/*

 * Copyright (c) 2012, 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.hotspot;

import static org.graalvm.compiler.replacements.arraycopy.ArrayCopyForeignCalls.UNSAFE_ARRAYCOPY;

import java.util.EnumSet;

import jdk.internal.vm.compiler.collections.EconomicMap;

import jdk.internal.vm.compiler.collections.EconomicSet;

import jdk.internal.vm.compiler.collections.Equivalence;

import jdk.internal.vm.compiler.collections.MapCursor;

import org.graalvm.compiler.code.CompilationResult;

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

import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;

import org.graalvm.compiler.core.common.spi.ForeignCallDescriptor;

import org.graalvm.compiler.core.common.spi.ForeignCallLinkage;

import org.graalvm.compiler.core.target.Backend;

import org.graalvm.compiler.graph.Node.ConstantNodeParameter;

import org.graalvm.compiler.graph.Node.NodeIntrinsic;

import org.graalvm.compiler.hotspot.meta.HotSpotProviders;

import org.graalvm.compiler.hotspot.nodes.VMErrorNode;

import org.graalvm.compiler.hotspot.nodes.aot.ResolveConstantStubCall;

import org.graalvm.compiler.hotspot.replacements.AESCryptSubstitutions;

import org.graalvm.compiler.hotspot.replacements.BigIntegerSubstitutions;

import org.graalvm.compiler.hotspot.replacements.CipherBlockChainingSubstitutions;

import org.graalvm.compiler.hotspot.replacements.DigestBaseSubstitutions;

import org.graalvm.compiler.hotspot.replacements.SHA2Substitutions;

import org.graalvm.compiler.hotspot.replacements.SHA5Substitutions;

import org.graalvm.compiler.hotspot.replacements.SHASubstitutions;

import org.graalvm.compiler.hotspot.stubs.ExceptionHandlerStub;

import org.graalvm.compiler.hotspot.stubs.Stub;

import org.graalvm.compiler.hotspot.stubs.UnwindExceptionToCallerStub;

import org.graalvm.compiler.hotspot.word.KlassPointer;

import org.graalvm.compiler.hotspot.word.MethodCountersPointer;

import org.graalvm.compiler.lir.LIR;

import org.graalvm.compiler.lir.LIRFrameState;

import org.graalvm.compiler.lir.LIRInstruction;

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

import org.graalvm.compiler.lir.LIRInstruction.OperandMode;

import org.graalvm.compiler.lir.StandardOp.LabelOp;

import org.graalvm.compiler.lir.StandardOp.RestoreRegistersOp;

import org.graalvm.compiler.lir.StandardOp.SaveRegistersOp;

import org.graalvm.compiler.lir.ValueConsumer;

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

import org.graalvm.compiler.lir.framemap.FrameMap;

import org.graalvm.compiler.nodes.UnwindNode;

import org.graalvm.compiler.nodes.extended.ForeignCallNode;

import org.graalvm.compiler.options.Option;

import org.graalvm.compiler.options.OptionKey;

import org.graalvm.compiler.options.OptionType;

import org.graalvm.compiler.options.OptionValues;

import org.graalvm.compiler.phases.tiers.SuitesProvider;

import org.graalvm.compiler.serviceprovider.JavaVersionUtil;

import org.graalvm.compiler.word.Word;

import jdk.internal.vm.compiler.word.Pointer;

import jdk.vm.ci.code.CallingConvention;

import jdk.vm.ci.code.CompilationRequest;

import jdk.vm.ci.code.CompiledCode;

import jdk.vm.ci.code.Register;

import jdk.vm.ci.code.StackSlot;

import jdk.vm.ci.code.ValueUtil;

import jdk.vm.ci.hotspot.HotSpotCompilationRequest;

import jdk.vm.ci.hotspot.HotSpotJVMCIRuntime;

import jdk.vm.ci.hotspot.HotSpotResolvedJavaMethod;

import jdk.vm.ci.meta.AllocatableValue;

import jdk.vm.ci.meta.ResolvedJavaMethod;

import jdk.vm.ci.meta.Value;

import jdk.vm.ci.runtime.JVMCICompiler;

/**

 * HotSpot specific backend.

