Ryujinx/Ryujinx.Graphics.Shader/CodeGen/Glsl/Instructions/InstGenMemory.cs

using Ryujinx.Graphics.Shader.IntermediateRepresentation;
using Ryujinx.Graphics.Shader.StructuredIr;
using System;

using static Ryujinx.Graphics.Shader.CodeGen.Glsl.Instructions.InstGenHelper;
using static Ryujinx.Graphics.Shader.StructuredIr.InstructionInfo;

namespace Ryujinx.Graphics.Shader.CodeGen.Glsl.Instructions
{
    static class InstGenMemory
    {
        public static string ImageLoadOrStore(CodeGenContext context, AstOperation operation)
        {
            AstTextureOperation texOp = (AstTextureOperation)operation;

            bool isBindless = (texOp.Flags & TextureFlags.Bindless) != 0;

            // TODO: Bindless texture support. For now we just return 0/do nothing.
            if (isBindless)
            {
                return texOp.Inst == Instruction.ImageLoad ? NumberFormatter.FormatFloat(0) : "// imageStore(bindless)";
            }

            bool isArray   = (texOp.Type & SamplerType.Array)   != 0;
            bool isIndexed = (texOp.Type & SamplerType.Indexed) != 0;

            string texCall = texOp.Inst == Instruction.ImageLoad ? "imageLoad" : "imageStore";

            int srcIndex = isBindless ? 1 : 0;

            string Src(VariableType type)
            {
                return GetSoureExpr(context, texOp.GetSource(srcIndex++), type);
            }

            string indexExpr = null;

            if (isIndexed)
            {
                indexExpr = Src(VariableType.S32);
            }

            string imageName = OperandManager.GetImageName(context.Config.Stage, texOp, indexExpr);

            texCall += "(" + imageName;

            int coordsCount = texOp.Type.GetDimensions();

            int pCount = coordsCount + (isArray ? 1 : 0);

            void Append(string str)
            {
                texCall += ", " + str;
            }

            string ApplyScaling(string vector)
            {
                int index = context.FindImageDescriptorIndex(texOp);
                TextureUsageFlags flags = TextureUsageFlags.NeedsScaleValue;

                if ((context.Config.Stage == ShaderStage.Fragment || context.Config.Stage == ShaderStage.Compute) &&
                    texOp.Inst == Instruction.ImageLoad &&
                    !isBindless &&
                    !isIndexed)
                {
                    // Image scales start after texture ones.
                    int scaleIndex = context.TextureDescriptors.Count + index;

                    if (pCount == 3 && isArray)
                    {
                        // The array index is not scaled, just x and y.
                        vector = "ivec3(Helper_TexelFetchScale((" + vector + ").xy, " + scaleIndex + "), (" + vector + ").z)";
                    }
                    else if (pCount == 2 && !isArray)
                    {
                        vector = "Helper_TexelFetchScale(" + vector + ", " + scaleIndex + ")";
                    }
                    else
                    {
                        flags |= TextureUsageFlags.ResScaleUnsupported;
                    }
                }
                else
                {
                    flags |= TextureUsageFlags.ResScaleUnsupported;
                }

                if (!isBindless)
                {
                    context.ImageDescriptors[index] = context.ImageDescriptors[index].SetFlag(flags);
                }

                return vector;
            }

            if (pCount > 1)
            {
                string[] elems = new string[pCount];

                for (int index = 0; index < pCount; index++)
                {
                    elems[index] = Src(VariableType.S32);
                }

                Append(ApplyScaling("ivec" + pCount + "(" + string.Join(", ", elems) + ")"));
            }
            else
            {
                Append(Src(VariableType.S32));
            }

            if (texOp.Inst == Instruction.ImageStore)
            {
                int texIndex = context.FindImageDescriptorIndex(texOp);
                context.ImageDescriptors[texIndex] = context.ImageDescriptors[texIndex].SetFlag(TextureUsageFlags.ImageStore);

