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The GraalVM compiler and the Graal-truffle optimizer.
/*
* Copyright (c) 2018, 2021, 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* 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
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*/
package jdk.graal.compiler.lir.amd64;
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 java.util.EnumSet;
import jdk.graal.compiler.asm.Label;
import jdk.graal.compiler.asm.amd64.AMD64Address;
import jdk.graal.compiler.asm.amd64.AMD64Assembler.ConditionFlag;
import jdk.graal.compiler.asm.amd64.AMD64BaseAssembler.EVEXComparisonPredicate;
import jdk.graal.compiler.asm.amd64.AMD64MacroAssembler;
import jdk.graal.compiler.asm.amd64.AVXKind.AVXSize;
import jdk.graal.compiler.core.common.LIRKind;
import jdk.graal.compiler.core.common.Stride;
import jdk.graal.compiler.debug.Assertions;
import jdk.graal.compiler.lir.LIRInstructionClass;
import jdk.graal.compiler.lir.Opcode;
import jdk.graal.compiler.lir.SyncPort;
import jdk.graal.compiler.lir.asm.CompilationResultBuilder;
import jdk.graal.compiler.lir.gen.LIRGeneratorTool;
import jdk.graal.compiler.serviceprovider.JavaVersionUtil;
import jdk.vm.ci.amd64.AMD64;
import jdk.vm.ci.amd64.AMD64.CPUFeature;
import jdk.vm.ci.amd64.AMD64Kind;
import jdk.vm.ci.code.CodeUtil;
import jdk.vm.ci.code.Register;
import jdk.vm.ci.meta.JavaKind;
import jdk.vm.ci.meta.Value;
// @formatter:off
@SyncPort(from = "https://github.com/openjdk/jdk/blob/7bb59dc8da0c61c5da5c3aab5d56a6e4880001ce/src/hotspot/cpu/x86/macroAssembler_x86.cpp#L8941-L9149",
sha1 = "3e365037f473204b3f742ab364bd9ad514e72161")
// @formatter:on
@Opcode("AMD64_STRING_COMPRESS")
public final class AMD64StringUTF16CompressOp extends AMD64ComplexVectorOp {
public static final LIRInstructionClass TYPE = LIRInstructionClass.create(AMD64StringUTF16CompressOp.class);
private final int useAVX3Threshold;
@Def({OperandFlag.REG}) private Value rres;
@Use({OperandFlag.REG}) private Value rsrc;
@Use({OperandFlag.REG}) private Value rdst;
@Use({OperandFlag.REG}) private Value rlen;
@Temp({OperandFlag.REG}) private Value rsrcTemp;
@Temp({OperandFlag.REG}) private Value rdstTemp;
@Temp({OperandFlag.REG}) private Value rlenTemp;
@Temp({OperandFlag.REG}) private Value vtmp1;
@Temp({OperandFlag.REG}) private Value vtmp2;
@Temp({OperandFlag.REG}) private Value vtmp3;
@Temp({OperandFlag.REG}) private Value vtmp4;
@Temp({OperandFlag.REG}) private Value rtmp5;
@Temp({OperandFlag.REG}) private Value[] maskRegisters;
public AMD64StringUTF16CompressOp(LIRGeneratorTool tool, EnumSet runtimeCheckedCPUFeatures, int useAVX3Threshold, Value res, Value src, Value dst, Value len) {
super(TYPE, tool, runtimeCheckedCPUFeatures,
supportsAVX512VLBW(tool.target(), runtimeCheckedCPUFeatures) && supports(tool.target(), runtimeCheckedCPUFeatures, CPUFeature.BMI2) ? AVXSize.ZMM : AVXSize.XMM);
assert useAVX3Threshold == 0 || CodeUtil.isPowerOf2(useAVX3Threshold) : "AVX3Threshold must be 0 or a power of 2 :" + useAVX3Threshold;
this.useAVX3Threshold = useAVX3Threshold;
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 = LIRKind.value(getVectorKind(JavaKind.Byte));
vtmp1 = tool.newVariable(vkind);
vtmp2 = tool.newVariable(vkind);
