// Copyright 2015 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <algorithm>
#include <cmath>
#include <cstdint>
#include <xmmintrin.h>

#include <nihstro/shader_bytecode.h>

#include "common/assert.h"
#include "common/logging/log.h"
#include "common/vector_math.h"
#include "common/x64/abi.h"
#include "common/x64/cpu_detect.h"
#include "common/x64/emitter.h"

#include "shader.h"
#include "shader_jit_x64.h"

#include "video_core/pica_state.h"
#include "video_core/pica_types.h"

namespace Pica {

namespace Shader {

using namespace Gen;

typedef void (JitShader::*JitFunction)(Instruction instr);

const JitFunction instr_table[64] = {
    &JitShader::Compile_ADD,        // add
    &JitShader::Compile_DP3,        // dp3
    &JitShader::Compile_DP4,        // dp4
    &JitShader::Compile_DPH,        // dph
    nullptr,                        // unknown
    &JitShader::Compile_EX2,        // ex2
    &JitShader::Compile_LG2,        // lg2
    nullptr,                        // unknown
    &JitShader::Compile_MUL,        // mul
    &JitShader::Compile_SGE,        // sge
    &JitShader::Compile_SLT,        // slt
    &JitShader::Compile_FLR,        // flr
    &JitShader::Compile_MAX,        // max
    &JitShader::Compile_MIN,        // min
    &JitShader::Compile_RCP,        // rcp
    &JitShader::Compile_RSQ,        // rsq
    nullptr,                        // unknown
    nullptr,                        // unknown
    &JitShader::Compile_MOVA,       // mova
    &JitShader::Compile_MOV,        // mov
    nullptr,                        // unknown
    nullptr,                        // unknown
    nullptr,                        // unknown
    nullptr,                        // unknown
    &JitShader::Compile_DPH,        // dphi
    nullptr,                        // unknown
    &JitShader::Compile_SGE,        // sgei
    &JitShader::Compile_SLT,        // slti
    nullptr,                        // unknown
    nullptr,                        // unknown
    nullptr,                        // unknown
    nullptr,                        // unknown
    nullptr,                        // unknown
    &JitShader::Compile_NOP,        // nop
    &JitShader::Compile_END,        // end
    nullptr,                        // break
    &JitShader::Compile_CALL,       // call
    &JitShader::Compile_CALLC,      // callc
    &JitShader::Compile_CALLU,      // callu
    &JitShader::Compile_IF,         // ifu
    &JitShader::Compile_IF,         // ifc
    &JitShader::Compile_LOOP,       // loop
    nullptr,                        // emit
    nullptr,                        // sete
    &JitShader::Compile_JMP,        // jmpc
    &JitShader::Compile_JMP,        // jmpu
    &JitShader::Compile_CMP,        // cmp
    &JitShader::Compile_CMP,        // cmp
    &JitShader::Compile_MAD,        // madi
    &JitShader::Compile_MAD,        // madi
    &JitShader::Compile_MAD,        // madi
    &JitShader::Compile_MAD,        // madi
    &JitShader::Compile_MAD,        // madi
    &JitShader::Compile_MAD,        // madi
    &JitShader::Compile_MAD,        // madi
    &JitShader::Compile_MAD,        // madi
    &JitShader::Compile_MAD,        // mad
    &JitShader::Compile_MAD,        // mad
    &JitShader::Compile_MAD,        // mad
    &JitShader::Compile_MAD,        // mad
    &JitShader::Compile_MAD,        // mad
    &JitShader::Compile_MAD,        // mad
    &JitShader::Compile_MAD,        // mad
    &JitShader::Compile_MAD,        // mad
};

// The following is used to alias some commonly used registers. Generally, RAX-RDX and XMM0-XMM3 can
// be used as scratch registers within a compiler function. The other registers have designated
// purposes, as documented below:

