spirv_glsl.cpp

/*
 * Copyright 2015-2021 Arm Limited
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * At your option, you may choose to accept this material under either:
 *  1. The Apache License, Version 2.0, found at <http://www.apache.org/licenses/LICENSE-2.0>, or
 *  2. The MIT License, found at <http://opensource.org/licenses/MIT>.
 */

#include "spirv_glsl.hpp"
#include "GLSL.std.450.h"
#include "spirv_common.hpp"
#include <algorithm>
#include <assert.h>
#include <cmath>
#include <limits>
#include <locale.h>
#include <utility>

#ifndef _WIN32
#include <langinfo.h>
#endif
#include <locale.h>

using namespace spv;
using namespace SPIRV_CROSS_NAMESPACE;
using namespace std;

enum ExtraSubExpressionType
{
	// Create masks above any legal ID range to allow multiple address spaces into the extra_sub_expressions map.
	EXTRA_SUB_EXPRESSION_TYPE_STREAM_OFFSET = 0x10000000,
	EXTRA_SUB_EXPRESSION_TYPE_AUX = 0x20000000
};

static bool is_unsigned_opcode(Op op)
{
	// Don't have to be exhaustive, only relevant for legacy target checking ...
	switch (op)
	{
	case OpShiftRightLogical:
	case OpUGreaterThan:
	case OpUGreaterThanEqual:
	case OpULessThan:
	case OpULessThanEqual:
	case OpUConvert:
	case OpUDiv:
	case OpUMod:
	case OpUMulExtended:
	case OpConvertUToF:
	case OpConvertFToU:
		return true;

	default:
		return false;
	}
}

static bool is_unsigned_glsl_opcode(GLSLstd450 op)
{
	// Don't have to be exhaustive, only relevant for legacy target checking ...
	switch (op)
	{
	case GLSLstd450UClamp:
	case GLSLstd450UMin:
	case GLSLstd450UMax:
	case GLSLstd450FindUMsb:
		return true;

	default:
		return false;
	}
}

static bool packing_is_vec4_padded(BufferPackingStandard packing)
{
	switch (packing)
	{
	case BufferPackingHLSLCbuffer:
	case BufferPackingHLSLCbufferPackOffset:
	case BufferPackingStd140:
	case BufferPackingStd140EnhancedLayout:
		return true;

	default:
		return false;
	}
}

static bool packing_is_hlsl(BufferPackingStandard packing)
{
	switch (packing)
	{
	case BufferPackingHLSLCbuffer:
	case BufferPackingHLSLCbufferPackOffset:
		return true;

	default:
		return false;
	}
}

static bool packing_has_flexible_offset(BufferPackingStandard packing)
{
	switch (packing)
	{
	case BufferPackingStd140:
	case BufferPackingStd430:
	case BufferPackingScalar:
	case BufferPackingHLSLCbuffer:
		return false;

	default:
		return true;
	}
}

static bool packing_is_scalar(BufferPackingStandard packing)
{
	switch (packing)
	{
	case BufferPackingScalar:
	case BufferPackingScalarEnhancedLayout:
		return true;

	default:
		return false;
	}
}

static BufferPackingStandard packing_to_substruct_packing(BufferPackingStandard packing)
{
	switch (packing)
	{
	case BufferPackingStd140EnhancedLayout:
		return BufferPackingStd140;
	case BufferPackingStd430EnhancedLayout:
		return BufferPackingStd430;
	case BufferPackingHLSLCbufferPackOffset:
		return BufferPackingHLSLCbuffer;
	case BufferPackingScalarEnhancedLayout:
		return BufferPackingScalar;
	default:
		return packing;
	}
}

void CompilerGLSL::init()
{
	if (ir.source.known)
	{
		options.es = ir.source.es;
		options.version = ir.source.version;
	}

	// Query the locale to see what the decimal point is.
	// We'll rely on fixing it up ourselves in the rare case we have a comma-as-decimal locale
	// rather than setting locales ourselves. Settings locales in a safe and isolated way is rather
	// tricky.
#ifdef _WIN32
	// On Windows, localeconv uses thread-local storage, so it should be fine.
	const struct lconv *conv = localeconv();
	if (conv && conv->decimal_point)
		current_locale_radix_character = *conv->decimal_point;
#elif defined(__ANDROID__) && __ANDROID_API__ < 26
	// nl_langinfo is not supported on this platform, fall back to the worse alternative.
	const struct lconv *conv = localeconv();
	if (conv && conv->decimal_point)
		current_locale_radix_character = *conv->decimal_point;
#else
	// localeconv, the portable function is not MT safe ...
	const char *decimal_point = nl_langinfo(RADIXCHAR);
	if (decimal_point && *decimal_point != '\0')
		current_locale_radix_character = *decimal_point;
#endif
}

static const char *to_pls_layout(PlsFormat format)
{
	switch (format)
	{
	case PlsR11FG11FB10F:
		return "layout(r11f_g11f_b10f) ";
	case PlsR32F:
		return "layout(r32f) ";
	case PlsRG16F:
		return "layout(rg16f) ";
	case PlsRGB10A2:
		return "layout(rgb10_a2) ";
	case PlsRGBA8:
		return "layout(rgba8) ";
	case PlsRG16:
		return "layout(rg16) ";
	case PlsRGBA8I:
		return "layout(rgba8i)";
	case PlsRG16I:
		return "layout(rg16i) ";
	case PlsRGB10A2UI:
		return "layout(rgb10_a2ui) ";
	case PlsRGBA8UI:
		return "layout(rgba8ui) ";
	case PlsRG16UI:
		return "layout(rg16ui) ";
	case PlsR32UI:
		return "layout(r32ui) ";
	default:
		return "";
	}
}

static SPIRType::BaseType pls_format_to_basetype(PlsFormat format)
{
	switch (format)
	{
	default:
	case PlsR11FG11FB10F:
	case PlsR32F:
	case PlsRG16F:
	case PlsRGB10A2:
	case PlsRGBA8:
	case PlsRG16:
		return SPIRType::Float;

	case PlsRGBA8I:
	case PlsRG16I:
		return SPIRType::Int;

	case PlsRGB10A2UI:
	case PlsRGBA8UI:
	case PlsRG16UI:
	case PlsR32UI:
		return SPIRType::UInt;
	}
}

static uint32_t pls_format_to_components(PlsFormat format)
{
	switch (format)
	{
	default:
	case PlsR32F:
	case PlsR32UI:
		return 1;

	case PlsRG16F:
	case PlsRG16:
	case PlsRG16UI:
	case PlsRG16I:
		return 2;

	case PlsR11FG11FB10F:
		return 3;

	case PlsRGB10A2:
	case PlsRGBA8:
	case PlsRGBA8I:
	case PlsRGB10A2UI:
	case PlsRGBA8UI:
		return 4;
	}
}

const char *CompilerGLSL::vector_swizzle(int vecsize, int index)
{
	static const char *const swizzle[4][4] = {
		{ ".x", ".y", ".z", ".w" },
		{ ".xy", ".yz", ".zw", nullptr },
		{ ".xyz", ".yzw", nullptr, nullptr },
#if defined(__GNUC__) && (__GNUC__ == 9)
		// This works around a GCC 9 bug, see details in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90947.
		// This array ends up being compiled as all nullptrs, tripping the assertions below.
		{ "", nullptr, nullptr, "$" },
#else
		{ "", nullptr, nullptr, nullptr },
#endif
	};

	assert(vecsize >= 1 && vecsize <= 4);
	assert(index >= 0 && index < 4);
	assert(swizzle[vecsize - 1][index]);

	return swizzle[vecsize - 1][index];
}

void CompilerGLSL::reset(uint32_t iteration_count)
{
	// Sanity check the iteration count to be robust against a certain class of bugs where
	// we keep forcing recompilations without making clear forward progress.
	// In buggy situations we will loop forever, or loop for an unbounded number of iterations.
	// Certain types of recompilations are considered to make forward progress,
	// but in almost all situations, we'll never see more than 3 iterations.
	// It is highly context-sensitive when we need to force recompilation,
	// and it is not practical with the current architecture
	// to resolve everything up front.
	if (iteration_count >= options.force_recompile_max_debug_iterations && !is_force_recompile_forward_progress)
		SPIRV_CROSS_THROW("Maximum compilation loops detected and no forward progress was made. Must be a SPIRV-Cross bug!");

	// We do some speculative optimizations which should pretty much always work out,
	// but just in case the SPIR-V is rather weird, recompile until it's happy.
	// This typically only means one extra pass.
	clear_force_recompile();

	// Clear invalid expression tracking.
	invalid_expressions.clear();
	composite_insert_overwritten.clear();
	current_function = nullptr;

	// Clear temporary usage tracking.
	expression_usage_counts.clear();
	forwarded_temporaries.clear();
	suppressed_usage_tracking.clear();

