include/GLSLANG/ShaderLang.h

//
// Copyright 2002 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
#ifndef GLSLANG_SHADERLANG_H_
#define GLSLANG_SHADERLANG_H_

#include <stddef.h>

#include "KHR/khrplatform.h"

#include <array>
#include <map>
#include <set>
#include <string>
#include <vector>

//
// This is the platform independent interface between an OGL driver
// and the shading language compiler.
//

// Note: make sure to increment ANGLE_SH_VERSION when changing ShaderVars.h
#include "ShaderVars.h"

// Version number for shader translation API.
// It is incremented every time the API changes.
#define ANGLE_SH_VERSION 372

enum ShShaderSpec
{
    SH_GLES2_SPEC,
    SH_WEBGL_SPEC,

    SH_GLES3_SPEC,
    SH_WEBGL2_SPEC,

    SH_GLES3_1_SPEC,
    SH_WEBGL3_SPEC,

    SH_GLES3_2_SPEC,
};

enum ShShaderOutput
{
    // NULL output for testing.
    SH_NULL_OUTPUT,

    // ESSL output only supported in some configurations.
    SH_ESSL_OUTPUT,

    // GLSL output only supported in some configurations.
    SH_GLSL_COMPATIBILITY_OUTPUT,
    // Note: GL introduced core profiles in 1.5.
    SH_GLSL_130_OUTPUT,
    SH_GLSL_140_OUTPUT,
    SH_GLSL_150_CORE_OUTPUT,
    SH_GLSL_330_CORE_OUTPUT,
    SH_GLSL_400_CORE_OUTPUT,
    SH_GLSL_410_CORE_OUTPUT,
    SH_GLSL_420_CORE_OUTPUT,
    SH_GLSL_430_CORE_OUTPUT,
    SH_GLSL_440_CORE_OUTPUT,
    SH_GLSL_450_CORE_OUTPUT,

    // Prefer using these to specify HLSL output type:
    SH_HLSL_3_0_OUTPUT,  // D3D 9
    SH_HLSL_4_1_OUTPUT,  // D3D 11

    // Output SPIR-V for the Vulkan backend.
    SH_SPIRV_VULKAN_OUTPUT,

    // Output for MSL
    SH_MSL_METAL_OUTPUT,

    // Output for WGSL
    SH_WGSL_OUTPUT,
};

struct ShCompileOptionsMetal
{
    // Direct-to-metal backend constants:

    // Binding index for driver uniforms:
    int driverUniformsBindingIndex = 0;
    // Binding index for default uniforms:
    int defaultUniformsBindingIndex = 0;
    // Binding index for UBO's argument buffer
    int UBOArgumentBufferBindingIndex = 0;

    bool generateShareableShaders = false;

    // Insert asm("") instructions into loop bodies, telling the compiler that all loops have side
    // effects and cannot be optimized out.
    bool injectAsmStatementIntoLoopBodies = false;
};

// For ANGLE_shader_pixel_local_storage.
// Instructs the compiler which pixel local storage configuration to generate code for.
enum class ShPixelLocalStorageType : uint8_t
{
    NotSupported,
    ImageLoadStore,
    FramebufferFetch,
};

// For ANGLE_shader_pixel_local_storage.
// Used to track the PLS format at each binding index in a shader.
enum class ShPixelLocalStorageFormat : uint8_t
{
    NotPLS,  // Indicates that no PLS uniform was declared at the binding index in question.
    RGBA8,
    RGBA8I,
    RGBA8UI,
    R32F,
    R32UI,
};

// For ANGLE_shader_pixel_local_storage_coherent.
// Instructs the compiler which fragment synchronization method to use, if any.
enum class ShFragmentSynchronizationType : uint8_t
{
    NotSupported,  // Fragments cannot be ordered or synchronized.

    Automatic,  // Fragments are automatically raster-ordered and synchronized.

    FragmentShaderInterlock_NV_GL,
    FragmentShaderOrdering_INTEL_GL,
    FragmentShaderInterlock_ARB_GL,  // Also compiles to SPV_EXT_fragment_shader_interlock.

    RasterizerOrderViews_D3D,

    RasterOrderGroups_Metal,

    InvalidEnum,
    EnumCount = InvalidEnum,
};

struct ShPixelLocalStorageOptions
{
    ShPixelLocalStorageType type = ShPixelLocalStorageType::NotSupported;

    // For ANGLE_shader_pixel_local_storage_coherent.
    ShFragmentSynchronizationType fragmentSyncType = ShFragmentSynchronizationType::NotSupported;

    // ShPixelLocalStorageType::ImageLoadStore only: Can we use rgba8/rgba8i/rgba8ui image formats?
    // Or do we need to manually pack and unpack from r32i/r32ui?
    bool supportsNativeRGBA8ImageFormats = false;

    // anglebug.com/42266263 -- Metal [[raster_order_group()]] does not work for read_write textures
    // on AMD when the render pass doesn't have a color attachment on slot 0. To work around this we
    // attach one of the PLS textures to GL_COLOR_ATTACHMENT0, if there isn't one already.
    bool renderPassNeedsAMDRasterOrderGroupsWorkaround = false;
};

struct ShCompileOptions
{
    ShCompileOptions();
    ShCompileOptions(const ShCompileOptions &other);
    ShCompileOptions &operator=(const ShCompileOptions &other);

    // Translates intermediate tree to glsl, hlsl, msl, or SPIR-V binary.  Can be queried by
    // calling sh::GetObjectCode().
    uint64_t objectCode : 1;

    // Whether debug info should be output in the shader.
    uint64_t outputDebugInfo : 1;

    // Tracks the source path for shaders.  Can be queried with getSourcePath().
    uint64_t sourcePath : 1;

    // Whether the internal representation of the AST should be output.
    uint64_t intermediateTree : 1;

    // If requested, validates the AST after every transformation.  Useful for debugging.
    uint64_t validateAST : 1;

    // Validates loop and indexing in the shader to ensure that they do not exceed the minimum
    // functionality mandated in GLSL 1.0 spec, Appendix A, Section 4 and 5.  There is no need to
    // specify this parameter when compiling for WebGL - it is implied.
    uint64_t validateLoopIndexing : 1;

