD operands are encoded as sign-extended 32-bit values. 
Params:
asm – 
imm – /**
         * Emit an immediate of this size. Note that immediate {@link #QWORD} operands are encoded
         * as sign-extended 32-bit values.
         *
         * @param asm
         * @param imm
         */
        protected void emitImmediate(AMD64BaseAssembler asm, int imm) {
            throw new UnsupportedOperationException();
        }

        protected int immediateSize() {
            throw new UnsupportedOperationException();
        }
    }

    public static class OperandDataAnnotation extends CodeAnnotation {
        
The position (bytes from the beginning of the method) of the operand.
/**
         * The position (bytes from the beginning of the method) of the operand.
         */
        public final int operandPosition;
        
The size of the operand, in bytes.
/**
         * The size of the operand, in bytes.
         */
        public final int operandSize;
        
The position (bytes from the beginning of the method) of the next instruction. On AMD64,
RIP-relative operands are relative to this position.
/**
         * The position (bytes from the beginning of the method) of the next instruction. On AMD64,
         * RIP-relative operands are relative to this position.
         */
        public final int nextInstructionPosition;

        OperandDataAnnotation(int instructionPosition, int operandPosition, int operandSize, int nextInstructionPosition) {
            super(instructionPosition);

            this.operandPosition = operandPosition;
            this.operandSize = operandSize;
            this.nextInstructionPosition = nextInstructionPosition;
        }

        @Override
        public String toString() {
            return getClass().getSimpleName() + " instruction [" + instructionPosition + ", " + nextInstructionPosition + "[ operand at " + operandPosition + " size " + operandSize;
        }
    }

    protected void annotatePatchingImmediate(int operandOffset, int operandSize) {
        if (codePatchingAnnotationConsumer != null) {
            int pos = position();
            codePatchingAnnotationConsumer.accept(new OperandDataAnnotation(pos, pos + operandOffset, operandSize, pos + operandOffset + operandSize));
        }
    }

    public final boolean supports(CPUFeature feature) {
        return ((AMD64) target.arch).getFeatures().contains(feature);
    }

    protected static boolean inRC(RegisterCategory rc, Register r) {
        return r.getRegisterCategory().equals(rc);
    }

    protected static int encode(Register r) {
        assert r.encoding >= 0 && (inRC(XMM, r) ? r.encoding < 32 : r.encoding < 16) : "encoding out of range: " + r.encoding;
        return r.encoding & 0x7;
    }

    private static final int MinEncodingNeedsRex = 8;

    
Constants for X86 prefix bytes.
/**
     * Constants for X86 prefix bytes.
     */
    private static class Prefix {
        private static final int REX = 0x40;
        private static final int REXB = 0x41;
        private static final int REXX = 0x42;
        private static final int REXXB = 0x43;
        private static final int REXR = 0x44;
        private static final int REXRB = 0x45;
        private static final int REXRX = 0x46;
        private static final int REXRXB = 0x47;
        private static final int REXW = 0x48;
        private static final int REXWB = 0x49;
        private static final int REXWX = 0x4A;
        private static final int REXWXB = 0x4B;
        private static final int REXWR = 0x4C;
        private static final int REXWRB = 0x4D;
        private static final int REXWRX = 0x4E;
        private static final int REXWRXB = 0x4F;

        private static final int VEX2 = 0xC5;
        private static final int VEX3 = 0xC4;
        private static final int EVEX = 0x62;
    }

    protected final void rexw() {
        emitByte(Prefix.REXW);
    }

    protected final void prefix(Register reg) {
        prefix(reg, false);
    }

    protected final void prefix(Register reg, boolean byteinst) {
        int regEnc = reg.encoding;
        if (regEnc >= 8) {
            emitByte(Prefix.REXB);
        } else if (byteinst && regEnc >= 4) {
            emitByte(Prefix.REX);
        }
    }

    protected final void prefixq(Register reg) {
        if (reg.encoding < 8) {
            emitByte(Prefix.REXW);
        } else {
            emitByte(Prefix.REXWB);
        }
    }

    protected final void prefix(Register dst, Register src) {
        prefix(dst, false, src, false);
    }

    protected final void prefix(Register dst, boolean dstIsByte, Register src, boolean srcIsByte) {
        int dstEnc = dst.encoding;
        int srcEnc = src.encoding;
        if (dstEnc < 8) {
            if (srcEnc >= 8) {
                emitByte(Prefix.REXB);
            } else if ((srcIsByte && srcEnc >= 4) || (dstIsByte && dstEnc >= 4)) {
                emitByte(Prefix.REX);
            }
        } else {
            if (srcEnc < 8) {
                emitByte(Prefix.REXR);
            } else {
                emitByte(Prefix.REXRB);
            }
        }
    }