/// Pointer to the uniform memory
static const X64Reg UNIFORMS = R9;
/// The two 32-bit VS address offset registers set by the MOVA instruction
static const X64Reg ADDROFFS_REG_0 = R10;
static const X64Reg ADDROFFS_REG_1 = R11;
/// VS loop count register
static const X64Reg LOOPCOUNT_REG = R12;
/// Current VS loop iteration number (we could probably use LOOPCOUNT_REG, but this quicker)
static const X64Reg LOOPCOUNT = RSI;
/// Number to increment LOOPCOUNT_REG by on each loop iteration
static const X64Reg LOOPINC = RDI;
/// Result of the previous CMP instruction for the X-component comparison
static const X64Reg COND0 = R13;
/// Result of the previous CMP instruction for the Y-component comparison
static const X64Reg COND1 = R14;
/// Pointer to the UnitState instance for the current VS unit
static const X64Reg REGISTERS = R15;
/// SIMD scratch register
static const X64Reg SCRATCH = XMM0;
/// Loaded with the first swizzled source register, otherwise can be used as a scratch register
static const X64Reg SRC1 = XMM1;
/// Loaded with the second swizzled source register, otherwise can be used as a scratch register
static const X64Reg SRC2 = XMM2;
/// Loaded with the third swizzled source register, otherwise can be used as a scratch register
static const X64Reg SRC3 = XMM3;
/// Additional scratch register
static const X64Reg SCRATCH2 = XMM4;
/// Constant vector of [1.0f, 1.0f, 1.0f, 1.0f], used to efficiently set a vector to one
static const X64Reg ONE = XMM14;
/// Constant vector of [-0.f, -0.f, -0.f, -0.f], used to efficiently negate a vector with XOR
static const X64Reg NEGBIT = XMM15;

// State registers that must not be modified by external functions calls
// Scratch registers, e.g., SRC1 and SCRATCH, have to be saved on the side if needed
static const BitSet32 persistent_regs = {
    UNIFORMS, REGISTERS, // Pointers to register blocks
    ADDROFFS_REG_0, ADDROFFS_REG_1, LOOPCOUNT_REG, COND0, COND1, // Cached registers
    ONE+16, NEGBIT+16, // Constants
};

/// Raw constant for the source register selector that indicates no swizzling is performed
static const u8 NO_SRC_REG_SWIZZLE = 0x1b;
/// Raw constant for the destination register enable mask that indicates all components are enabled
static const u8 NO_DEST_REG_MASK = 0xf;

/**
 * Get the vertex shader instruction for a given offset in the current shader program
 * @param offset Offset in the current shader program of the instruction
 * @return Instruction at the specified offset
 */
static Instruction GetVertexShaderInstruction(size_t offset) {
    return { g_state.vs.program_code[offset] };
}

static void LogCritical(const char* msg) {
    LOG_CRITICAL(HW_GPU, "%s", msg);
}

void JitShader::Compile_Assert(bool condition, const char* msg) {
    if (!condition) {
        ABI_CallFunctionP(reinterpret_cast<const void*>(LogCritical), const_cast<char*>(msg));
    }
}

/**
 * Loads and swizzles a source register into the specified XMM register.
 * @param instr VS instruction, used for determining how to load the source register
 * @param src_num Number indicating which source register to load (1 = src1, 2 = src2, 3 = src3)
 * @param src_reg SourceRegister object corresponding to the source register to load
 * @param dest Destination XMM register to store the loaded, swizzled source register
 */
void JitShader::Compile_SwizzleSrc(Instruction instr, unsigned src_num, SourceRegister src_reg, X64Reg dest) {
    X64Reg src_ptr;
    size_t src_offset;

    if (src_reg.GetRegisterType() == RegisterType::FloatUniform) {
        src_ptr = UNIFORMS;
        src_offset = src_reg.GetIndex() * sizeof(float24) * 4;
    } else {
        src_ptr = REGISTERS;
        src_offset = UnitState<false>::InputOffset(src_reg);
    }

    int src_offset_disp = (int)src_offset;
    ASSERT_MSG(src_offset == src_offset_disp, "Source register offset too large for int type");

    unsigned operand_desc_id;

    const bool is_inverted = (0 != (instr.opcode.Value().GetInfo().subtype & OpCode::Info::SrcInversed));

    unsigned address_register_index;
    unsigned offset_src;

    if (instr.opcode.Value().EffectiveOpCode() == OpCode::Id::MAD ||
        instr.opcode.Value().EffectiveOpCode() == OpCode::Id::MADI) {
        operand_desc_id = instr.mad.operand_desc_id;
        offset_src = is_inverted ? 3 : 2;
        address_register_index = instr.mad.address_register_index;
    } else {
        operand_desc_id = instr.common.operand_desc_id;
        offset_src = is_inverted ? 2 : 1;
        address_register_index = instr.common.address_register_index;
    }

    if (src_num == offset_src && address_register_index != 0) {
        switch (address_register_index) {
        case 1: // address offset 1
            MOVAPS(dest, MComplex(src_ptr, ADDROFFS_REG_0, SCALE_1, src_offset_disp));
            break;
        case 2: // address offset 2
            MOVAPS(dest, MComplex(src_ptr, ADDROFFS_REG_1, SCALE_1, src_offset_disp));
            break;
        case 3: // address offset 3
            MOVAPS(dest, MComplex(src_ptr, LOOPCOUNT_REG, SCALE_1, src_offset_disp));
            break;
        default:
            UNREACHABLE();
            break;
        }
    } else {
        // Load the source
        MOVAPS(dest, MDisp(src_ptr, src_offset_disp));
    }