                VariableType type = texOp.Format.GetComponentType();

                string[] cElems = new string[4];

                for (int index = 0; index < 4; index++)
                {
                    if (srcIndex < texOp.SourcesCount)
                    {
                        cElems[index] = Src(type);
                    }
                    else
                    {
                        cElems[index] = type switch
                        {
                            VariableType.S32 => NumberFormatter.FormatInt(0),
                            VariableType.U32 => NumberFormatter.FormatUint(0),
                            _                => NumberFormatter.FormatFloat(0)
                        };
                    }
                }

                string prefix = type switch
                {
                    VariableType.S32 => "i",
                    VariableType.U32 => "u",
                    _                => string.Empty
                };

                Append(prefix + "vec4(" + string.Join(", ", cElems) + ")");
            }

            texCall += ")" + (texOp.Inst == Instruction.ImageLoad ? GetMask(texOp.Index) : "");

            return texCall;
        }

        public static string LoadAttribute(CodeGenContext context, AstOperation operation)
        {
            IAstNode src1 = operation.GetSource(0);
            IAstNode src2 = operation.GetSource(1);

            if (!(src1 is AstOperand attr) || attr.Type != OperandType.Attribute)
            {
                throw new InvalidOperationException("First source of LoadAttribute must be a attribute.");
            }

            string indexExpr = GetSoureExpr(context, src2, GetSrcVarType(operation.Inst, 1));

            return OperandManager.GetAttributeName(attr, context.Config, isOutAttr: false, indexExpr);
        }

        public static string LoadConstant(CodeGenContext context, AstOperation operation)
        {
            IAstNode src1 = operation.GetSource(0);
            IAstNode src2 = operation.GetSource(1);

            string offsetExpr = GetSoureExpr(context, src2, GetSrcVarType(operation.Inst, 1));

            offsetExpr = Enclose(offsetExpr, src2, Instruction.ShiftRightS32, isLhs: true);

            if (src1 is AstOperand oper && oper.Type == OperandType.Constant)
            {
                return OperandManager.GetConstantBufferName(oper.Value, offsetExpr, context.Config.Stage, context.CbIndexable);
            }
            else
            {
                string slotExpr = GetSoureExpr(context, src1, GetSrcVarType(operation.Inst, 0));

                return OperandManager.GetConstantBufferName(slotExpr, offsetExpr, context.Config.Stage);
            }
        }

        public static string LoadLocal(CodeGenContext context, AstOperation operation)
        {
            return LoadLocalOrShared(context, operation, DefaultNames.LocalMemoryName);
        }

        public static string LoadShared(CodeGenContext context, AstOperation operation)
        {
            return LoadLocalOrShared(context, operation, DefaultNames.SharedMemoryName);
        }

        private static string LoadLocalOrShared(CodeGenContext context, AstOperation operation, string arrayName)
        {
            IAstNode src1 = operation.GetSource(0);

            string offsetExpr = GetSoureExpr(context, src1, GetSrcVarType(operation.Inst, 0));

            return $"{arrayName}[{offsetExpr}]";
        }

        public static string LoadStorage(CodeGenContext context, AstOperation operation)
        {
            IAstNode src1 = operation.GetSource(0);
            IAstNode src2 = operation.GetSource(1);

            string indexExpr  = GetSoureExpr(context, src1, GetSrcVarType(operation.Inst, 0));
            string offsetExpr = GetSoureExpr(context, src2, GetSrcVarType(operation.Inst, 1));

            return GetStorageBufferAccessor(indexExpr, offsetExpr, context.Config.Stage);
        }

        public static string Lod(CodeGenContext context, AstOperation operation)
        {
            AstTextureOperation texOp = (AstTextureOperation)operation;

            int coordsCount = texOp.Type.GetDimensions();

            bool isBindless = (texOp.Flags & TextureFlags.Bindless) != 0;

            // TODO: Bindless texture support. For now we just return 0.
            if (isBindless)
            {
                return NumberFormatter.FormatFloat(0);
            }

            bool isIndexed = (texOp.Type & SamplerType.Indexed) != 0;

            string indexExpr = null;

            if (isIndexed)
            {
                indexExpr = GetSoureExpr(context, texOp.GetSource(0), VariableType.S32);
            }

            string samplerName = OperandManager.GetSamplerName(context.Config.Stage, texOp, indexExpr);

            int coordsIndex = isBindless || isIndexed ? 1 : 0;

            string coordsExpr;

            if (coordsCount > 1)
            {
                string[] elems = new string[coordsCount];