    
Creates prefix for the operands. If the given operands exceed 3 bits, the 4th bit is encoded
in the prefix.
/**
     * Creates prefix for the operands. If the given operands exceed 3 bits, the 4th bit is encoded
     * in the prefix.
     */
    protected final void prefixq(Register reg, Register rm) {
        int regEnc = reg.encoding;
        int rmEnc = rm.encoding;
        if (regEnc < 8) {
            if (rmEnc < 8) {
                emitByte(Prefix.REXW);
            } else {
                emitByte(Prefix.REXWB);
            }
        } else {
            if (rmEnc < 8) {
                emitByte(Prefix.REXWR);
            } else {
                emitByte(Prefix.REXWRB);
            }
        }
    }

    private static boolean needsRex(Register reg) {
        return reg.encoding >= MinEncodingNeedsRex;
    }

    protected final void prefix(AMD64Address adr) {
        if (needsRex(adr.getBase())) {
            if (needsRex(adr.getIndex())) {
                emitByte(Prefix.REXXB);
            } else {
                emitByte(Prefix.REXB);
            }
        } else {
            if (needsRex(adr.getIndex())) {
                emitByte(Prefix.REXX);
            }
        }
    }

    protected final void prefixq(AMD64Address adr) {
        if (needsRex(adr.getBase())) {
            if (needsRex(adr.getIndex())) {
                emitByte(Prefix.REXWXB);
            } else {
                emitByte(Prefix.REXWB);
            }
        } else {
            if (needsRex(adr.getIndex())) {
                emitByte(Prefix.REXWX);
            } else {
                emitByte(Prefix.REXW);
            }
        }
    }

    protected void prefixb(AMD64Address adr, Register reg) {
        prefix(adr, reg, true);
    }

    protected void prefix(AMD64Address adr, Register reg) {
        prefix(adr, reg, false);
    }

    protected void prefix(AMD64Address adr, Register reg, boolean byteinst) {
        if (reg.encoding < 8) {
            if (needsRex(adr.getBase())) {
                if (needsRex(adr.getIndex())) {
                    emitByte(Prefix.REXXB);
                } else {
                    emitByte(Prefix.REXB);
                }
            } else {
                if (needsRex(adr.getIndex())) {
                    emitByte(Prefix.REXX);
                } else if (byteinst && reg.encoding >= 4) {
                    emitByte(Prefix.REX);
                }
            }
        } else {
            if (needsRex(adr.getBase())) {
                if (needsRex(adr.getIndex())) {
                    emitByte(Prefix.REXRXB);
                } else {
                    emitByte(Prefix.REXRB);
                }
            } else {
                if (needsRex(adr.getIndex())) {
                    emitByte(Prefix.REXRX);
                } else {
                    emitByte(Prefix.REXR);
                }
            }
        }
    }

    protected void prefixq(AMD64Address adr, Register src) {
        if (src.encoding < 8) {
            if (needsRex(adr.getBase())) {
                if (needsRex(adr.getIndex())) {
                    emitByte(Prefix.REXWXB);
                } else {
                    emitByte(Prefix.REXWB);
                }
            } else {
                if (needsRex(adr.getIndex())) {
                    emitByte(Prefix.REXWX);
                } else {
                    emitByte(Prefix.REXW);
                }
            }
        } else {
            if (needsRex(adr.getBase())) {
                if (needsRex(adr.getIndex())) {
                    emitByte(Prefix.REXWRXB);
                } else {
                    emitByte(Prefix.REXWRB);
                }
            } else {
                if (needsRex(adr.getIndex())) {
                    emitByte(Prefix.REXWRX);
                } else {
                    emitByte(Prefix.REXWR);
                }
            }
        }
    }

    
Get RXB bits for register-register instruction. In that encoding, ModRM.rm contains a
register index. The R bit extends the ModRM.reg field and the B bit extends the ModRM.rm
field. The X bit must be 0.
/**
     * Get RXB bits for register-register instruction. In that encoding, ModRM.rm contains a
     * register index. The R bit extends the ModRM.reg field and the B bit extends the ModRM.rm
     * field. The X bit must be 0.
     */
    protected static int getRXB(Register reg, Register rm) {
        int rxb = (reg == null ? 0 : reg.encoding & 0x08) >> 1;
        rxb |= (rm == null ? 0 : rm.encoding & 0x08) >> 3;
        return rxb;
    }

    
Get RXB bits for register-memory instruction. The R bit extends the ModRM.reg field. There
are two cases for the memory operand:

ModRM.rm contains the base register: In that case, B extends the ModRM.rm field and X = 0.


There is an SIB byte: In that case, X extends SIB.index and B extends SIB.base.
/**
     * Get RXB bits for register-memory instruction. The R bit extends the ModRM.reg field. There
     * are two cases for the memory operand:<br>
     * ModRM.rm contains the base register: In that case, B extends the ModRM.rm field and X = 0.
     * <br>
     * There is an SIB byte: In that case, X extends SIB.index and B extends SIB.base.
     */
    protected static int getRXB(Register reg, AMD64Address rm) {
        int rxb = (reg == null ? 0 : reg.encoding & 0x08) >> 1;
        if (!rm.getIndex().equals(Register.None)) {
            rxb |= (rm.getIndex().encoding & 0x08) >> 2;
        }
        if (!rm.getBase().equals(Register.None)) {
            rxb |= (rm.getBase().encoding & 0x08) >> 3;
        }
        return rxb;
    }

    
Emit the ModR/M byte for one register operand and an opcode extension in the R field.

Format: [ 11 reg r/m ]
/**
     * Emit the ModR/M byte for one register operand and an opcode extension in the R field.
     * <p>
     * Format: [ 11 reg r/m ]
     */
    protected final void emitModRM(int reg, Register rm) {
        assert (reg & 0x07) == reg;
        emitByte(0xC0 | (reg << 3) | (rm.encoding & 0x07));
    }

    
Emit the ModR/M byte for two register operands.