 */

public abstract class HotSpotBackend extends Backend implements FrameMap.ReferenceMapBuilderFactory {

    public static class Options {

        // @formatter:off

        @Option(help = "Use Graal arithmetic stubs instead of HotSpot stubs where possible")

        public static final OptionKey<Boolean> GraalArithmeticStubs = new OptionKey<>(JavaVersionUtil.JAVA_SPEC >= 9);

        @Option(help = "Enables instruction profiling on assembler level. Valid values are a comma separated list of supported instructions." +

                        " Compare with subclasses of Assembler.InstructionCounter.", type = OptionType.Debug)

        public static final OptionKey<String> ASMInstructionProfiling = new OptionKey<>(null);

        // @formatter:on

    }

    /**

     * Descriptor for {@link ExceptionHandlerStub}. This stub is called by the

     * {@linkplain GraalHotSpotVMConfig#MARKID_EXCEPTION_HANDLER_ENTRY exception handler} in a

     * compiled method.

     */

    public static final ForeignCallDescriptor EXCEPTION_HANDLER = new ForeignCallDescriptor("exceptionHandler", void.class, Object.class, Word.class);

    /**

     * Descriptor for SharedRuntime::get_ic_miss_stub().

     */

    public static final ForeignCallDescriptor IC_MISS_HANDLER = new ForeignCallDescriptor("icMissHandler", void.class);

    /**

     * Descriptor for SharedRuntime::get_handle_wrong_method_stub().

     */

    public static final ForeignCallDescriptor WRONG_METHOD_HANDLER = new ForeignCallDescriptor("wrongMethodHandler", void.class);

    /**

     * Descriptor for {@link UnwindExceptionToCallerStub}. This stub is called by code generated

     * from {@link UnwindNode}.

     */

    public static final ForeignCallDescriptor UNWIND_EXCEPTION_TO_CALLER = new ForeignCallDescriptor("unwindExceptionToCaller", void.class, Object.class, Word.class);

    /**

     * Descriptor for the arguments when unwinding to an exception handler in a caller.

     */

    public static final ForeignCallDescriptor EXCEPTION_HANDLER_IN_CALLER = new ForeignCallDescriptor("exceptionHandlerInCaller", void.class, Object.class, Word.class);

    private final HotSpotGraalRuntimeProvider runtime;

    /**

     * @see AESCryptSubstitutions#encryptBlockStub(ForeignCallDescriptor, Word, Word, Pointer)

     */

    public static final ForeignCallDescriptor ENCRYPT_BLOCK = new ForeignCallDescriptor("encrypt_block", void.class, Word.class, Word.class, Pointer.class);

    /**

     * @see AESCryptSubstitutions#decryptBlockStub(ForeignCallDescriptor, Word, Word, Pointer)

     */

    public static final ForeignCallDescriptor DECRYPT_BLOCK = new ForeignCallDescriptor("decrypt_block", void.class, Word.class, Word.class, Pointer.class);

    /**

     * @see AESCryptSubstitutions#decryptBlockStub(ForeignCallDescriptor, Word, Word, Pointer)

     */

    public static final ForeignCallDescriptor DECRYPT_BLOCK_WITH_ORIGINAL_KEY = new ForeignCallDescriptor("decrypt_block_with_original_key", void.class, Word.class, Word.class, Pointer.class,

                    Pointer.class);

    /**

     * @see CipherBlockChainingSubstitutions#crypt

     */

    public static final ForeignCallDescriptor ENCRYPT = new ForeignCallDescriptor("encrypt", void.class, Word.class, Word.class, Pointer.class, Pointer.class, int.class);

    /**

     * @see CipherBlockChainingSubstitutions#crypt

     */

    public static final ForeignCallDescriptor DECRYPT = new ForeignCallDescriptor("decrypt", void.class, Word.class, Word.class, Pointer.class, Pointer.class, int.class);

    /**

     * @see CipherBlockChainingSubstitutions#crypt

     */

    public static final ForeignCallDescriptor DECRYPT_WITH_ORIGINAL_KEY = new ForeignCallDescriptor("decrypt_with_original_key", void.class, Word.class, Word.class, Pointer.class, Pointer.class,

                    int.class, Pointer.class);