                for (int index = 0; index < coordsCount; index++)
                {
                    elems[index] = GetSoureExpr(context, texOp.GetSource(coordsIndex + index), VariableType.F32);
                }

                coordsExpr = "vec" + coordsCount + "(" + string.Join(", ", elems) + ")";
            }
            else
            {
                coordsExpr = GetSoureExpr(context, texOp.GetSource(coordsIndex), VariableType.F32);
            }

            return $"textureQueryLod({samplerName}, {coordsExpr}){GetMask(texOp.Index)}";
        }

        public static string StoreLocal(CodeGenContext context, AstOperation operation)
        {
            return StoreLocalOrShared(context, operation, DefaultNames.LocalMemoryName);
        }

        public static string StoreShared(CodeGenContext context, AstOperation operation)
        {
            return StoreLocalOrShared(context, operation, DefaultNames.SharedMemoryName);
        }

        private static string StoreLocalOrShared(CodeGenContext context, AstOperation operation, string arrayName)
        {
            IAstNode src1 = operation.GetSource(0);
            IAstNode src2 = operation.GetSource(1);

            string offsetExpr = GetSoureExpr(context, src1, GetSrcVarType(operation.Inst, 0));

            VariableType srcType = OperandManager.GetNodeDestType(context, src2);

            string src = TypeConversion.ReinterpretCast(context, src2, srcType, VariableType.U32);

            return $"{arrayName}[{offsetExpr}] = {src}";
        }

        public static string StoreStorage(CodeGenContext context, AstOperation operation)
        {
            IAstNode src1 = operation.GetSource(0);
            IAstNode src2 = operation.GetSource(1);
            IAstNode src3 = operation.GetSource(2);

            string indexExpr  = GetSoureExpr(context, src1, GetSrcVarType(operation.Inst, 0));
            string offsetExpr = GetSoureExpr(context, src2, GetSrcVarType(operation.Inst, 1));

            VariableType srcType = OperandManager.GetNodeDestType(context, src3);

            string src = TypeConversion.ReinterpretCast(context, src3, srcType, VariableType.U32);

            SetStorageWriteFlag(context, src1, context.Config.Stage);
            string sb = GetStorageBufferAccessor(indexExpr, offsetExpr, context.Config.Stage);

            return $"{sb} = {src}";
        }

        public static string TextureSample(CodeGenContext context, AstOperation operation)
        {
            AstTextureOperation texOp = (AstTextureOperation)operation;

            bool isBindless     = (texOp.Flags & TextureFlags.Bindless)    != 0;
            bool isGather       = (texOp.Flags & TextureFlags.Gather)      != 0;
            bool hasDerivatives = (texOp.Flags & TextureFlags.Derivatives) != 0;
            bool intCoords      = (texOp.Flags & TextureFlags.IntCoords)   != 0;
            bool hasLodBias     = (texOp.Flags & TextureFlags.LodBias)     != 0;
            bool hasLodLevel    = (texOp.Flags & TextureFlags.LodLevel)    != 0;
            bool hasOffset      = (texOp.Flags & TextureFlags.Offset)      != 0;
            bool hasOffsets     = (texOp.Flags & TextureFlags.Offsets)     != 0;

            bool isArray       = (texOp.Type & SamplerType.Array)       != 0;
            bool isIndexed     = (texOp.Type & SamplerType.Indexed)     != 0;
            bool isMultisample = (texOp.Type & SamplerType.Multisample) != 0;
            bool isShadow      = (texOp.Type & SamplerType.Shadow)      != 0;

            // TODO: Bindless texture support. For now we just return 0.
            if (isBindless)
            {
                return NumberFormatter.FormatFloat(0);
            }