Format: [ 11 reg r/m ]
/**
     * Emit the ModR/M byte for two register operands.
     * <p>
     * Format: [ 11 reg r/m ]
     */
    protected final void emitModRM(Register reg, Register rm) {
        emitModRM(reg.encoding & 0x07, rm);
    }

    public static final int DEFAULT_DISP8_SCALE = 1;

    
Emits the ModR/M byte and optionally the SIB byte for one register and one memory operand.
Params:
force4Byte – use 4 byte encoding for displacements that would normally fit in a byte/**
     * Emits the ModR/M byte and optionally the SIB byte for one register and one memory operand.
     *
     * @param force4Byte use 4 byte encoding for displacements that would normally fit in a byte
     */
    protected final void emitOperandHelper(Register reg, AMD64Address addr, boolean force4Byte, int additionalInstructionSize) {
        assert !reg.equals(Register.None);
        emitOperandHelper(encode(reg), addr, force4Byte, additionalInstructionSize, DEFAULT_DISP8_SCALE);
    }

    protected final void emitOperandHelper(int reg, AMD64Address addr, int additionalInstructionSize) {
        emitOperandHelper(reg, addr, false, additionalInstructionSize, DEFAULT_DISP8_SCALE);
    }

    protected final void emitOperandHelper(Register reg, AMD64Address addr, int additionalInstructionSize) {
        assert !reg.equals(Register.None);
        emitOperandHelper(encode(reg), addr, false, additionalInstructionSize, DEFAULT_DISP8_SCALE);
    }

    protected final void emitOperandHelper(Register reg, AMD64Address addr, int additionalInstructionSize, int evexDisp8Scale) {
        assert !reg.equals(Register.None);
        emitOperandHelper(encode(reg), addr, false, additionalInstructionSize, evexDisp8Scale);
    }

    
Emits the ModR/M byte and optionally the SIB byte for one memory operand and an opcode
extension in the R field.
Params:
force4Byte – use 4 byte encoding for displacements that would normally fit in a byte
additionalInstructionSize – the number of bytes that will be emitted after the operand,
           so that the start position of the next instruction can be computed even though
           this instruction has not been completely emitted yet.
evexDisp8Scale – the scaling factor for computing the compressed displacement of
           EVEX-encoded instructions. This scaling factor only matters when the emitted
           instruction uses one-byte-displacement form./**
     * Emits the ModR/M byte and optionally the SIB byte for one memory operand and an opcode
     * extension in the R field.
     *
     * @param force4Byte use 4 byte encoding for displacements that would normally fit in a byte
     * @param additionalInstructionSize the number of bytes that will be emitted after the operand,
     *            so that the start position of the next instruction can be computed even though
     *            this instruction has not been completely emitted yet.
     * @param evexDisp8Scale the scaling factor for computing the compressed displacement of
     *            EVEX-encoded instructions. This scaling factor only matters when the emitted
     *            instruction uses one-byte-displacement form.
     */
    private void emitOperandHelper(int reg, AMD64Address addr, boolean force4Byte, int additionalInstructionSize, int evexDisp8Scale) {
        assert (reg & 0x07) == reg;
        int regenc = reg << 3;

        Register base = addr.getBase();
        Register index = addr.getIndex();

        Scale scale = addr.getScale();
        int disp = addr.getDisplacement();

        if (base.equals(AMD64.rip)) { // also matches addresses returned by getPlaceholder()
            // [00 000 101] disp32
            assert index.equals(Register.None) : "cannot use RIP relative addressing with index register";
            emitByte(0x05 | regenc);
            if (codePatchingAnnotationConsumer != null && addr.instructionStartPosition >= 0) {
                codePatchingAnnotationConsumer.accept(new OperandDataAnnotation(addr.instructionStartPosition, position(), 4, position() + 4 + additionalInstructionSize));
            }
            emitInt(disp);
        } else if (base.isValid()) {
            boolean overriddenForce4Byte = force4Byte;
            int baseenc = base.isValid() ? encode(base) : 0;