    /**

     * @see BigIntegerSubstitutions#multiplyToLen

     */

    public static final ForeignCallDescriptor MULTIPLY_TO_LEN = new ForeignCallDescriptor("multiplyToLen", void.class, Word.class, int.class, Word.class, int.class, Word.class, int.class);

    public static void multiplyToLenStub(Word xAddr, int xlen, Word yAddr, int ylen, Word zAddr, int zLen) {

        multiplyToLenStub(HotSpotBackend.MULTIPLY_TO_LEN, xAddr, xlen, yAddr, ylen, zAddr, zLen);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native void multiplyToLenStub(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word xIn, int xLen, Word yIn, int yLen, Word zIn, int zLen);

    /**

     * @see BigIntegerSubstitutions#mulAdd

     */

    public static final ForeignCallDescriptor MUL_ADD = new ForeignCallDescriptor("mulAdd", int.class, Word.class, Word.class, int.class, int.class, int.class);

    public static int mulAddStub(Word inAddr, Word outAddr, int newOffset, int len, int k) {

        return mulAddStub(HotSpotBackend.MUL_ADD, inAddr, outAddr, newOffset, len, k);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native int mulAddStub(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word inAddr, Word outAddr, int newOffset, int len, int k);

    /**

     * @see BigIntegerSubstitutions#implMontgomeryMultiply

     */

    public static final ForeignCallDescriptor MONTGOMERY_MULTIPLY = new ForeignCallDescriptor("implMontgomeryMultiply", void.class, Word.class, Word.class, Word.class, int.class, long.class,

                    Word.class);

    public static void implMontgomeryMultiply(Word aAddr, Word bAddr, Word nAddr, int len, long inv, Word productAddr) {

        implMontgomeryMultiply(HotSpotBackend.MONTGOMERY_MULTIPLY, aAddr, bAddr, nAddr, len, inv, productAddr);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native void implMontgomeryMultiply(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word aAddr, Word bAddr, Word nAddr, int len, long inv, Word productAddr);

    /**

     * @see BigIntegerSubstitutions#implMontgomerySquare

     */

    public static final ForeignCallDescriptor MONTGOMERY_SQUARE = new ForeignCallDescriptor("implMontgomerySquare", void.class, Word.class, Word.class, int.class, long.class, Word.class);

    public static void implMontgomerySquare(Word aAddr, Word nAddr, int len, long inv, Word productAddr) {

        implMontgomerySquare(HotSpotBackend.MONTGOMERY_SQUARE, aAddr, nAddr, len, inv, productAddr);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native void implMontgomerySquare(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word aAddr, Word nAddr, int len, long inv, Word productAddr);

    /**

     * @see BigIntegerSubstitutions#implSquareToLen

     */

    public static final ForeignCallDescriptor SQUARE_TO_LEN = new ForeignCallDescriptor("implSquareToLen", void.class, Word.class, int.class, Word.class, int.class);

    public static void implSquareToLen(Word xAddr, int len, Word zAddr, int zLen) {

        implSquareToLen(SQUARE_TO_LEN, xAddr, len, zAddr, zLen);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native void implSquareToLen(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word xAddr, int len, Word zAddr, int zLen);

    /**

     * @see SHASubstitutions#implCompress0

     */

    public static final ForeignCallDescriptor SHA_IMPL_COMPRESS = new ForeignCallDescriptor("shaImplCompress", void.class, Word.class, Object.class);

    public static void shaImplCompressStub(Word bufAddr, Object state) {

        shaImplCompressStub(HotSpotBackend.SHA_IMPL_COMPRESS, bufAddr, state);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native void shaImplCompressStub(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word bufAddr, Object state);

    /**

     * @see SHA2Substitutions#implCompress0

     */

    public static final ForeignCallDescriptor SHA2_IMPL_COMPRESS = new ForeignCallDescriptor("sha2ImplCompress", void.class, Word.class, Object.class);

    public static void sha2ImplCompressStub(Word bufAddr, Object state) {

        sha2ImplCompressStub(HotSpotBackend.SHA2_IMPL_COMPRESS, bufAddr, state);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native void sha2ImplCompressStub(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word bufAddr, Object state);

