/*

 * 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.lir.amd64;

import static jdk.vm.ci.amd64.AMD64.k1;

import static jdk.vm.ci.amd64.AMD64.k2;

import static jdk.vm.ci.amd64.AMD64.k3;

import static jdk.vm.ci.amd64.AMD64.rax;

import static jdk.vm.ci.amd64.AMD64.rdi;

import static jdk.vm.ci.amd64.AMD64.rdx;

import static jdk.vm.ci.amd64.AMD64.rsi;

import static jdk.vm.ci.amd64.AMD64.rsp;

import static jdk.vm.ci.code.ValueUtil.asRegister;

import static org.graalvm.compiler.lir.LIRInstruction.OperandFlag.REG;

import static org.graalvm.compiler.lir.amd64.AMD64StringLatin1InflateOp.useAVX512ForStringInflateCompress;

import org.graalvm.compiler.asm.Label;

import org.graalvm.compiler.asm.amd64.AMD64Address;

import org.graalvm.compiler.asm.amd64.AMD64Assembler;

import org.graalvm.compiler.asm.amd64.AMD64MacroAssembler;

import org.graalvm.compiler.core.common.LIRKind;

import org.graalvm.compiler.lir.LIRInstructionClass;

import org.graalvm.compiler.lir.Opcode;

import org.graalvm.compiler.lir.asm.CompilationResultBuilder;

import org.graalvm.compiler.lir.gen.LIRGeneratorTool;

import jdk.vm.ci.amd64.AMD64;

import jdk.vm.ci.amd64.AMD64Kind;

import jdk.vm.ci.code.Register;

import jdk.vm.ci.meta.Value;

@Opcode("AMD64_STRING_COMPRESS")

public final class AMD64StringUTF16CompressOp extends AMD64LIRInstruction {

    public static final LIRInstructionClass<AMD64StringUTF16CompressOp> TYPE = LIRInstructionClass.create(AMD64StringUTF16CompressOp.class);

    @Def({REG}) private Value rres;

    @Use({REG}) private Value rsrc;

    @Use({REG}) private Value rdst;

    @Use({REG}) private Value rlen;

    @Temp({REG}) private Value rsrcTemp;

    @Temp({REG}) private Value rdstTemp;

    @Temp({REG}) private Value rlenTemp;

    @Temp({REG}) private Value vtmp1;

    @Temp({REG}) private Value vtmp2;

    @Temp({REG}) private Value vtmp3;

    @Temp({REG}) private Value vtmp4;

    @Temp({REG}) private Value rtmp5;

    public AMD64StringUTF16CompressOp(LIRGeneratorTool tool, Value res, Value src, Value dst, Value len) {

        super(TYPE);

        assert asRegister(src).equals(rsi);

        assert asRegister(dst).equals(rdi);

        assert asRegister(len).equals(rdx);

        assert asRegister(res).equals(rax);

        rres = res;

        rsrcTemp = rsrc = src;

        rdstTemp = rdst = dst;

        rlenTemp = rlen = len;

        LIRKind vkind = useAVX512ForStringInflateCompress(tool.target()) ? LIRKind.value(AMD64Kind.V512_BYTE) : LIRKind.value(AMD64Kind.V128_BYTE);

        vtmp1 = tool.newVariable(vkind);

        vtmp2 = tool.newVariable(vkind);

        vtmp3 = tool.newVariable(vkind);

        vtmp4 = tool.newVariable(vkind);

        rtmp5 = tool.newVariable(LIRKind.value(AMD64Kind.DWORD));

    }

    @Override

    public void emitCode(CompilationResultBuilder crb, AMD64MacroAssembler masm) {

        Register res = asRegister(rres);

        Register src = asRegister(rsrc);

        Register dst = asRegister(rdst);

        Register len = asRegister(rlen);

        Register tmp1 = asRegister(vtmp1);

        Register tmp2 = asRegister(vtmp2);

        Register tmp3 = asRegister(vtmp3);

        Register tmp4 = asRegister(vtmp4);

        Register tmp5 = asRegister(rtmp5);

        charArrayCompress(masm, src, dst, len, tmp1, tmp2, tmp3, tmp4, tmp5, res);

    }

    /**

     * Compress a UTF16 string which de facto is a Latin1 string into a byte array representation

     * (buffer).