    // Emits #line directives in HLSL.
    uint64_t lineDirectives : 1;

    // Due to spec difference between GLSL 4.1 or lower and ESSL3, some platforms (for example, Mac
    // OSX core profile) require a variable's "invariant"/"centroid" qualifiers to match between
    // vertex and fragment shader. A simple solution to allow such shaders to link is to omit the
    // two qualifiers.  AMD driver in Linux requires invariant qualifier to match between vertex and
    // fragment shaders, while ESSL3 disallows invariant qualifier in fragment shader and GLSL >=
    // 4.2 doesn't require invariant qualifier to match between shaders. Remove invariant qualifier
    // from vertex shader to workaround AMD driver bug.
    // Note that the two flags take effect on ESSL3 input shaders translated to GLSL 4.1 or lower
    // and to GLSL 4.2 or newer on Linux AMD.
    // TODO(zmo): This is not a good long-term solution. Simply dropping these qualifiers may break
    // some developers' content. A more complex workaround of dynamically generating, compiling, and
    // re-linking shaders that use these qualifiers should be implemented.
    uint64_t removeInvariantAndCentroidForESSL3 : 1;

    // This flag works around bug in Intel Mac drivers related to abs(i) where i is an integer.
    uint64_t emulateAbsIntFunction : 1;

    // Enforce the GLSL 1.017 Appendix A section 7 packing restrictions.  This flag only enforces
    // (and can only enforce) the packing restrictions for uniform variables in both vertex and
    // fragment shaders. ShCheckVariablesWithinPackingLimits() lets embedders enforce the packing
    // restrictions for varying variables during program link time.
    uint64_t enforcePackingRestrictions : 1;

    // This flag ensures all indirect (expression-based) array indexing is clamped to the bounds of
    // the array. This ensures, for example, that you cannot read off the end of a uniform, whether
    // an array vec234, or mat234 type.
    uint64_t clampIndirectArrayBounds : 1;

    // This flag limits the complexity of an expression.
    uint64_t limitExpressionComplexity : 1;

    // This flag limits the depth of the call stack.
    uint64_t limitCallStackDepth : 1;

    // This flag initializes gl_Position to vec4(0,0,0,0) at the beginning of the vertex shader's
    // main(), and has no effect in the fragment shader. It is intended as a workaround for drivers
    // which incorrectly fail to link programs if gl_Position is not written.
    uint64_t initGLPosition : 1;

    // This flag replaces
    //   "a && b" with "a ? b : false",
    //   "a || b" with "a ? true : b".
    // This is to work around a MacOSX driver bug that |b| is executed independent of |a|'s value.
    uint64_t unfoldShortCircuit : 1;

    // This flag initializes output variables to 0 at the beginning of main().  It is to avoid
    // undefined behaviors.
    uint64_t initOutputVariables : 1;

    // This flag scalarizes vec/ivec/bvec/mat constructor args.  It is intended as a workaround for
    // Linux/Mac driver bugs.
    uint64_t scalarizeVecAndMatConstructorArgs : 1;

    // This flag overwrites a struct name with a unique prefix.  It is intended as a workaround for
    // drivers that do not handle struct scopes correctly, including all Mac drivers and Linux AMD.
    uint64_t regenerateStructNames : 1;

    // This flag works around bugs in Mac drivers related to do-while by transforming them into an
    // other construct.
    uint64_t rewriteDoWhileLoops : 1;

    // This flag works around a bug in the HLSL compiler optimizer that folds certain constant pow
    // expressions incorrectly. Only applies to the HLSL back-end. It works by expanding the integer
    // pow expressions into a series of multiplies.
    uint64_t expandSelectHLSLIntegerPowExpressions : 1;

    // Flatten "#pragma STDGL invariant(all)" into the declarations of varying variables and
    // built-in GLSL variables. This compiler option is enabled automatically when needed.
    uint64_t flattenPragmaSTDGLInvariantAll : 1;

    // Some drivers do not take into account the base level of the texture in the results of the
    // HLSL GetDimensions builtin.  This flag instructs the compiler to manually add the base level
    // offsetting.
    uint64_t HLSLGetDimensionsIgnoresBaseLevel : 1;

    // This flag works around an issue in translating GLSL function texelFetchOffset on INTEL
    // drivers. It works by translating texelFetchOffset into texelFetch.
    uint64_t rewriteTexelFetchOffsetToTexelFetch : 1;

    // This flag works around condition bug of for and while loops in Intel Mac OSX drivers.
    // Condition calculation is not correct. Rewrite it from "CONDITION" to "CONDITION && true".
    uint64_t addAndTrueToLoopCondition : 1;

    // This flag works around a bug in evaluating unary minus operator on integer on some INTEL
    // drivers. It works by translating -(int) into ~(int) + 1.
    uint64_t rewriteIntegerUnaryMinusOperator : 1;

    // This flag works around a bug in evaluating isnan() on some INTEL D3D and Mac OSX drivers.  It
    // works by using an expression to emulate this function.
    uint64_t emulateIsnanFloatFunction : 1;

    // This flag will use all uniforms of unused std140 and shared uniform blocks at the beginning
    // of the vertex/fragment shader's main(). It is intended as a workaround for Mac drivers with
    // shader version 4.10. In those drivers, they will treat unused std140 and shared uniform
    // blocks' members as inactive. However, WebGL2.0 based on OpenGL ES3.0.4 requires all members
    // of a named uniform block declared with a shared or std140 layout qualifier to be considered
    // active. The uniform block itself is also considered active.
    uint64_t useUnusedStandardSharedBlocks : 1;

    // This flag works around a bug in unary minus operator on float numbers on Intel Mac OSX 10.11
    // drivers. It works by translating -float into 0.0 - float.
    uint64_t rewriteFloatUnaryMinusOperator : 1;

    // This flag works around a bug in evaluating atan(y, x) on some NVIDIA OpenGL drivers.  It
    // works by using an expression to emulate this function.
    uint64_t emulateAtan2FloatFunction : 1;

    // Set to initialize uninitialized local and global temporary variables. Should only be used
    // with GLSL output. In HLSL output variables are initialized regardless of if this flag is set.
    uint64_t initializeUninitializedLocals : 1;