    /**

     * @see SHA5Substitutions#implCompress0

     */

    public static final ForeignCallDescriptor SHA5_IMPL_COMPRESS = new ForeignCallDescriptor("sha5ImplCompress", void.class, Word.class, Object.class);

    public static void sha5ImplCompressStub(Word bufAddr, Object state) {

        sha5ImplCompressStub(HotSpotBackend.SHA5_IMPL_COMPRESS, bufAddr, state);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native void sha5ImplCompressStub(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word bufAddr, Object state);

    /**

     * @see DigestBaseSubstitutions#implCompressMultiBlock0

     */

    public static final ForeignCallDescriptor SHA_IMPL_COMPRESS_MB = new ForeignCallDescriptor("shaImplCompressMB", int.class, Word.class, Object.class, int.class, int.class);

    public static int shaImplCompressMBStub(Word bufAddr, Object stateAddr, int ofs, int limit) {

        return shaImplCompressMBStub(HotSpotBackend.SHA_IMPL_COMPRESS_MB, bufAddr, stateAddr, ofs, limit);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native int shaImplCompressMBStub(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word bufAddr, Object state, int ofs, int limit);

    public static final ForeignCallDescriptor SHA2_IMPL_COMPRESS_MB = new ForeignCallDescriptor("sha2ImplCompressMB", int.class, Word.class, Object.class, int.class, int.class);

    public static int sha2ImplCompressMBStub(Word bufAddr, Object stateAddr, int ofs, int limit) {

        return sha2ImplCompressMBStub(HotSpotBackend.SHA2_IMPL_COMPRESS_MB, bufAddr, stateAddr, ofs, limit);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native int sha2ImplCompressMBStub(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word bufAddr, Object state, int ofs, int limit);

    public static final ForeignCallDescriptor SHA5_IMPL_COMPRESS_MB = new ForeignCallDescriptor("sha5ImplCompressMB", int.class, Word.class, Object.class, int.class, int.class);

    public static int sha5ImplCompressMBStub(Word bufAddr, Object stateAddr, int ofs, int limit) {

        return sha5ImplCompressMBStub(HotSpotBackend.SHA5_IMPL_COMPRESS_MB, bufAddr, stateAddr, ofs, limit);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native int sha5ImplCompressMBStub(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word bufAddr, Object state, int ofs, int limit);

    public static void unsafeArraycopy(Word srcAddr, Word dstAddr, Word size) {

        unsafeArraycopyStub(UNSAFE_ARRAYCOPY, srcAddr, dstAddr, size);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native void unsafeArraycopyStub(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word srcAddr, Word dstAddr, Word size);

    /**

     * Descriptor for {@code StubRoutines::_ghash_processBlocks}.

     */

    public static final ForeignCallDescriptor GHASH_PROCESS_BLOCKS = new ForeignCallDescriptor("ghashProcessBlocks", void.class, Word.class, Word.class, Word.class, int.class);

    /**

     * Descriptor for {@code StubRoutines::_base64_encodeBlock}.

     */

    public static final ForeignCallDescriptor BASE64_ENCODE_BLOCK = new ForeignCallDescriptor("base64EncodeBlock", void.class, Word.class, int.class, int.class, Word.class, int.class, boolean.class);

    /**

     * Descriptor for {@code StubRoutines::_counterMode_AESCrypt}.

     */

    public static final ForeignCallDescriptor COUNTERMODE_IMPL_CRYPT = new ForeignCallDescriptor("counterModeAESCrypt", int.class, Word.class, Word.class, Word.class, Word.class, int.class,

                    Word.class, Word.class);

    public static int counterModeAESCrypt(Word srcAddr, Word dstAddr, Word kPtr, Word cntPtr, int len, Word encCntPtr, Word used) {

        return counterModeAESCrypt(COUNTERMODE_IMPL_CRYPT, srcAddr, dstAddr, kPtr, cntPtr, len, encCntPtr, used);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native int counterModeAESCrypt(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word srcAddr, Word dstAddr, Word kPtr, Word cntPtr, int len, Word encCntPtr,

                    Word used);

    /**

     * Descriptor for {@code StubRoutines::_vectorizedMismatch}.

