/*******************************************************************************
 * Copyright IBM Corp. and others 2000
 *
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which accompanies this
 * distribution and is available at https://www.eclipse.org/legal/epl-2.0/
 * or the Apache License, Version 2.0 which accompanies this distribution
 * and is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License, v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception [1] and GNU General Public
 * License, version 2 with the OpenJDK Assembly Exception [2].
 *
 * [1] https://www.gnu.org/software/classpath/license.html
 * [2] https://openjdk.org/legal/assembly-exception.html
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0 OR GPL-2.0-only WITH OpenJDK-assembly-exception-1.0
 *******************************************************************************/

#include "codegen/CodeGenerator.hpp"
#include "codegen/CodeGenerator_inlines.hpp"

#include <limits.h>
#include <stddef.h>
#include <stdint.h>
#include "codegen/CodeGenerator.hpp"
#include "env/FrontEnd.hpp"
#include "codegen/Machine.hpp"
#include "codegen/RealRegister.hpp"
#include "codegen/RecognizedMethods.hpp"
#include "codegen/Register.hpp"
#include "codegen/RegisterConstants.hpp"
#include "codegen/RegisterPair.hpp"
#include "codegen/TreeEvaluator.hpp"
#include "compile/Compilation.hpp"
#include "control/Options.hpp"
#include "control/Options_inlines.hpp"
#include "env/TRMemory.hpp"
#include "il/Block.hpp"
#include "il/DataTypes.hpp"
#include "il/ILOpCodes.hpp"
#include "il/ILOps.hpp"
#include "il/Node.hpp"
#include "il/Node_inlines.hpp"
#include "il/ResolvedMethodSymbol.hpp"
#include "il/Symbol.hpp"
#include "il/SymbolReference.hpp"
#include "infra/Assert.hpp"
#include "infra/BitVector.hpp"
#include "infra/Link.hpp"
#include "optimizer/RegisterCandidate.hpp"
#include "optimizer/Structure.hpp"
#include "x/codegen/IntegerMultiplyDecomposer.hpp"
#include "x/codegen/X86Instruction.hpp"
#include "codegen/InstOpCode.hpp"

OMR::X86::I386::CodeGenerator::CodeGenerator(TR::Compilation *comp)
    : OMR::X86::CodeGenerator(comp)
{}

void OMR::X86::I386::CodeGenerator::initialize()
{
    self()->OMR::X86::CodeGenerator::initialize();

    TR::CodeGenerator *cg = self();
    TR::Compilation *comp = self()->comp();

    // Common X86 initialization
    //
    cg->initializeX86(comp);

    cg->setUsesRegisterPairsForLongs();

    if (debug("supportsArrayTranslateAndTest"))
        cg->setSupportsArrayTranslateAndTest();
    if (debug("supportsArrayCmp"))
        cg->setSupportsArrayCmp();
    if (debug("supportsArrayCmpLen"))
        cg->setSupportsArrayCmpLen();

    cg->setSupportsDoubleWordCAS();
    cg->setSupportsDoubleWordSet();

    if (comp->target().isWindows()) {
        if (comp->getOption(TR_DisableTraps)) {
            _numberBytesReadInaccessible = 0;
            _numberBytesWriteInaccessible = 0;
        } else {
            _numberBytesReadInaccessible = 4096;
            _numberBytesWriteInaccessible = 4096;
            cg->setHasResumableTrapHandler();
            cg->setEnableImplicitDivideCheck();
        }
        cg->setSupportsDivCheck();
        cg->setJNILinkageCalleeCleanup();
        cg->setRealVMThreadRegister(cg->machine()->getRealRegister(TR::RealRegister::ebp));
    } else if (comp->target().isLinux()) {
        if (comp->getOption(TR_DisableTraps)) {
            _numberBytesReadInaccessible = 0;
            _numberBytesWriteInaccessible = 0;
        } else {
            _numberBytesReadInaccessible = 4096;
            _numberBytesWriteInaccessible = 4096;
            cg->setHasResumableTrapHandler();
            cg->setEnableImplicitDivideCheck();
        }
        cg->setRealVMThreadRegister(cg->machine()->getRealRegister(TR::RealRegister::ebp));
        cg->setSupportsDivCheck();
    } else {
        TR_ASSERT(0, "unknown target");
    }