    SwizzlePattern swiz = { g_state.vs.swizzle_data[operand_desc_id] };

    // Generate instructions for source register swizzling as needed
    u8 sel = swiz.GetRawSelector(src_num);
    if (sel != NO_SRC_REG_SWIZZLE) {
        // Selector component order needs to be reversed for the SHUFPS instruction
        sel = ((sel & 0xc0) >> 6) | ((sel & 3) << 6) | ((sel & 0xc) << 2) | ((sel & 0x30) >> 2);

        // Shuffle inputs for swizzle
        SHUFPS(dest, R(dest), sel);
    }

    // If the source register should be negated, flip the negative bit using XOR
    const bool negate[] = { swiz.negate_src1, swiz.negate_src2, swiz.negate_src3 };
    if (negate[src_num - 1]) {
        XORPS(dest, R(NEGBIT));
    }
}

void JitShader::Compile_DestEnable(Instruction instr,X64Reg src) {
    DestRegister dest;
    unsigned operand_desc_id;
    if (instr.opcode.Value().EffectiveOpCode() == OpCode::Id::MAD ||
        instr.opcode.Value().EffectiveOpCode() == OpCode::Id::MADI) {
        operand_desc_id = instr.mad.operand_desc_id;
        dest = instr.mad.dest.Value();
    } else {
        operand_desc_id = instr.common.operand_desc_id;
        dest = instr.common.dest.Value();
    }

    SwizzlePattern swiz = { g_state.vs.swizzle_data[operand_desc_id] };

    int dest_offset_disp = (int)UnitState<false>::OutputOffset(dest);
    ASSERT_MSG(dest_offset_disp == UnitState<false>::OutputOffset(dest), "Destinaton offset too large for int type");

    // If all components are enabled, write the result to the destination register
    if (swiz.dest_mask == NO_DEST_REG_MASK) {
        // Store dest back to memory
        MOVAPS(MDisp(REGISTERS, dest_offset_disp), src);

    } else {
        // Not all components are enabled, so mask the result when storing to the destination register...
        MOVAPS(SCRATCH, MDisp(REGISTERS, dest_offset_disp));

        if (Common::GetCPUCaps().sse4_1) {
            u8 mask = ((swiz.dest_mask & 1) << 3) | ((swiz.dest_mask & 8) >> 3) | ((swiz.dest_mask & 2) << 1) | ((swiz.dest_mask & 4) >> 1);
            BLENDPS(SCRATCH, R(src), mask);
        } else {
            MOVAPS(SCRATCH2, R(src));
            UNPCKHPS(SCRATCH2, R(SCRATCH)); // Unpack X/Y components of source and destination
            UNPCKLPS(SCRATCH, R(src)); // Unpack Z/W components of source and destination

            // Compute selector to selectively copy source components to destination for SHUFPS instruction
            u8 sel = ((swiz.DestComponentEnabled(0) ? 1 : 0) << 0) |
                     ((swiz.DestComponentEnabled(1) ? 3 : 2) << 2) |
                     ((swiz.DestComponentEnabled(2) ? 0 : 1) << 4) |
                     ((swiz.DestComponentEnabled(3) ? 2 : 3) << 6);
            SHUFPS(SCRATCH, R(SCRATCH2), sel);
        }

        // Store dest back to memory
        MOVAPS(MDisp(REGISTERS, dest_offset_disp), SCRATCH);
    }
}

void JitShader::Compile_SanitizedMul(Gen::X64Reg src1, Gen::X64Reg src2, Gen::X64Reg scratch) {
    MOVAPS(scratch, R(src1));
    CMPPS(scratch, R(src2), CMP_ORD);

    MULPS(src1, R(src2));

    MOVAPS(src2, R(src1));
    CMPPS(src2, R(src2), CMP_UNORD);