	// Ensure that we declare phi-variable copies even if the original declaration isn't deferred
	flushed_phi_variables.clear();

	current_emitting_switch_stack.clear();

	reset_name_caches();

	ir.for_each_typed_id<SPIRFunction>([&](uint32_t, SPIRFunction &func) {
		func.active = false;
		func.flush_undeclared = true;
	});

	ir.for_each_typed_id<SPIRVariable>([&](uint32_t, SPIRVariable &var) { var.dependees.clear(); });

	ir.reset_all_of_type<SPIRExpression>();
	ir.reset_all_of_type<SPIRAccessChain>();

	statement_count = 0;
	indent = 0;
	current_loop_level = 0;
}

void CompilerGLSL::remap_pls_variables()
{
	for (auto &input : pls_inputs)
	{
		auto &var = get<SPIRVariable>(input.id);

		bool input_is_target = false;
		if (var.storage == StorageClassUniformConstant)
		{
			auto &type = get<SPIRType>(var.basetype);
			input_is_target = type.image.dim == DimSubpassData;
		}

		if (var.storage != StorageClassInput && !input_is_target)
			SPIRV_CROSS_THROW("Can only use in and target variables for PLS inputs.");
		var.remapped_variable = true;
	}

	for (auto &output : pls_outputs)
	{
		auto &var = get<SPIRVariable>(output.id);
		if (var.storage != StorageClassOutput)
			SPIRV_CROSS_THROW("Can only use out variables for PLS outputs.");
		var.remapped_variable = true;
	}
}

void CompilerGLSL::remap_ext_framebuffer_fetch(uint32_t input_attachment_index, uint32_t color_location, bool coherent)
{
	subpass_to_framebuffer_fetch_attachment.push_back({ input_attachment_index, color_location });
	inout_color_attachments.push_back({ color_location, coherent });
}

bool CompilerGLSL::location_is_framebuffer_fetch(uint32_t location) const
{
	return std::find_if(begin(inout_color_attachments), end(inout_color_attachments),
	                    [&](const std::pair<uint32_t, bool> &elem) {
		                    return elem.first == location;
	                    }) != end(inout_color_attachments);
}

bool CompilerGLSL::location_is_non_coherent_framebuffer_fetch(uint32_t location) const
{
	return std::find_if(begin(inout_color_attachments), end(inout_color_attachments),
	                    [&](const std::pair<uint32_t, bool> &elem) {
		                    return elem.first == location && !elem.second;
	                    }) != end(inout_color_attachments);
}

void CompilerGLSL::find_static_extensions()
{
	ir.for_each_typed_id<SPIRType>([&](uint32_t, const SPIRType &type) {
		if (type.basetype == SPIRType::Double)
		{
			if (options.es)
				SPIRV_CROSS_THROW("FP64 not supported in ES profile.");
			if (!options.es && options.version < 400)
				require_extension_internal("GL_ARB_gpu_shader_fp64");
		}
		else if (type.basetype == SPIRType::Int64 || type.basetype == SPIRType::UInt64)
		{
			if (options.es && options.version < 310) // GL_NV_gpu_shader5 fallback requires 310.
				SPIRV_CROSS_THROW("64-bit integers not supported in ES profile before version 310.");
			require_extension_internal("GL_ARB_gpu_shader_int64");
		}
		else if (type.basetype == SPIRType::Half)
		{
			require_extension_internal("GL_EXT_shader_explicit_arithmetic_types_float16");
			if (options.vulkan_semantics)
				require_extension_internal("GL_EXT_shader_16bit_storage");
		}
		else if (type.basetype == SPIRType::SByte || type.basetype == SPIRType::UByte)
		{
			require_extension_internal("GL_EXT_shader_explicit_arithmetic_types_int8");
			if (options.vulkan_semantics)
				require_extension_internal("GL_EXT_shader_8bit_storage");
		}
		else if (type.basetype == SPIRType::Short || type.basetype == SPIRType::UShort)
		{
			require_extension_internal("GL_EXT_shader_explicit_arithmetic_types_int16");
			if (options.vulkan_semantics)
				require_extension_internal("GL_EXT_shader_16bit_storage");
		}
	});

	auto &execution = get_entry_point();
	switch (execution.model)
	{
	case ExecutionModelGLCompute:
		if (!options.es && options.version < 430)
			require_extension_internal("GL_ARB_compute_shader");
		if (options.es && options.version < 310)
			SPIRV_CROSS_THROW("At least ESSL 3.10 required for compute shaders.");
		break;

	case ExecutionModelGeometry:
		if (options.es && options.version < 320)
			require_extension_internal("GL_EXT_geometry_shader");
		if (!options.es && options.version < 150)
			require_extension_internal("GL_ARB_geometry_shader4");

		if (execution.flags.get(ExecutionModeInvocations) && execution.invocations != 1)
		{
			// Instanced GS is part of 400 core or this extension.
			if (!options.es && options.version < 400)
				require_extension_internal("GL_ARB_gpu_shader5");
		}
		break;

	case ExecutionModelTessellationEvaluation:
	case ExecutionModelTessellationControl:
		if (options.es && options.version < 320)
			require_extension_internal("GL_EXT_tessellation_shader");
		if (!options.es && options.version < 400)
			require_extension_internal("GL_ARB_tessellation_shader");
		break;

	case ExecutionModelRayGenerationKHR:
	case ExecutionModelIntersectionKHR:
	case ExecutionModelAnyHitKHR:
	case ExecutionModelClosestHitKHR:
	case ExecutionModelMissKHR:
	case ExecutionModelCallableKHR:
		// NV enums are aliases.
		if (options.es || options.version < 460)
			SPIRV_CROSS_THROW("Ray tracing shaders require non-es profile with version 460 or above.");
		if (!options.vulkan_semantics)
			SPIRV_CROSS_THROW("Ray tracing requires Vulkan semantics.");

		// Need to figure out if we should target KHR or NV extension based on capabilities.
		for (auto &cap : ir.declared_capabilities)
		{
			if (cap == CapabilityRayTracingKHR || cap == CapabilityRayQueryKHR ||
			    cap == CapabilityRayTraversalPrimitiveCullingKHR)
			{
				ray_tracing_is_khr = true;
				break;
			}
		}

		if (ray_tracing_is_khr)
		{
			// In KHR ray tracing we pass payloads by pointer instead of location,
			// so make sure we assign locations properly.
			ray_tracing_khr_fixup_locations();
			require_extension_internal("GL_EXT_ray_tracing");
		}
		else
			require_extension_internal("GL_NV_ray_tracing");
		break;

	case ExecutionModelMeshEXT:
	case ExecutionModelTaskEXT:
		if (options.es || options.version < 450)
			SPIRV_CROSS_THROW("Mesh shaders require GLSL 450 or above.");
		if (!options.vulkan_semantics)
			SPIRV_CROSS_THROW("Mesh shaders require Vulkan semantics.");
		require_extension_internal("GL_EXT_mesh_shader");
		break;

	default:
		break;
	}

	if (!pls_inputs.empty() || !pls_outputs.empty())
	{
		if (execution.model != ExecutionModelFragment)
			SPIRV_CROSS_THROW("Can only use GL_EXT_shader_pixel_local_storage in fragment shaders.");
		require_extension_internal("GL_EXT_shader_pixel_local_storage");
	}

	if (!inout_color_attachments.empty())
	{
		if (execution.model != ExecutionModelFragment)
			SPIRV_CROSS_THROW("Can only use GL_EXT_shader_framebuffer_fetch in fragment shaders.");
		if (options.vulkan_semantics)
			SPIRV_CROSS_THROW("Cannot use EXT_shader_framebuffer_fetch in Vulkan GLSL.");

		bool has_coherent = false;
		bool has_incoherent = false;

		for (auto &att : inout_color_attachments)
		{
			if (att.second)
				has_coherent = true;
			else
				has_incoherent = true;
		}

		if (has_coherent)
			require_extension_internal("GL_EXT_shader_framebuffer_fetch");
		if (has_incoherent)
			require_extension_internal("GL_EXT_shader_framebuffer_fetch_non_coherent");
	}

	if (options.separate_shader_objects && !options.es && options.version < 410)
		require_extension_internal("GL_ARB_separate_shader_objects");

	if (ir.addressing_model == AddressingModelPhysicalStorageBuffer64EXT)
	{
		if (!options.vulkan_semantics)
			SPIRV_CROSS_THROW("GL_EXT_buffer_reference is only supported in Vulkan GLSL.");
		if (options.es && options.version < 320)
			SPIRV_CROSS_THROW("GL_EXT_buffer_reference requires ESSL 320.");
		else if (!options.es && options.version < 450)
			SPIRV_CROSS_THROW("GL_EXT_buffer_reference requires GLSL 450.");
		require_extension_internal("GL_EXT_buffer_reference");
	}
	else if (ir.addressing_model != AddressingModelLogical)
	{
		SPIRV_CROSS_THROW("Only Logical and PhysicalStorageBuffer64EXT addressing models are supported.");
	}

	// Check for nonuniform qualifier and passthrough.
	// Instead of looping over all decorations to find this, just look at capabilities.
	for (auto &cap : ir.declared_capabilities)
	{
		switch (cap)
		{
		case CapabilityShaderNonUniformEXT:
			if (!options.vulkan_semantics)
				require_extension_internal("GL_NV_gpu_shader5");
			else
				require_extension_internal("GL_EXT_nonuniform_qualifier");
			break;
		case CapabilityRuntimeDescriptorArrayEXT:
			if (!options.vulkan_semantics)
				SPIRV_CROSS_THROW("GL_EXT_nonuniform_qualifier is only supported in Vulkan GLSL.");
			require_extension_internal("GL_EXT_nonuniform_qualifier");
			break;

		case CapabilityGeometryShaderPassthroughNV:
			if (execution.model == ExecutionModelGeometry)
			{
				require_extension_internal("GL_NV_geometry_shader_passthrough");
				execution.geometry_passthrough = true;
			}
			break;

		case CapabilityVariablePointers:
		case CapabilityVariablePointersStorageBuffer:
			SPIRV_CROSS_THROW("VariablePointers capability is not supported in GLSL.");

		case CapabilityMultiView:
			if (options.vulkan_semantics)
				require_extension_internal("GL_EXT_multiview");
			else
			{
				require_extension_internal("GL_OVR_multiview2");
				if (options.ovr_multiview_view_count == 0)
					SPIRV_CROSS_THROW("ovr_multiview_view_count must be non-zero when using GL_OVR_multiview2.");
				if (get_execution_model() != ExecutionModelVertex)
					SPIRV_CROSS_THROW("OVR_multiview2 can only be used with Vertex shaders.");
			}
			break;

		case CapabilityRayQueryKHR:
			if (options.es || options.version < 460 || !options.vulkan_semantics)
				SPIRV_CROSS_THROW("RayQuery requires Vulkan GLSL 460.");
			require_extension_internal("GL_EXT_ray_query");
			ray_tracing_is_khr = true;
			break;

		case CapabilityRayTraversalPrimitiveCullingKHR:
			if (options.es || options.version < 460 || !options.vulkan_semantics)
				SPIRV_CROSS_THROW("RayQuery requires Vulkan GLSL 460.");
			require_extension_internal("GL_EXT_ray_flags_primitive_culling");
			ray_tracing_is_khr = true;
			break;

		default:
			break;
		}
	}

	if (options.ovr_multiview_view_count)
	{
		if (options.vulkan_semantics)
			SPIRV_CROSS_THROW("OVR_multiview2 cannot be used with Vulkan semantics.");
		if (get_execution_model() != ExecutionModelVertex)
			SPIRV_CROSS_THROW("OVR_multiview2 can only be used with Vertex shaders.");
		require_extension_internal("GL_OVR_multiview2");
	}