            if (index.isValid()) {
                int indexenc = encode(index) << 3;
                // [base + indexscale + disp]
                if (disp == 0 && !base.equals(rbp) && !base.equals(r13)) {
                    // [base + indexscale]
                    // [00 reg 100][ss index base]
                    assert !index.equals(rsp) : "illegal addressing mode";
                    emitByte(0x04 | regenc);
                    emitByte(scale.log2 << 6 | indexenc | baseenc);
                } else {
                    if (evexDisp8Scale > 1 && !overriddenForce4Byte) {
                        if (disp % evexDisp8Scale == 0) {
                            int newDisp = disp / evexDisp8Scale;
                            if (isByte(newDisp)) {
                                disp = newDisp;
                                assert isByte(disp) && !overriddenForce4Byte;
                            }
                        } else {
                            overriddenForce4Byte = true;
                        }
                    }
                    if (isByte(disp) && !overriddenForce4Byte) {
                        // [base + indexscale + imm8]
                        // [01 reg 100][ss index base] imm8
                        assert !index.equals(rsp) : "illegal addressing mode";
                        emitByte(0x44 | regenc);
                        emitByte(scale.log2 << 6 | indexenc | baseenc);
                        emitByte(disp & 0xFF);
                    } else {
                        // [base + indexscale + disp32]
                        // [10 reg 100][ss index base] disp32
                        assert !index.equals(rsp) : "illegal addressing mode";
                        emitByte(0x84 | regenc);
                        emitByte(scale.log2 << 6 | indexenc | baseenc);
                        emitInt(disp);
                    }
                }
            } else if (base.equals(rsp) || base.equals(r12)) {
                // [rsp + disp]
                if (disp == 0) {
                    // [rsp]
                    // [00 reg 100][00 100 100]
                    emitByte(0x04 | regenc);
                    emitByte(0x24);
                } else {
                    if (evexDisp8Scale > 1 && !overriddenForce4Byte) {
                        if (disp % evexDisp8Scale == 0) {
                            int newDisp = disp / evexDisp8Scale;
                            if (isByte(newDisp)) {
                                disp = newDisp;
                                assert isByte(disp) && !overriddenForce4Byte;
                            }
                        } else {
                            overriddenForce4Byte = true;
                        }
                    }
                    if (isByte(disp) && !overriddenForce4Byte) {
                        // [rsp + imm8]
                        // [01 reg 100][00 100 100] disp8
                        emitByte(0x44 | regenc);
                        emitByte(0x24);
                        emitByte(disp & 0xFF);
                    } else {
                        // [rsp + imm32]
                        // [10 reg 100][00 100 100] disp32
                        emitByte(0x84 | regenc);
                        emitByte(0x24);
                        emitInt(disp);
                    }
                }
            } else {
                // [base + disp]
                assert !base.equals(rsp) && !base.equals(r12) : "illegal addressing mode";
                if (disp == 0 && !base.equals(rbp) && !base.equals(r13)) {
                    // [base]
                    // [00 reg base]
                    emitByte(0x00 | regenc | baseenc);
                } else {
                    if (evexDisp8Scale > 1 && !overriddenForce4Byte) {
                        if (disp % evexDisp8Scale == 0) {
                            int newDisp = disp / evexDisp8Scale;
                            if (isByte(newDisp)) {
                                disp = newDisp;
                                assert isByte(disp) && !overriddenForce4Byte;
                            }
                        } else {
                            overriddenForce4Byte = true;
                        }
                    }
                    if (isByte(disp) && !overriddenForce4Byte) {
                        // [base + disp8]
                        // [01 reg base] disp8
                        emitByte(0x40 | regenc | baseenc);
                        emitByte(disp & 0xFF);
                    } else {
                        // [base + disp32]
                        // [10 reg base] disp32
                        emitByte(0x80 | regenc | baseenc);
                        emitInt(disp);
                    }
                }
            }
        } else {
            if (index.isValid()) {
                int indexenc = encode(index) << 3;
                // [indexscale + disp]
                // [00 reg 100][ss index 101] disp32
                assert !index.equals(rsp) : "illegal addressing mode";
                emitByte(0x04 | regenc);
                emitByte(scale.log2 << 6 | indexenc | 0x05);
                emitInt(disp);
            } else {
                // [disp] ABSOLUTE
                // [00 reg 100][00 100 101] disp32
                emitByte(0x04 | regenc);
                emitByte(0x25);
                emitInt(disp);
            }
        }
    }

    private interface SIMDEncoder {

        void simdPrefix(Register xreg, Register nds, AMD64Address adr, int sizePrefix, int opcodeEscapePrefix, boolean isRexW);

        void simdPrefix(Register dst, Register nds, Register src, int sizePrefix, int opcodeEscapePrefix, boolean isRexW);

    }

    private class SSEEncoderImpl implements SIMDEncoder {

        @Override
        public void simdPrefix(Register xreg, Register nds, AMD64Address adr, int sizePrefix, int opcodeEscapePrefix, boolean isRexW) {
            assert (!nds.isValid()) || nds.equals(xreg);
            if (sizePrefix > 0) {
                emitByte(sizePrefix);
            }
            if (isRexW) {
                prefixq(adr, xreg);
            } else {
                prefix(adr, xreg);
            }
            if (opcodeEscapePrefix > 0xFF) {
                emitShort(opcodeEscapePrefix);
            } else if (opcodeEscapePrefix > 0) {
                emitByte(opcodeEscapePrefix);
            }
        }

        @Override
        public void simdPrefix(Register dst, Register nds, Register src, int sizePrefix, int opcodeEscapePrefix, boolean isRexW) {
            assert (!nds.isValid()) || nds.equals(dst) || nds.equals(src);
            if (sizePrefix > 0) {
                emitByte(sizePrefix);
            }
            if (isRexW) {
                prefixq(dst, src);
            } else {
                prefix(dst, src);
            }
            if (opcodeEscapePrefix > 0xFF) {
                emitShort(opcodeEscapePrefix);
            } else if (opcodeEscapePrefix > 0) {
                emitByte(opcodeEscapePrefix);
            }
        }
    }

    public static final class VEXPrefixConfig {
        public static final int L128 = 0;
        public static final int L256 = 1;
        public static final int L512 = 2;
        public static final int LZ = 0;

        public static final int W0 = 0;
        public static final int W1 = 1;
        public static final int WIG = 0;

        public static final int P_ = 0x0;
        public static final int P_66 = 0x1;
        public static final int P_F3 = 0x2;
        public static final int P_F2 = 0x3;

        public static final int M_0F = 0x1;
        public static final int M_0F38 = 0x2;
        public static final int M_0F3A = 0x3;

        private VEXPrefixConfig() {
        }
    }

    private class VEXEncoderImpl implements SIMDEncoder {

        private int sizePrefixToPP(int sizePrefix) {
            switch (sizePrefix) {
                case 0x66:
                    return P_66;
                case 0xF2:
                    return P_F2;
                case 0xF3:
                    return P_F3;
                default:
                    return P_;
            }
        }

        private int opcodeEscapePrefixToMMMMM(int opcodeEscapePrefix) {
            switch (opcodeEscapePrefix) {
                case 0x0F:
                    return M_0F;
                case 0x380F:
                    return M_0F38;
                case 0x3A0F:
                    return M_0F3A;
                default:
                    return 0;
            }
        }