    cg->setSupportsInlinedAtomicLongVolatiles();

    static char *dontConsiderAllAutosForGRA = feGetEnv("TR_dontConsiderAllAutosForGRA");
    if (!dontConsiderAllAutosForGRA)
        cg->setConsiderAllAutosAsTacticalGlobalRegisterCandidates();

    if (comp->target().cpu.supportsFeature(OMR_FEATURE_X86_BMI2)
        && comp->target().cpu.supportsFeature(OMR_FEATURE_X86_AVX)) {
        static bool disableBitwiseCompress = feGetEnv("TR_disableBitwiseCompress") != NULL;
        if (!disableBitwiseCompress) {
            cg->setSupports32BitCompress();
        }

        static bool disableBitwiseExpand = feGetEnv("TR_disableBitwiseExpand") != NULL;
        if (!disableBitwiseExpand) {
            cg->setSupports32BitExpand();
        }
    }
}

TR::Register *OMR::X86::I386::CodeGenerator::longClobberEvaluate(TR::Node *node)
{
    TR_ASSERT(node->getOpCode().is8Byte(), "assertion failure");
    if (node->getReferenceCount() > 1) {
        TR::Register *temp = self()->evaluate(node);
        TR::Register *lowReg = self()->allocateRegister();
        TR::Register *highReg = self()->allocateRegister();
        TR::RegisterPair *longReg = self()->allocateRegisterPair(lowReg, highReg);

        generateRegRegInstruction(TR::InstOpCode::MOV4RegReg, node, lowReg, temp->getLowOrder(), self());
        generateRegRegInstruction(TR::InstOpCode::MOV4RegReg, node, highReg, temp->getHighOrder(), self());
        return longReg;
    } else {
        return self()->evaluate(node);
    }
}

TR_GlobalRegisterNumber OMR::X86::I386::CodeGenerator::pickRegister(TR::RegisterCandidate *rc, TR::Block **allBlocks,
    TR_BitVector &availableRegisters, TR_GlobalRegisterNumber &highRegisterNumber,
    TR_LinkHead<TR::RegisterCandidate> *candidates)
{
    if (!self()->comp()->getOption(TR_DisableRegisterPressureSimulation)) {
        if (self()->comp()->getOption(TR_AssignEveryGlobalRegister)) {
            // This is not really necessary except for testing purposes.
            // Conceptually, the common pickRegister code should be free to make
            // its choices based only on performance considerations, and shouldn't
            // need to worry about correctness.  When SupportsVMThreadGRA is not set,
            // it is incorrect to choose the VMThread register.  Therefore we mask
            // it out here.
            //
            // Having said that, the common code *does* already mask out the
            // VMThread register for convenience, so under normal circumstances,
            // this code is redundant.  It is only necessary when
            // TR_AssignEveryGlobalRegister is set.
            //
            availableRegisters -= *self()->getGlobalRegisters(TR_vmThreadSpill,
                self()->comp()->getMethodSymbol()->getLinkageConvention());
        }
        return OMR::CodeGenerator::pickRegister(rc, allBlocks, availableRegisters, highRegisterNumber, candidates);
    }

    if ((rc->getSymbol()->getDataType() == TR::Float) || (rc->getSymbol()->getDataType() == TR::Double)) {
        if (availableRegisters.get(7))
            return 7;
        if (availableRegisters.get(8))
            return 8;
        if (availableRegisters.get(9))
            return 9;
        if (availableRegisters.get(10))
            return 10;
        if (availableRegisters.get(11))
            return 11;
        if (availableRegisters.get(12))
            return 12;

        return -1;
    }

    if (!_assignedGlobalRegisters)
        _assignedGlobalRegisters = new (self()->trStackMemory())
            TR_BitVector(self()->comp()->getSymRefCount(), self()->trMemory(), stackAlloc, growable);

    if (availableRegisters.get(5))
        return 5; // esi

    if (availableRegisters.get(2))
        return 2; // ecx

    static char *dontUseEBXasGPR = feGetEnv("dontUseEBXasGPR");
    if (!dontUseEBXasGPR && availableRegisters.get(1))
        return 1;