            // This combination is valid, but not available on GLSL.
            // For now, ignore the LOD level and do a normal sample.
            // TODO: How to implement it properly?
            if (hasLodLevel && isArray && isShadow)
            {
                hasLodLevel = false;
            }

            string texCall = intCoords ? "texelFetch" : "texture";

            if (isGather)
            {
                texCall += "Gather";
            }
            else if (hasDerivatives)
            {
                texCall += "Grad";
            }
            else if (hasLodLevel && !intCoords)
            {
                texCall += "Lod";
            }

            if (hasOffset)
            {
                texCall += "Offset";
            }
            else if (hasOffsets)
            {
                texCall += "Offsets";
            }

            int srcIndex = isBindless ? 1 : 0;

            string Src(VariableType type)
            {
                return GetSoureExpr(context, texOp.GetSource(srcIndex++), type);
            }

            string indexExpr = null;

            if (isIndexed)
            {
                indexExpr = Src(VariableType.S32);
            }

            string samplerName = OperandManager.GetSamplerName(context.Config.Stage, texOp, indexExpr);

            texCall += "(" + samplerName;

            int coordsCount = texOp.Type.GetDimensions();

            int pCount = coordsCount;

            int arrayIndexElem = -1;

            if (isArray)
            {
                arrayIndexElem = pCount++;
            }

            // The sampler 1D shadow overload expects a
            // dummy value on the middle of the vector, who knows why...
            bool hasDummy1DShadowElem = texOp.Type == (SamplerType.Texture1D | SamplerType.Shadow);

            if (hasDummy1DShadowElem)
            {
                pCount++;
            }

            if (isShadow && !isGather)
            {
                pCount++;
            }

            // On textureGather*, the comparison value is
            // always specified as an extra argument.
            bool hasExtraCompareArg = isShadow && isGather;

            if (pCount == 5)
            {
                pCount = 4;

                hasExtraCompareArg = true;
            }

            void Append(string str)
            {
                texCall += ", " + str;
            }

            VariableType coordType = intCoords ? VariableType.S32 : VariableType.F32;

            string AssemblePVector(int count)
            {
                if (count > 1)
                {
                    string[] elems = new string[count];

                    for (int index = 0; index < count; index++)
                    {
                        if (arrayIndexElem == index)
                        {
                            elems[index] = Src(VariableType.S32);

                            if (!intCoords)
                            {
                                elems[index] = "float(" + elems[index] + ")";
                            }
                        }
                        else if (index == 1 && hasDummy1DShadowElem)
                        {
                            elems[index] = NumberFormatter.FormatFloat(0);
                        }
                        else
                        {
                            elems[index] = Src(coordType);
                        }
                    }

                    string prefix = intCoords ? "i" : string.Empty;

                    return prefix + "vec" + count + "(" + string.Join(", ", elems) + ")";
                }
                else
                {
                    return Src(coordType);
                }
            }

            string ApplyScaling(string vector)
            {
                if (intCoords)
                {
                    int index = context.FindTextureDescriptorIndex(texOp);
                    TextureUsageFlags flags = TextureUsageFlags.NeedsScaleValue;

                    if ((context.Config.Stage == ShaderStage.Fragment || context.Config.Stage == ShaderStage.Compute) &&
                        !isBindless &&
                        !isIndexed)
                    {
                        if (pCount == 3 && isArray)
                        {
                            // The array index is not scaled, just x and y.
                            vector = "ivec3(Helper_TexelFetchScale((" + vector + ").xy, " + index + "), (" + vector + ").z)";
                        }
                        else if (pCount == 2 && !isArray)
                        {
                            vector = "Helper_TexelFetchScale(" + vector + ", " + index + ")";
                        }
                        else
                        {
                            flags |= TextureUsageFlags.ResScaleUnsupported;
                        }
                    } 
                    else
                    {
                        // Resolution scaling cannot be applied to this texture right now.
                        // Flag so that we know to blacklist scaling on related textures when binding them.

                        flags |= TextureUsageFlags.ResScaleUnsupported;
                    }

                    if (!isBindless)
                    {
                        context.TextureDescriptors[index] = context.TextureDescriptors[index].SetFlag(flags);
                    }
                }

                return vector;
            }

            Append(ApplyScaling(AssemblePVector(pCount)));

            string AssembleDerivativesVector(int count)
            {
                if (count > 1)
                {
                    string[] elems = new string[count];

                    for (int index = 0; index < count; index++)
                    {
                        elems[index] = Src(VariableType.F32);
                    }

                    return "vec" + count + "(" + string.Join(", ", elems) + ")";
                }
                else
                {
                    return Src(VariableType.F32);
                }
            }

            if (hasExtraCompareArg)
            {
                Append(Src(VariableType.F32));
            }

