UnrealEngineUWP/Engine/Source/Developer/VulkanShaderFormat/Private/VulkanBackend.h

// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "CoreMinimal.h"
#include "hlslcc.h"
#include "LanguageSpec.h"
#include "VulkanCommon.h"

class FVulkanLanguageSpec : public ILanguageSpec
{
protected:
	bool bShareSamplers;
	bool bRequiresOESExtensions;

public:
	FVulkanLanguageSpec(bool bInShareSamplers, bool bInRequiresOESExtensions)
		: bShareSamplers(bInShareSamplers)
		, bRequiresOESExtensions(bInRequiresOESExtensions)
	{}

	virtual bool SupportsDeterminantIntrinsic() const override
	{
		return true;
	}

	virtual bool SupportsTransposeIntrinsic() const override
	{
		return true;
	}

	virtual bool SupportsIntegerModulo() const override
	{
		return true;
	}

	virtual bool SupportsMatrixConversions() const override { return true; }

	virtual void SetupLanguageIntrinsics(_mesa_glsl_parse_state* State, exec_list* ir) override;

	virtual bool AllowsSharingSamplers() const override { return bShareSamplers; }

	virtual bool RequiresNegateDDY() const override { return false; }

public:
	bool RequiresOESExtensions() const { return bRequiresOESExtensions; }
};

class ir_variable;

// Generates Vulkan compliant code from IR tokens
#ifdef __GNUC__
#pragma GCC visibility push(default)
#endif // __GNUC__

struct FVulkanBindingTable
{
	struct FBinding
	{
		FBinding();
		FBinding(const char* InName, int32 InVirtualIndex, EVulkanBindingType::EType InType, int8 InSubType);

		char		Name[256];
		int32		VirtualIndex = -1;
		EVulkanBindingType::EType	Type;
		int8		SubType;	// HLSL CC subtype, PACKED_TYPENAME_HIGHP and etc
	};
		
	FVulkanBindingTable(EHlslShaderFrequency ShaderStage) : Stage(ShaderStage) {}

	int32 RegisterBinding(const char* InName, const char* BlockName, EVulkanBindingType::EType Type);

	const TArray<FBinding>& GetBindings() const
	{
		check(bSorted);
		return Bindings;
	}

	void SortBindings();
	void PrintBindingTableDefines(char** OutBuffer) const;

	int32 GetRealBindingIndex(int32 InVirtualIndex) const
	{
		for (int32 Index = 0; Index < Bindings.Num(); ++Index)
		{
			if (Bindings[Index].VirtualIndex == InVirtualIndex)
			{
				return Index;
			}
		}

		return -1;
	}

	uint32 InputAttachmentsMask = 0;

private:
	// Previous implementation supported bindings only for textures.
	// However, layout(binding=%d) must be also used for uniform buffers.

	EHlslShaderFrequency Stage;
	TArray<FBinding> Bindings;

	bool bSorted = false;

	friend class FGenerateVulkanVisitor;
};

struct FVulkanCodeBackend : public FCodeBackend
{
	FVulkanCodeBackend(	unsigned int InHlslCompileFlags,
						FVulkanBindingTable& InBindingTable,
						EHlslCompileTarget InTarget) :
		FCodeBackend(InHlslCompileFlags, InTarget),
		BindingTable(InBindingTable),
		bExplicitDepthWrites(false)
	{
	}

	virtual char* GenerateCode(struct exec_list* ir, struct _mesa_glsl_parse_state* ParseState, EHlslShaderFrequency Frequency) override;

	// Return false if there were restrictions that made compilation fail
	virtual bool ApplyAndVerifyPlatformRestrictions(exec_list* Instructions, _mesa_glsl_parse_state* ParseState, EHlslShaderFrequency Frequency) override;

	/**
	* Generate a GLSL main() function that calls the entry point and handles
	* reading and writing all input and output semantics.
	* @param Frequency - The shader frequency.
	* @param EntryPoint - The name of the shader entry point.
	* @param Instructions - IR code.
	* @param ParseState - Parse state.
	*/
	virtual bool GenerateMain(EHlslShaderFrequency Frequency, const char* EntryPoint, exec_list* Instructions, _mesa_glsl_parse_state* ParseState) override;

	void FixIntrinsics(_mesa_glsl_parse_state* ParseState, exec_list* ir);

	void GenShaderPatchConstantFunctionInputs(_mesa_glsl_parse_state* ParseState, ir_variable* OutputPatchVar, exec_list &PostCallInstructions);

	void CallPatchConstantFunction(_mesa_glsl_parse_state* ParseState, ir_variable* OutputPatchVar, ir_function_signature* PatchConstantSig, exec_list& DeclInstructions, exec_list &PostCallInstructions);

	ir_function_signature* FindPatchConstantFunction(exec_list* Instructions, _mesa_glsl_parse_state* ParseState);

	FVulkanBindingTable& BindingTable;
	bool bExplicitDepthWrites;
};

// InputAttachments
// 0 - reserved for depth input, 1-8 for color
extern const char* VULKAN_SUBPASS_FETCH[9];
extern const char* VULKAN_SUBPASS_FETCH_VAR[9];
extern const TCHAR* VULKAN_SUBPASS_FETCH_VAR_W[9];

#ifdef __GNUC__
#pragma GCC visibility pop
#endif // __GNUC__