#ifdef J9_PROJECT_SPECIFIC
    TR::RecognizedMethod rm = self()->comp()->getMethodSymbol()->getRecognizedMethod();
    if (rm == TR::java_util_HashtableHashEnumerator_hasMoreElements) {
        if (availableRegisters.get(4))
            return 4; // edi
        if (availableRegisters.get(3))
            return 3; // edx
    } else
#endif
    {
        int32_t numExtraRegs = 0;
        int32_t maxRegisterPressure = 0;

        vcount_t visitCount = self()->comp()->incVisitCount();
        TR_BitVectorIterator bvi(rc->getBlocksLiveOnEntry());
        int32_t maxFrequency = 0;
        while (bvi.hasMoreElements()) {
            int32_t liveBlockNum = bvi.getNextElement();
            TR::Block *block = allBlocks[liveBlockNum];
            if (block->getFrequency() > maxFrequency)
                maxFrequency = block->getFrequency();
        }

        int32_t maxStaticFrequency = 0;
        if (maxFrequency == 0) {
            bvi.setBitVector(rc->getBlocksLiveOnEntry());
            while (bvi.hasMoreElements()) {
                int32_t liveBlockNum = bvi.getNextElement();
                TR::Block *block = allBlocks[liveBlockNum];
                TR_BlockStructure *blockStructure = block->getStructureOf();
                int32_t blockWeight = 1;
                if (blockStructure && !block->isCold()) {
                    blockStructure->calculateFrequencyOfExecution(&blockWeight);
                    if (blockWeight > maxStaticFrequency)
                        maxStaticFrequency = blockWeight;
                }
            }
        }

        bool assigningEDX = false;
        if (!availableRegisters.get(4) && availableRegisters.get(3))
            assigningEDX = true;

        bool vmThreadUsed = false;

        bvi.setBitVector(rc->getBlocksLiveOnEntry());
        while (bvi.hasMoreElements()) {
            int32_t liveBlockNum = bvi.getNextElement();
            TR::Block *block = allBlocks[liveBlockNum];

            _assignedGlobalRegisters->empty();
            int32_t numAssignedGlobalRegs = 0;
            TR::RegisterCandidate *prev;
            for (prev = candidates->getFirst(); prev; prev = prev->getNext()) {
                bool gprCandidate = true;
                if ((prev->getSymbol()->getDataType() == TR::Float) || (prev->getSymbol()->getDataType() == TR::Double))
                    gprCandidate = false;
                if (gprCandidate && prev->getBlocksLiveOnEntry().get(liveBlockNum)) {
                    numAssignedGlobalRegs++;
                    if (prev->getDataType() == TR::Int64)
                        numAssignedGlobalRegs++;
                    _assignedGlobalRegisters->set(prev->getSymbolReference()->getReferenceNumber());
                }
            }

            maxRegisterPressure = self()->estimateRegisterPressure(block, visitCount, maxStaticFrequency, maxFrequency,
                vmThreadUsed, numAssignedGlobalRegs, _assignedGlobalRegisters, rc->getSymbolReference(), assigningEDX);

            if (maxRegisterPressure >= self()->getMaximumNumbersOfAssignableGPRs())
                break;
        }

        // Determine if we can spare any extra registers for this candidate without spilling
        // in any hot (critical) blocks
        //
        if (maxRegisterPressure < self()->getMaximumNumbersOfAssignableGPRs())
            numExtraRegs = self()->getMaximumNumbersOfAssignableGPRs() - maxRegisterPressure;

