/*
 * Copyright (c) 2012, 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 com.oracle.graal.hotspot.amd64;

import static com.oracle.graal.amd64.AMD64.*;
import static com.oracle.graal.api.code.CallingConvention.Type.*;
import static com.oracle.graal.api.code.ValueUtil.*;
import static com.oracle.graal.phases.GraalOptions.*;
import static java.lang.reflect.Modifier.*;

import java.util.*;

import sun.misc.*;

import com.oracle.graal.amd64.*;
import com.oracle.graal.api.code.*;
import com.oracle.graal.api.meta.*;
import com.oracle.graal.asm.*;
import com.oracle.graal.asm.amd64.*;
import com.oracle.graal.asm.amd64.AMD64Assembler.ConditionFlag;
import com.oracle.graal.compiler.gen.*;
import com.oracle.graal.compiler.target.*;
import com.oracle.graal.hotspot.*;
import com.oracle.graal.hotspot.bridge.*;
import com.oracle.graal.hotspot.meta.*;
import com.oracle.graal.hotspot.stubs.*;
import com.oracle.graal.lir.*;
import com.oracle.graal.lir.LIRInstruction.ValueProcedure;
import com.oracle.graal.lir.StandardOp.LabelOp;
import com.oracle.graal.lir.amd64.*;
import com.oracle.graal.lir.asm.*;
import com.oracle.graal.nodes.*;
import com.oracle.graal.nodes.cfg.*;

/**
 * HotSpot AMD64 specific backend.
 */
public class AMD64HotSpotBackend extends HotSpotBackend {

    private static final Unsafe unsafe = Unsafe.getUnsafe();

    public AMD64HotSpotBackend(HotSpotGraalRuntime runtime, HotSpotProviders providers) {
        super(runtime, providers);
    }

    @Override
    public boolean shouldAllocateRegisters() {
        return true;
    }

    @Override
    public FrameMap newFrameMap() {
        return new AMD64FrameMap(getCodeCache());
    }

    @Override
    public LIRGenerator newLIRGenerator(StructuredGraph graph, FrameMap frameMap, CallingConvention cc, LIR lir) {
        return new AMD64HotSpotLIRGenerator(graph, getProviders(), getRuntime().getConfig(), frameMap, cc, lir);
    }

    /**
     * Emits code to do stack overflow checking.
     * 
     * @param afterFrameInit specifies if the stack pointer has already been adjusted to allocate
     *            the current frame
     */
    protected static void emitStackOverflowCheck(TargetMethodAssembler tasm, boolean afterFrameInit) {
        if (StackShadowPages.getValue() > 0) {

            AMD64MacroAssembler asm = (AMD64MacroAssembler) tasm.asm;
            int frameSize = tasm.frameMap.frameSize();
            if (frameSize > 0) {
                int lastFramePage = frameSize / unsafe.pageSize();
                // emit multiple stack bangs for methods with frames larger than a page
                for (int i = 0; i <= lastFramePage; i++) {
                    int disp = (i + StackShadowPages.getValue()) * unsafe.pageSize();
                    if (afterFrameInit) {
                        disp -= frameSize;
                    }
                    tasm.blockComment("[stack overflow check]");
                    asm.movq(new AMD64Address(rsp, -disp), AMD64.rax);
                }
            }
        }
    }

    class HotSpotFrameContext implements FrameContext {

        final boolean isStub;

        HotSpotFrameContext(boolean isStub) {
            this.isStub = isStub;
        }

        @Override
        public void enter(TargetMethodAssembler tasm) {
            FrameMap frameMap = tasm.frameMap;
            int frameSize = frameMap.frameSize();

            AMD64MacroAssembler asm = (AMD64MacroAssembler) tasm.asm;
            if (!isStub) {
                emitStackOverflowCheck(tasm, false);
            }
            asm.decrementq(rsp, frameSize);
            if (ZapStackOnMethodEntry.getValue()) {
                final int intSize = 4;
                for (int i = 0; i < frameSize / intSize; ++i) {
                    asm.movl(new AMD64Address(rsp, i * intSize), 0xC1C1C1C1);
                }
            }
            CalleeSaveLayout csl = frameMap.registerConfig.getCalleeSaveLayout();
            if (csl != null && csl.size != 0) {
                int frameToCSA = frameMap.offsetToCalleeSaveArea();
                assert frameToCSA >= 0;
                asm.save(csl, frameToCSA);
            }
        }