     */

    public static final ForeignCallDescriptor VECTORIZED_MISMATCHED = new ForeignCallDescriptor("vectorizedMismatch", int.class, Word.class, Word.class, int.class, int.class);

    public static int vectorizedMismatch(Word aAddr, Word bAddr, int length, int log2ArrayIndexScale) {

        return vectorizedMismatchStub(VECTORIZED_MISMATCHED, aAddr, bAddr, length, log2ArrayIndexScale);

    }

    @NodeIntrinsic(ForeignCallNode.class)

    private static native int vectorizedMismatchStub(@ConstantNodeParameter ForeignCallDescriptor descriptor, Word aAddr, Word bAddr, int length, int log2ArrayIndexScale);

    /**

     * @see VMErrorNode

     */

    public static final ForeignCallDescriptor VM_ERROR = new ForeignCallDescriptor("vm_error", void.class, Object.class, Object.class, long.class);

    /**

     * New multi array stub that throws an {@link OutOfMemoryError} on allocation failure.

     */

    public static final ForeignCallDescriptor NEW_MULTI_ARRAY = new ForeignCallDescriptor("new_multi_array", Object.class, KlassPointer.class, int.class, Word.class);

    /**

     * New multi array stub that will return null on allocation failure.

     */

    public static final ForeignCallDescriptor NEW_MULTI_ARRAY_OR_NULL = new ForeignCallDescriptor("new_multi_array_or_null", Object.class, KlassPointer.class, int.class, Word.class);

    /**

     * New array stub that throws an {@link OutOfMemoryError} on allocation failure.

     */

    public static final ForeignCallDescriptor NEW_ARRAY = new ForeignCallDescriptor("new_array", Object.class, KlassPointer.class, int.class);

    /**

     * New array stub that will return null on allocation failure.

     */

    public static final ForeignCallDescriptor NEW_ARRAY_OR_NULL = new ForeignCallDescriptor("new_array_or_null", Object.class, KlassPointer.class, int.class);

    /**

     * New instance stub that throws an {@link OutOfMemoryError} on allocation failure.

     */

    public static final ForeignCallDescriptor NEW_INSTANCE = new ForeignCallDescriptor("new_instance", Object.class, KlassPointer.class);

    /**

     * New instance stub that will return null on allocation failure.

     */

    public static final ForeignCallDescriptor NEW_INSTANCE_OR_NULL = new ForeignCallDescriptor("new_instance_or_null", Object.class, KlassPointer.class);

    /**

     * @see ResolveConstantStubCall

     */

    public static final ForeignCallDescriptor RESOLVE_STRING_BY_SYMBOL = new ForeignCallDescriptor("resolve_string_by_symbol", Object.class, Word.class, Word.class);

    /**

     * @see ResolveConstantStubCall

     */

    public static final ForeignCallDescriptor RESOLVE_DYNAMIC_INVOKE = new ForeignCallDescriptor("resolve_dynamic_invoke", Object.class, Word.class);

    /**

     * @see ResolveConstantStubCall

     */

    public static final ForeignCallDescriptor RESOLVE_KLASS_BY_SYMBOL = new ForeignCallDescriptor("resolve_klass_by_symbol", Word.class, Word.class, Word.class);

    /**

     * @see ResolveConstantStubCall

     */

    public static final ForeignCallDescriptor INITIALIZE_KLASS_BY_SYMBOL = new ForeignCallDescriptor("initialize_klass_by_symbol", Word.class, Word.class, Word.class);

    /**

     * @see ResolveConstantStubCall

     */

    public static final ForeignCallDescriptor RESOLVE_METHOD_BY_SYMBOL_AND_LOAD_COUNTERS = new ForeignCallDescriptor("resolve_method_by_symbol_and_load_counters", Word.class, Word.class, Word.class,

                    Word.class);

    /**

     * Tiered support.

     */

    public static final ForeignCallDescriptor INVOCATION_EVENT = new ForeignCallDescriptor("invocation_event", void.class, MethodCountersPointer.class);

    public static final ForeignCallDescriptor BACKEDGE_EVENT = new ForeignCallDescriptor("backedge_event", void.class, MethodCountersPointer.class, int.class, int.class);

    public HotSpotBackend(HotSpotGraalRuntimeProvider runtime, HotSpotProviders providers) {

        super(providers);

        this.runtime = runtime;

    }

    public HotSpotGraalRuntimeProvider getRuntime() {

        return runtime;

    }

    /**

     * Performs any remaining initialization that was deferred until the {@linkplain #getRuntime()

     * runtime} object was initialized and this backend was registered with it.