        @Override
        public void simdPrefix(Register reg, Register nds, AMD64Address rm, int sizePrefix, int opcodeEscapePrefix, boolean isRexW) {
            assert reg.encoding < 16 : "encoding out of range: " + reg.encoding;
            assert nds.encoding < 16 : "encoding out of range: " + nds.encoding;
            emitVEX(L128, sizePrefixToPP(sizePrefix), opcodeEscapePrefixToMMMMM(opcodeEscapePrefix), isRexW ? W1 : W0, getRXB(reg, rm), nds.isValid() ? nds.encoding : 0, true);
        }

        @Override
        public void simdPrefix(Register dst, Register nds, Register src, int sizePrefix, int opcodeEscapePrefix, boolean isRexW) {
            assert dst.encoding < 16 : "encoding out of range: " + dst.encoding;
            assert src.encoding < 16 : "encoding out of range: " + src.encoding;
            assert nds.encoding < 16 : "encoding out of range: " + nds.encoding;
            emitVEX(L128, sizePrefixToPP(sizePrefix), opcodeEscapePrefixToMMMMM(opcodeEscapePrefix), isRexW ? W1 : W0, getRXB(dst, src), nds.isValid() ? nds.encoding : 0, true);
        }
    }

    protected final void simdPrefix(Register xreg, Register nds, AMD64Address adr, OperandSize size, int overriddenSizePrefix, int opcodeEscapePrefix, boolean isRexW) {
        simdEncoder.simdPrefix(xreg, nds, adr, overriddenSizePrefix != 0 ? overriddenSizePrefix : size.sizePrefix, opcodeEscapePrefix, isRexW);
    }

    protected final void simdPrefix(Register xreg, Register nds, AMD64Address adr, OperandSize size, int opcodeEscapePrefix, boolean isRexW) {
        simdEncoder.simdPrefix(xreg, nds, adr, size.sizePrefix, opcodeEscapePrefix, isRexW);
    }

    protected final void simdPrefix(Register dst, Register nds, Register src, OperandSize size, int overriddenSizePrefix, int opcodeEscapePrefix, boolean isRexW) {
        simdEncoder.simdPrefix(dst, nds, src, overriddenSizePrefix != 0 ? overriddenSizePrefix : size.sizePrefix, opcodeEscapePrefix, isRexW);
    }

    protected final void simdPrefix(Register dst, Register nds, Register src, OperandSize size, int opcodeEscapePrefix, boolean isRexW) {
        simdEncoder.simdPrefix(dst, nds, src, size.sizePrefix, opcodeEscapePrefix, isRexW);
    }

 // @formatter:off
 //
 // Instruction Format and VEX illustrated below (optional []):
 //
 // #of bytes:    2,3      1       1       1       1,2,4       1
 // [Prefixes]    VEX   OpCode   ModR/M  [SIB]   [Disp8*N] [Immediate]
 //                                             [Disp16,32]
 //
 // VEX: 0xC4 | P1 | P2
 //
 //     7   6   5   4   3   2   1   0
 // P1  R   X   B   m   m   m   m   m      P[ 7:0]
 // P2  W   v   v   v   v   L   p   p      P[15:8]
 //
 // VEX: 0xC5 | B1
 //
 //     7   6   5   4   3   2   1   0
 // P1  R   v   v   v   v   L   p   p      P[7:0]
 //
 // Figure. Bit Field Layout of the VEX Prefix
 //
 // Table. VEX Prefix Bit Field Functional Grouping
 //
 // Notation        Bit field Group        Position        Comment
 // ----------  -------------------------  --------  -------------------
 // VEX.RXB     Next-8 register specifier  P[7:5]    Combine with ModR/M.reg, ModR/M.rm (base, index/vidx).
 // VEX.R       REX.R inverse              P[7]      Combine with EVEX.R and ModR/M.reg.
 // VEX.X       REX.X inverse              P[6]      Combine with EVEX.B and ModR/M.rm, when SIB/VSIB absent.
 // VEX.B       REX.B inverse              P[5]
 // VEX.mmmmmm  0F, 0F_38, 0F_3A encoding  P[4:0]    b01/0x0F, b10/0F_38, b11/0F_3A (all other reserved)
 //
 // VEX.W       Opcode specific            P[15]
 // VEX.vvvv    A register specifier       P[14:11]  In inverse form, b1111 if not used.
 //                                        P[6:3]
 // VEX.L       Vector length/RC           P[10]     b0/scalar or 128b vec, b1/256b vec.
 //                                        P[2]
 // VEX.pp      Compressed legacy prefix   P[9:8]    b00/None, b01/0x66, b10/0xF3, b11/0xF2
 //                                        P[1:0]
 // @formatter:on

    
Low-level function to encode and emit the VEX prefix.

2 byte form: [1100 0101] [R vvvv L pp]

3 byte form: [1100 0100] [RXB m-mmmm] [W vvvv L pp]

The RXB and vvvv fields are stored in 1's complement in the prefix encoding. This function
performs the 1s complement conversion, the caller is expected to pass plain unencoded
arguments.