        @Override
        public void leave(TargetMethodAssembler tasm) {
            int frameSize = tasm.frameMap.frameSize();
            AMD64MacroAssembler asm = (AMD64MacroAssembler) tasm.asm;
            CalleeSaveLayout csl = tasm.frameMap.registerConfig.getCalleeSaveLayout();

            if (csl != null && csl.size != 0) {
                tasm.compilationResult.setRegisterRestoreEpilogueOffset(asm.codeBuffer.position());
                // saved all registers, restore all registers
                int frameToCSA = tasm.frameMap.offsetToCalleeSaveArea();
                asm.restore(csl, frameToCSA);
            }

            asm.incrementq(rsp, frameSize);
        }
    }

    @Override
    protected AbstractAssembler createAssembler(FrameMap frameMap) {
        return new AMD64MacroAssembler(getTarget(), frameMap.registerConfig);
    }

    @Override
    public TargetMethodAssembler newAssembler(LIRGenerator lirGen, CompilationResult compilationResult) {
        // Omit the frame if the method:
        // - has no spill slots or other slots allocated during register allocation
        // - has no callee-saved registers
        // - has no incoming arguments passed on the stack
        // - has no deoptimization points
        // - makes no foreign calls (which require an aligned stack)
        AMD64HotSpotLIRGenerator gen = (AMD64HotSpotLIRGenerator) lirGen;
        FrameMap frameMap = gen.frameMap;
        LIR lir = gen.lir;
        assert gen.deoptimizationRescueSlot == null || frameMap.frameNeedsAllocating() : "method that can deoptimize must have a frame";
        boolean omitFrame = CanOmitFrame.getValue() && !frameMap.frameNeedsAllocating() && !lir.hasArgInCallerFrame() && !gen.hasForeignCall();

        Stub stub = gen.getStub();
        AbstractAssembler masm = createAssembler(frameMap);
        HotSpotFrameContext frameContext = omitFrame ? null : new HotSpotFrameContext(stub != null);
        TargetMethodAssembler tasm = new TargetMethodAssembler(getCodeCache(), getForeignCalls(), frameMap, masm, frameContext, compilationResult);
        tasm.setFrameSize(frameMap.frameSize());
        StackSlot deoptimizationRescueSlot = gen.deoptimizationRescueSlot;
        if (deoptimizationRescueSlot != null && stub == null) {
            tasm.compilationResult.setCustomStackAreaOffset(frameMap.offsetForStackSlot(deoptimizationRescueSlot));
        }

        if (stub != null) {

            final Set<Register> definedRegisters = gatherDefinedRegisters(lir);
            stub.initDestroyedRegisters(definedRegisters);

            // Eliminate unnecessary register preservation and
            // record where preserved registers are saved
            for (Map.Entry<LIRFrameState, AMD64RegistersPreservationOp> e : gen.calleeSaveInfo.entrySet()) {
                AMD64RegistersPreservationOp save = e.getValue();
                DebugInfo info = e.getKey() == null ? null : e.getKey().debugInfo();
                save.update(definedRegisters, info, frameMap);
            }
        }

        return tasm;
    }

    /**
     * Finds all the registers that are defined by some given LIR.
     * 
     * @param lir the LIR to examine
     * @return the registers that are defined by or used as temps for any instruction in {@code lir}
     */
    private static Set<Register> gatherDefinedRegisters(LIR lir) {
        final Set<Register> definedRegisters = new HashSet<>();
        ValueProcedure defProc = new ValueProcedure() {

            @Override
            public Value doValue(Value value) {
                if (ValueUtil.isRegister(value)) {
                    final Register reg = ValueUtil.asRegister(value);
                    definedRegisters.add(reg);
                }
                return value;
            }
        };
        for (Block block : lir.codeEmittingOrder()) {
            for (LIRInstruction op : lir.lir(block)) {
                if (op instanceof LabelOp) {
                    // Don't consider this as a definition
                } else {
                    op.forEachTemp(defProc);
                    op.forEachOutput(defProc);
                }
            }
        }
        return definedRegisters;
    }