	// KHR one is likely to get promoted at some point, so if we don't see an explicit SPIR-V extension, assume KHR.
	for (auto &ext : ir.declared_extensions)
		if (ext == "SPV_NV_fragment_shader_barycentric")
			barycentric_is_nv = true;
}

void CompilerGLSL::require_polyfill(Polyfill polyfill, bool relaxed)
{
	uint32_t &polyfills = (relaxed && options.es) ? required_polyfills_relaxed : required_polyfills;

	if ((polyfills & polyfill) == 0)
	{
		polyfills |= polyfill;
		force_recompile();
	}
}

void CompilerGLSL::ray_tracing_khr_fixup_locations()
{
	uint32_t location = 0;
	ir.for_each_typed_id<SPIRVariable>([&](uint32_t, SPIRVariable &var) {
		// Incoming payload storage can also be used for tracing.
		if (var.storage != StorageClassRayPayloadKHR && var.storage != StorageClassCallableDataKHR &&
		    var.storage != StorageClassIncomingRayPayloadKHR && var.storage != StorageClassIncomingCallableDataKHR)
			return;
		if (is_hidden_variable(var))
			return;
		set_decoration(var.self, DecorationLocation, location++);
	});
}

string CompilerGLSL::compile()
{
	ir.fixup_reserved_names();

	if (!options.vulkan_semantics)
	{
		// only NV_gpu_shader5 supports divergent indexing on OpenGL, and it does so without extra qualifiers
		backend.nonuniform_qualifier = "";
		backend.needs_row_major_load_workaround = options.enable_row_major_load_workaround;
	}
	backend.allow_precision_qualifiers = options.vulkan_semantics || options.es;
	backend.force_gl_in_out_block = true;
	backend.supports_extensions = true;
	backend.use_array_constructor = true;
	backend.workgroup_size_is_hidden = true;
	backend.requires_relaxed_precision_analysis = options.es || options.vulkan_semantics;
	backend.support_precise_qualifier =
			(!options.es && options.version >= 400) || (options.es && options.version >= 320);

	if (is_legacy_es())
		backend.support_case_fallthrough = false;

	// Scan the SPIR-V to find trivial uses of extensions.
	fixup_anonymous_struct_names();
	fixup_type_alias();
	reorder_type_alias();
	build_function_control_flow_graphs_and_analyze();
	find_static_extensions();
	fixup_image_load_store_access();
	update_active_builtins();
	analyze_image_and_sampler_usage();
	analyze_interlocked_resource_usage();
	if (!inout_color_attachments.empty())
		emit_inout_fragment_outputs_copy_to_subpass_inputs();

	// Shaders might cast unrelated data to pointers of non-block types.
	// Find all such instances and make sure we can cast the pointers to a synthesized block type.
	if (ir.addressing_model == AddressingModelPhysicalStorageBuffer64EXT)
		analyze_non_block_pointer_types();

	uint32_t pass_count = 0;
	do
	{
		reset(pass_count);

		buffer.reset();

		emit_header();
		emit_resources();
		emit_extension_workarounds(get_execution_model());

		if (required_polyfills != 0)
			emit_polyfills(required_polyfills, false);
		if (options.es && required_polyfills_relaxed != 0)
			emit_polyfills(required_polyfills_relaxed, true);

		emit_function(get<SPIRFunction>(ir.default_entry_point), Bitset());

		pass_count++;
	} while (is_forcing_recompilation());

	// Implement the interlocked wrapper function at the end.
	// The body was implemented in lieu of main().
	if (interlocked_is_complex)
	{
		statement("void main()");
		begin_scope();
		statement("// Interlocks were used in a way not compatible with GLSL, this is very slow.");
		statement("SPIRV_Cross_beginInvocationInterlock();");
		statement("spvMainInterlockedBody();");
		statement("SPIRV_Cross_endInvocationInterlock();");
		end_scope();
	}

	// Entry point in GLSL is always main().
	get_entry_point().name = "main";

	return buffer.str();
}

std::string CompilerGLSL::get_partial_source()
{
	return buffer.str();
}

void CompilerGLSL::build_workgroup_size(SmallVector<string> &arguments, const SpecializationConstant &wg_x,
                                        const SpecializationConstant &wg_y, const SpecializationConstant &wg_z)
{
	auto &execution = get_entry_point();
	bool builtin_workgroup = execution.workgroup_size.constant != 0;
	bool use_local_size_id = !builtin_workgroup && execution.flags.get(ExecutionModeLocalSizeId);

	if (wg_x.id)
	{
		if (options.vulkan_semantics)
			arguments.push_back(join("local_size_x_id = ", wg_x.constant_id));
		else
			arguments.push_back(join("local_size_x = ", get<SPIRConstant>(wg_x.id).specialization_constant_macro_name));
	}
	else if (use_local_size_id && execution.workgroup_size.id_x)
		arguments.push_back(join("local_size_x = ", get<SPIRConstant>(execution.workgroup_size.id_x).scalar()));
	else
		arguments.push_back(join("local_size_x = ", execution.workgroup_size.x));

	if (wg_y.id)
	{
		if (options.vulkan_semantics)
			arguments.push_back(join("local_size_y_id = ", wg_y.constant_id));
		else
			arguments.push_back(join("local_size_y = ", get<SPIRConstant>(wg_y.id).specialization_constant_macro_name));
	}
	else if (use_local_size_id && execution.workgroup_size.id_y)
		arguments.push_back(join("local_size_y = ", get<SPIRConstant>(execution.workgroup_size.id_y).scalar()));
	else
		arguments.push_back(join("local_size_y = ", execution.workgroup_size.y));

	if (wg_z.id)
	{
		if (options.vulkan_semantics)
			arguments.push_back(join("local_size_z_id = ", wg_z.constant_id));
		else
			arguments.push_back(join("local_size_z = ", get<SPIRConstant>(wg_z.id).specialization_constant_macro_name));
	}
	else if (use_local_size_id && execution.workgroup_size.id_z)
		arguments.push_back(join("local_size_z = ", get<SPIRConstant>(execution.workgroup_size.id_z).scalar()));
	else
		arguments.push_back(join("local_size_z = ", execution.workgroup_size.z));
}

void CompilerGLSL::request_subgroup_feature(ShaderSubgroupSupportHelper::Feature feature)
{
	if (options.vulkan_semantics)
	{
		auto khr_extension = ShaderSubgroupSupportHelper::get_KHR_extension_for_feature(feature);
		require_extension_internal(ShaderSubgroupSupportHelper::get_extension_name(khr_extension));
	}
	else
	{
		if (!shader_subgroup_supporter.is_feature_requested(feature))
			force_recompile();
		shader_subgroup_supporter.request_feature(feature);
	}
}

void CompilerGLSL::emit_header()
{
	auto &execution = get_entry_point();
	statement("#version ", options.version, options.es && options.version > 100 ? " es" : "");

	if (!options.es && options.version < 420)
	{
		// Needed for binding = # on UBOs, etc.
		if (options.enable_420pack_extension)
		{
			statement("#ifdef GL_ARB_shading_language_420pack");
			statement("#extension GL_ARB_shading_language_420pack : require");
			statement("#endif");
		}
		// Needed for: layout(early_fragment_tests) in;
		if (execution.flags.get(ExecutionModeEarlyFragmentTests))
			require_extension_internal("GL_ARB_shader_image_load_store");
	}

	// Needed for: layout(post_depth_coverage) in;
	if (execution.flags.get(ExecutionModePostDepthCoverage))
		require_extension_internal("GL_ARB_post_depth_coverage");