    XORPS(scratch, R(src2));
    ANDPS(src1, R(scratch));
}

void JitShader::Compile_EvaluateCondition(Instruction instr) {
    // Note: NXOR is used below to check for equality
    switch (instr.flow_control.op) {
    case Instruction::FlowControlType::Or:
        MOV(32, R(RAX), R(COND0));
        MOV(32, R(RBX), R(COND1));
        XOR(32, R(RAX), Imm32(instr.flow_control.refx.Value() ^ 1));
        XOR(32, R(RBX), Imm32(instr.flow_control.refy.Value() ^ 1));
        OR(32, R(RAX), R(RBX));
        break;

    case Instruction::FlowControlType::And:
        MOV(32, R(RAX), R(COND0));
        MOV(32, R(RBX), R(COND1));
        XOR(32, R(RAX), Imm32(instr.flow_control.refx.Value() ^ 1));
        XOR(32, R(RBX), Imm32(instr.flow_control.refy.Value() ^ 1));
        AND(32, R(RAX), R(RBX));
        break;

    case Instruction::FlowControlType::JustX:
        MOV(32, R(RAX), R(COND0));
        XOR(32, R(RAX), Imm32(instr.flow_control.refx.Value() ^ 1));
        break;

    case Instruction::FlowControlType::JustY:
        MOV(32, R(RAX), R(COND1));
        XOR(32, R(RAX), Imm32(instr.flow_control.refy.Value() ^ 1));
        break;
    }
}

void JitShader::Compile_UniformCondition(Instruction instr) {
    int offset = offsetof(decltype(g_state.vs.uniforms), b) + (instr.flow_control.bool_uniform_id * sizeof(bool));
    CMP(sizeof(bool) * 8, MDisp(UNIFORMS, offset), Imm8(0));
}

BitSet32 JitShader::PersistentCallerSavedRegs() {
    return persistent_regs & ABI_ALL_CALLER_SAVED;
}

void JitShader::Compile_ADD(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
    Compile_SwizzleSrc(instr, 2, instr.common.src2, SRC2);
    ADDPS(SRC1, R(SRC2));
    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_DP3(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
    Compile_SwizzleSrc(instr, 2, instr.common.src2, SRC2);

    Compile_SanitizedMul(SRC1, SRC2, SCRATCH);

    MOVAPS(SRC2, R(SRC1));
    SHUFPS(SRC2, R(SRC2), _MM_SHUFFLE(1, 1, 1, 1));

    MOVAPS(SRC3, R(SRC1));
    SHUFPS(SRC3, R(SRC3), _MM_SHUFFLE(2, 2, 2, 2));

    SHUFPS(SRC1, R(SRC1), _MM_SHUFFLE(0, 0, 0, 0));
    ADDPS(SRC1, R(SRC2));
    ADDPS(SRC1, R(SRC3));

    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_DP4(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
    Compile_SwizzleSrc(instr, 2, instr.common.src2, SRC2);

    Compile_SanitizedMul(SRC1, SRC2, SCRATCH);

    MOVAPS(SRC2, R(SRC1));
    SHUFPS(SRC1, R(SRC1), _MM_SHUFFLE(2, 3, 0, 1)); // XYZW -> ZWXY
    ADDPS(SRC1, R(SRC2));

    MOVAPS(SRC2, R(SRC1));
    SHUFPS(SRC1, R(SRC1), _MM_SHUFFLE(0, 1, 2, 3)); // XYZW -> WZYX
    ADDPS(SRC1, R(SRC2));

    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_DPH(Instruction instr) {
    if (instr.opcode.Value().EffectiveOpCode() == OpCode::Id::DPHI) {
        Compile_SwizzleSrc(instr, 1, instr.common.src1i, SRC1);
        Compile_SwizzleSrc(instr, 2, instr.common.src2i, SRC2);
    } else {
        Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
        Compile_SwizzleSrc(instr, 2, instr.common.src2, SRC2);
    }

    if (Common::GetCPUCaps().sse4_1) {
        // Set 4th component to 1.0
        BLENDPS(SRC1, R(ONE), 0x8); // 0b1000
    } else {
        // Set 4th component to 1.0
        MOVAPS(SCRATCH, R(SRC1));
        UNPCKHPS(SCRATCH, R(ONE));  // XYZW, 1111 -> Z1__
        UNPCKLPD(SRC1, R(SCRATCH)); // XYZW, Z1__ -> XYZ1
    }

    Compile_SanitizedMul(SRC1, SRC2, SCRATCH);

    MOVAPS(SRC2, R(SRC1));
    SHUFPS(SRC1, R(SRC1), _MM_SHUFFLE(2, 3, 0, 1)); // XYZW -> ZWXY
    ADDPS(SRC1, R(SRC2));