The pp field encodes an extension to the opcode:

00: no extension

01: 66

10: F3

11: F2

The m-mmmm field encodes the leading bytes of the opcode:

00001: implied 0F leading opcode byte (default in 2-byte encoding)

00010: implied 0F 38 leading opcode bytes

00011: implied 0F 3A leading opcode bytes

This function automatically chooses the 2 or 3 byte encoding, based on the XBW flags and the
m-mmmm field.
/**
     * Low-level function to encode and emit the VEX prefix.
     * <p>
     * 2 byte form: [1100 0101] [R vvvv L pp]<br>
     * 3 byte form: [1100 0100] [RXB m-mmmm] [W vvvv L pp]
     * <p>
     * The RXB and vvvv fields are stored in 1's complement in the prefix encoding. This function
     * performs the 1s complement conversion, the caller is expected to pass plain unencoded
     * arguments.
     * <p>
     * The pp field encodes an extension to the opcode:<br>
     * 00: no extension<br>
     * 01: 66<br>
     * 10: F3<br>
     * 11: F2
     * <p>
     * The m-mmmm field encodes the leading bytes of the opcode:<br>
     * 00001: implied 0F leading opcode byte (default in 2-byte encoding)<br>
     * 00010: implied 0F 38 leading opcode bytes<br>
     * 00011: implied 0F 3A leading opcode bytes
     * <p>
     * This function automatically chooses the 2 or 3 byte encoding, based on the XBW flags and the
     * m-mmmm field.
     */
    protected final void emitVEX(int l, int pp, int mmmmm, int w, int rxb, int vvvv, boolean checkAVX) {
        assert !checkAVX || ((AMD64) target.arch).getFeatures().contains(CPUFeature.AVX) : "emitting VEX prefix on a CPU without AVX support";

        assert l == L128 || l == L256 : "invalid value for VEX.L";
        assert pp == P_ || pp == P_66 || pp == P_F3 || pp == P_F2 : "invalid value for VEX.pp";
        assert mmmmm == M_0F || mmmmm == M_0F38 || mmmmm == M_0F3A : "invalid value for VEX.m-mmmm";
        assert w == W0 || w == W1 : "invalid value for VEX.W";

        assert (rxb & 0x07) == rxb : "invalid value for VEX.RXB";
        assert (vvvv & 0x0F) == vvvv : "invalid value for VEX.vvvv";

        int rxb1s = rxb ^ 0x07;
        int vvvv1s = vvvv ^ 0x0F;
        if ((rxb & 0x03) == 0 && w == WIG && mmmmm == M_0F) {
            // 2 byte encoding
            int byte2 = 0;
            byte2 |= (rxb1s & 0x04) << 5;
            byte2 |= vvvv1s << 3;
            byte2 |= l << 2;
            byte2 |= pp;

            emitByte(Prefix.VEX2);
            emitByte(byte2);
        } else {
            // 3 byte encoding
            int byte2 = 0;
            byte2 = (rxb1s & 0x07) << 5;
            byte2 |= mmmmm;

            int byte3 = 0;
            byte3 |= w << 7;
            byte3 |= vvvv1s << 3;
            byte3 |= l << 2;
            byte3 |= pp;

            emitByte(Prefix.VEX3);
            emitByte(byte2);
            emitByte(byte3);
        }
    }

    public static int getLFlag(AVXSize size) {
        switch (size) {
            case XMM:
                return L128;
            case YMM:
                return L256;
            case ZMM:
                return L512;
            default:
                return LZ;
        }
    }

    public static boolean isAVX512Register(Register reg) {
        return reg != null && reg.isValid() && AMD64.XMM.equals(reg.getRegisterCategory()) && reg.encoding > 15;
    }

    public final boolean vexPrefix(Register dst, Register nds, Register src, AVXSize size, int pp, int mmmmm, int w, int wEvex, boolean checkAVX) {
        if (isAVX512Register(dst) || isAVX512Register(nds) || isAVX512Register(src) || size == AVXSize.ZMM) {
            evexPrefix(dst, Register.None, nds, src, size, pp, mmmmm, wEvex, Z0, B0);
            return true;
        }
        emitVEX(getLFlag(size), pp, mmmmm, w, getRXB(dst, src), nds.isValid() ? nds.encoding() : 0, checkAVX);
        return false;
    }

    public final boolean vexPrefix(Register dst, Register nds, AMD64Address src, AVXSize size, int pp, int mmmmm, int w, int wEvex, boolean checkAVX) {
        if (isAVX512Register(dst) || isAVX512Register(nds) || size == AVXSize.ZMM) {
            evexPrefix(dst, Register.None, nds, src, size, pp, mmmmm, wEvex, Z0, B0);
            return true;
        }
        emitVEX(getLFlag(size), pp, mmmmm, w, getRXB(dst, src), nds.isValid() ? nds.encoding() : 0, checkAVX);
        return false;
    }

    protected static final class EVEXPrefixConfig {
        public static final int Z0 = 0x0;
        public static final int Z1 = 0x1;

        public static final int B0 = 0x0;
        public static final int B1 = 0x1;

        private EVEXPrefixConfig() {
        }
    }

    private static final int NOT_SUPPORTED_VECTOR_LENGTH = -1;