            if (hasDerivatives)
            {
                Append(AssembleDerivativesVector(coordsCount)); // dPdx
                Append(AssembleDerivativesVector(coordsCount)); // dPdy
            }

            if (isMultisample)
            {
                Append(Src(VariableType.S32));
            }
            else if (hasLodLevel)
            {
                Append(Src(coordType));
            }

            string AssembleOffsetVector(int count)
            {
                if (count > 1)
                {
                    string[] elems = new string[count];

                    for (int index = 0; index < count; index++)
                    {
                        elems[index] = Src(VariableType.S32);
                    }

                    return "ivec" + count + "(" + string.Join(", ", elems) + ")";
                }
                else
                {
                    return Src(VariableType.S32);
                }
            }

            if (hasOffset)
            {
                Append(AssembleOffsetVector(coordsCount));
            }
            else if (hasOffsets)
            {
                texCall += $", ivec{coordsCount}[4](";

                texCall += AssembleOffsetVector(coordsCount) + ", ";
                texCall += AssembleOffsetVector(coordsCount) + ", ";
                texCall += AssembleOffsetVector(coordsCount) + ", ";
                texCall += AssembleOffsetVector(coordsCount) + ")";
            }

            if (hasLodBias)
            {
               Append(Src(VariableType.F32));
            }

            // textureGather* optional extra component index,
            // not needed for shadow samplers.
            if (isGather && !isShadow)
            {
               Append(Src(VariableType.S32));
            }

            texCall += ")" + (isGather || !isShadow ? GetMask(texOp.Index) : "");

            return texCall;
        }

        public static string TextureSize(CodeGenContext context, AstOperation operation)
        {
            AstTextureOperation texOp = (AstTextureOperation)operation;

            bool isBindless = (texOp.Flags & TextureFlags.Bindless) != 0;

            // TODO: Bindless texture support. For now we just return 0.
            if (isBindless)
            {
                return NumberFormatter.FormatInt(0);
            }

            bool isIndexed = (texOp.Type & SamplerType.Indexed) != 0;

            string indexExpr = null;

            if (isIndexed)
            {
                indexExpr = GetSoureExpr(context, texOp.GetSource(0), VariableType.S32);
            }

            string samplerName = OperandManager.GetSamplerName(context.Config.Stage, texOp, indexExpr);

            int lodSrcIndex = isBindless || isIndexed ? 1 : 0;

            IAstNode lod = operation.GetSource(lodSrcIndex);

            string lodExpr = GetSoureExpr(context, lod, GetSrcVarType(operation.Inst, lodSrcIndex));

            if (texOp.Index == 3)
            {
                return $"textureQueryLevels({samplerName})";
            }
            else
            {
                return $"textureSize({samplerName}, {lodExpr}){GetMask(texOp.Index)}";
            }
        }

        private static void SetStorageWriteFlag(CodeGenContext context, IAstNode indexExpr, ShaderStage stage)
        {
            // Attempt to find a BufferDescriptor with the given index.
            // If it cannot be resolved or is not constant, assume that the slot expression could potentially index any of them,
            // and set the flag on all storage buffers.

            int index = -1;

            if (indexExpr is AstOperand operand && operand.Type == OperandType.Constant)
            {
                index = context.SBufferDescriptors.FindIndex(buffer => buffer.Slot == operand.Value);
            }

            if (index != -1)
            {
                context.SBufferDescriptors[index] = context.SBufferDescriptors[index].SetFlag(BufferUsageFlags.Write);
            }
            else
            {
                for (int i = 0; i < context.SBufferDescriptors.Count; i++)
                {
                    context.SBufferDescriptors[i] = context.SBufferDescriptors[i].SetFlag(BufferUsageFlags.Write);
                }
            }
        }

        private static string GetStorageBufferAccessor(string slotExpr, string offsetExpr, ShaderStage stage)
        {
            string sbName = OperandManager.GetShaderStagePrefix(stage);

            sbName += "_" + DefaultNames.StorageNamePrefix;

            return $"{sbName}[{slotExpr}].{DefaultNames.DataName}[{offsetExpr}]";
        }

        private static string GetMask(int index)
        {
            return '.' + "rgba".Substring(index, 1);
        }
    }
}