vtmp3 = tool.newVariable(vkind);
vtmp4 = tool.newVariable(vkind);
rtmp5 = tool.newVariable(LIRKind.value(AMD64Kind.DWORD));
if (canUseAVX512Variant()) {
maskRegisters = new Value[]{
k2.asValue(),
k3.asValue(),
};
} else {
maskRegisters = new Value[0];
}
}
@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);
if (JavaVersionUtil.JAVA_SPEC >= 22) {
charArrayCompress(masm, src, dst, len, tmp1, tmp2, tmp3, tmp4, tmp5, res);
} else {
charArrayCompressLegacy(masm, src, dst, len, tmp1, tmp2, tmp3, tmp4, tmp5, res);
}
}
private boolean canUseAVX512Variant() {
return useAVX3Threshold == 0 && supportsAVX512VLBWAndZMM() && supportsBMI2();
}
/**
* 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 tmp1Reg (xmm) temporary xmm register
* @param tmp2Reg (xmm) temporary xmm register
* @param tmp3Reg (xmm) temporary xmm register
* @param tmp4Reg (xmm) temporary xmm register
* @param tmp5 (gpr) temporary gpr register
* @param result (rax) the result code (length on success, zero otherwise)
*/
private void charArrayCompress(AMD64MacroAssembler masm, Register src, Register dst, Register len, Register tmp1Reg,
Register tmp2Reg, Register tmp3Reg, Register tmp4Reg, Register tmp5, Register result) {
assert tmp1Reg.getRegisterCategory().equals(AMD64.XMM);
assert tmp2Reg.getRegisterCategory().equals(AMD64.XMM);
assert tmp3Reg.getRegisterCategory().equals(AMD64.XMM);
assert tmp4Reg.getRegisterCategory().equals(AMD64.XMM);
Label labelCopyCharsLoop = new Label();
Label labelResetSp = new Label();
Label labelDone = new Label();
Label labelCopyTail = new Label();
assert len.number != result.number : Assertions.errorMessageContext("len", len, "result", result);
// Save length for return.
masm.movl(result, len);
if (canUseAVX512Variant()) {
Label labelCopy32Loop = new Label();
Label labelCopyLoopTail = new Label();
Label labelBelowThreshold = new Label();
Label labelPostAlignment = new Label();
Label labelResetForCopyTail = new Label();
// If the length of the string is less than 32, we chose not to use the
// AVX512 instructions.
masm.testlAndJcc(len, -32, ConditionFlag.Zero, labelBelowThreshold, false);
// First check whether a character is compressible (<= 0xff).
// Create mask to test for Unicode chars inside (zmm) vector.
masm.movl(tmp5, 0x00ff);
masm.evpbroadcastw(tmp2Reg, tmp5);
masm.testlAndJcc(len, -64, ConditionFlag.Zero, labelPostAlignment, true);
masm.movl(tmp5, dst);
masm.andl(tmp5, (32 - 1));
masm.negl(tmp5);
masm.andl(tmp5, (32 - 1));
// bail out when there is nothing to be done
masm.testlAndJcc(tmp5, tmp5, ConditionFlag.Zero, labelPostAlignment, true);
// Compute (1 << N) - 1 = ~(~0 << N), where N is the remaining number
// of characters to process.
masm.movl(len, 0xFFFFFFFF);
masm.shlxl(len, len, tmp5);
masm.notl(len);
masm.kmovd(k3, len);
masm.movl(len, result);
masm.evmovdqu16(tmp1Reg, k3, new AMD64Address(src));
masm.evpcmpuw(k2, k3, tmp1Reg, tmp2Reg, EVEXComparisonPredicate.LE);
masm.ktestd(k2, k3);
masm.jcc(ConditionFlag.CarryClear, labelCopyTail);
masm.evpmovwb(new AMD64Address(dst), k3, tmp1Reg);
masm.addq(src, tmp5);
masm.addq(src, tmp5);
masm.addq(dst, tmp5);
masm.subl(len, tmp5);
masm.bind(labelPostAlignment);
// end of alignment
masm.movl(tmp5, len);
masm.andl(tmp5, 32 - 1); // The tail count (in chars).
