/* This file is part of the dynarmic project.
 * Copyright (c) 2016 MerryMage
 * This software may be used and distributed according to the terms of the GNU
 * General Public License version 2 or any later version.
 */

#include <unordered_map>
#include <unordered_set>

#include "backend_x64/a64_emit_x64.h"
#include "backend_x64/a64_jitstate.h"
#include "backend_x64/abi.h"
#include "backend_x64/block_of_code.h"
#include "backend_x64/emit_x64.h"
#include "common/address_range.h"
#include "common/assert.h"
#include "common/bit_util.h"
#include "common/common_types.h"
#include "common/variant_util.h"
#include "frontend/A64/location_descriptor.h"
#include "frontend/A64/types.h"
#include "frontend/ir/basic_block.h"
#include "frontend/ir/microinstruction.h"
#include "frontend/ir/opcodes.h"

// TODO: Have ARM flags in host flags and not have them use up GPR registers unless necessary.
// TODO: Actually implement that proper instruction selector you've always wanted to sweetheart.

namespace Dynarmic {
namespace BackendX64 {

using namespace Xbyak::util;

A64EmitContext::A64EmitContext(RegAlloc& reg_alloc, IR::Block& block)
    : EmitContext(reg_alloc, block) {}

A64::LocationDescriptor A64EmitContext::Location() const {
    return A64::LocationDescriptor{block.Location()};
}

bool A64EmitContext::FPSCR_RoundTowardsZero() const {
    return Location().FPCR().RMode() != A64::FPCR::RoundingMode::TowardsZero;
}

bool A64EmitContext::FPSCR_FTZ() const {
    return Location().FPCR().FZ();
}

bool A64EmitContext::FPSCR_DN() const {
    return Location().FPCR().DN();
}

A64EmitX64::A64EmitX64(BlockOfCode* code, A64::UserConfig conf)
    : EmitX64(code), conf(conf)
{
    code->PreludeComplete();
}

A64EmitX64::~A64EmitX64() {}

A64EmitX64::BlockDescriptor A64EmitX64::Emit(IR::Block& block) {
    code->align();
    const u8* const entrypoint = code->getCurr();

    // Start emitting.
    EmitCondPrelude(block);

    RegAlloc reg_alloc{code, A64JitState::SpillCount, SpillToOpArg<A64JitState>};
    A64EmitContext ctx{reg_alloc, block};

    for (auto iter = block.begin(); iter != block.end(); ++iter) {
        IR::Inst* inst = &*iter;

        // Call the relevant Emit* member function.
        switch (inst->GetOpcode()) {

#define OPCODE(name, type, ...)                 \
        case IR::Opcode::name:                  \
            A64EmitX64::Emit##name(ctx, inst);  \
            break;
#define A32OPC(...)
#define A64OPC(name, type, ...)                    \
        case IR::Opcode::A64##name:                \
            A64EmitX64::EmitA64##name(ctx, inst);  \
            break;
#include "frontend/ir/opcodes.inc"
#undef OPCODE
#undef A32OPC
#undef A64OPC

        default:
            ASSERT_MSG(false, "Invalid opcode %zu", static_cast<size_t>(inst->GetOpcode()));
            break;
        }

        reg_alloc.EndOfAllocScope();
    }

    reg_alloc.AssertNoMoreUses();

    EmitAddCycles(block.CycleCount());
    EmitX64::EmitTerminal(block.GetTerminal(), block.Location());
    code->int3();

    const A64::LocationDescriptor descriptor{block.Location()};
    Patch(descriptor, entrypoint);

    const size_t size = static_cast<size_t>(code->getCurr() - entrypoint);
    const A64::LocationDescriptor end_location{block.EndLocation()};
    const auto range = boost::icl::discrete_interval<u64>::closed(descriptor.PC(), end_location.PC() - 1);
    A64EmitX64::BlockDescriptor block_desc{entrypoint, size, block.Location(), range};
    block_descriptors.emplace(descriptor.UniqueHash(), block_desc);
    block_ranges.add(std::make_pair(range, std::set<IR::LocationDescriptor>{descriptor}));

