/*

 * 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.stubs;

import static java.util.Collections.singletonList;

import static org.graalvm.compiler.core.GraalCompiler.emitFrontEnd;

import static org.graalvm.compiler.core.common.GraalOptions.GeneratePIC;

import static org.graalvm.compiler.debug.DebugContext.DEFAULT_LOG_STREAM;

import static org.graalvm.compiler.debug.DebugOptions.DebugStubsAndSnippets;

import static org.graalvm.compiler.hotspot.HotSpotHostBackend.UNCOMMON_TRAP_HANDLER;

import static org.graalvm.util.CollectionsUtil.allMatch;

import java.util.ListIterator;

import java.util.concurrent.atomic.AtomicInteger;

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

import org.graalvm.compiler.code.CompilationResult;

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

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

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

import org.graalvm.compiler.debug.DebugContext;

import org.graalvm.compiler.debug.DebugContext.Description;

import org.graalvm.compiler.hotspot.HotSpotCompiledCodeBuilder;

import org.graalvm.compiler.hotspot.HotSpotForeignCallLinkage;

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

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

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

import org.graalvm.compiler.lir.phases.LIRPhase;

import org.graalvm.compiler.lir.phases.LIRSuites;

import org.graalvm.compiler.lir.phases.PostAllocationOptimizationPhase.PostAllocationOptimizationContext;

import org.graalvm.compiler.lir.profiling.MoveProfilingPhase;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.options.OptionValues;

import org.graalvm.compiler.phases.OptimisticOptimizations;

import org.graalvm.compiler.phases.PhaseSuite;

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

import org.graalvm.compiler.printer.GraalDebugHandlersFactory;

import jdk.vm.ci.code.CodeCacheProvider;

import jdk.vm.ci.code.InstalledCode;

import jdk.vm.ci.code.Register;

import jdk.vm.ci.code.RegisterConfig;

import jdk.vm.ci.code.site.Call;

import jdk.vm.ci.code.site.ConstantReference;

import jdk.vm.ci.code.site.DataPatch;

import jdk.vm.ci.code.site.Infopoint;

import jdk.vm.ci.hotspot.HotSpotCompiledCode;

import jdk.vm.ci.hotspot.HotSpotMetaspaceConstant;

import jdk.vm.ci.meta.DefaultProfilingInfo;

import jdk.vm.ci.meta.ResolvedJavaMethod;

import jdk.vm.ci.meta.TriState;

//JaCoCo Exclude

/**

 * Base class for implementing some low level code providing the out-of-line slow path for a snippet

 * method.

 */

public abstract class Stub {

    /**

     * The linkage information for a call to this stub from compiled code.

     */

    protected final HotSpotForeignCallLinkage linkage;

    /**

     * The code installed for the stub.

     */

    protected InstalledCode code;

    /**

     * The registers destroyed by this stub (from the caller's perspective).

     */

    private EconomicSet<Register> destroyedCallerRegisters;

    private static boolean checkRegisterSetEquivalency(EconomicSet<Register> a, EconomicSet<Register> b) {

        if (a == b) {

            return true;

        }

        if (a.size() != b.size()) {

            return false;

        }

        return allMatch(a, e -> b.contains(e));

    }

    public void initDestroyedCallerRegisters(EconomicSet<Register> registers) {

        assert registers != null;

        assert destroyedCallerRegisters == null || checkRegisterSetEquivalency(registers, destroyedCallerRegisters) : "cannot redefine";

        destroyedCallerRegisters = registers;

    }

    /**

     * Gets the registers destroyed by this stub from a caller's perspective. These are the

     * temporaries of this stub and must thus be caller saved by a callers of this stub.