    // The flag modifies the shader in the following way:
    //
    // Every occurrence of gl_InstanceID is replaced by the global temporary variable InstanceID.
    // Every occurrence of gl_ViewID_OVR is replaced by the varying variable ViewID_OVR.
    // At the beginning of the body of main() in a vertex shader the following initializers are
    // added:
    //   ViewID_OVR = uint(gl_InstanceID) % num_views;
    //   InstanceID = gl_InstanceID / num_views;
    // ViewID_OVR is added as a varying variable to both the vertex and fragment shaders.
    uint64_t initializeBuiltinsForInstancedMultiview : 1;

    // With the flag enabled the GLSL/ESSL vertex shader is modified to include code for viewport
    // selection in the following way:
    // - Code to enable the extension ARB_shader_viewport_layer_array/NV_viewport_array2 is
    // included.
    // - Code to select the viewport index or layer is inserted at the beginning of main after
    //   ViewID_OVR's initialization.
    // - A declaration of the uniform multiviewBaseViewLayerIndex.
    // Note: The initializeBuiltinsForInstancedMultiview flag also has to be enabled to have the
    // temporary variable ViewID_OVR declared and initialized.
    uint64_t selectViewInNvGLSLVertexShader : 1;

    // If the flag is enabled, gl_PointSize is clamped to the maximum point size specified in
    // ShBuiltInResources in vertex shaders.
    uint64_t clampPointSize : 1;

    // This flag indicates whether advanced blend equation should be emulated.  Currently only
    // implemented for the Vulkan backend.
    uint64_t addAdvancedBlendEquationsEmulation : 1;

    // Don't use loops to initialize uninitialized variables. Only has an effect if some kind of
    // variable initialization is turned on.
    uint64_t dontUseLoopsToInitializeVariables : 1;

    // Don't use D3D constant register zero when allocating space for uniforms. This is targeted to
    // work around a bug in NVIDIA D3D driver version 388.59 where in very specific cases the driver
    // would not handle constant register zero correctly. Only has an effect on HLSL translation.
    uint64_t skipD3DConstantRegisterZero : 1;

    // Clamp gl_FragDepth to the range [0.0, 1.0] in case it is statically used.
    uint64_t clampFragDepth : 1;

    // Rewrite expressions like "v.x = z = expression;". Works around a bug in NVIDIA OpenGL drivers
    // prior to version 397.31.
    uint64_t rewriteRepeatedAssignToSwizzled : 1;

    // Rewrite gl_DrawID as a uniform int
    uint64_t emulateGLDrawID : 1;

    // This flag initializes shared variables to 0.  It is to avoid ompute shaders being able to
    // read undefined values that could be coming from another webpage/application.
    uint64_t initSharedVariables : 1;

    // Forces the value returned from an atomic operations to be always be resolved. This is
    // targeted to workaround a bug in NVIDIA D3D driver where the return value from
    // RWByteAddressBuffer.InterlockedAdd does not get resolved when used in the .yzw components of
    // a RWByteAddressBuffer.Store operation. Only has an effect on HLSL translation.
    // http://anglebug.com/42261924
    uint64_t forceAtomicValueResolution : 1;

    // Rewrite gl_BaseVertex and gl_BaseInstance as uniform int
    uint64_t emulateGLBaseVertexBaseInstance : 1;

    // Workaround for a driver bug with nested switches.
    uint64_t wrapSwitchInIfTrue : 1;

    // This flag controls how to translate WEBGL_video_texture sampling function.
    uint64_t takeVideoTextureAsExternalOES : 1;

    // This flag works around a inconsistent behavior in Mac AMD driver where gl_VertexID doesn't
    // include base vertex value. It replaces gl_VertexID with (gl_VertexID + angle_BaseVertex) when
    // angle_BaseVertex is available.
    uint64_t addBaseVertexToVertexID : 1;

    // This works around the dynamic lvalue indexing of swizzled vectors on various platforms.
    uint64_t removeDynamicIndexingOfSwizzledVector : 1;

    // This flag works around a slow fxc compile performance issue with dynamic uniform indexing.
    uint64_t allowTranslateUniformBlockToStructuredBuffer : 1;

    // This flag allows us to add a decoration for layout(yuv) in shaders.
    uint64_t addVulkanYUVLayoutQualifier : 1;

    // This flag allows disabling ARB_texture_rectangle on a per-compile basis. This is necessary
    // for WebGL contexts becuase ARB_texture_rectangle may be necessary for the WebGL
    // implementation internally but shouldn't be exposed to WebGL user code.
    uint64_t disableARBTextureRectangle : 1;

    // This flag works around a driver bug by rewriting uses of row-major matrices as column-major
    // in ESSL 3.00 and greater shaders.
    uint64_t rewriteRowMajorMatrices : 1;

    // Drop any explicit precision qualifiers from shader.
    uint64_t ignorePrecisionQualifiers : 1;

    // Ask compiler to generate code for depth correction to conform to the Vulkan clip space.  If
    // VK_EXT_depth_clip_control is supported, this code is not generated, saving a uniform look up.
    uint64_t addVulkanDepthCorrection : 1;

    uint64_t forceShaderPrecisionHighpToMediump : 1;

    // Allow compiler to use specialization constant to do pre-rotation and y flip.
    uint64_t useSpecializationConstant : 1;

    // Ask compiler to generate Vulkan transform feedback emulation support code.
    uint64_t addVulkanXfbEmulationSupportCode : 1;

    // Ask compiler to generate Vulkan transform feedback support code when using the
    // VK_EXT_transform_feedback extension.
    uint64_t addVulkanXfbExtensionSupportCode : 1;

    // This flag initializes fragment shader's output variables to zero at the beginning of the
    // fragment shader's main(). It is intended as a workaround for drivers which get context lost
    // if gl_FragColor is not written.
    uint64_t initFragmentOutputVariables : 1;

    // Always write explicit location layout qualifiers for fragment outputs.
    uint64_t explicitFragmentLocations : 1;

    // Insert explicit casts for float/double/unsigned/signed int on macOS 10.15 with Intel driver
    uint64_t addExplicitBoolCasts : 1;