	// Needed for: layout({pixel,sample}_interlock_[un]ordered) in;
	bool interlock_used = execution.flags.get(ExecutionModePixelInterlockOrderedEXT) ||
	                      execution.flags.get(ExecutionModePixelInterlockUnorderedEXT) ||
	                      execution.flags.get(ExecutionModeSampleInterlockOrderedEXT) ||
	                      execution.flags.get(ExecutionModeSampleInterlockUnorderedEXT);

	if (interlock_used)
	{
		if (options.es)
		{
			if (options.version < 310)
				SPIRV_CROSS_THROW("At least ESSL 3.10 required for fragment shader interlock.");
			require_extension_internal("GL_NV_fragment_shader_interlock");
		}
		else
		{
			if (options.version < 420)
				require_extension_internal("GL_ARB_shader_image_load_store");
			require_extension_internal("GL_ARB_fragment_shader_interlock");
		}
	}

	for (auto &ext : forced_extensions)
	{
		if (ext == "GL_ARB_gpu_shader_int64")
		{
			statement("#if defined(GL_ARB_gpu_shader_int64)");
			statement("#extension GL_ARB_gpu_shader_int64 : require");
			if (!options.vulkan_semantics || options.es)
			{
				statement("#elif defined(GL_NV_gpu_shader5)");
				statement("#extension GL_NV_gpu_shader5 : require");
			}
			statement("#else");
			statement("#error No extension available for 64-bit integers.");
			statement("#endif");
		}
		else if (ext == "GL_EXT_shader_explicit_arithmetic_types_float16")
		{
			// Special case, this extension has a potential fallback to another vendor extension in normal GLSL.
			// GL_AMD_gpu_shader_half_float is a superset, so try that first.
			statement("#if defined(GL_AMD_gpu_shader_half_float)");
			statement("#extension GL_AMD_gpu_shader_half_float : require");
			if (!options.vulkan_semantics)
			{
				statement("#elif defined(GL_NV_gpu_shader5)");
				statement("#extension GL_NV_gpu_shader5 : require");
			}
			else
			{
				statement("#elif defined(GL_EXT_shader_explicit_arithmetic_types_float16)");
				statement("#extension GL_EXT_shader_explicit_arithmetic_types_float16 : require");
			}
			statement("#else");
			statement("#error No extension available for FP16.");
			statement("#endif");
		}
		else if (ext == "GL_EXT_shader_explicit_arithmetic_types_int8")
		{
			if (options.vulkan_semantics)
				statement("#extension GL_EXT_shader_explicit_arithmetic_types_int8 : require");
			else
			{
				statement("#if defined(GL_EXT_shader_explicit_arithmetic_types_int8)");
				statement("#extension GL_EXT_shader_explicit_arithmetic_types_int8 : require");
				statement("#elif defined(GL_NV_gpu_shader5)");
				statement("#extension GL_NV_gpu_shader5 : require");
				statement("#else");
				statement("#error No extension available for Int8.");
				statement("#endif");
			}
		}
		else if (ext == "GL_EXT_shader_explicit_arithmetic_types_int16")
		{
			if (options.vulkan_semantics)
				statement("#extension GL_EXT_shader_explicit_arithmetic_types_int16 : require");
			else
			{
				statement("#if defined(GL_EXT_shader_explicit_arithmetic_types_int16)");
				statement("#extension GL_EXT_shader_explicit_arithmetic_types_int16 : require");
				statement("#elif defined(GL_AMD_gpu_shader_int16)");
				statement("#extension GL_AMD_gpu_shader_int16 : require");
				statement("#elif defined(GL_NV_gpu_shader5)");
				statement("#extension GL_NV_gpu_shader5 : require");
				statement("#else");
				statement("#error No extension available for Int16.");
				statement("#endif");
			}
		}
		else if (ext == "GL_ARB_post_depth_coverage")
		{
			if (options.es)
				statement("#extension GL_EXT_post_depth_coverage : require");
			else
			{
				statement("#if defined(GL_ARB_post_depth_coverge)");
				statement("#extension GL_ARB_post_depth_coverage : require");
				statement("#else");
				statement("#extension GL_EXT_post_depth_coverage : require");
				statement("#endif");
			}
		}
		else if (!options.vulkan_semantics && ext == "GL_ARB_shader_draw_parameters")
		{
			// Soft-enable this extension on plain GLSL.
			statement("#ifdef ", ext);
			statement("#extension ", ext, " : enable");
			statement("#endif");
		}
		else if (ext == "GL_EXT_control_flow_attributes")
		{
			// These are just hints so we can conditionally enable and fallback in the shader.
			statement("#if defined(GL_EXT_control_flow_attributes)");
			statement("#extension GL_EXT_control_flow_attributes : require");
			statement("#define SPIRV_CROSS_FLATTEN [[flatten]]");
			statement("#define SPIRV_CROSS_BRANCH [[dont_flatten]]");
			statement("#define SPIRV_CROSS_UNROLL [[unroll]]");
			statement("#define SPIRV_CROSS_LOOP [[dont_unroll]]");
			statement("#else");
			statement("#define SPIRV_CROSS_FLATTEN");
			statement("#define SPIRV_CROSS_BRANCH");
			statement("#define SPIRV_CROSS_UNROLL");
			statement("#define SPIRV_CROSS_LOOP");
			statement("#endif");
		}
		else if (ext == "GL_NV_fragment_shader_interlock")
		{
			statement("#extension GL_NV_fragment_shader_interlock : require");
			statement("#define SPIRV_Cross_beginInvocationInterlock() beginInvocationInterlockNV()");
			statement("#define SPIRV_Cross_endInvocationInterlock() endInvocationInterlockNV()");
		}
		else if (ext == "GL_ARB_fragment_shader_interlock")
		{
			statement("#ifdef GL_ARB_fragment_shader_interlock");
			statement("#extension GL_ARB_fragment_shader_interlock : enable");
			statement("#define SPIRV_Cross_beginInvocationInterlock() beginInvocationInterlockARB()");
			statement("#define SPIRV_Cross_endInvocationInterlock() endInvocationInterlockARB()");
			statement("#elif defined(GL_INTEL_fragment_shader_ordering)");
			statement("#extension GL_INTEL_fragment_shader_ordering : enable");
			statement("#define SPIRV_Cross_beginInvocationInterlock() beginFragmentShaderOrderingINTEL()");
			statement("#define SPIRV_Cross_endInvocationInterlock()");
			statement("#endif");
		}
		else
			statement("#extension ", ext, " : require");
	}

	if (!options.vulkan_semantics)
	{
		using Supp = ShaderSubgroupSupportHelper;
		auto result = shader_subgroup_supporter.resolve();

		for (uint32_t feature_index = 0; feature_index < Supp::FeatureCount; feature_index++)
		{
			auto feature = static_cast<Supp::Feature>(feature_index);
			if (!shader_subgroup_supporter.is_feature_requested(feature))
				continue;

			auto exts = Supp::get_candidates_for_feature(feature, result);
			if (exts.empty())
				continue;

			statement("");

			for (auto &ext : exts)
			{
				const char *name = Supp::get_extension_name(ext);
				const char *extra_predicate = Supp::get_extra_required_extension_predicate(ext);
				auto extra_names = Supp::get_extra_required_extension_names(ext);
				statement(&ext != &exts.front() ? "#elif" : "#if", " defined(", name, ")",
				          (*extra_predicate != '\0' ? " && " : ""), extra_predicate);
				for (const auto &e : extra_names)
					statement("#extension ", e, " : enable");
				statement("#extension ", name, " : require");
			}

			if (!Supp::can_feature_be_implemented_without_extensions(feature))
			{
				statement("#else");
				statement("#error No extensions available to emulate requested subgroup feature.");
			}

			statement("#endif");
		}
	}

	for (auto &header : header_lines)
		statement(header);

	SmallVector<string> inputs;
	SmallVector<string> outputs;

	switch (execution.model)
	{
	case ExecutionModelVertex:
		if (options.ovr_multiview_view_count)
			inputs.push_back(join("num_views = ", options.ovr_multiview_view_count));
		break;
	case ExecutionModelGeometry:
		if ((execution.flags.get(ExecutionModeInvocations)) && execution.invocations != 1)
			inputs.push_back(join("invocations = ", execution.invocations));
		if (execution.flags.get(ExecutionModeInputPoints))
			inputs.push_back("points");
		if (execution.flags.get(ExecutionModeInputLines))
			inputs.push_back("lines");
		if (execution.flags.get(ExecutionModeInputLinesAdjacency))
			inputs.push_back("lines_adjacency");
		if (execution.flags.get(ExecutionModeTriangles))
			inputs.push_back("triangles");
		if (execution.flags.get(ExecutionModeInputTrianglesAdjacency))
			inputs.push_back("triangles_adjacency");

		if (!execution.geometry_passthrough)
		{
			// For passthrough, these are implies and cannot be declared in shader.
			outputs.push_back(join("max_vertices = ", execution.output_vertices));
			if (execution.flags.get(ExecutionModeOutputTriangleStrip))
				outputs.push_back("triangle_strip");
			if (execution.flags.get(ExecutionModeOutputPoints))
				outputs.push_back("points");
			if (execution.flags.get(ExecutionModeOutputLineStrip))
				outputs.push_back("line_strip");
		}
		break;

	case ExecutionModelTessellationControl:
		if (execution.flags.get(ExecutionModeOutputVertices))
			outputs.push_back(join("vertices = ", execution.output_vertices));
		break;

	case ExecutionModelTessellationEvaluation:
		if (execution.flags.get(ExecutionModeQuads))
			inputs.push_back("quads");
		if (execution.flags.get(ExecutionModeTriangles))
			inputs.push_back("triangles");
		if (execution.flags.get(ExecutionModeIsolines))
			inputs.push_back("isolines");
		if (execution.flags.get(ExecutionModePointMode))
			inputs.push_back("point_mode");

		if (!execution.flags.get(ExecutionModeIsolines))
		{
			if (execution.flags.get(ExecutionModeVertexOrderCw))
				inputs.push_back("cw");
			if (execution.flags.get(ExecutionModeVertexOrderCcw))
				inputs.push_back("ccw");
		}

		if (execution.flags.get(ExecutionModeSpacingFractionalEven))
			inputs.push_back("fractional_even_spacing");
		if (execution.flags.get(ExecutionModeSpacingFractionalOdd))
			inputs.push_back("fractional_odd_spacing");
		if (execution.flags.get(ExecutionModeSpacingEqual))
			inputs.push_back("equal_spacing");
		break;

	case ExecutionModelGLCompute:
	case ExecutionModelTaskEXT:
	case ExecutionModelMeshEXT:
	{
		if (execution.workgroup_size.constant != 0 || execution.flags.get(ExecutionModeLocalSizeId))
		{
			SpecializationConstant wg_x, wg_y, wg_z;
			get_work_group_size_specialization_constants(wg_x, wg_y, wg_z);