// The vector count (in chars).
masm.andlAndJcc(len, ~(32 - 1), ConditionFlag.Zero, labelCopyLoopTail, true);
masm.leaq(src, new AMD64Address(src, len, Stride.S2));
masm.leaq(dst, new AMD64Address(dst, len, Stride.S1));
masm.negq(len);
// Test and compress 32 chars per iteration, reading 512-bit vectors and
// writing 256-bit compressed ditto.
masm.bind(labelCopy32Loop);
masm.evmovdqu16(tmp1Reg, new AMD64Address(src, len, Stride.S2));
masm.evpcmpuw(k2, tmp1Reg, tmp2Reg, EVEXComparisonPredicate.LE);
masm.kortestd(k2, k2);
masm.jcc(ConditionFlag.CarryClear, labelResetForCopyTail);
// All 32 chars in the current vector (chunk) are valid for compression,
// write truncated byte elements to memory.
masm.evpmovwb(new AMD64Address(dst, len, Stride.S1), tmp1Reg);
masm.addqAndJcc(len, 32, ConditionFlag.NotZero, labelCopy32Loop, true);
masm.bind(labelCopyLoopTail);
// All done if the tail count is zero.
masm.testlAndJcc(tmp5, tmp5, ConditionFlag.Zero, labelDone, false);
masm.movl(len, tmp5);
// Compute (1 << N) - 1 = ~(~0 << N), where N is the remaining number
// of characters to process.
masm.movl(tmp5, -1);
masm.shlxl(tmp5, tmp5, len);
masm.notl(tmp5);
masm.kmovd(k3, tmp5);
masm.evmovdqu16(tmp1Reg, k3, new AMD64Address(src));
masm.evpcmpuw(k2, k3, tmp1Reg, tmp2Reg, EVEXComparisonPredicate.LE);
masm.ktestd(k2, k3);
masm.jcc(ConditionFlag.CarryClear, labelCopyTail);
masm.evpmovwb(new AMD64Address(dst), k3, tmp1Reg);
masm.jmp(labelDone);
masm.bind(labelResetForCopyTail);
masm.leaq(src, new AMD64Address(src, tmp5, Stride.S2));
masm.leaq(dst, new AMD64Address(dst, tmp5, Stride.S1));
masm.subq(len, tmp5);
masm.jmp(labelCopyCharsLoop);
masm.bind(labelBelowThreshold);
}
if (masm.supports(CPUFeature.SSE4_2)) {
Label labelCopy32Loop = new Label();
Label labelCopy16 = new Label();
Label labelCopyTailSSE = new Label();
Label labelResetForCopyTail = new Label();
// vectored compression
masm.testlAndJcc(len, 0xfffffff8, ConditionFlag.Zero, labelCopyTail, false);
masm.movl(tmp5, 0xff00ff00); // Create mask to test for Unicode chars in vectors.
masm.movdl(tmp1Reg, tmp5);
masm.pshufd(tmp1Reg, tmp1Reg, 0); // Store Unicode mask in 'vtmp1'.
masm.andlAndJcc(len, 0xfffffff0, ConditionFlag.Zero, labelCopy16, true);
// Compress 16 chars per iteration.
masm.pxor(tmp4Reg, tmp4Reg);
masm.leaq(src, new AMD64Address(src, len, Stride.S2));
masm.leaq(dst, new AMD64Address(dst, len, Stride.S1));
masm.negq(len);
// Test and compress 16 chars per iteration, reading 128-bit vectors and
// writing 64-bit compressed ditto.
masm.bind(labelCopy32Loop);
// load 1st 8 characters
masm.movdqu(tmp2Reg, new AMD64Address(src, len, Stride.S2));
masm.por(tmp4Reg, tmp2Reg);
// load next 8 characters
masm.movdqu(tmp3Reg, new AMD64Address(src, len, Stride.S2, 16));
masm.por(tmp4Reg, tmp3Reg);
masm.ptest(tmp4Reg, tmp1Reg); // Check for Unicode chars in vector.
masm.jccb(ConditionFlag.NotZero, labelResetForCopyTail);
masm.packuswb(tmp2Reg, tmp3Reg); // Only ASCII chars; compress each to a byte.