        // dumpOptDetails("For global register candidate %d reg pressure is %d maxRegs %d numExtraRegs %d\n",
        // rc->getSymbolReference()->getReferenceNumber(), maxRegisterPressure,
        // comp()->cg()->getMaximumNumbersOfAssignableGPRs(), numExtraRegs);

        if (numExtraRegs > 0) {
            if (availableRegisters.get(4))
                return 4; // edi

            if (availableRegisters.get(3))
                return 3; // edx
        }
    }

    return -1; // -1 ==> don't use a global register
}

int32_t OMR::X86::I386::CodeGenerator::getMaximumNumberOfGPRsAllowedAcrossEdge(TR::Node *node)
{
    // TODO: Currently, lookupEvaluator doesn't deal properly with different
    // glRegDeps on different cases of a lookupswitch.
    //
    static const char *enableLookupswitch = feGetEnv("TR_enableGRAAcrossLookupSwitch");
    if (!enableLookupswitch && node->getOpCode().getOpCodeValue() == TR::lookup)
        return 1;

    if (node->getOpCode().getOpCodeValue() == TR::table) {
        // 1 for jump table base reg, which is not apparent in the trees
        // 1 for ebp when it is needed for the VMThread
        //
        return self()->getNumberOfGlobalGPRs() - 2;
    }

    if (node->getOpCode().isIf()) {
        // we run out of all but one/two registers in these cases
        //
        if (node->getFirstChild()->getType().isInt64()) {
            if (node->getOpCode().isBranch()) {
                TR::Node *firstChild = node->getFirstChild();
                TR::Node *secondChild = node->getSecondChild();
                int extraRegsAvailable = 0;

                if (firstChild->getOpCodeValue() == TR::d2l || secondChild->getOpCodeValue() == TR::d2l) {
                    return 1;
                }

                if ((firstChild->getReferenceCount() == 1 && firstChild->getOpCode().isLoadVarDirect())
                    || (secondChild->getReferenceCount() == 1 && firstChild->getOpCode().isLoadVarDirect()))
                    extraRegsAvailable
                        += 0; // TODO: put it back to 2 when looking at GRA, GRA pushes allocation of 8 registers

                return 2 + extraRegsAvailable;
            } else {
                // TR_lcmpXX opcodes take up 5 regs
                //
                return 1;
            }
        }

        // we run out of all but one register in these cases....last time I tried....
        //

        if (node->getFirstChild()->getOpCodeValue() == TR:: instanceof) {
            if (!TR::TreeEvaluator::instanceOfOrCheckCastNeedSuperTest(node->getFirstChild(), self())
                && TR::TreeEvaluator::instanceOfOrCheckCastNeedEqualityTest(node->getFirstChild(), self()))
                return self()->getNumberOfGlobalGPRs() - 4; // ebp plus three other regs if vft masking is enabled
            else
                return 0;
        }

        // All other conditional branches, we usually need one reg for the compare and possibly one for the vmthread
        // return getNumberOfGlobalGPRs() - 1 - (node->isVMThreadRequired()? 1 : 0);
        // vmThread required might be set on a node after GRA has ran
        return self()->getNumberOfGlobalGPRs() - 2;
    }

    return INT_MAX;
}

bool OMR::X86::I386::CodeGenerator::codegenMulDecomposition(int64_t multiplier)
{
    bool iMulDecomposeReport = self()->comp()->getOptions()->trace(OMR::treeSimplification);
    bool answer = false;
    if (iMulDecomposeReport)
        diagnostic("\nCodegen was queried for the value of %d, ", (int32_t)multiplier);
    answer = TR_X86IntegerMultiplyDecomposer::hasDecomposition(multiplier);

    if (iMulDecomposeReport)
        diagnostic("codegen said [%c]\n", (answer) ? 'Y' : 'N');

    return answer;
}