     */

    public EconomicSet<Register> getDestroyedCallerRegisters() {

        assert destroyedCallerRegisters != null : "not yet initialized";

        return destroyedCallerRegisters;

    }

    public boolean shouldSaveRegistersAroundCalls() {

        return linkage.getEffect() == HotSpotForeignCallLinkage.RegisterEffect.COMPUTES_REGISTERS_KILLED;

    }

    protected final OptionValues options;

    protected final HotSpotProviders providers;

    /**

     * Creates a new stub.

     *

     * @param linkage linkage details for a call to the stub

     */

    public Stub(OptionValues options, HotSpotProviders providers, HotSpotForeignCallLinkage linkage) {

        this.linkage = linkage;

        this.providers = providers;

    }

    /**

     * Gets the linkage for a call to this stub from compiled code.

     */

    public HotSpotForeignCallLinkage getLinkage() {

        return linkage;

    }

    public RegisterConfig getRegisterConfig() {

        return null;

    }

    /**

     * Gets the graph that from which the code for this stub will be compiled.

     *

     * @param compilationId unique compilation id for the stub

     */

    protected abstract StructuredGraph getGraph(DebugContext debug, CompilationIdentifier compilationId);

    @Override

    public String toString() {

        return "Stub<" + linkage.getDescriptor() + ">";

    }

    /**

     * Gets the method the stub's code will be associated with once installed. This may be null.

     */

    protected abstract ResolvedJavaMethod getInstalledCodeOwner();

    /**

     * Gets a context object for the debug scope created when producing the code for this stub.

     */

    protected abstract Object debugScopeContext();

    private static final AtomicInteger nextStubId = new AtomicInteger();

    private DebugContext openDebugContext(DebugContext outer) {

        if (DebugStubsAndSnippets.getValue(options)) {

            Description description = new Description(linkage, "Stub_" + nextStubId.incrementAndGet());

            return DebugContext.create(options, description, outer.getGlobalMetrics(), DEFAULT_LOG_STREAM, singletonList(new GraalDebugHandlersFactory(providers.getSnippetReflection())));

        }

        return DebugContext.disabled(options);

    }

    /**

     * Gets the code for this stub, compiling it first if necessary.

     */

    @SuppressWarnings("try")

    public synchronized InstalledCode getCode(final Backend backend) {

        if (code == null) {

            try (DebugContext debug = openDebugContext(DebugContext.forCurrentThread())) {

                try (DebugContext.Scope d = debug.scope("CompilingStub", providers.getCodeCache(), debugScopeContext())) {

                    CodeCacheProvider codeCache = providers.getCodeCache();

                    CompilationResult compResult = buildCompilationResult(debug, backend);

                    try (DebugContext.Scope s = debug.scope("CodeInstall", compResult);

                                    DebugContext.Activation a = debug.activate()) {

                        assert destroyedCallerRegisters != null;

                        // Add a GeneratePIC check here later, we don't want to install

                        // code if we don't have a corresponding VM global symbol.

                        HotSpotCompiledCode compiledCode = HotSpotCompiledCodeBuilder.createCompiledCode(codeCache, null, null, compResult, options);

                        code = codeCache.installCode(null, compiledCode, null, null, false);

                    } catch (Throwable e) {

                        throw debug.handle(e);

                    }

                } catch (Throwable e) {

                    throw debug.handle(e);

                }

                assert code != null : "error installing stub " + this;

            }

        }

        return code;

    }

    @SuppressWarnings("try")

    private CompilationResult buildCompilationResult(DebugContext debug, final Backend backend) {

        CompilationIdentifier compilationId = getStubCompilationId();

        final StructuredGraph graph = getGraph(debug, compilationId);

        CompilationResult compResult = new CompilationResult(compilationId, toString(), GeneratePIC.getValue(options));

        // Stubs cannot be recompiled so they cannot be compiled with assumptions

        assert graph.getAssumptions() == null;

        if (!(graph.start() instanceof StubStartNode)) {

            StubStartNode newStart = graph.add(new StubStartNode(Stub.this));

            newStart.setStateAfter(graph.start().stateAfter());

            graph.replaceFixed(graph.start(), newStart);