			// If there are any spec constants on legacy GLSL, defer declaration, we need to set up macro
			// declarations before we can emit the work group size.
			if (options.vulkan_semantics ||
			    ((wg_x.id == ConstantID(0)) && (wg_y.id == ConstantID(0)) && (wg_z.id == ConstantID(0))))
				build_workgroup_size(inputs, wg_x, wg_y, wg_z);
		}
		else
		{
			inputs.push_back(join("local_size_x = ", execution.workgroup_size.x));
			inputs.push_back(join("local_size_y = ", execution.workgroup_size.y));
			inputs.push_back(join("local_size_z = ", execution.workgroup_size.z));
		}

		if (execution.model == ExecutionModelMeshEXT)
		{
			outputs.push_back(join("max_vertices = ", execution.output_vertices));
			outputs.push_back(join("max_primitives = ", execution.output_primitives));
			if (execution.flags.get(ExecutionModeOutputTrianglesEXT))
				outputs.push_back("triangles");
			else if (execution.flags.get(ExecutionModeOutputLinesEXT))
				outputs.push_back("lines");
			else if (execution.flags.get(ExecutionModeOutputPoints))
				outputs.push_back("points");
		}
		break;
	}

	case ExecutionModelFragment:
		if (options.es)
		{
			switch (options.fragment.default_float_precision)
			{
			case Options::Lowp:
				statement("precision lowp float;");
				break;

			case Options::Mediump:
				statement("precision mediump float;");
				break;

			case Options::Highp:
				statement("precision highp float;");
				break;

			default:
				break;
			}

			switch (options.fragment.default_int_precision)
			{
			case Options::Lowp:
				statement("precision lowp int;");
				break;

			case Options::Mediump:
				statement("precision mediump int;");
				break;

			case Options::Highp:
				statement("precision highp int;");
				break;

			default:
				break;
			}
		}

		if (execution.flags.get(ExecutionModeEarlyFragmentTests))
			inputs.push_back("early_fragment_tests");
		if (execution.flags.get(ExecutionModePostDepthCoverage))
			inputs.push_back("post_depth_coverage");

		if (interlock_used)
			statement("#if defined(GL_ARB_fragment_shader_interlock)");

		if (execution.flags.get(ExecutionModePixelInterlockOrderedEXT))
			statement("layout(pixel_interlock_ordered) in;");
		else if (execution.flags.get(ExecutionModePixelInterlockUnorderedEXT))
			statement("layout(pixel_interlock_unordered) in;");
		else if (execution.flags.get(ExecutionModeSampleInterlockOrderedEXT))
			statement("layout(sample_interlock_ordered) in;");
		else if (execution.flags.get(ExecutionModeSampleInterlockUnorderedEXT))
			statement("layout(sample_interlock_unordered) in;");

		if (interlock_used)
		{
			statement("#elif !defined(GL_INTEL_fragment_shader_ordering)");
			statement("#error Fragment Shader Interlock/Ordering extension missing!");
			statement("#endif");
		}

		if (!options.es && execution.flags.get(ExecutionModeDepthGreater))
			statement("layout(depth_greater) out float gl_FragDepth;");
		else if (!options.es && execution.flags.get(ExecutionModeDepthLess))
			statement("layout(depth_less) out float gl_FragDepth;");

		break;

	default:
		break;
	}

	for (auto &cap : ir.declared_capabilities)
		if (cap == CapabilityRayTraversalPrimitiveCullingKHR)
			statement("layout(primitive_culling);");

	if (!inputs.empty())
		statement("layout(", merge(inputs), ") in;");
	if (!outputs.empty())
		statement("layout(", merge(outputs), ") out;");

	statement("");
}

bool CompilerGLSL::type_is_empty(const SPIRType &type)
{
	return type.basetype == SPIRType::Struct && type.member_types.empty();
}

void CompilerGLSL::emit_struct(SPIRType &type)
{
	// Struct types can be stamped out multiple times
	// with just different offsets, matrix layouts, etc ...
	// Type-punning with these types is legal, which complicates things
	// when we are storing struct and array types in an SSBO for example.
	// If the type master is packed however, we can no longer assume that the struct declaration will be redundant.
	if (type.type_alias != TypeID(0) &&
	    !has_extended_decoration(type.type_alias, SPIRVCrossDecorationBufferBlockRepacked))
		return;

	add_resource_name(type.self);
	auto name = type_to_glsl(type);

	statement(!backend.explicit_struct_type ? "struct " : "", name);
	begin_scope();

	type.member_name_cache.clear();

	uint32_t i = 0;
	bool emitted = false;
	for (auto &member : type.member_types)
	{
		add_member_name(type, i);
		emit_struct_member(type, member, i);
		i++;
		emitted = true;
	}

	// Don't declare empty structs in GLSL, this is not allowed.
	if (type_is_empty(type) && !backend.supports_empty_struct)
	{
		statement("int empty_struct_member;");
		emitted = true;
	}

	if (has_extended_decoration(type.self, SPIRVCrossDecorationPaddingTarget))
		emit_struct_padding_target(type);

	end_scope_decl();

	if (emitted)
		statement("");
}

string CompilerGLSL::to_interpolation_qualifiers(const Bitset &flags)
{
	string res;
	//if (flags & (1ull << DecorationSmooth))
	//    res += "smooth ";
	if (flags.get(DecorationFlat))
		res += "flat ";
	if (flags.get(DecorationNoPerspective))
	{
		if (options.es)
		{
			if (options.version < 300)
				SPIRV_CROSS_THROW("noperspective requires ESSL 300.");
			require_extension_internal("GL_NV_shader_noperspective_interpolation");
		}
		else if (is_legacy_desktop())
			require_extension_internal("GL_EXT_gpu_shader4");
		res += "noperspective ";
	}
	if (flags.get(DecorationCentroid))
		res += "centroid ";
	if (flags.get(DecorationPatch))
		res += "patch ";
	if (flags.get(DecorationSample))
	{
		if (options.es)
		{
			if (options.version < 300)
				SPIRV_CROSS_THROW("sample requires ESSL 300.");
			else if (options.version < 320)
				require_extension_internal("GL_OES_shader_multisample_interpolation");
		}
		res += "sample ";
	}
	if (flags.get(DecorationInvariant) && (options.es || options.version >= 120))
		res += "invariant ";
	if (flags.get(DecorationPerPrimitiveEXT))
	    res += "perprimitiveEXT ";

	if (flags.get(DecorationExplicitInterpAMD))
	{
		require_extension_internal("GL_AMD_shader_explicit_vertex_parameter");
		res += "__explicitInterpAMD ";
	}

	if (flags.get(DecorationPerVertexKHR))
	{
		if (options.es && options.version < 320)
			SPIRV_CROSS_THROW("pervertexEXT requires ESSL 320.");
		else if (!options.es && options.version < 450)
			SPIRV_CROSS_THROW("pervertexEXT requires GLSL 450.");

		if (barycentric_is_nv)
		{
			require_extension_internal("GL_NV_fragment_shader_barycentric");
			res += "pervertexNV ";
		}
		else
		{
			require_extension_internal("GL_EXT_fragment_shader_barycentric");
			res += "pervertexEXT ";
		}
	}

	return res;
}

string CompilerGLSL::layout_for_member(const SPIRType &type, uint32_t index)
{
	if (is_legacy())
		return "";

	bool is_block = has_decoration(type.self, DecorationBlock) || has_decoration(type.self, DecorationBufferBlock);
	if (!is_block)
		return "";

	auto &memb = ir.meta[type.self].members;
	if (index >= memb.size())
		return "";
	auto &dec = memb[index];

	SmallVector<string> attr;

	if (has_member_decoration(type.self, index, DecorationPassthroughNV))
		attr.push_back("passthrough");

	// We can only apply layouts on members in block interfaces.
	// This is a bit problematic because in SPIR-V decorations are applied on the struct types directly.
	// This is not supported on GLSL, so we have to make the assumption that if a struct within our buffer block struct
	// has a decoration, it was originally caused by a top-level layout() qualifier in GLSL.
	//
	// We would like to go from (SPIR-V style):
	//
	// struct Foo { layout(row_major) mat4 matrix; };
	// buffer UBO { Foo foo; };
	//
	// to
	//
	// struct Foo { mat4 matrix; }; // GLSL doesn't support any layout shenanigans in raw struct declarations.
	// buffer UBO { layout(row_major) Foo foo; }; // Apply the layout on top-level.
	auto flags = combined_decoration_for_member(type, index);

	if (flags.get(DecorationRowMajor))
		attr.push_back("row_major");
	// We don't emit any global layouts, so column_major is default.
	//if (flags & (1ull << DecorationColMajor))
	//    attr.push_back("column_major");

	if (dec.decoration_flags.get(DecorationLocation) && can_use_io_location(type.storage, true))
		attr.push_back(join("location = ", dec.location));

	// Can only declare component if we can declare location.
	if (dec.decoration_flags.get(DecorationComponent) && can_use_io_location(type.storage, true))
	{
		if (!options.es)
		{
			if (options.version < 440 && options.version >= 140)
				require_extension_internal("GL_ARB_enhanced_layouts");
			else if (options.version < 140)
				SPIRV_CROSS_THROW("Component decoration is not supported in targets below GLSL 1.40.");
			attr.push_back(join("component = ", dec.component));
		}
		else
			SPIRV_CROSS_THROW("Component decoration is not supported in ES targets.");
	}