    
EVEX-encoded instructions use a compressed displacement scheme by multiplying disp8 with a
scaling factor N depending on the tuple type and the vector length.
Reference: Intel Software Developer's Manual Volume 2, Section 2.6.5
/**
     * EVEX-encoded instructions use a compressed displacement scheme by multiplying disp8 with a
     * scaling factor N depending on the tuple type and the vector length.
     *
     * Reference: Intel Software Developer's Manual Volume 2, Section 2.6.5
     */
    protected enum EVEXTuple {
        INVALID(NOT_SUPPORTED_VECTOR_LENGTH, NOT_SUPPORTED_VECTOR_LENGTH, NOT_SUPPORTED_VECTOR_LENGTH),
        FV_NO_BROADCAST_32BIT(16, 32, 64),
        FV_BROADCAST_32BIT(4, 4, 4),
        FV_NO_BROADCAST_64BIT(16, 32, 64),
        FV_BROADCAST_64BIT(8, 8, 8),
        HV_NO_BROADCAST_32BIT(8, 16, 32),
        HV_BROADCAST_32BIT(4, 4, 4),
        FVM(16, 32, 64),
        T1S_8BIT(1, 1, 1),
        T1S_16BIT(2, 2, 2),
        T1S_32BIT(4, 4, 4),
        T1S_64BIT(8, 8, 8),
        T1F_32BIT(4, 4, 4),
        T1F_64BIT(8, 8, 8),
        T2_32BIT(8, 8, 8),
        T2_64BIT(NOT_SUPPORTED_VECTOR_LENGTH, 16, 16),
        T4_32BIT(NOT_SUPPORTED_VECTOR_LENGTH, 16, 16),
        T4_64BIT(NOT_SUPPORTED_VECTOR_LENGTH, NOT_SUPPORTED_VECTOR_LENGTH, 32),
        T8_32BIT(NOT_SUPPORTED_VECTOR_LENGTH, NOT_SUPPORTED_VECTOR_LENGTH, 32),
        HVM(8, 16, 32),
        QVM(4, 8, 16),
        OVM(2, 4, 8),
        M128(16, 16, 16),
        DUP(8, 32, 64);

        private final int scalingFactorVL128;
        private final int scalingFactorVL256;
        private final int scalingFactorVL512;

        EVEXTuple(int scalingFactorVL128, int scalingFactorVL256, int scalingFactorVL512) {
            this.scalingFactorVL128 = scalingFactorVL128;
            this.scalingFactorVL256 = scalingFactorVL256;
            this.scalingFactorVL512 = scalingFactorVL512;
        }

        private static int verifyScalingFactor(int scalingFactor) {
            if (scalingFactor == NOT_SUPPORTED_VECTOR_LENGTH) {
                throw GraalError.shouldNotReachHere("Invalid scaling factor.");
            }
            return scalingFactor;
        }

        public int getDisp8ScalingFactor(AVXSize size) {
            switch (size) {
                case XMM:
                    return verifyScalingFactor(scalingFactorVL128);
                case YMM:
                    return verifyScalingFactor(scalingFactorVL256);
                case ZMM:
                    return verifyScalingFactor(scalingFactorVL512);
                default:
                    throw GraalError.shouldNotReachHere("Unsupported vector size.");
            }
        }
    }

 // @formatter:off
 //
 // Instruction Format and EVEX illustrated below (optional []):
 //
 // #of bytes:      4       1       1       1       1,2,4       1
 // [Prefixes]    EVEX   OpCode   ModR/M  [SIB]   [Disp8*N] [Immediate]
 //                                              [Disp16,32]
 //
 // The EVEX prefix is a 4-byte prefix, with the first two bytes derived from unused encoding
 // form of the 32-bit-mode-only BOUND instruction. The layout of the EVEX prefix is shown in
 // the figure below. The first byte must be 0x62, followed by three pay-load bytes, denoted
 // as P1, P2, and P3 individually or collectively as P[23:0] (see below).
 //
 // EVEX: 0x62 | P1 | P2 | P3
 //
 //     7   6   5   4   3   2   1   0
 // P1  R   X   B   R'  0   0   m   m      P[ 7: 0]
 // P2  W   v   v   v   v   1   p   p      P[15: 8]
 // P3  z   L'  L   b   V'  a   a   a      P[23:16]
 //
 // Figure. Bit Field Layout of the EVEX Prefix
 //
 // Table. EVEX Prefix Bit Field Functional Grouping
 //
 // Notation        Bit field Group        Position        Comment
 // ---------  --------------------------  --------  -----------------------
 // EVEX.RXB   Next-8 register specifier   P[7:5]    Combine with ModR/M.reg, ModR/M.rm (base, index/vidx).
 // EVEX.X     High-16 register specifier  P[6]      Combine with EVEX.B and ModR/M.rm, when SIB/VSIB absent.
 // EVEX.R'    High-16 register specifier  P[4]      Combine with EVEX.R and ModR/M.reg.
 // --         Reserved                    P[3:2]    Must be 0.
 // EVEX.mm    Compressed legacy escape    P[1:0]    Identical to low two bits of VEX.mmmmm.
 //
 // EVEX.W     Osize promotion/Opcode ext  P[15]
 // EVEX.vvvv  NDS register specifier      P[14:11]  Same as VEX.vvvv.
 // --         Fixed Value                 P[10]     Must be 1.
 // EVEX.pp    Compressed legacy prefix    P[9:8]    Identical to VEX.pp.
 //
 // EVEX.z     Zeroing/Merging             P[23]
 // EVEX.L'L   Vector length/RC            P[22:21]
 // EVEX.b     Broadcast/RC/SAE Context    P[20]
 // EVEX.V'    High-16 NDS/VIDX register   P[19]     Combine with EVEX.vvvv or VSIB when present.
 // EVEX.aaa   Embedded opmask register    P[18:16]
 //
 // @formatter:on

    
Low-level function to encode and emit the EVEX prefix.