     *

     * @param masm the assembler

     * @param src (rsi) the start address of source char[] to be compressed

     * @param dst (rdi) the start address of destination byte[] vector

     * @param len (rdx) the length

     * @param tmp1 (xmm) temporary xmm register

     * @param tmp2 (xmm) temporary xmm register

     * @param tmp3 (xmm) temporary xmm register

     * @param tmp4 (xmm) temporary xmm register

     * @param tmp (gpr) temporary gpr register

     * @param res (rax) the result code (length on success, zero otherwise)

     */

    private static void charArrayCompress(AMD64MacroAssembler masm, Register src, Register dst, Register len, Register tmp1,

                    Register tmp2, Register tmp3, Register tmp4, Register tmp, Register res) {

        assert tmp1.getRegisterCategory().equals(AMD64.XMM);

        assert tmp2.getRegisterCategory().equals(AMD64.XMM);

        assert tmp3.getRegisterCategory().equals(AMD64.XMM);

        assert tmp4.getRegisterCategory().equals(AMD64.XMM);

        Label labelReturnLength = new Label();

        Label labelReturnZero = new Label();

        Label labelDone = new Label();

        Label labelBelowThreshold = new Label();

        assert len.number != res.number;

        masm.push(len);      // Save length for return.

        if (useAVX512ForStringInflateCompress(masm.target)) {

            Label labelRestoreK1ReturnZero = new Label();

            Label labelAvxPostAlignment = new Label();

            // If the length of the string is less than 32, we chose not to use the

            // AVX512 instructions.

            masm.testl(len, -32);

            masm.jcc(AMD64Assembler.ConditionFlag.Zero, labelBelowThreshold);

            // First check whether a character is compressible (<= 0xff).

            // Create mask to test for Unicode chars inside (zmm) vector.

            masm.movl(res, 0x00ff);

            masm.evpbroadcastw(tmp2, res);

            masm.kmovq(k3, k1);      // Save k1

            masm.testl(len, -64);

            masm.jcc(AMD64Assembler.ConditionFlag.Zero, labelAvxPostAlignment);

            masm.movl(tmp, dst);

            masm.andl(tmp, (32 - 1));

            masm.negl(tmp);

            masm.andl(tmp, (32 - 1));

            // bail out when there is nothing to be done

            masm.testl(tmp, tmp);

            masm.jcc(AMD64Assembler.ConditionFlag.Zero, labelAvxPostAlignment);

            // Compute (1 << N) - 1 = ~(~0 << N), where N is the remaining number

            // of characters to process.

            masm.movl(res, -1);

            masm.shlxl(res, res, tmp);

            masm.notl(res);

            masm.kmovd(k1, res);

            masm.evmovdqu16(tmp1, k1, new AMD64Address(src));

            masm.evpcmpuw(k2, k1, tmp1, tmp2, 2 /* le */);

            masm.ktestd(k2, k1);

            masm.jcc(AMD64Assembler.ConditionFlag.CarryClear, labelRestoreK1ReturnZero);

            masm.evpmovwb(new AMD64Address(dst), k1, tmp1);

            masm.addq(src, tmp);

            masm.addq(src, tmp);

            masm.addq(dst, tmp);

            masm.subl(len, tmp);

            masm.bind(labelAvxPostAlignment);

            // end of alignment

            Label labelAvx512LoopTail = new Label();

            masm.movl(tmp, len);

            masm.andl(tmp, -32);         // The vector count (in chars).

            masm.jcc(AMD64Assembler.ConditionFlag.Zero, labelAvx512LoopTail);

            masm.andl(len, 32 - 1);      // The tail count (in chars).

            masm.leaq(src, new AMD64Address(src, tmp, AMD64Address.Scale.Times2));

            masm.leaq(dst, new AMD64Address(dst, tmp, AMD64Address.Scale.Times1));

            masm.negq(tmp);

            Label labelAvx512Loop = new Label();

            // Test and compress 32 chars per iteration, reading 512-bit vectors and

            // writing 256-bit compressed ditto.

            masm.bind(labelAvx512Loop);

            masm.evmovdqu16(tmp1, new AMD64Address(src, tmp, AMD64Address.Scale.Times2));

            masm.evpcmpuw(k2, tmp1, tmp2, 2 /* le */);

            masm.kortestd(k2, k2);

            masm.jcc(AMD64Assembler.ConditionFlag.CarryClear, labelRestoreK1ReturnZero);

            // All 32 chars in the current vector (chunk) are valid for compression,

            // write truncated byte elements to memory.

            masm.evpmovwb(new AMD64Address(dst, tmp, AMD64Address.Scale.Times1), tmp1);

            masm.addq(tmp, 32);

            masm.jcc(AMD64Assembler.ConditionFlag.NotZero, labelAvx512Loop);

            masm.bind(labelAvx512LoopTail);

            masm.kmovq(k1, k3);      // Restore k1

            // All done if the tail count is zero.

            masm.testl(len, len);

            masm.jcc(AMD64Assembler.ConditionFlag.Zero, labelReturnLength);

            // Compute (1 << N) - 1 = ~(~0 << N), where N is the remaining number

            // of characters to process.

            masm.movl(res, -1);

            masm.shlxl(res, res, len);

            masm.notl(res);

            masm.kmovd(k1, res);

            masm.evmovdqu16(tmp1, k1, new AMD64Address(src));

            masm.evpcmpuw(k2, k1, tmp1, tmp2, 2 /* le */);

            masm.ktestd(k2, k1);

            masm.jcc(AMD64Assembler.ConditionFlag.CarryClear, labelRestoreK1ReturnZero);

            masm.evpmovwb(new AMD64Address(dst), k1, tmp1);

            masm.kmovq(k1, k3);      // Restore k1

            masm.jmp(labelReturnLength);

            masm.bind(labelRestoreK1ReturnZero);

            masm.kmovq(k1, k3);      // Restore k1

            masm.jmp(labelReturnZero);