	// SPIRVCrossDecorationPacked is set by layout_for_variable earlier to mark that we need to emit offset qualifiers.
	// This is only done selectively in GLSL as needed.
	if (has_extended_decoration(type.self, SPIRVCrossDecorationExplicitOffset) &&
	    dec.decoration_flags.get(DecorationOffset))
		attr.push_back(join("offset = ", dec.offset));
	else if (type.storage == StorageClassOutput && dec.decoration_flags.get(DecorationOffset))
		attr.push_back(join("xfb_offset = ", dec.offset));

	if (attr.empty())
		return "";

	string res = "layout(";
	res += merge(attr);
	res += ") ";
	return res;
}

const char *CompilerGLSL::format_to_glsl(spv::ImageFormat format)
{
	if (options.es && is_desktop_only_format(format))
		SPIRV_CROSS_THROW("Attempting to use image format not supported in ES profile.");

	switch (format)
	{
	case ImageFormatRgba32f:
		return "rgba32f";
	case ImageFormatRgba16f:
		return "rgba16f";
	case ImageFormatR32f:
		return "r32f";
	case ImageFormatRgba8:
		return "rgba8";
	case ImageFormatRgba8Snorm:
		return "rgba8_snorm";
	case ImageFormatRg32f:
		return "rg32f";
	case ImageFormatRg16f:
		return "rg16f";
	case ImageFormatRgba32i:
		return "rgba32i";
	case ImageFormatRgba16i:
		return "rgba16i";
	case ImageFormatR32i:
		return "r32i";
	case ImageFormatRgba8i:
		return "rgba8i";
	case ImageFormatRg32i:
		return "rg32i";
	case ImageFormatRg16i:
		return "rg16i";
	case ImageFormatRgba32ui:
		return "rgba32ui";
	case ImageFormatRgba16ui:
		return "rgba16ui";
	case ImageFormatR32ui:
		return "r32ui";
	case ImageFormatRgba8ui:
		return "rgba8ui";
	case ImageFormatRg32ui:
		return "rg32ui";
	case ImageFormatRg16ui:
		return "rg16ui";
	case ImageFormatR11fG11fB10f:
		return "r11f_g11f_b10f";
	case ImageFormatR16f:
		return "r16f";
	case ImageFormatRgb10A2:
		return "rgb10_a2";
	case ImageFormatR8:
		return "r8";
	case ImageFormatRg8:
		return "rg8";
	case ImageFormatR16:
		return "r16";
	case ImageFormatRg16:
		return "rg16";
	case ImageFormatRgba16:
		return "rgba16";
	case ImageFormatR16Snorm:
		return "r16_snorm";
	case ImageFormatRg16Snorm:
		return "rg16_snorm";
	case ImageFormatRgba16Snorm:
		return "rgba16_snorm";
	case ImageFormatR8Snorm:
		return "r8_snorm";
	case ImageFormatRg8Snorm:
		return "rg8_snorm";
	case ImageFormatR8ui:
		return "r8ui";
	case ImageFormatRg8ui:
		return "rg8ui";
	case ImageFormatR16ui:
		return "r16ui";
	case ImageFormatRgb10a2ui:
		return "rgb10_a2ui";
	case ImageFormatR8i:
		return "r8i";
	case ImageFormatRg8i:
		return "rg8i";
	case ImageFormatR16i:
		return "r16i";
	default:
	case ImageFormatUnknown:
		return nullptr;
	}
}

uint32_t CompilerGLSL::type_to_packed_base_size(const SPIRType &type, BufferPackingStandard)
{
	switch (type.basetype)
	{
	case SPIRType::Double:
	case SPIRType::Int64:
	case SPIRType::UInt64:
		return 8;
	case SPIRType::Float:
	case SPIRType::Int:
	case SPIRType::UInt:
		return 4;
	case SPIRType::Half:
	case SPIRType::Short:
	case SPIRType::UShort:
		return 2;
	case SPIRType::SByte:
	case SPIRType::UByte:
		return 1;

	default:
		SPIRV_CROSS_THROW("Unrecognized type in type_to_packed_base_size.");
	}
}

uint32_t CompilerGLSL::type_to_packed_alignment(const SPIRType &type, const Bitset &flags,
                                                BufferPackingStandard packing)
{
	// If using PhysicalStorageBufferEXT storage class, this is a pointer,
	// and is 64-bit.
	if (type.storage == StorageClassPhysicalStorageBufferEXT)
	{
		if (!type.pointer)
			SPIRV_CROSS_THROW("Types in PhysicalStorageBufferEXT must be pointers.");

		if (ir.addressing_model == AddressingModelPhysicalStorageBuffer64EXT)
		{
			if (packing_is_vec4_padded(packing) && type_is_array_of_pointers(type))
				return 16;
			else
				return 8;
		}
		else
			SPIRV_CROSS_THROW("AddressingModelPhysicalStorageBuffer64EXT must be used for PhysicalStorageBufferEXT.");
	}

	if (!type.array.empty())
	{
		uint32_t minimum_alignment = 1;
		if (packing_is_vec4_padded(packing))
			minimum_alignment = 16;

		auto *tmp = &get<SPIRType>(type.parent_type);
		while (!tmp->array.empty())
			tmp = &get<SPIRType>(tmp->parent_type);

		// Get the alignment of the base type, then maybe round up.
		return max(minimum_alignment, type_to_packed_alignment(*tmp, flags, packing));
	}

	if (type.basetype == SPIRType::Struct)
	{
		// Rule 9. Structs alignments are maximum alignment of its members.
		uint32_t alignment = 1;
		for (uint32_t i = 0; i < type.member_types.size(); i++)
		{
			auto member_flags = ir.meta[type.self].members[i].decoration_flags;
			alignment =
			    max(alignment, type_to_packed_alignment(get<SPIRType>(type.member_types[i]), member_flags, packing));
		}

		// In std140, struct alignment is rounded up to 16.
		if (packing_is_vec4_padded(packing))
			alignment = max<uint32_t>(alignment, 16u);

		return alignment;
	}
	else
	{
		const uint32_t base_alignment = type_to_packed_base_size(type, packing);

		// Alignment requirement for scalar block layout is always the alignment for the most basic component.
		if (packing_is_scalar(packing))
			return base_alignment;

		// Vectors are *not* aligned in HLSL, but there's an extra rule where vectors cannot straddle
		// a vec4, this is handled outside since that part knows our current offset.
		if (type.columns == 1 && packing_is_hlsl(packing))
			return base_alignment;

		// From 7.6.2.2 in GL 4.5 core spec.
		// Rule 1
		if (type.vecsize == 1 && type.columns == 1)
			return base_alignment;

		// Rule 2
		if ((type.vecsize == 2 || type.vecsize == 4) && type.columns == 1)
			return type.vecsize * base_alignment;

		// Rule 3
		if (type.vecsize == 3 && type.columns == 1)
			return 4 * base_alignment;

		// Rule 4 implied. Alignment does not change in std430.

		// Rule 5. Column-major matrices are stored as arrays of
		// vectors.
		if (flags.get(DecorationColMajor) && type.columns > 1)
		{
			if (packing_is_vec4_padded(packing))
				return 4 * base_alignment;
			else if (type.vecsize == 3)
				return 4 * base_alignment;
			else
				return type.vecsize * base_alignment;
		}

		// Rule 6 implied.

		// Rule 7.
		if (flags.get(DecorationRowMajor) && type.vecsize > 1)
		{
			if (packing_is_vec4_padded(packing))
				return 4 * base_alignment;
			else if (type.columns == 3)
				return 4 * base_alignment;
			else
				return type.columns * base_alignment;
		}

		// Rule 8 implied.
	}

	SPIRV_CROSS_THROW("Did not find suitable rule for type. Bogus decorations?");
}

uint32_t CompilerGLSL::type_to_packed_array_stride(const SPIRType &type, const Bitset &flags,
                                                   BufferPackingStandard packing)
{
	// Array stride is equal to aligned size of the underlying type.
	uint32_t parent = type.parent_type;
	assert(parent);

	auto &tmp = get<SPIRType>(parent);

	uint32_t size = type_to_packed_size(tmp, flags, packing);
	uint32_t alignment = type_to_packed_alignment(type, flags, packing);
	return (size + alignment - 1) & ~(alignment - 1);
}

uint32_t CompilerGLSL::type_to_packed_size(const SPIRType &type, const Bitset &flags, BufferPackingStandard packing)
{
	if (!type.array.empty())
	{
		uint32_t packed_size = to_array_size_literal(type) * type_to_packed_array_stride(type, flags, packing);

		// For arrays of vectors and matrices in HLSL, the last element has a size which depends on its vector size,
		// so that it is possible to pack other vectors into the last element.
		if (packing_is_hlsl(packing) && type.basetype != SPIRType::Struct)
			packed_size -= (4 - type.vecsize) * (type.width / 8);

		return packed_size;
	}

	// If using PhysicalStorageBufferEXT storage class, this is a pointer,
	// and is 64-bit.
	if (type.storage == StorageClassPhysicalStorageBufferEXT)
	{
		if (!type.pointer)
			SPIRV_CROSS_THROW("Types in PhysicalStorageBufferEXT must be pointers.");

		if (ir.addressing_model == AddressingModelPhysicalStorageBuffer64EXT)
			return 8;
		else
			SPIRV_CROSS_THROW("AddressingModelPhysicalStorageBuffer64EXT must be used for PhysicalStorageBufferEXT.");
	}

	uint32_t size = 0;

	if (type.basetype == SPIRType::Struct)
	{
		uint32_t pad_alignment = 1;

		for (uint32_t i = 0; i < type.member_types.size(); i++)
		{
			auto member_flags = ir.meta[type.self].members[i].decoration_flags;
			auto &member_type = get<SPIRType>(type.member_types[i]);

			uint32_t packed_alignment = type_to_packed_alignment(member_type, member_flags, packing);
			uint32_t alignment = max(packed_alignment, pad_alignment);