        }

        try (DebugContext.Scope s0 = debug.scope("StubCompilation", graph, providers.getCodeCache())) {

            Suites suites = createSuites();

            emitFrontEnd(providers, backend, graph, providers.getSuites().getDefaultGraphBuilderSuite(), OptimisticOptimizations.ALL, DefaultProfilingInfo.get(TriState.UNKNOWN), suites);

            LIRSuites lirSuites = createLIRSuites();

            backend.emitBackEnd(graph, Stub.this, getInstalledCodeOwner(), compResult, CompilationResultBuilderFactory.Default, getRegisterConfig(), lirSuites);

            assert checkStubInvariants(compResult);

        } catch (Throwable e) {

            throw debug.handle(e);

        }

        return compResult;

    }

    /**

     * Gets a {@link CompilationResult} that can be used for code generation. Required for AOT.

     */

    @SuppressWarnings("try")

    public CompilationResult getCompilationResult(DebugContext debug, final Backend backend) {

        try (DebugContext.Scope d = debug.scope("CompilingStub", providers.getCodeCache(), debugScopeContext())) {

            return buildCompilationResult(debug, backend);

        } catch (Throwable e) {

            throw debug.handle(e);

        }

    }

    public CompilationIdentifier getStubCompilationId() {

        return new StubCompilationIdentifier(this);

    }

    /**

     * Checks the conditions a compilation must satisfy to be installed as a RuntimeStub.

     */

    private boolean checkStubInvariants(CompilationResult compResult) {

        assert compResult.getExceptionHandlers().isEmpty() : this;

        // Stubs cannot be recompiled so they cannot be compiled with

        // assumptions and there is no point in recording evol_method dependencies

        assert compResult.getAssumptions() == null : "stubs should not use assumptions: " + this;

        for (DataPatch data : compResult.getDataPatches()) {

            if (data.reference instanceof ConstantReference) {

                ConstantReference ref = (ConstantReference) data.reference;

                if (ref.getConstant() instanceof HotSpotMetaspaceConstant) {

                    HotSpotMetaspaceConstant c = (HotSpotMetaspaceConstant) ref.getConstant();

                    if (c.asResolvedJavaType() != null && c.asResolvedJavaType().getName().equals("[I")) {

                        // special handling for NewArrayStub

                        // embedding the type '[I' is safe, since it is never unloaded

                        continue;

                    }

                }

            }

            assert !(data.reference instanceof ConstantReference) : this + " cannot have embedded object or metadata constant: " + data.reference;

        }

        for (Infopoint infopoint : compResult.getInfopoints()) {

            assert infopoint instanceof Call : this + " cannot have non-call infopoint: " + infopoint;

            Call call = (Call) infopoint;

            assert call.target instanceof HotSpotForeignCallLinkage : this + " cannot have non runtime call: " + call.target;

            HotSpotForeignCallLinkage callLinkage = (HotSpotForeignCallLinkage) call.target;

            assert !callLinkage.isCompiledStub() || callLinkage.getDescriptor().equals(UNCOMMON_TRAP_HANDLER) : this + " cannot call compiled stub " + callLinkage;

        }

        return true;

    }

    protected Suites createSuites() {

        Suites defaultSuites = providers.getSuites().getDefaultSuites(options);

        return new Suites(new PhaseSuite<>(), defaultSuites.getMidTier(), defaultSuites.getLowTier());

    }

    protected LIRSuites createLIRSuites() {

        LIRSuites lirSuites = new LIRSuites(providers.getSuites().getDefaultLIRSuites(options));

        ListIterator<LIRPhase<PostAllocationOptimizationContext>> moveProfiling = lirSuites.getPostAllocationOptimizationStage().findPhase(MoveProfilingPhase.class);

        if (moveProfiling != null) {

            moveProfiling.remove();

        }

        return lirSuites;

    }

}