    // Add round() after applying dither.  This works around a Qualcomm quirk where values can get
    // ceil()ed instead.
    uint64_t roundOutputAfterDithering : 1;

    // issuetracker.google.com/274859104 add OpQuantizeToF16 instruction to cast
    // mediump floating-point values to 16 bit. ARM compiler utilized RelaxedPrecision
    // to minimize type case and keep a mediump float as 32 bit when assigning it with
    // a highp floating-point value. It is possible that GLSL shader code is comparing
    // two meiump values, but ARM compiler is comparing a 32 bit value with a 16 bit value,
    // causing the comparison to fail.
    uint64_t castMediumpFloatTo16Bit : 1;

    // anglebug.com/42265995: packUnorm4x8 fails on Pixel 4 if it is not passed a highp vec4.
    // TODO(anglebug.com/42265995): This workaround is currently only applied for pixel local
    // storage. We may want to apply it generally.
    uint64_t passHighpToPackUnormSnormBuiltins : 1;

    // Use an integer uniform to pass a bitset of enabled clip distances.
    uint64_t emulateClipDistanceState : 1;

    // Use a uniform to emulate GL_CLIP_ORIGIN_EXT state.
    uint64_t emulateClipOrigin : 1;

    // issuetracker.google.com/266235549 add aliased memory decoration to ssbo if the variable is
    // not declared with "restrict" memory qualifier in GLSL
    uint64_t aliasedUnlessRestrict : 1;

    // Use fragment shaders to compute and set coverage mask based on the alpha value
    uint64_t emulateAlphaToCoverage : 1;

    // Rescope globals that are only used in one function to be function-local.
    uint64_t rescopeGlobalVariables : 1;

    // Pre-transform explicit cubemap derivatives for Apple GPUs.
    uint64_t preTransformTextureCubeGradDerivatives : 1;

    // Workaround for a driver bug with the use of the OpSelect SPIR-V instruction.
    uint64_t avoidOpSelectWithMismatchingRelaxedPrecision : 1;

    // Whether SPIR-V 1.4 can be emitted.  If not set, SPIR-V 1.3 is emitted.
    uint64_t emitSPIRV14 : 1;

    // Reject shaders with obvious undefined behavior:
    //
    // - Shader contains easy-to-detect infinite loops
    //
    uint64_t rejectWebglShadersWithUndefinedBehavior : 1;

    // Emulate r32f image with an r32ui image
    uint64_t emulateR32fImageAtomicExchange : 1;

    // Rewrite for and while loops to loop normal form.
    uint64_t simplifyLoopConditions : 1;

    // Specify struct in one statement, declare instance in other.
    uint64_t separateCompoundStructDeclarations : 1;

    ShCompileOptionsMetal metal;
    ShPixelLocalStorageOptions pls;
};

// The 64 bits hash function. The first parameter is the input string; the
// second parameter is the string length.
using ShHashFunction64 = khronos_uint64_t (*)(const char *, size_t);

//
// Implementation dependent built-in resources (constants and extensions).
// The names for these resources has been obtained by stripping gl_/GL_.
//
struct ShBuiltInResources
{
    ShBuiltInResources();
    ShBuiltInResources(const ShBuiltInResources &other);
    ShBuiltInResources &operator=(const ShBuiltInResources &other);

    // Constants.
    int MaxVertexAttribs;
    int MaxVertexUniformVectors;
    int MaxVaryingVectors;
    int MaxVertexTextureImageUnits;
    int MaxCombinedTextureImageUnits;
    int MaxTextureImageUnits;
    int MaxFragmentUniformVectors;
    int MaxDrawBuffers;

    // Extensions.
    // Set to 1 to enable the extension, else 0.
    int OES_standard_derivatives;
    int OES_EGL_image_external;
    int OES_EGL_image_external_essl3;
    int NV_EGL_stream_consumer_external;
    int ARB_texture_rectangle;
    int EXT_blend_func_extended;
    int EXT_conservative_depth;
    int EXT_draw_buffers;
    int EXT_frag_depth;
    int EXT_shader_texture_lod;
    int EXT_shader_framebuffer_fetch;
    int EXT_shader_framebuffer_fetch_non_coherent;
    int NV_shader_framebuffer_fetch;
    int NV_shader_noperspective_interpolation;
    int ARM_shader_framebuffer_fetch;
    int ARM_shader_framebuffer_fetch_depth_stencil;
    int OVR_multiview;
    int OVR_multiview2;
    int EXT_multisampled_render_to_texture;
    int EXT_multisampled_render_to_texture2;
    int EXT_YUV_target;
    int EXT_geometry_shader;
    int OES_geometry_shader;
    int OES_shader_io_blocks;
    int EXT_shader_io_blocks;
    int EXT_gpu_shader5;
    int OES_gpu_shader5;
    int EXT_shader_non_constant_global_initializers;
    int OES_texture_storage_multisample_2d_array;
    int OES_texture_3D;
    int ANGLE_shader_pixel_local_storage;
    int ANGLE_texture_multisample;
    int ANGLE_multi_draw;
    // TODO(angleproject:3402) remove after chromium side removal to pass compilation
    int ANGLE_base_vertex_base_instance;
    int WEBGL_video_texture;
    int APPLE_clip_distance;
    int OES_texture_cube_map_array;
    int EXT_texture_cube_map_array;
    int EXT_texture_query_lod;
    int EXT_texture_shadow_lod;
    int EXT_shadow_samplers;
    int OES_shader_multisample_interpolation;
    int OES_shader_image_atomic;
    int EXT_tessellation_shader;
    int OES_tessellation_shader;
    int OES_texture_buffer;
    int EXT_texture_buffer;
    int OES_sample_variables;
    int EXT_clip_cull_distance;
    int ANGLE_clip_cull_distance;
    int EXT_primitive_bounding_box;
    int OES_primitive_bounding_box;
    int EXT_separate_shader_objects;
    int ANGLE_base_vertex_base_instance_shader_builtin;
    int ANDROID_extension_pack_es31a;
    int KHR_blend_equation_advanced;

    // Set to 1 to enable replacing GL_EXT_draw_buffers #extension directives
    // with GL_NV_draw_buffers in ESSL output. This flag can be used to emulate
    // EXT_draw_buffers by using it in combination with GLES3.0 glDrawBuffers
    // function. This applies to Tegra K1 devices.
    int NV_draw_buffers;

    // Set to 1 if highp precision is supported in the ESSL 1.00 version of the
    // fragment language. Does not affect versions of the language where highp
    // support is mandatory.
    // Default is 0.
    int FragmentPrecisionHigh;

    // GLSL ES 3.0 constants.
    int MaxVertexOutputVectors;
    int MaxFragmentInputVectors;
    int MinProgramTexelOffset;
    int MaxProgramTexelOffset;

    // Extension constants.