			// The next member following a struct member is aligned to the base alignment of the struct that came before.
			// GL 4.5 spec, 7.6.2.2.
			if (member_type.basetype == SPIRType::Struct)
				pad_alignment = packed_alignment;
			else
				pad_alignment = 1;

			size = (size + alignment - 1) & ~(alignment - 1);
			size += type_to_packed_size(member_type, member_flags, packing);
		}
	}
	else
	{
		const uint32_t base_alignment = type_to_packed_base_size(type, packing);

		if (packing_is_scalar(packing))
		{
			size = type.vecsize * type.columns * base_alignment;
		}
		else
		{
			if (type.columns == 1)
				size = type.vecsize * base_alignment;

			if (flags.get(DecorationColMajor) && type.columns > 1)
			{
				if (packing_is_vec4_padded(packing))
					size = type.columns * 4 * base_alignment;
				else if (type.vecsize == 3)
					size = type.columns * 4 * base_alignment;
				else
					size = type.columns * type.vecsize * base_alignment;
			}

			if (flags.get(DecorationRowMajor) && type.vecsize > 1)
			{
				if (packing_is_vec4_padded(packing))
					size = type.vecsize * 4 * base_alignment;
				else if (type.columns == 3)
					size = type.vecsize * 4 * base_alignment;
				else
					size = type.vecsize * type.columns * base_alignment;
			}

			// For matrices in HLSL, the last element has a size which depends on its vector size,
			// so that it is possible to pack other vectors into the last element.
			if (packing_is_hlsl(packing) && type.columns > 1)
				size -= (4 - type.vecsize) * (type.width / 8);
		}
	}

	return size;
}

bool CompilerGLSL::buffer_is_packing_standard(const SPIRType &type, BufferPackingStandard packing,
                                              uint32_t *failed_validation_index, uint32_t start_offset,
                                              uint32_t end_offset)
{
	// This is very tricky and error prone, but try to be exhaustive and correct here.
	// SPIR-V doesn't directly say if we're using std430 or std140.
	// SPIR-V communicates this using Offset and ArrayStride decorations (which is what really matters),
	// so we have to try to infer whether or not the original GLSL source was std140 or std430 based on this information.
	// We do not have to consider shared or packed since these layouts are not allowed in Vulkan SPIR-V (they are useless anyways, and custom offsets would do the same thing).
	//
	// It is almost certain that we're using std430, but it gets tricky with arrays in particular.
	// We will assume std430, but infer std140 if we can prove the struct is not compliant with std430.
	//
	// The only two differences between std140 and std430 are related to padding alignment/array stride
	// in arrays and structs. In std140 they take minimum vec4 alignment.
	// std430 only removes the vec4 requirement.

	uint32_t offset = 0;
	uint32_t pad_alignment = 1;

	bool is_top_level_block =
	    has_decoration(type.self, DecorationBlock) || has_decoration(type.self, DecorationBufferBlock);

	for (uint32_t i = 0; i < type.member_types.size(); i++)
	{
		auto &memb_type = get<SPIRType>(type.member_types[i]);
		auto member_flags = ir.meta[type.self].members[i].decoration_flags;

		// Verify alignment rules.
		uint32_t packed_alignment = type_to_packed_alignment(memb_type, member_flags, packing);

		// This is a rather dirty workaround to deal with some cases of OpSpecConstantOp used as array size, e.g:
		// layout(constant_id = 0) const int s = 10;
		// const int S = s + 5; // SpecConstantOp
		// buffer Foo { int data[S]; }; // <-- Very hard for us to deduce a fixed value here,
		// we would need full implementation of compile-time constant folding. :(
		// If we are the last member of a struct, there might be cases where the actual size of that member is irrelevant
		// for our analysis (e.g. unsized arrays).
		// This lets us simply ignore that there are spec constant op sized arrays in our buffers.
		// Querying size of this member will fail, so just don't call it unless we have to.
		//
		// This is likely "best effort" we can support without going into unacceptably complicated workarounds.
		bool member_can_be_unsized =
		    is_top_level_block && size_t(i + 1) == type.member_types.size() && !memb_type.array.empty();

		uint32_t packed_size = 0;
		if (!member_can_be_unsized || packing_is_hlsl(packing))
			packed_size = type_to_packed_size(memb_type, member_flags, packing);

		// We only need to care about this if we have non-array types which can straddle the vec4 boundary.
		uint32_t actual_offset = type_struct_member_offset(type, i);

		if (packing_is_hlsl(packing))
		{
			// If a member straddles across a vec4 boundary, alignment is actually vec4.
			uint32_t begin_word = actual_offset / 16;
			uint32_t end_word = (actual_offset + packed_size - 1) / 16;
			if (begin_word != end_word)
				packed_alignment = max<uint32_t>(packed_alignment, 16u);
		}

		// Field is not in the specified range anymore and we can ignore any further fields.
		if (actual_offset >= end_offset)
			break;

		uint32_t alignment = max(packed_alignment, pad_alignment);
		offset = (offset + alignment - 1) & ~(alignment - 1);

		// The next member following a struct member is aligned to the base alignment of the struct that came before.
		// GL 4.5 spec, 7.6.2.2.
		if (memb_type.basetype == SPIRType::Struct && !memb_type.pointer)
			pad_alignment = packed_alignment;
		else
			pad_alignment = 1;

		// Only care about packing if we are in the given range
		if (actual_offset >= start_offset)
		{
			// We only care about offsets in std140, std430, etc ...
			// For EnhancedLayout variants, we have the flexibility to choose our own offsets.
			if (!packing_has_flexible_offset(packing))
			{
				if (actual_offset != offset) // This cannot be the packing we're looking for.
				{
					if (failed_validation_index)
						*failed_validation_index = i;
					return false;
				}
			}
			else if ((actual_offset & (alignment - 1)) != 0)
			{
				// We still need to verify that alignment rules are observed, even if we have explicit offset.
				if (failed_validation_index)
					*failed_validation_index = i;
				return false;
			}

			// Verify array stride rules.
			if (!memb_type.array.empty() && type_to_packed_array_stride(memb_type, member_flags, packing) !=
			                                    type_struct_member_array_stride(type, i))
			{
				if (failed_validation_index)
					*failed_validation_index = i;
				return false;
			}

			// Verify that sub-structs also follow packing rules.
			// We cannot use enhanced layouts on substructs, so they better be up to spec.
			auto substruct_packing = packing_to_substruct_packing(packing);

			if (!memb_type.pointer && !memb_type.member_types.empty() &&
			    !buffer_is_packing_standard(memb_type, substruct_packing))
			{
				if (failed_validation_index)
					*failed_validation_index = i;
				return false;
			}
		}

		// Bump size.
		offset = actual_offset + packed_size;
	}

	return true;
}

bool CompilerGLSL::can_use_io_location(StorageClass storage, bool block)
{
	// Location specifiers are must have in SPIR-V, but they aren't really supported in earlier versions of GLSL.
	// Be very explicit here about how to solve the issue.
	if ((get_execution_model() != ExecutionModelVertex && storage == StorageClassInput) ||
	    (get_execution_model() != ExecutionModelFragment && storage == StorageClassOutput))
	{
		uint32_t minimum_desktop_version = block ? 440 : 410;
		// ARB_enhanced_layouts vs ARB_separate_shader_objects ...

		if (!options.es && options.version < minimum_desktop_version && !options.separate_shader_objects)
			return false;
		else if (options.es && options.version < 310)
			return false;
	}

	if ((get_execution_model() == ExecutionModelVertex && storage == StorageClassInput) ||
	    (get_execution_model() == ExecutionModelFragment && storage == StorageClassOutput))
	{
		if (options.es && options.version < 300)
			return false;
		else if (!options.es && options.version < 330)
			return false;
	}

	if (storage == StorageClassUniform || storage == StorageClassUniformConstant || storage == StorageClassPushConstant)
	{
		if (options.es && options.version < 310)
			return false;
		else if (!options.es && options.version < 430)
			return false;
	}

	return true;
}

string CompilerGLSL::layout_for_variable(const SPIRVariable &var)
{
	// FIXME: Come up with a better solution for when to disable layouts.
	// Having layouts depend on extensions as well as which types
	// of layouts are used. For now, the simple solution is to just disable
	// layouts for legacy versions.
	if (is_legacy())
		return "";

	if (subpass_input_is_framebuffer_fetch(var.self))
		return "";

	SmallVector<string> attr;

	auto &type = get<SPIRType>(var.basetype);
	auto &flags = get_decoration_bitset(var.self);
	auto &typeflags = get_decoration_bitset(type.self);

	if (flags.get(DecorationPassthroughNV))
		attr.push_back("passthrough");

	if (options.vulkan_semantics && var.storage == StorageClassPushConstant)
		attr.push_back("push_constant");
	else if (var.storage == StorageClassShaderRecordBufferKHR)
		attr.push_back(ray_tracing_is_khr ? "shaderRecordEXT" : "shaderRecordNV");

	if (flags.get(DecorationRowMajor))
		attr.push_back("row_major");
	if (flags.get(DecorationColMajor))
		attr.push_back("column_major");

	if (options.vulkan_semantics)
	{
		if (flags.get(DecorationInputAttachmentIndex))
			attr.push_back(join("input_attachment_index = ", get_decoration(var.self, DecorationInputAttachmentIndex)));
	}

	bool is_block = has_decoration(type.self, DecorationBlock);
	if (flags.get(DecorationLocation) && can_use_io_location(var.storage, is_block))
	{
		Bitset combined_decoration;
		for (uint32_t i = 0; i < ir.meta[type.self].members.size(); i++)
			combined_decoration.merge_or(combined_decoration_for_member(type, i));