    MOVAPS(SRC2, R(SRC1));
    SHUFPS(SRC1, R(SRC1), _MM_SHUFFLE(0, 1, 2, 3)); // XYZW -> WZYX
    ADDPS(SRC1, R(SRC2));

    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_EX2(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
    MOVSS(XMM0, R(SRC1));

    ABI_PushRegistersAndAdjustStack(PersistentCallerSavedRegs(), 0);
    ABI_CallFunction(reinterpret_cast<const void*>(exp2f));
    ABI_PopRegistersAndAdjustStack(PersistentCallerSavedRegs(), 0);

    SHUFPS(XMM0, R(XMM0), _MM_SHUFFLE(0, 0, 0, 0));
    MOVAPS(SRC1, R(XMM0));
    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_LG2(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
    MOVSS(XMM0, R(SRC1));

    ABI_PushRegistersAndAdjustStack(PersistentCallerSavedRegs(), 0);
    ABI_CallFunction(reinterpret_cast<const void*>(log2f));
    ABI_PopRegistersAndAdjustStack(PersistentCallerSavedRegs(), 0);

    SHUFPS(XMM0, R(XMM0), _MM_SHUFFLE(0, 0, 0, 0));
    MOVAPS(SRC1, R(XMM0));
    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_MUL(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
    Compile_SwizzleSrc(instr, 2, instr.common.src2, SRC2);
    Compile_SanitizedMul(SRC1, SRC2, SCRATCH);
    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_SGE(Instruction instr) {
    if (instr.opcode.Value().EffectiveOpCode() == OpCode::Id::SGEI) {
        Compile_SwizzleSrc(instr, 1, instr.common.src1i, SRC1);
        Compile_SwizzleSrc(instr, 2, instr.common.src2i, SRC2);
    } else {
        Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
        Compile_SwizzleSrc(instr, 2, instr.common.src2, SRC2);
    }

    CMPPS(SRC2, R(SRC1), CMP_LE);
    ANDPS(SRC2, R(ONE));

    Compile_DestEnable(instr, SRC2);
}

void JitShader::Compile_SLT(Instruction instr) {
    if (instr.opcode.Value().EffectiveOpCode() == OpCode::Id::SLTI) {
        Compile_SwizzleSrc(instr, 1, instr.common.src1i, SRC1);
        Compile_SwizzleSrc(instr, 2, instr.common.src2i, SRC2);
    } else {
        Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
        Compile_SwizzleSrc(instr, 2, instr.common.src2, SRC2);
    }

    CMPPS(SRC1, R(SRC2), CMP_LT);
    ANDPS(SRC1, R(ONE));

    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_FLR(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);

    if (Common::GetCPUCaps().sse4_1) {
        ROUNDFLOORPS(SRC1, R(SRC1));
    } else {
        CVTPS2DQ(SRC1, R(SRC1));
        CVTDQ2PS(SRC1, R(SRC1));
    }

    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_MAX(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
    Compile_SwizzleSrc(instr, 2, instr.common.src2, SRC2);
    // SSE semantics match PICA200 ones: In case of NaN, SRC2 is returned.
    MAXPS(SRC1, R(SRC2));
    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_MIN(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
    Compile_SwizzleSrc(instr, 2, instr.common.src2, SRC2);
    // SSE semantics match PICA200 ones: In case of NaN, SRC2 is returned.
    MINPS(SRC1, R(SRC2));
    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_MOVA(Instruction instr) {
    SwizzlePattern swiz = { g_state.vs.swizzle_data[instr.common.operand_desc_id] };

    if (!swiz.DestComponentEnabled(0) && !swiz.DestComponentEnabled(1)) {
        return; // NoOp
    }

    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);

    // Convert floats to integers using truncation (only care about X and Y components)
    CVTTPS2DQ(SRC1, R(SRC1));

    // Get result
    MOVQ_xmm(R(RAX), SRC1);

    // Handle destination enable
    if (swiz.DestComponentEnabled(0) && swiz.DestComponentEnabled(1)) {
        // Move and sign-extend low 32 bits
        MOVSX(64, 32, ADDROFFS_REG_0, R(RAX));

        // Move and sign-extend high 32 bits
        SHR(64, R(RAX), Imm8(32));
        MOVSX(64, 32, ADDROFFS_REG_1, R(RAX));