    // Value of GL_MAX_DUAL_SOURCE_DRAW_BUFFERS_EXT for OpenGL ES output context.
    // Value of GL_MAX_DUAL_SOURCE_DRAW_BUFFERS for OpenGL output context.
    // GLES SL version 100 gl_MaxDualSourceDrawBuffersEXT value for EXT_blend_func_extended.
    int MaxDualSourceDrawBuffers;

    // Value of GL_MAX_VIEWS_OVR.
    int MaxViewsOVR;

    // Name Hashing.
    // Set a 64 bit hash function to enable user-defined name hashing.
    // Default is NULL.
    ShHashFunction64 HashFunction;

    // The maximum complexity an expression can be when limitExpressionComplexity is turned on.
    int MaxExpressionComplexity;

    // The maximum depth of certain nestable statements (while, switch);
    int MaxStatementDepth;

    // The maximum depth a call stack can be.
    int MaxCallStackDepth;

    // The maximum number of parameters a function can have when limitExpressionComplexity is turned
    // on.
    int MaxFunctionParameters;

    // GLES 3.1 constants

    // texture gather offset constraints.
    int MinProgramTextureGatherOffset;
    int MaxProgramTextureGatherOffset;

    // maximum number of available image units
    int MaxImageUnits;

    // OES_sample_variables constant
    // maximum number of available samples
    int MaxSamples;

    // maximum number of image uniforms in a vertex shader
    int MaxVertexImageUniforms;

    // maximum number of image uniforms in a fragment shader
    int MaxFragmentImageUniforms;

    // maximum number of image uniforms in a compute shader
    int MaxComputeImageUniforms;

    // maximum total number of image uniforms in a program
    int MaxCombinedImageUniforms;

    // maximum number of uniform locations
    int MaxUniformLocations;

    // maximum number of ssbos and images in a shader
    int MaxCombinedShaderOutputResources;

    // maximum number of groups in each dimension
    std::array<int, 3> MaxComputeWorkGroupCount;
    // maximum number of threads per work group in each dimension
    std::array<int, 3> MaxComputeWorkGroupSize;

    // maximum number of total uniform components
    int MaxComputeUniformComponents;

    // maximum number of texture image units in a compute shader
    int MaxComputeTextureImageUnits;

    // maximum number of atomic counters in a compute shader
    int MaxComputeAtomicCounters;

    // maximum number of atomic counter buffers in a compute shader
    int MaxComputeAtomicCounterBuffers;

    // maximum number of atomic counters in a vertex shader
    int MaxVertexAtomicCounters;

    // maximum number of atomic counters in a fragment shader
    int MaxFragmentAtomicCounters;

    // maximum number of atomic counters in a program
    int MaxCombinedAtomicCounters;

    // maximum binding for an atomic counter
    int MaxAtomicCounterBindings;

    // maximum number of atomic counter buffers in a vertex shader
    int MaxVertexAtomicCounterBuffers;

    // maximum number of atomic counter buffers in a fragment shader
    int MaxFragmentAtomicCounterBuffers;

    // maximum number of atomic counter buffers in a program
    int MaxCombinedAtomicCounterBuffers;

    // maximum number of buffer object storage in machine units
    int MaxAtomicCounterBufferSize;

    // maximum number of uniform block bindings
    int MaxUniformBufferBindings;

    // maximum number of shader storage buffer bindings
    int MaxShaderStorageBufferBindings;

    // minimum point size (lower limit from ALIASED_POINT_SIZE_RANGE)
    float MinPointSize;

    // maximum point size (higher limit from ALIASED_POINT_SIZE_RANGE)
    float MaxPointSize;

    // EXT_geometry_shader constants
    int MaxGeometryUniformComponents;
    int MaxGeometryUniformBlocks;
    int MaxGeometryInputComponents;
    int MaxGeometryOutputComponents;
    int MaxGeometryOutputVertices;
    int MaxGeometryTotalOutputComponents;
    int MaxGeometryTextureImageUnits;
    int MaxGeometryAtomicCounterBuffers;
    int MaxGeometryAtomicCounters;
    int MaxGeometryShaderStorageBlocks;
    int MaxGeometryShaderInvocations;
    int MaxGeometryImageUniforms;

    // EXT_tessellation_shader constants
    int MaxTessControlInputComponents;
    int MaxTessControlOutputComponents;
    int MaxTessControlTextureImageUnits;
    int MaxTessControlUniformComponents;
    int MaxTessControlTotalOutputComponents;
    int MaxTessControlImageUniforms;
    int MaxTessControlAtomicCounters;
    int MaxTessControlAtomicCounterBuffers;

    int MaxTessPatchComponents;
    int MaxPatchVertices;
    int MaxTessGenLevel;

    int MaxTessEvaluationInputComponents;
    int MaxTessEvaluationOutputComponents;
    int MaxTessEvaluationTextureImageUnits;
    int MaxTessEvaluationUniformComponents;
    int MaxTessEvaluationImageUniforms;
    int MaxTessEvaluationAtomicCounters;
    int MaxTessEvaluationAtomicCounterBuffers;

    // Subpixel bits used in rasterization.
    int SubPixelBits;

    // APPLE_clip_distance / EXT_clip_cull_distance / ANGLE_clip_cull_distance constants
    int MaxClipDistances;
    int MaxCullDistances;
    int MaxCombinedClipAndCullDistances;

    // ANGLE_shader_pixel_local_storage.
    int MaxPixelLocalStoragePlanes;
    int MaxCombinedDrawBuffersAndPixelLocalStoragePlanes;
};