    @Override
    public void emitCode(TargetMethodAssembler tasm, LIRGenerator lirGen, ResolvedJavaMethod installedCodeOwner) {
        AMD64MacroAssembler asm = (AMD64MacroAssembler) tasm.asm;
        FrameMap frameMap = tasm.frameMap;
        RegisterConfig regConfig = frameMap.registerConfig;
        HotSpotVMConfig config = getRuntime().getConfig();
        Label verifiedStub = new Label();

        // Emit the prefix
        emitCodePrefix(installedCodeOwner, tasm, asm, regConfig, config, verifiedStub);

        // Emit code for the LIR
        emitCodeBody(installedCodeOwner, tasm, lirGen);

        // Emit the suffix
        emitCodeSuffix(installedCodeOwner, tasm, lirGen, asm, frameMap);
    }

    /**
     * @param installedCodeOwner see {@link Backend#emitCode}
     */
    protected void emitCodePrefix(ResolvedJavaMethod installedCodeOwner, TargetMethodAssembler tasm, AMD64MacroAssembler asm, RegisterConfig regConfig, HotSpotVMConfig config, Label verifiedStub) {
        HotSpotProviders providers = getProviders();
        if (installedCodeOwner != null && !isStatic(installedCodeOwner.getModifiers())) {
            tasm.recordMark(Marks.MARK_UNVERIFIED_ENTRY);
            CallingConvention cc = regConfig.getCallingConvention(JavaCallee, null, new JavaType[]{providers.getMetaAccess().lookupJavaType(Object.class)}, getTarget(), false);
            Register inlineCacheKlass = rax; // see definition of IC_Klass in
                                             // c1_LIRAssembler_x86.cpp
            Register receiver = asRegister(cc.getArgument(0));
            AMD64Address src = new AMD64Address(receiver, config.hubOffset);

            if (config.useCompressedClassPointers) {
                Register register = r10;
                AMD64HotSpotMove.decodeKlassPointer(asm, register, providers.getRegisters().getHeapBaseRegister(), src, config.narrowKlassBase, config.narrowOopBase, config.narrowKlassShift,
                                config.logKlassAlignment);
                asm.cmpq(inlineCacheKlass, register);
            } else {
                asm.cmpq(inlineCacheKlass, src);
            }
            AMD64Call.directConditionalJmp(tasm, asm, getForeignCalls().lookupForeignCall(IC_MISS_HANDLER), ConditionFlag.NotEqual);
        }

        asm.align(config.codeEntryAlignment);
        tasm.recordMark(Marks.MARK_OSR_ENTRY);
        asm.bind(verifiedStub);
        tasm.recordMark(Marks.MARK_VERIFIED_ENTRY);
    }

    /**
     * @param installedCodeOwner see {@link Backend#emitCode}
     */
    protected void emitCodeBody(ResolvedJavaMethod installedCodeOwner, TargetMethodAssembler tasm, LIRGenerator lirGen) {
        lirGen.lir.emitCode(tasm);
    }

    /**
     * @param installedCodeOwner see {@link Backend#emitCode}
     */
    protected void emitCodeSuffix(ResolvedJavaMethod installedCodeOwner, TargetMethodAssembler tasm, LIRGenerator lirGen, AMD64MacroAssembler asm, FrameMap frameMap) {
        HotSpotProviders providers = getProviders();
        HotSpotFrameContext frameContext = (HotSpotFrameContext) tasm.frameContext;
        if (frameContext != null && !frameContext.isStub) {
            HotSpotForeignCallsProvider foreignCalls = providers.getForeignCalls();
            tasm.recordMark(Marks.MARK_EXCEPTION_HANDLER_ENTRY);
            AMD64Call.directCall(tasm, asm, foreignCalls.lookupForeignCall(EXCEPTION_HANDLER), null, false, null);
            tasm.recordMark(Marks.MARK_DEOPT_HANDLER_ENTRY);
            AMD64Call.directCall(tasm, asm, foreignCalls.lookupForeignCall(DEOPT_HANDLER), null, false, null);
        } else {
            // No need to emit the stubs for entries back into the method since
            // it has no calls that can cause such "return" entries
            assert !frameMap.accessesCallerFrame() : lirGen.getGraph();
        }
    }
}