        // Multiply by 16 to be used as an offset later
        SHL(64, R(ADDROFFS_REG_0), Imm8(4));
        SHL(64, R(ADDROFFS_REG_1), Imm8(4));
    } else {
        if (swiz.DestComponentEnabled(0)) {
            // Move and sign-extend low 32 bits
            MOVSX(64, 32, ADDROFFS_REG_0, R(RAX));

            // Multiply by 16 to be used as an offset later
            SHL(64, R(ADDROFFS_REG_0), Imm8(4));
        } else if (swiz.DestComponentEnabled(1)) {
            // Move and sign-extend high 32 bits
            SHR(64, R(RAX), Imm8(32));
            MOVSX(64, 32, ADDROFFS_REG_1, R(RAX));

            // Multiply by 16 to be used as an offset later
            SHL(64, R(ADDROFFS_REG_1), Imm8(4));
        }
    }
}

void JitShader::Compile_MOV(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_RCP(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);

    // TODO(bunnei): RCPSS is a pretty rough approximation, this might cause problems if Pica
    // performs this operation more accurately. This should be checked on hardware.
    RCPSS(SRC1, R(SRC1));
    SHUFPS(SRC1, R(SRC1), _MM_SHUFFLE(0, 0, 0, 0)); // XYWZ -> XXXX

    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_RSQ(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);

    // TODO(bunnei): RSQRTSS is a pretty rough approximation, this might cause problems if Pica
    // performs this operation more accurately. This should be checked on hardware.
    RSQRTSS(SRC1, R(SRC1));
    SHUFPS(SRC1, R(SRC1), _MM_SHUFFLE(0, 0, 0, 0)); // XYWZ -> XXXX

    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_NOP(Instruction instr) {
}

void JitShader::Compile_END(Instruction instr) {
    ABI_PopRegistersAndAdjustStack(ABI_ALL_CALLEE_SAVED, 8);
    RET();
}

void JitShader::Compile_CALL(Instruction instr) {
    // Push offset of the return
    PUSH(64, Imm32(instr.flow_control.dest_offset + instr.flow_control.num_instructions));

    // Call the subroutine
    FixupBranch b = CALL();
    fixup_branches.push_back({ b, instr.flow_control.dest_offset });

    // Skip over the return offset that's on the stack
    ADD(64, R(RSP), Imm32(8));
}

void JitShader::Compile_CALLC(Instruction instr) {
    Compile_EvaluateCondition(instr);
    FixupBranch b = J_CC(CC_Z, true);
    Compile_CALL(instr);
    SetJumpTarget(b);
}

void JitShader::Compile_CALLU(Instruction instr) {
    Compile_UniformCondition(instr);
    FixupBranch b = J_CC(CC_Z, true);
    Compile_CALL(instr);
    SetJumpTarget(b);
}

void JitShader::Compile_CMP(Instruction instr) {
    using Op = Instruction::Common::CompareOpType::Op;
    Op op_x = instr.common.compare_op.x;
    Op op_y = instr.common.compare_op.y;

    Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
    Compile_SwizzleSrc(instr, 2, instr.common.src2, SRC2);

    // SSE doesn't have greater-than (GT) or greater-equal (GE) comparison operators. You need to
    // emulate them by swapping the lhs and rhs and using LT and LE. NLT and NLE can't be used here
    // because they don't match when used with NaNs.
    static const u8 cmp[] = { CMP_EQ, CMP_NEQ, CMP_LT, CMP_LE, CMP_LT, CMP_LE };

    bool invert_op_x = (op_x == Op::GreaterThan || op_x == Op::GreaterEqual);
    Gen::X64Reg lhs_x = invert_op_x ? SRC2 : SRC1;
    Gen::X64Reg rhs_x = invert_op_x ? SRC1 : SRC2;

    if (op_x == op_y) {
        // Compare X-component and Y-component together
        CMPPS(lhs_x, R(rhs_x), cmp[op_x]);
        MOVQ_xmm(R(COND0), lhs_x);

        MOV(64, R(COND1), R(COND0));
    } else {
        bool invert_op_y = (op_y == Op::GreaterThan || op_y == Op::GreaterEqual);
        Gen::X64Reg lhs_y = invert_op_y ? SRC2 : SRC1;
        Gen::X64Reg rhs_y = invert_op_y ? SRC1 : SRC2;

        // Compare X-component
        MOVAPS(SCRATCH, R(lhs_x));
        CMPSS(SCRATCH, R(rhs_x), cmp[op_x]);

        // Compare Y-component
        CMPPS(lhs_y, R(rhs_y), cmp[op_y]);