     *

     * @param jvmciRuntime

     * @param options

     */

    public void completeInitialization(HotSpotJVMCIRuntime jvmciRuntime, OptionValues options) {

    }

    /**

     * Finds all the registers that are defined by some given LIR.

     *

     * @param gen the result to examine

     * @return the registers that are defined by or used as temps for any instruction in {@code lir}

     */

    private EconomicSet<Register> gatherDestroyedCallerRegisters(HotSpotLIRGenerationResult gen) {

        LIR lir = gen.getLIR();

        final EconomicSet<Register> preservedRegisters = EconomicSet.create(Equivalence.IDENTITY);

        final EconomicSet<Register> destroyedRegisters = EconomicSet.create(Equivalence.IDENTITY);

        ValueConsumer defConsumer = new ValueConsumer() {

            @Override

            public void visitValue(Value value, OperandMode mode, EnumSet<OperandFlag> flags) {

                if (ValueUtil.isRegister(value)) {

                    final Register reg = ValueUtil.asRegister(value);

                    if (!preservedRegisters.contains(reg)) {

                        destroyedRegisters.add(reg);

                    }

                }

            }

        };

        boolean sawSaveRegisters = false;

        for (AbstractBlockBase<?> block : lir.codeEmittingOrder()) {

            if (block == null) {

                continue;

            }

            // Ignore the effects of instructions bracketed by save/restore

            SaveRegistersOp save = null;

            for (LIRInstruction op : lir.getLIRforBlock(block)) {

                if (op instanceof LabelOp) {

                    // Don't consider this as a definition

                } else if (op instanceof SaveRegistersOp) {

                    save = (SaveRegistersOp) op;

                    sawSaveRegisters = true;

                    preservedRegisters.addAll(save.getSaveableRegisters());

                } else if (op instanceof RestoreRegistersOp) {

                    save = null;

                    preservedRegisters.clear();

                } else {

                    op.visitEachTemp(defConsumer);

                    op.visitEachOutput(defConsumer);

                }

            }

            assert save == null : "missing RestoreRegistersOp";

        }

        if (sawSaveRegisters) {

            // The return value must be killed so it can be propagated out

            CallingConvention cc = gen.getCallingConvention();

            AllocatableValue returnValue = cc.getReturn();

            if (returnValue != null) {

                if (ValueUtil.isRegister(returnValue)) {

                    destroyedRegisters.add(ValueUtil.asRegister(returnValue));

                }

            }

        }

        return translateToCallerRegisters(destroyedRegisters);

    }

    /**

     * Translates a set of registers from the callee's perspective to the caller's perspective. This

     * is needed for architectures where input/output registers are renamed during a call (e.g.

     * register windows on SPARC). Registers which are not visible by the caller are removed.

     */

    protected abstract EconomicSet<Register> translateToCallerRegisters(EconomicSet<Register> calleeRegisters);

    /**

     * Updates a given stub with respect to the registers it destroys by

     * {@link #gatherDestroyedCallerRegisters(HotSpotLIRGenerationResult) computing the destroyed

     * registers} and removing those registers from the {@linkplain SaveRegistersOp SaveRegistersOp}

     * as these registers are declared as temporaries in the stub's {@linkplain ForeignCallLinkage

     * linkage} (and thus will be saved by the stub's caller).

     *

     * @param stub the stub to update

     * @param gen the HotSpotLIRGenerationResult being emitted

     * @param frameMap used to {@linkplain FrameMap#offsetForStackSlot(StackSlot) convert} a virtual

     */

    protected void updateStub(Stub stub, HotSpotLIRGenerationResult gen, FrameMap frameMap) {

        EconomicSet<Register> destroyedRegisters = gatherDestroyedCallerRegisters(gen);

        EconomicMap<LIRFrameState, SaveRegistersOp> calleeSaveInfo = gen.getCalleeSaveInfo();

        if (stub.getLinkage().needsDebugInfo() && calleeSaveInfo.isEmpty()) {

            // This call is a safepoint but no register saving was done so we must ensure that all

            // registers appear to be killed. The Native ABI may allow caller save registers but

            // for HotSpot they must be described in a RegisterMap so they are accessible.