masm.movdqu(new AMD64Address(dst, len, Stride.S1), tmp2Reg);
masm.addqAndJcc(len, 16, ConditionFlag.NotZero, labelCopy32Loop, true);
// Test and compress another 8 chars before final tail copy.
masm.bind(labelCopy16);
// len = 0
masm.testlAndJcc(result, 0x00000008, ConditionFlag.Zero, labelCopyTailSSE, true);
masm.pxor(tmp3Reg, tmp3Reg);
masm.movdqu(tmp2Reg, new AMD64Address(src));
masm.ptest(tmp2Reg, tmp1Reg); // Check for Unicode chars in vector.
masm.jccb(ConditionFlag.NotZero, labelResetForCopyTail);
masm.packuswb(tmp2Reg, tmp3Reg); // Only ASCII chars; compress each to a byte.
masm.movq(new AMD64Address(dst), tmp2Reg);
masm.addq(src, 16);
masm.addq(dst, 8);
masm.jmpb(labelCopyTailSSE);
masm.bind(labelResetForCopyTail);
masm.movl(tmp5, result);
masm.andl(tmp5, 0x0000000f);
masm.leaq(src, new AMD64Address(src, tmp5, Stride.S2));
masm.leaq(dst, new AMD64Address(dst, tmp5, Stride.S1));
masm.subq(len, tmp5);
masm.jmpb(labelCopyCharsLoop);
masm.bind(labelCopyTailSSE);
masm.movl(len, result);
masm.andl(len, 0x00000007); // tail count (in chars)
}
masm.bind(labelCopyTail);
// Compress any remaining characters using a vanilla implementation.
masm.testlAndJcc(len, len, ConditionFlag.Zero, labelDone, true);
masm.leaq(src, new AMD64Address(src, len, Stride.S2));
masm.leaq(dst, new AMD64Address(dst, len, Stride.S1));
masm.negq(len);
// Compress a single character per iteration.
masm.bind(labelCopyCharsLoop);
masm.movzwl(tmp5, new AMD64Address(src, len, Stride.S2));
// Check if Unicode character.
masm.testlAndJcc(tmp5, 0xff00, ConditionFlag.NotZero, labelResetSp, true);
// An ASCII character; compress to a byte.
masm.movb(new AMD64Address(dst, len, Stride.S1), tmp5);
masm.incqAndJcc(len, ConditionFlag.NotZero, labelCopyCharsLoop, true);
// add len then return (len will be zero if compress succeeded, otherwise negative)
masm.bind(labelResetSp);
masm.addl(result, len);
masm.bind(labelDone);
}
/**
* 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 tmp1Reg (xmm) temporary xmm register
* @param tmp2Reg (xmm) temporary xmm register
* @param tmp3Reg (xmm) temporary xmm register
* @param tmp4Reg (xmm) temporary xmm register
* @param tmp5 (gpr) temporary gpr register
* @param result (rax) the result code (length on success, zero otherwise)
*/
private void charArrayCompressLegacy(AMD64MacroAssembler masm, Register src, Register dst, Register len, Register tmp1Reg,
Register tmp2Reg, Register tmp3Reg, Register tmp4Reg, Register tmp5, Register result) {
assert tmp1Reg.getRegisterCategory().equals(AMD64.XMM);
assert tmp2Reg.getRegisterCategory().equals(AMD64.XMM);
assert tmp3Reg.getRegisterCategory().equals(AMD64.XMM);
assert tmp4Reg.getRegisterCategory().equals(AMD64.XMM);
Label labelCopyCharsLoop = new Label();
Label labelReturnLength = new Label();
Label labelReturnZero = new Label();
Label labelDone = new Label();
assert len.number != result.number : Assertions.errorMessageContext("len", len, "result", result);
// Save length for return.
masm.push(len);
if (canUseAVX512Variant()) {
Label labelCopy32Loop = new Label();
Label labelCopyLoopTail = new Label();
Label labelBelowThreshold = new Label();
Label labelPostAlignment = new Label();
// If the length of the string is less than 32, we chose not to use the
// AVX512 instructions.
masm.testlAndJcc(len, -32, ConditionFlag.Zero, labelBelowThreshold, false);
// First check whether a character is compressible (<= 0xff).