        }

        if (masm.supports(AMD64.CPUFeature.SSE4_2)) {

            Label labelSSETail = new Label();

            masm.bind(labelBelowThreshold);

            masm.movl(tmp, 0xff00ff00);  // Create mask to test for Unicode chars in vectors.

            masm.movl(res, len);

            masm.andl(res, -16);

            masm.jccb(AMD64Assembler.ConditionFlag.Zero, labelSSETail);

            masm.andl(len, 16 - 1);

            // Compress 16 chars per iteration.

            masm.movdl(tmp1, tmp);

            masm.pshufd(tmp1, tmp1, 0);    // Store Unicode mask in 'vtmp1'.

            masm.pxor(tmp4, tmp4);

            masm.leaq(src, new AMD64Address(src, res, AMD64Address.Scale.Times2));

            masm.leaq(dst, new AMD64Address(dst, res, AMD64Address.Scale.Times1));

            masm.negq(res);

            Label lSSELoop = new Label();

            // Test and compress 16 chars per iteration, reading 128-bit vectors and

            // writing 64-bit compressed ditto.

            masm.bind(lSSELoop);

            masm.movdqu(tmp2, new AMD64Address(src, res, AMD64Address.Scale.Times2));     // load

                                                                                          // 1st 8

                                                                                          // characters

            masm.movdqu(tmp3, new AMD64Address(src, res, AMD64Address.Scale.Times2, 16)); // load

                                                                                          // next 8

                                                                                          // characters

            masm.por(tmp4, tmp2);

            masm.por(tmp4, tmp3);

            masm.ptest(tmp4, tmp1);        // Check for Unicode chars in vector.

            masm.jcc(AMD64Assembler.ConditionFlag.NotZero, labelReturnZero);

            masm.packuswb(tmp2, tmp3);     // Only ASCII chars; compress each to a byte.

            masm.movdqu(new AMD64Address(dst, res, AMD64Address.Scale.Times1), tmp2);

            masm.addq(res, 16);

            masm.jcc(AMD64Assembler.ConditionFlag.NotZero, lSSELoop);

            Label labelCopyChars = new Label();

            // Test and compress another 8 chars before final tail copy.

            masm.bind(labelSSETail);

            masm.movl(res, len);

            masm.andl(res, -8);

            masm.jccb(AMD64Assembler.ConditionFlag.Zero, labelCopyChars);

            masm.andl(len, 8 - 1);

            masm.movdl(tmp1, tmp);

            masm.pshufd(tmp1, tmp1, 0);    // Store Unicode mask in 'vtmp1'.

            masm.pxor(tmp3, tmp3);

            masm.movdqu(tmp2, new AMD64Address(src));

            masm.ptest(tmp2, tmp1);        // Check for Unicode chars in vector.

            masm.jccb(AMD64Assembler.ConditionFlag.NotZero, labelReturnZero);

            masm.packuswb(tmp2, tmp3);     // Only ASCII chars; compress each to a byte.

            masm.movq(new AMD64Address(dst), tmp2);

            masm.addq(src, 16);

            masm.addq(dst, 8);

            masm.bind(labelCopyChars);

        }

        // Compress any remaining characters using a vanilla implementation.

        masm.testl(len, len);

        masm.jccb(AMD64Assembler.ConditionFlag.Zero, labelReturnLength);

        masm.leaq(src, new AMD64Address(src, len, AMD64Address.Scale.Times2));

        masm.leaq(dst, new AMD64Address(dst, len, AMD64Address.Scale.Times1));

        masm.negq(len);

        Label labelCopyCharsLoop = new Label();

        // Compress a single character per iteration.

        masm.bind(labelCopyCharsLoop);

        masm.movzwl(res, new AMD64Address(src, len, AMD64Address.Scale.Times2));

        masm.testl(res, 0xff00);     // Check if Unicode character.

        masm.jccb(AMD64Assembler.ConditionFlag.NotZero, labelReturnZero);

        // An ASCII character; compress to a byte.

        masm.movb(new AMD64Address(dst, len, AMD64Address.Scale.Times1), res);

        masm.incrementq(len, 1);

        masm.jcc(AMD64Assembler.ConditionFlag.NotZero, labelCopyCharsLoop);

        // If compression succeeded, return the length.

        masm.bind(labelReturnLength);

        masm.pop(res);

        masm.jmpb(labelDone);

        // If compression failed, return 0.

        masm.bind(labelReturnZero);

        masm.xorl(res, res);

        masm.addq(rsp, 8 /* wordSize */);

        masm.bind(labelDone);

    }

}