//
// ShHandle held by but opaque to the driver.  It is allocated,
// managed, and de-allocated by the compiler. Its contents
// are defined by and used by the compiler.
//
// If handle creation fails, 0 will be returned.
//
using ShHandle = void *;

namespace sh
{
using BinaryBlob       = std::vector<uint32_t>;
using ShaderBinaryBlob = std::vector<uint8_t>;

//
// Driver must call this first, once, before doing any other compiler operations.
// If the function succeeds, the return value is true, else false.
//
bool Initialize();
//
// Driver should call this at shutdown.
// If the function succeeds, the return value is true, else false.
//
bool Finalize();

//
// Initialize built-in resources with minimum expected values.
// Parameters:
// resources: The object to initialize. Will be comparable with memcmp.
//
void InitBuiltInResources(ShBuiltInResources *resources);

//
// Returns a copy of the current ShBuiltInResources stored in the compiler.
// Parameters:
// handle: Specifies the handle of the compiler to be used.
ShBuiltInResources GetBuiltInResources(const ShHandle handle);

//
// Returns the a concatenated list of the items in ShBuiltInResources as a null-terminated string.
// This function must be updated whenever ShBuiltInResources is changed.
// Parameters:
// handle: Specifies the handle of the compiler to be used.
const std::string &GetBuiltInResourcesString(const ShHandle handle);

//
// Driver calls these to create and destroy compiler objects.
//
// Returns the handle of constructed compiler, null if the requested compiler is not supported.
// Parameters:
// type: Specifies the type of shader - GL_FRAGMENT_SHADER or GL_VERTEX_SHADER.
// spec: Specifies the language spec the compiler must conform to - SH_GLES2_SPEC or SH_WEBGL_SPEC.
// output: Specifies the output code type - for example SH_ESSL_OUTPUT, SH_GLSL_OUTPUT,
//         SH_HLSL_3_0_OUTPUT or SH_HLSL_4_1_OUTPUT. Note: Each output type may only
//         be supported in some configurations.
// resources: Specifies the built-in resources.
ShHandle ConstructCompiler(sh::GLenum type,
                           ShShaderSpec spec,
                           ShShaderOutput output,
                           const ShBuiltInResources *resources);
void Destruct(ShHandle handle);

//
// Compiles the given shader source.
// If the function succeeds, the return value is true, else false.
// Parameters:
// handle: Specifies the handle of compiler to be used.
// shaderStrings: Specifies an array of pointers to null-terminated strings containing the shader
// source code.
// numStrings: Specifies the number of elements in shaderStrings array.
// compileOptions: A mask of compile options defined above.
bool Compile(const ShHandle handle,
             const char *const shaderStrings[],
             size_t numStrings,
             const ShCompileOptions &compileOptions);

// Clears the results from the previous compilation.
void ClearResults(const ShHandle handle);

// Return the version of the shader language.
int GetShaderVersion(const ShHandle handle);

// Return the currently set language output type.
ShShaderOutput GetShaderOutputType(const ShHandle handle);

// Returns null-terminated information log for a compiled shader.
// Parameters:
// handle: Specifies the compiler
const std::string &GetInfoLog(const ShHandle handle);

// Returns null-terminated object code for a compiled shader.  Only valid for output types that
// generate human-readable code (GLSL, ESSL or HLSL).
// Parameters:
// handle: Specifies the compiler
const std::string &GetObjectCode(const ShHandle handle);

// Returns object binary blob for a compiled shader.  Only valid for output types that
// generate binary blob (SPIR-V).
// Parameters:
// handle: Specifies the compiler
const BinaryBlob &GetObjectBinaryBlob(const ShHandle handle);

// Returns a full binary for a compiled shader, to be loaded with glShaderBinary during runtime.
// Parameters:
// handle: Specifies the compiler
bool GetShaderBinary(const ShHandle handle,
                     const char *const shaderStrings[],
                     size_t numStrings,
                     const ShCompileOptions &compileOptions,
                     ShaderBinaryBlob *const binaryOut);

// Returns a (original_name, hash) map containing all the user defined names in the shader,
// including variable names, function names, struct names, and struct field names.
// Parameters:
// handle: Specifies the compiler
const std::map<std::string, std::string> *GetNameHashingMap(const ShHandle handle);

// Shader variable inspection.
// Returns a pointer to a list of variables of the designated type.
// (See ShaderVars.h for type definitions, included above)
// Returns NULL on failure.
// Parameters:
// handle: Specifies the compiler
const std::vector<sh::ShaderVariable> *GetUniforms(const ShHandle handle);
const std::vector<sh::ShaderVariable> *GetVaryings(const ShHandle handle);
const std::vector<sh::ShaderVariable> *GetInputVaryings(const ShHandle handle);
const std::vector<sh::ShaderVariable> *GetOutputVaryings(const ShHandle handle);
const std::vector<sh::ShaderVariable> *GetAttributes(const ShHandle handle);
const std::vector<sh::ShaderVariable> *GetOutputVariables(const ShHandle handle);
const std::vector<sh::InterfaceBlock> *GetInterfaceBlocks(const ShHandle handle);
const std::vector<sh::InterfaceBlock> *GetUniformBlocks(const ShHandle handle);
const std::vector<sh::InterfaceBlock> *GetShaderStorageBlocks(const ShHandle handle);
sh::WorkGroupSize GetComputeShaderLocalGroupSize(const ShHandle handle);
// Returns the number of views specified through the num_views layout qualifier. If num_views is
// not set, the function returns -1.
int GetVertexShaderNumViews(const ShHandle handle);
// Returns the pixel local storage uniform format at each binding index, or "NotPLS" if there is
// not one.
const std::vector<ShPixelLocalStorageFormat> *GetPixelLocalStorageFormats(const ShHandle handle);

// Returns specialization constant usage bits
uint32_t GetShaderSpecConstUsageBits(const ShHandle handle);

// Returns true if the passed in variables pack in maxVectors followingthe packing rules from the
// GLSL 1.017 spec, Appendix A, section 7.
// Returns false otherwise. Also look at the enforcePackingRestrictions flag above.
// Parameters:
// maxVectors: the available rows of registers.
// variables: an array of variables.
bool CheckVariablesWithinPackingLimits(int maxVectors,
                                       const std::vector<sh::ShaderVariable> &variables);