        MOVQ_xmm(R(COND0), SCRATCH);
        MOVQ_xmm(R(COND1), lhs_y);
    }

    SHR(32, R(COND0), Imm8(31));
    SHR(64, R(COND1), Imm8(63));
}

void JitShader::Compile_MAD(Instruction instr) {
    Compile_SwizzleSrc(instr, 1, instr.mad.src1, SRC1);

    if (instr.opcode.Value().EffectiveOpCode() == OpCode::Id::MADI) {
        Compile_SwizzleSrc(instr, 2, instr.mad.src2i, SRC2);
        Compile_SwizzleSrc(instr, 3, instr.mad.src3i, SRC3);
    } else {
        Compile_SwizzleSrc(instr, 2, instr.mad.src2, SRC2);
        Compile_SwizzleSrc(instr, 3, instr.mad.src3, SRC3);
    }

    Compile_SanitizedMul(SRC1, SRC2, SCRATCH);
    ADDPS(SRC1, R(SRC3));

    Compile_DestEnable(instr, SRC1);
}

void JitShader::Compile_IF(Instruction instr) {
    Compile_Assert(instr.flow_control.dest_offset >= program_counter, "Backwards if-statements not supported");

    // Evaluate the "IF" condition
    if (instr.opcode.Value() == OpCode::Id::IFU) {
        Compile_UniformCondition(instr);
    } else if (instr.opcode.Value() == OpCode::Id::IFC) {
        Compile_EvaluateCondition(instr);
    }
    FixupBranch b = J_CC(CC_Z, true);

    // Compile the code that corresponds to the condition evaluating as true
    Compile_Block(instr.flow_control.dest_offset);

    // If there isn't an "ELSE" condition, we are done here
    if (instr.flow_control.num_instructions == 0) {
        SetJumpTarget(b);
        return;
    }

    FixupBranch b2 = J(true);

    SetJumpTarget(b);

    // This code corresponds to the "ELSE" condition
    // Comple the code that corresponds to the condition evaluating as false
    Compile_Block(instr.flow_control.dest_offset + instr.flow_control.num_instructions);

    SetJumpTarget(b2);
}

void JitShader::Compile_LOOP(Instruction instr) {
    Compile_Assert(instr.flow_control.dest_offset >= program_counter, "Backwards loops not supported");
    Compile_Assert(!looping, "Nested loops not supported");

    looping = true;

    int offset = offsetof(decltype(g_state.vs.uniforms), i) + (instr.flow_control.int_uniform_id * sizeof(Math::Vec4<u8>));
    MOV(32, R(LOOPCOUNT), MDisp(UNIFORMS, offset));
    MOV(32, R(LOOPCOUNT_REG), R(LOOPCOUNT));
    SHR(32, R(LOOPCOUNT_REG), Imm8(8));
    AND(32, R(LOOPCOUNT_REG), Imm32(0xff)); // Y-component is the start
    MOV(32, R(LOOPINC), R(LOOPCOUNT));
    SHR(32, R(LOOPINC), Imm8(16));
    MOVZX(32, 8, LOOPINC, R(LOOPINC)); // Z-component is the incrementer
    MOVZX(32, 8, LOOPCOUNT, R(LOOPCOUNT)); // X-component is iteration count
    ADD(32, R(LOOPCOUNT), Imm8(1)); // Iteration count is X-component + 1

    auto loop_start = GetCodePtr();

    Compile_Block(instr.flow_control.dest_offset + 1);

    ADD(32, R(LOOPCOUNT_REG), R(LOOPINC)); // Increment LOOPCOUNT_REG by Z-component
    SUB(32, R(LOOPCOUNT), Imm8(1)); // Increment loop count by 1
    J_CC(CC_NZ, loop_start); // Loop if not equal

    looping = false;
}

void JitShader::Compile_JMP(Instruction instr) {
    if (instr.opcode.Value() == OpCode::Id::JMPC)
        Compile_EvaluateCondition(instr);
    else if (instr.opcode.Value() == OpCode::Id::JMPU)
        Compile_UniformCondition(instr);
    else
        UNREACHABLE();

    bool inverted_condition = (instr.opcode.Value() == OpCode::Id::JMPU) &&
        (instr.flow_control.num_instructions & 1);