62 [0 1 1 0 0 0 1 0]

P1 [R X B R'0 0 m m]

P2 [W v v v v 1 p p]

P3 [z L'L b V'a a a]

The pp field encodes an extension to the opcode:

00: no extension

01: 66

10: F3

11: F2

The mm field encodes the leading bytes of the opcode:

01: implied 0F leading opcode byte

10: implied 0F 38 leading opcode bytes

11: implied 0F 3A leading opcode bytes

The z field encodes the merging mode (merge or zero).

The b field encodes the source broadcast or data rounding modes.

The aaa field encodes the operand mask register.
/**
     * Low-level function to encode and emit the EVEX prefix.
     * <p>
     * 62 [0 1 1 0 0 0 1 0]<br>
     * P1 [R X B R'0 0 m m]<br>
     * P2 [W v v v v 1 p p]<br>
     * P3 [z L'L b V'a a a]
     * <p>
     * The pp field encodes an extension to the opcode:<br>
     * 00: no extension<br>
     * 01: 66<br>
     * 10: F3<br>
     * 11: F2
     * <p>
     * The mm field encodes the leading bytes of the opcode:<br>
     * 01: implied 0F leading opcode byte<br>
     * 10: implied 0F 38 leading opcode bytes<br>
     * 11: implied 0F 3A leading opcode bytes
     * <p>
     * The z field encodes the merging mode (merge or zero).
     * <p>
     * The b field encodes the source broadcast or data rounding modes.
     * <p>
     * The aaa field encodes the operand mask register.
     */
    private void emitEVEX(int l, int pp, int mm, int w, int rxb, int reg, int vvvvv, int z, int b, int aaa) {
        assert ((AMD64) target.arch).getFeatures().contains(CPUFeature.AVX512F) : "emitting EVEX prefix on a CPU without AVX512 support";

        assert l == L128 || l == L256 || l == L512 : "invalid value for EVEX.L'L";
        assert pp == P_ || pp == P_66 || pp == P_F3 || pp == P_F2 : "invalid value for EVEX.pp";
        assert mm == M_0F || mm == M_0F38 || mm == M_0F3A : "invalid value for EVEX.mm";
        assert w == W0 || w == W1 : "invalid value for EVEX.W";

        assert (rxb & 0x07) == rxb : "invalid value for EVEX.RXB";
        assert (reg & 0x1F) == reg : "invalid value for EVEX.R'";
        assert (vvvvv & 0x1F) == vvvvv : "invalid value for EVEX.V'vvvv";

        assert z == Z0 || z == Z1 : "invalid value for EVEX.z";
        assert b == B0 || b == B1 : "invalid value for EVEX.b";
        assert (aaa & 0x07) == aaa : "invalid value for EVEX.aaa";

        emitByte(Prefix.EVEX);
        int p1 = 0;
        p1 |= ((rxb ^ 0x07) & 0x07) << 5;
        p1 |= reg < 16 ? 0x10 : 0;
        p1 |= mm;
        emitByte(p1);

        int p2 = 0;
        p2 |= w << 7;
        p2 |= ((vvvvv ^ 0x0F) & 0x0F) << 3;
        p2 |= 0x04;
        p2 |= pp;
        emitByte(p2);

        int p3 = 0;
        p3 |= z << 7;
        p3 |= l << 5;
        p3 |= b << 4;
        p3 |= vvvvv < 16 ? 0x08 : 0;
        p3 |= aaa;
        emitByte(p3);
    }

    
Get RXB bits for register-register instructions in EVEX-encoding, where ModRM.rm contains a
register index. The R bit extends the ModRM.reg field and the X and B bits extends the
ModRM.rm field.
/**
     * Get RXB bits for register-register instructions in EVEX-encoding, where ModRM.rm contains a
     * register index. The R bit extends the ModRM.reg field and the X and B bits extends the
     * ModRM.rm field.
     */
    private static int getRXBForEVEX(Register reg, Register rm) {
        int rxb = (reg == null ? 0 : reg.encoding & 0x08) >> 1;
        rxb |= (rm == null ? 0 : rm.encoding & 0x018) >> 3;
        return rxb;
    }

    
Helper method for emitting EVEX prefix in the form of RRRR.
/**
     * Helper method for emitting EVEX prefix in the form of RRRR.
     */
    protected final void evexPrefix(Register dst, Register mask, Register nds, Register src, AVXSize size, int pp, int mm, int w, int z, int b) {
        assert !mask.isValid() || inRC(MASK, mask);
        emitEVEX(getLFlag(size), pp, mm, w, getRXBForEVEX(dst, src), dst.encoding, nds.isValid() ? nds.encoding() : 0, z, b, mask.isValid() ? mask.encoding : 0);
    }

    
Helper method for emitting EVEX prefix in the form of RRRM. Because the memory addressing in EVEX-encoded instructions employ a compressed displacement scheme when using disp8 form, the user of this API should make sure to encode the operands using emitOperandHelper(Register, AMD64Address, int, int). /**
     * Helper method for emitting EVEX prefix in the form of RRRM. Because the memory addressing in
     * EVEX-encoded instructions employ a compressed displacement scheme when using disp8 form, the
     * user of this API should make sure to encode the operands using
     * {@link #emitOperandHelper(Register, AMD64Address, int, int)}.
     */
    protected final void evexPrefix(Register dst, Register mask, Register nds, AMD64Address src, AVXSize size, int pp, int mm, int w, int z, int b) {
        assert !mask.isValid() || inRC(MASK, mask);
        emitEVEX(getLFlag(size), pp, mm, w, getRXB(dst, src), dst.encoding, nds.isValid() ? nds.encoding() : 0, z, b, mask.isValid() ? mask.encoding : 0);
    }

}