// Gives the compiler-assigned register for a shader storage block.
// The method writes the value to the output variable "indexOut".
// Returns true if it found a valid shader storage block, false otherwise.
// Parameters:
// handle: Specifies the compiler
// shaderStorageBlockName: Specifies the shader storage block
// indexOut: output variable that stores the assigned register
bool GetShaderStorageBlockRegister(const ShHandle handle,
                                   const std::string &shaderStorageBlockName,
                                   unsigned int *indexOut);

// Gives the compiler-assigned register for a uniform block.
// The method writes the value to the output variable "indexOut".
// Returns true if it found a valid uniform block, false otherwise.
// Parameters:
// handle: Specifies the compiler
// uniformBlockName: Specifies the uniform block
// indexOut: output variable that stores the assigned register
bool GetUniformBlockRegister(const ShHandle handle,
                             const std::string &uniformBlockName,
                             unsigned int *indexOut);

bool ShouldUniformBlockUseStructuredBuffer(const ShHandle handle,
                                           const std::string &uniformBlockName);
const std::set<std::string> *GetSlowCompilingUniformBlockSet(const ShHandle handle);

// Gives a map from uniform names to compiler-assigned registers in the default uniform block.
// Note that the map contains also registers of samplers that have been extracted from structs.
const std::map<std::string, unsigned int> *GetUniformRegisterMap(const ShHandle handle);

// Sampler, image and atomic counters share registers(t type and u type),
// GetReadonlyImage2DRegisterIndex and GetImage2DRegisterIndex return the first index into
// a range of reserved registers for image2D/iimage2D/uimage2D variables.
// Parameters: handle: Specifies the compiler
unsigned int GetReadonlyImage2DRegisterIndex(const ShHandle handle);
unsigned int GetImage2DRegisterIndex(const ShHandle handle);

// The method records these used function names related with image2D/iimage2D/uimage2D, these
// functions will be dynamically generated.
// Parameters:
// handle: Specifies the compiler
const std::set<std::string> *GetUsedImage2DFunctionNames(const ShHandle handle);

uint8_t GetClipDistanceArraySize(const ShHandle handle);
uint8_t GetCullDistanceArraySize(const ShHandle handle);
GLenum GetGeometryShaderInputPrimitiveType(const ShHandle handle);
GLenum GetGeometryShaderOutputPrimitiveType(const ShHandle handle);
int GetGeometryShaderInvocations(const ShHandle handle);
int GetGeometryShaderMaxVertices(const ShHandle handle);
unsigned int GetShaderSharedMemorySize(const ShHandle handle);
int GetTessControlShaderVertices(const ShHandle handle);
GLenum GetTessGenMode(const ShHandle handle);
GLenum GetTessGenSpacing(const ShHandle handle);
GLenum GetTessGenVertexOrder(const ShHandle handle);
GLenum GetTessGenPointMode(const ShHandle handle);

// Returns a bitset of sh::MetadataFlags.  This bundles various bits purely for convenience.
uint32_t GetMetadataFlags(const ShHandle handle);

// Returns the blend equation list supported in the fragment shader.  This is a bitset of
// gl::BlendEquationType, and can only include bits from KHR_blend_equation_advanced.
uint32_t GetAdvancedBlendEquations(const ShHandle handle);

//
// Helper function to identify specs that are based on the WebGL spec.
//
inline bool IsWebGLBasedSpec(ShShaderSpec spec)
{
    return (spec == SH_WEBGL_SPEC || spec == SH_WEBGL2_SPEC || spec == SH_WEBGL3_SPEC);
}

// Can't prefix with just _ because then we might introduce a double underscore, which is not safe
// in GLSL (ESSL 3.00.6 section 3.8: All identifiers containing a double underscore are reserved for
// use by the underlying implementation). u is short for user-defined.
extern const char kUserDefinedNamePrefix[];

enum class MetadataFlags
{
    // Applicable to vertex shaders (technically all pre-rasterization shaders could use this flag,
    // but the current and only user is GL, which does not support geometry/tessellation).
    HasClipDistance,
    // Applicable to fragment shaders
    HasDiscard,
    EnablesPerSampleShading,
    HasInputAttachment0,
    // Flag for attachment i is HasInputAttachment0 + i
    HasInputAttachment7 = HasInputAttachment0 + 7,
    HasDepthInputAttachment,
    HasStencilInputAttachment,
    // Applicable to geometry shaders
    HasValidGeometryShaderInputPrimitiveType,
    HasValidGeometryShaderOutputPrimitiveType,
    HasValidGeometryShaderMaxVertices,
    // Applicable to tessellation shaders
    HasValidTessGenMode,
    HasValidTessGenSpacing,
    HasValidTessGenVertexOrder,
    HasValidTessGenPointMode,

    InvalidEnum,
    EnumCount = InvalidEnum,
};

namespace vk
{

// Specialization constant ids
enum class SpecializationConstantId : uint32_t
{
    SurfaceRotation = 0,
    Dither          = 1,

    InvalidEnum = 2,
    EnumCount   = InvalidEnum,
};

enum class SpecConstUsage : uint32_t
{
    Rotation = 0,
    Dither   = 1,

    InvalidEnum = 2,
    EnumCount   = InvalidEnum,
};

enum ColorAttachmentDitherControl
{
    // See comments in ContextVk::updateDither and EmulateDithering.cpp
    kDitherControlNoDither   = 0,
    kDitherControlDither4444 = 1,
    kDitherControlDither5551 = 2,
    kDitherControlDither565  = 3,
};

namespace spirv
{
enum NonSemanticInstruction
{
    // The overview instruction containing information such as what predefined ids are present in
    // the SPIR-V.  Simultaneously, this instruction identifies the location where the
    // types/constants/variables section ends and the functions section starts.
    kNonSemanticOverview,
    // The instruction identifying the entry to the shader, i.e. at the start of main()
    kNonSemanticEnter,
    // The instruction identifying where vertex or fragment data is output.
    // This is before return from main() in vertex, tessellation, and fragment shaders,
    // and before OpEmitVertex in geometry shaders.
    kNonSemanticOutput,
    // The instruction identifying the location where transform feedback emulation should be
    // written.
    kNonSemanticTransformFeedbackEmulation,
};