    FixupBranch b = J_CC(inverted_condition ? CC_Z : CC_NZ, true);
    fixup_branches.push_back({ b, instr.flow_control.dest_offset });
}

void JitShader::Compile_Block(unsigned end) {
    while (program_counter < end) {
        Compile_NextInstr();
    }
}

void JitShader::Compile_Return() {
    // Peek return offset on the stack and check if we're at that offset
    MOV(64, R(RAX), MDisp(RSP, 8));
    CMP(32, R(RAX), Imm32(program_counter));

    // If so, jump back to before CALL
    FixupBranch b = J_CC(CC_NZ, true);
    RET();
    SetJumpTarget(b);
}

void JitShader::Compile_NextInstr() {
    if (std::binary_search(return_offsets.begin(), return_offsets.end(), program_counter)) {
        Compile_Return();
    }

    ASSERT_MSG(code_ptr[program_counter] == nullptr, "Tried to compile already compiled shader location!");
    code_ptr[program_counter] = GetCodePtr();

    Instruction instr = GetVertexShaderInstruction(program_counter++);

    OpCode::Id opcode = instr.opcode.Value();
    auto instr_func = instr_table[static_cast<unsigned>(opcode)];

    if (instr_func) {
        // JIT the instruction!
        ((*this).*instr_func)(instr);
    } else {
        // Unhandled instruction
        LOG_CRITICAL(HW_GPU, "Unhandled instruction: 0x%02x (0x%08x)",
                instr.opcode.Value().EffectiveOpCode(), instr.hex);
    }
}

void JitShader::FindReturnOffsets() {
    return_offsets.clear();

    for (size_t offset = 0; offset < g_state.vs.program_code.size(); ++offset) {
        Instruction instr = GetVertexShaderInstruction(offset);

        switch (instr.opcode.Value()) {
        case OpCode::Id::CALL:
        case OpCode::Id::CALLC:
        case OpCode::Id::CALLU:
            return_offsets.push_back(instr.flow_control.dest_offset + instr.flow_control.num_instructions);
            break;
        default:
            break;
        }
    }

    // Sort for efficient binary search later
    std::sort(return_offsets.begin(), return_offsets.end());
}

void JitShader::Compile() {
    // Reset flow control state
    program = (CompiledShader*)GetCodePtr();
    program_counter = 0;
    looping = false;
    code_ptr.fill(nullptr);
    fixup_branches.clear();

    // Find all `CALL` instructions and identify return locations
    FindReturnOffsets();

    // The stack pointer is 8 modulo 16 at the entry of a procedure
    ABI_PushRegistersAndAdjustStack(ABI_ALL_CALLEE_SAVED, 8);

    MOV(PTRBITS, R(REGISTERS), R(ABI_PARAM1));
    MOV(PTRBITS, R(UNIFORMS), ImmPtr(&g_state.vs.uniforms));

    // Zero address/loop  registers
    XOR(64, R(ADDROFFS_REG_0), R(ADDROFFS_REG_0));
    XOR(64, R(ADDROFFS_REG_1), R(ADDROFFS_REG_1));
    XOR(64, R(LOOPCOUNT_REG), R(LOOPCOUNT_REG));

    // Used to set a register to one
    static const __m128 one = { 1.f, 1.f, 1.f, 1.f };
    MOV(PTRBITS, R(RAX), ImmPtr(&one));
    MOVAPS(ONE, MatR(RAX));

    // Used to negate registers
    static const __m128 neg = { -0.f, -0.f, -0.f, -0.f };
    MOV(PTRBITS, R(RAX), ImmPtr(&neg));
    MOVAPS(NEGBIT, MatR(RAX));

    // Jump to start of the shader program
    JMPptr(R(ABI_PARAM2));

    // Compile entire program
    Compile_Block(static_cast<unsigned>(g_state.vs.program_code.size()));

    // Set the target for any incomplete branches now that the entire shader program has been emitted
    for (const auto& branch : fixup_branches) {
        SetJumpTarget(branch.first, code_ptr[branch.second]);
    }

    // Free memory that's no longer needed
    return_offsets.clear();
    return_offsets.shrink_to_fit();
    fixup_branches.clear();
    fixup_branches.shrink_to_fit();

    uintptr_t size = reinterpret_cast<uintptr_t>(GetCodePtr()) - reinterpret_cast<uintptr_t>(program);
    ASSERT_MSG(size <= MAX_SHADER_SIZE, "Compiled a shader that exceeds the allocated size!");

    LOG_DEBUG(HW_GPU, "Compiled shader size=%lu", size);
}

JitShader::JitShader() {
    AllocCodeSpace(MAX_SHADER_SIZE);
}

} // namespace Shader

} // namespace Pica