// Create mask to test for Unicode chars inside (zmm) vector.
masm.movl(result, 0x00ff);
masm.evpbroadcastw(tmp2Reg, result);
masm.testlAndJcc(len, -64, ConditionFlag.Zero, labelPostAlignment, false);
masm.movl(tmp5, dst);
masm.andl(tmp5, (32 - 1));
masm.negl(tmp5);
masm.andl(tmp5, (32 - 1));
// bail out when there is nothing to be done
masm.testlAndJcc(tmp5, tmp5, ConditionFlag.Zero, labelPostAlignment, false);
// Compute (1 << N) - 1 = ~(~0 << N), where N is the remaining number
// of characters to process.
masm.movl(result, 0xFFFFFFFF);
masm.shlxl(result, result, tmp5);
masm.notl(result);
masm.kmovd(k3, result);
masm.evmovdqu16(tmp1Reg, k3, new AMD64Address(src));
masm.evpcmpuw(k2, k3, tmp1Reg, tmp2Reg, EVEXComparisonPredicate.LE);
masm.ktestd(k2, k3);
masm.jcc(ConditionFlag.CarryClear, labelReturnZero);
masm.evpmovwb(new AMD64Address(dst), k3, tmp1Reg);
masm.addq(src, tmp5);
masm.addq(src, tmp5);
masm.addq(dst, tmp5);
masm.subl(len, tmp5);
masm.bind(labelPostAlignment);
// end of alignment
masm.movl(tmp5, len);
masm.andl(tmp5, 32 - 1); // The tail count (in chars).
// The vector count (in chars).
masm.andlAndJcc(len, ~(32 - 1), ConditionFlag.Zero, labelCopyLoopTail, false);
masm.leaq(src, new AMD64Address(src, len, Stride.S2));
masm.leaq(dst, new AMD64Address(dst, len, Stride.S1));
masm.negq(len);
// Test and compress 32 chars per iteration, reading 512-bit vectors and
// writing 256-bit compressed ditto.
masm.bind(labelCopy32Loop);
masm.evmovdqu16(tmp1Reg, new AMD64Address(src, len, Stride.S2));
masm.evpcmpuw(k2, tmp1Reg, tmp2Reg, EVEXComparisonPredicate.LE);
masm.kortestd(k2, k2);
masm.jcc(ConditionFlag.CarryClear, labelReturnZero);
// All 32 chars in the current vector (chunk) are valid for compression,
// write truncated byte elements to memory.
masm.evpmovwb(new AMD64Address(dst, len, Stride.S1), tmp1Reg);
masm.addqAndJcc(len, 32, ConditionFlag.NotZero, labelCopy32Loop, false);
masm.bind(labelCopyLoopTail);
// All done if the tail count is zero.
masm.testlAndJcc(tmp5, tmp5, ConditionFlag.Zero, labelReturnLength, false);
masm.movl(len, tmp5);
// Compute (1 << N) - 1 = ~(~0 << N), where N is the remaining number
// of characters to process.
masm.movl(result, -1);
masm.shlxl(result, result, len);
masm.notl(result);
masm.kmovd(k3, result);
masm.evmovdqu16(tmp1Reg, k3, new AMD64Address(src));
masm.evpcmpuw(k2, k3, tmp1Reg, tmp2Reg, EVEXComparisonPredicate.LE);
masm.ktestd(k2, k3);
masm.jcc(ConditionFlag.CarryClear, labelReturnZero);
masm.evpmovwb(new AMD64Address(dst), k3, tmp1Reg);
masm.jmp(labelReturnLength);
masm.bind(labelBelowThreshold);
}
if (masm.supports(CPUFeature.SSE4_2)) {
Label labelCopy32Loop = new Label();
Label labelCopy16 = new Label();
Label labelCopyTail = new Label();
masm.movl(result, len);
masm.movl(tmp5, 0xff00ff00); // Create mask to test for Unicode chars in vectors.