// The non-semantic instruction id has many bits available.  With kNonSemanticOverview, they are
// used to provide additional overview details.  Providing this information in the instruction's
// payload require OpConstants and recovering those, which is unnecessary complexity.
constexpr uint32_t kNonSemanticInstructionBits       = 4;
constexpr uint32_t kNonSemanticInstructionMask       = 0xF;
constexpr uint32_t kOverviewHasSampleRateShadingMask = 0x10;
constexpr uint32_t kOverviewHasSampleIDMask          = 0x20;
constexpr uint32_t kOverviewHasOutputPerVertexMask   = 0x40;

enum ReservedIds
{
    kIdInvalid = 0,

    // =============================================================================================
    // Ids that are fixed and are always present in the SPIR-V where applicable.  The SPIR-V
    // transformer can thus reliably use these ids.

    // Global information
    kIdNonSemanticInstructionSet,
    kIdEntryPoint,

    // Basic types
    kIdVoid,
    kIdFloat,
    kIdVec2,
    kIdVec3,
    kIdVec4,
    kIdMat2,
    kIdMat3,
    kIdMat4,
    kIdInt,
    kIdIVec4,
    kIdUint,

    // Common constants
    kIdIntZero,
    kIdIntOne,
    kIdIntTwo,
    kIdIntThree,

    // Type pointers
    kIdIntInputTypePointer,
    kIdVec4OutputTypePointer,
    kIdIVec4FunctionTypePointer,
    kIdOutputPerVertexTypePointer,

    // Pre-rotation and Z-correction support
    kIdTransformPositionFunction,
    kIdInputPerVertexBlockArray,
    kIdOutputPerVertexBlockArray,
    kIdOutputPerVertexVar,

    // Transform feedback support
    kIdXfbEmulationGetOffsetsFunction,
    kIdXfbEmulationCaptureFunction,
    kIdXfbEmulationBufferVarZero,
    kIdXfbEmulationBufferVarOne,
    kIdXfbEmulationBufferVarTwo,
    kIdXfbEmulationBufferVarThree,

    // Multisampling support
    kIdSampleID,

    // =============================================================================================
    // ANGLE internal shader variables, which are not produced as ShaderVariables.
    // kIdShaderVariablesBegin marks the beginning of these ids.  variableId -> info maps in the
    // backend can use |variableId - kIdShaderVariablesBegin| as key into a flat array.
    //
    // Note that for blocks, only the block id is in this section as that is the id used in the
    // variableId -> info maps.
    kIdShaderVariablesBegin,

    // gl_PerVertex
    kIdInputPerVertexBlock = kIdShaderVariablesBegin,
    kIdOutputPerVertexBlock,
    // The driver and default uniform blocks
    kIdDriverUniformsBlock,
    kIdDefaultUniformsBlock,
    // The atomic counter block
    kIdAtomicCounterBlock,
    // Buffer block used for transform feedback emulation
    kIdXfbEmulationBufferBlockZero,
    kIdXfbEmulationBufferBlockOne,
    kIdXfbEmulationBufferBlockTwo,
    kIdXfbEmulationBufferBlockThree,
    // Additional varying added to hold untransformed gl_Position for transform feedback capture
    kIdXfbExtensionPosition,
    // Input attachments used for framebuffer fetch and advanced blend emulation
    kIdInputAttachment0,
    kIdInputAttachment7 = kIdInputAttachment0 + 7,
    kIdDepthInputAttachment,
    kIdStencilInputAttachment,

    kIdFirstUnreserved,
};
}  // namespace spirv

// Packing information for driver uniform's misc field:
// - 1 bit for whether surface rotation results in swapped axes
// - 5 bits for advanced blend equation
// - 6 bits for sample count
// - 8 bits for enabled clip planes
// - 1 bit for whether depth should be transformed to Vulkan clip space
// - 1 bit for whether alpha to coverage is enabled
// - 1 bit for whether the framebuffer is layered
// - 9 bits unused
constexpr uint32_t kDriverUniformsMiscSwapXYMask                  = 0x1;
constexpr uint32_t kDriverUniformsMiscAdvancedBlendEquationOffset = 1;
constexpr uint32_t kDriverUniformsMiscAdvancedBlendEquationMask   = 0x1F;
constexpr uint32_t kDriverUniformsMiscSampleCountOffset           = 6;
constexpr uint32_t kDriverUniformsMiscSampleCountMask             = 0x3F;
constexpr uint32_t kDriverUniformsMiscEnabledClipPlanesOffset     = 12;
constexpr uint32_t kDriverUniformsMiscEnabledClipPlanesMask       = 0xFF;
constexpr uint32_t kDriverUniformsMiscTransformDepthOffset        = 20;
constexpr uint32_t kDriverUniformsMiscTransformDepthMask          = 0x1;
constexpr uint32_t kDriverUniformsMiscAlphaToCoverageOffset       = 21;
constexpr uint32_t kDriverUniformsMiscAlphaToCoverageMask         = 0x1;
constexpr uint32_t kDriverUniformsMiscLayeredFramebufferOffset    = 22;
constexpr uint32_t kDriverUniformsMiscLayeredFramebufferMask      = 0x1;
}  // namespace vk

namespace mtl
{
// Specialization constant to enable multisampled rendering behavior.
extern const char kMultisampledRenderingConstName[];

// Specialization constant to emulate rasterizer discard.
extern const char kRasterizerDiscardEnabledConstName[];

// Specialization constant to enable depth write in fragment shaders.
extern const char kDepthWriteEnabledConstName[];

// Specialization constant to enable alpha to coverage.
extern const char kEmulateAlphaToCoverageConstName[];

// Specialization constant to write helper sample mask output.
extern const char kWriteHelperSampleMaskConstName[];

// Specialization constant to enable sample mask output.
extern const char kSampleMaskWriteEnabledConstName[];
}  // namespace mtl

}  // namespace sh

#endif  // GLSLANG_SHADERLANG_H_