    return block_desc;
}

void A64EmitX64::EmitTerminalImpl(IR::Term::Interpret terminal, IR::LocationDescriptor) {
    code->mov(code->ABI_PARAM1.cvt32(), A64::LocationDescriptor{terminal.next}.PC());
    //code->mov(code->ABI_PARAM2, reinterpret_cast<u64>(jit_interface));
    //code->mov(code->ABI_PARAM3, reinterpret_cast<u64>(cb.user_arg));
    //code->mov(MJitStateReg(A64::Reg::PC), code->ABI_PARAM1.cvt32());
    code->SwitchMxcsrOnExit();
    //code->CallFunction(cb.InterpreterFallback);
    code->ReturnFromRunCode(true); // TODO: Check cycles
}

void A64EmitX64::EmitTerminalImpl(IR::Term::ReturnToDispatch, IR::LocationDescriptor) {
    code->ReturnFromRunCode();
}

void A64EmitX64::EmitTerminalImpl(IR::Term::LinkBlock terminal, IR::LocationDescriptor) {
    code->cmp(qword[r15 + offsetof(A64JitState, cycles_remaining)], 0);

    patch_information[terminal.next].jg.emplace_back(code->getCurr());
    if (auto next_bb = GetBasicBlock(terminal.next)) {
        EmitPatchJg(terminal.next, next_bb->entrypoint);
    } else {
        EmitPatchJg(terminal.next);
    }
    Xbyak::Label dest;
    code->jmp(dest, Xbyak::CodeGenerator::T_NEAR);

    code->SwitchToFarCode();
    code->align(16);
    code->L(dest);
    //code->mov(MJitStateReg(A64::Reg::PC), A64::LocationDescriptor{terminal.next}.PC());
    PushRSBHelper(rax, rbx, terminal.next);
    code->ForceReturnFromRunCode();
    code->SwitchToNearCode();
}

void A64EmitX64::EmitTerminalImpl(IR::Term::LinkBlockFast terminal, IR::LocationDescriptor) {
    patch_information[terminal.next].jmp.emplace_back(code->getCurr());
    if (auto next_bb = GetBasicBlock(terminal.next)) {
        EmitPatchJmp(terminal.next, next_bb->entrypoint);
    } else {
        EmitPatchJmp(terminal.next);
    }
}

void A64EmitX64::EmitTerminalImpl(IR::Term::PopRSBHint, IR::LocationDescriptor) {
    ASSERT(false);
}

void A64EmitX64::EmitTerminalImpl(IR::Term::If terminal, IR::LocationDescriptor initial_location) {
    Xbyak::Label pass = EmitCond(terminal.if_);
    EmitTerminal(terminal.else_, initial_location);
    code->L(pass);
    EmitTerminal(terminal.then_, initial_location);
}

void A64EmitX64::EmitTerminalImpl(IR::Term::CheckHalt terminal, IR::LocationDescriptor initial_location) {
    code->cmp(code->byte[r15 + offsetof(A64JitState, halt_requested)], u8(0));
    code->jne(code->GetForceReturnFromRunCodeAddress());
    EmitTerminal(terminal.else_, initial_location);
}

void A64EmitX64::EmitPatchJg(const IR::LocationDescriptor& /*target_desc*/, CodePtr target_code_ptr) {
    const CodePtr patch_location = code->getCurr();
    if (target_code_ptr) {
        code->jg(target_code_ptr);
    } else {
        //code->mov(MJitStateReg(A64::Reg::PC), A64::LocationDescriptor{target_desc}.PC());
        code->jg(code->GetReturnFromRunCodeAddress());
    }
    code->EnsurePatchLocationSize(patch_location, 14);
}

void A64EmitX64::EmitPatchJmp(const IR::LocationDescriptor& /*target_desc*/, CodePtr target_code_ptr) {
    const CodePtr patch_location = code->getCurr();
    if (target_code_ptr) {
        code->jmp(target_code_ptr);
    } else {
        //code->mov(MJitStateReg(A64::Reg::PC), A64::LocationDescriptor{target_desc}.PC());
        code->jmp(code->GetReturnFromRunCodeAddress());
    }
    code->EnsurePatchLocationSize(patch_location, 13);
}

void A64EmitX64::EmitPatchMovRcx(CodePtr target_code_ptr) {
    if (!target_code_ptr) {
        target_code_ptr = code->GetReturnFromRunCodeAddress();
    }
    const CodePtr patch_location = code->getCurr();
    code->mov(code->rcx, reinterpret_cast<u64>(target_code_ptr));
    code->EnsurePatchLocationSize(patch_location, 10);
}

} // namespace BackendX64
} // namespace Dynarmic