// vectored compression
masm.andl(len, 0xfffffff0); // vector count (in chars)
masm.andl(result, 0x0000000f); // tail count (in chars)
masm.testlAndJcc(len, len, ConditionFlag.Zero, labelCopy16, false);
// Compress 16 chars per iteration.
masm.movdl(tmp1Reg, tmp5);
masm.pshufd(tmp1Reg, tmp1Reg, 0); // Store Unicode mask in 'vtmp1'.
masm.pxor(tmp4Reg, tmp4Reg);
masm.leaq(src, new AMD64Address(src, len, Stride.S2));
masm.leaq(dst, new AMD64Address(dst, len, Stride.S1));
masm.negq(len);
// Test and compress 16 chars per iteration, reading 128-bit vectors and
// writing 64-bit compressed ditto.
masm.bind(labelCopy32Loop);
// load 1st 8 characters
masm.movdqu(tmp2Reg, new AMD64Address(src, len, Stride.S2));
masm.por(tmp4Reg, tmp2Reg);
// load next 8 characters
masm.movdqu(tmp3Reg, new AMD64Address(src, len, Stride.S2, 16));
masm.por(tmp4Reg, tmp3Reg);
masm.ptest(tmp4Reg, tmp1Reg); // Check for Unicode chars in vector.
masm.jcc(ConditionFlag.NotZero, labelReturnZero);
masm.packuswb(tmp2Reg, tmp3Reg); // Only ASCII chars; compress each to a byte.
masm.movdqu(new AMD64Address(dst, len, Stride.S1), tmp2Reg);
masm.addqAndJcc(len, 16, ConditionFlag.NotZero, labelCopy32Loop, false);
// Test and compress another 8 chars before final tail copy.
masm.bind(labelCopy16);
masm.movl(len, result);
masm.andl(len, 0xfffffff8); // vector count (in chars)
masm.andl(result, 0x00000007); // tail count (in chars)
masm.testlAndJcc(len, len, ConditionFlag.Zero, labelCopyTail, true);
masm.movdl(tmp1Reg, tmp5);
masm.pshufd(tmp1Reg, tmp1Reg, 0); // Store Unicode mask in 'vtmp1'.
masm.pxor(tmp3Reg, tmp3Reg);
masm.movdqu(tmp2Reg, new AMD64Address(src));
masm.ptest(tmp2Reg, tmp1Reg); // Check for Unicode chars in vector.
masm.jccb(ConditionFlag.NotZero, labelReturnZero);
masm.packuswb(tmp2Reg, tmp3Reg); // Only ASCII chars; compress each to a byte.
masm.movq(new AMD64Address(dst), tmp2Reg);
masm.addq(src, 16);
masm.addq(dst, 8);
masm.bind(labelCopyTail);
masm.movl(len, result);
}
// Compress any remaining characters using a vanilla implementation.
masm.testlAndJcc(len, len, ConditionFlag.Zero, labelReturnLength, true);
masm.leaq(src, new AMD64Address(src, len, Stride.S2));
masm.leaq(dst, new AMD64Address(dst, len, Stride.S1));
masm.negq(len);
// Compress a single character per iteration.
masm.bind(labelCopyCharsLoop);
masm.movzwl(result, new AMD64Address(src, len, Stride.S2));
// Check if Unicode character.
masm.testlAndJcc(result, 0xff00, ConditionFlag.NotZero, labelReturnZero, true);
// An ASCII character; compress to a byte.
masm.movb(new AMD64Address(dst, len, Stride.S1), result);
masm.incqAndJcc(len, ConditionFlag.NotZero, labelCopyCharsLoop, false);
// If compression succeeded, return the length.
masm.bind(labelReturnLength);
masm.pop(result);
masm.jmpb(labelDone);
// If compression failed, return 0.
masm.bind(labelReturnZero);
masm.xorl(result, result);
masm.addq(rsp, 8 /* wordSize */);
masm.bind(labelDone);
}
@Override
public boolean modifiesStackPointer() {
// Only charArrayCompressLegacy modifies rsp.
return JavaVersionUtil.JAVA_SPEC < 22;
}
}
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