		// If our members have location decorations, we don't need to
		// emit location decorations at the top as well (looks weird).
		if (!combined_decoration.get(DecorationLocation))
			attr.push_back(join("location = ", get_decoration(var.self, DecorationLocation)));
	}

	if (get_execution_model() == ExecutionModelFragment && var.storage == StorageClassOutput &&
	    location_is_non_coherent_framebuffer_fetch(get_decoration(var.self, DecorationLocation)))
	{
		attr.push_back("noncoherent");
	}

	// Transform feedback
	bool uses_enhanced_layouts = false;
	if (is_block && var.storage == StorageClassOutput)
	{
		// For blocks, there is a restriction where xfb_stride/xfb_buffer must only be declared on the block itself,
		// since all members must match the same xfb_buffer. The only thing we will declare for members of the block
		// is the xfb_offset.
		uint32_t member_count = uint32_t(type.member_types.size());
		bool have_xfb_buffer_stride = false;
		bool have_any_xfb_offset = false;
		bool have_geom_stream = false;
		uint32_t xfb_stride = 0, xfb_buffer = 0, geom_stream = 0;

		if (flags.get(DecorationXfbBuffer) && flags.get(DecorationXfbStride))
		{
			have_xfb_buffer_stride = true;
			xfb_buffer = get_decoration(var.self, DecorationXfbBuffer);
			xfb_stride = get_decoration(var.self, DecorationXfbStride);
		}

		if (flags.get(DecorationStream))
		{
			have_geom_stream = true;
			geom_stream = get_decoration(var.self, DecorationStream);
		}

		// Verify that none of the members violate our assumption.
		for (uint32_t i = 0; i < member_count; i++)
		{
			if (has_member_decoration(type.self, i, DecorationStream))
			{
				uint32_t member_geom_stream = get_member_decoration(type.self, i, DecorationStream);
				if (have_geom_stream && member_geom_stream != geom_stream)
					SPIRV_CROSS_THROW("IO block member Stream mismatch.");
				have_geom_stream = true;
				geom_stream = member_geom_stream;
			}

			// Only members with an Offset decoration participate in XFB.
			if (!has_member_decoration(type.self, i, DecorationOffset))
				continue;
			have_any_xfb_offset = true;

			if (has_member_decoration(type.self, i, DecorationXfbBuffer))
			{
				uint32_t buffer_index = get_member_decoration(type.self, i, DecorationXfbBuffer);
				if (have_xfb_buffer_stride && buffer_index != xfb_buffer)
					SPIRV_CROSS_THROW("IO block member XfbBuffer mismatch.");
				have_xfb_buffer_stride = true;
				xfb_buffer = buffer_index;
			}

			if (has_member_decoration(type.self, i, DecorationXfbStride))
			{
				uint32_t stride = get_member_decoration(type.self, i, DecorationXfbStride);
				if (have_xfb_buffer_stride && stride != xfb_stride)
					SPIRV_CROSS_THROW("IO block member XfbStride mismatch.");
				have_xfb_buffer_stride = true;
				xfb_stride = stride;
			}
		}

		if (have_xfb_buffer_stride && have_any_xfb_offset)
		{
			attr.push_back(join("xfb_buffer = ", xfb_buffer));
			attr.push_back(join("xfb_stride = ", xfb_stride));
			uses_enhanced_layouts = true;
		}

		if (have_geom_stream)
		{
			if (get_execution_model() != ExecutionModelGeometry)
				SPIRV_CROSS_THROW("Geometry streams can only be used in geometry shaders.");
			if (options.es)
				SPIRV_CROSS_THROW("Multiple geometry streams not supported in ESSL.");
			if (options.version < 400)
				require_extension_internal("GL_ARB_transform_feedback3");
			attr.push_back(join("stream = ", get_decoration(var.self, DecorationStream)));
		}
	}
	else if (var.storage == StorageClassOutput)
	{
		if (flags.get(DecorationXfbBuffer) && flags.get(DecorationXfbStride) && flags.get(DecorationOffset))
		{
			// XFB for standalone variables, we can emit all decorations.
			attr.push_back(join("xfb_buffer = ", get_decoration(var.self, DecorationXfbBuffer)));
			attr.push_back(join("xfb_stride = ", get_decoration(var.self, DecorationXfbStride)));
			attr.push_back(join("xfb_offset = ", get_decoration(var.self, DecorationOffset)));
			uses_enhanced_layouts = true;
		}

		if (flags.get(DecorationStream))
		{
			if (get_execution_model() != ExecutionModelGeometry)
				SPIRV_CROSS_THROW("Geometry streams can only be used in geometry shaders.");
			if (options.es)
				SPIRV_CROSS_THROW("Multiple geometry streams not supported in ESSL.");
			if (options.version < 400)
				require_extension_internal("GL_ARB_transform_feedback3");
			attr.push_back(join("stream = ", get_decoration(var.self, DecorationStream)));
		}
	}

	// Can only declare Component if we can declare location.
	if (flags.get(DecorationComponent) && can_use_io_location(var.storage, is_block))
	{
		uses_enhanced_layouts = true;
		attr.push_back(join("component = ", get_decoration(var.self, DecorationComponent)));
	}

	if (uses_enhanced_layouts)
	{
		if (!options.es)
		{
			if (options.version < 440 && options.version >= 140)
				require_extension_internal("GL_ARB_enhanced_layouts");
			else if (options.version < 140)
				SPIRV_CROSS_THROW("GL_ARB_enhanced_layouts is not supported in targets below GLSL 1.40.");
			if (!options.es && options.version < 440)
				require_extension_internal("GL_ARB_enhanced_layouts");
		}
		else if (options.es)
			SPIRV_CROSS_THROW("GL_ARB_enhanced_layouts is not supported in ESSL.");
	}

	if (flags.get(DecorationIndex))
		attr.push_back(join("index = ", get_decoration(var.self, DecorationIndex)));

	// Do not emit set = decoration in regular GLSL output, but
	// we need to preserve it in Vulkan GLSL mode.
	if (var.storage != StorageClassPushConstant && var.storage != StorageClassShaderRecordBufferKHR)
	{
		if (flags.get(DecorationDescriptorSet) && options.vulkan_semantics)
			attr.push_back(join("set = ", get_decoration(var.self, DecorationDescriptorSet)));
	}

	bool push_constant_block = options.vulkan_semantics && var.storage == StorageClassPushConstant;
	bool ssbo_block = var.storage == StorageClassStorageBuffer || var.storage == StorageClassShaderRecordBufferKHR ||
	                  (var.storage == StorageClassUniform && typeflags.get(DecorationBufferBlock));
	bool emulated_ubo = var.storage == StorageClassPushConstant && options.emit_push_constant_as_uniform_buffer;
	bool ubo_block = var.storage == StorageClassUniform && typeflags.get(DecorationBlock);

	// GL 3.0/GLSL 1.30 is not considered legacy, but it doesn't have UBOs ...
	bool can_use_buffer_blocks = (options.es && options.version >= 300) || (!options.es && options.version >= 140);

	// pretend no UBOs when options say so
	if (ubo_block && options.emit_uniform_buffer_as_plain_uniforms)
		can_use_buffer_blocks = false;

	bool can_use_binding;
	if (options.es)
		can_use_binding = options.version >= 310;
	else
		can_use_binding = options.enable_420pack_extension || (options.version >= 420);

	// Make sure we don't emit binding layout for a classic uniform on GLSL 1.30.
	if (!can_use_buffer_blocks && var.storage == StorageClassUniform)
		can_use_binding = false;

	if (var.storage == StorageClassShaderRecordBufferKHR)
		can_use_binding = false;

	if (can_use_binding && flags.get(DecorationBinding))
		attr.push_back(join("binding = ", get_decoration(var.self, DecorationBinding)));

	if (var.storage != StorageClassOutput && flags.get(DecorationOffset))
		attr.push_back(join("offset = ", get_decoration(var.self, DecorationOffset)));

	// Instead of adding explicit offsets for every element here, just assume we're using std140 or std430.
	// If SPIR-V does not comply with either layout, we cannot really work around it.
	if (can_use_buffer_blocks && (ubo_block || emulated_ubo))
	{
		attr.push_back(buffer_to_packing_standard(type, false));
	}
	else if (can_use_buffer_blocks && (push_constant_block || ssbo_block))
	{
		attr.push_back(buffer_to_packing_standard(type, true));
	}

	// For images, the type itself adds a layout qualifer.
	// Only emit the format for storage images.
	if (type.basetype == SPIRType::Image && type.image.sampled == 2)
	{
		const char *fmt = format_to_glsl(type.image.format);
		if (fmt)
			attr.push_back(fmt);
	}

	if (attr.empty())
		return "";

	string res = "layout(";
	res += merge(attr);
	res += ") ";
	return res;
}

string CompilerGLSL::buffer_to_packing_standard(const SPIRType &type, bool support_std430_without_scalar_layout)
{
	if (support_std430_without_scalar_layout && buffer_is_packing_standard(type, BufferPackingStd430))
		return "std430";
	else if (buffer_is_packing_standard(type, BufferPackingStd140))
		return "std140";
	else if (options.vulkan_semantics && buffer_is_packing_standard(type, BufferPackingScalar))
	{
		require_extension_internal("GL_EXT_scalar_block_layout");
		return "scalar";
	}
	else if (support_std430_without_scalar_layout &&
	         buffer_is_packing_standard(type, BufferPackingStd430EnhancedLayout))
	{
		if (options.es && !options.vulkan_semantics)
			SPIRV_CROSS_THROW("Push constant block cannot be expressed as neither std430 nor std140. ES-targets do "
			                  "not support GL_ARB_enhanced_layouts.");
		if (!options.es && !options.vulkan_semantics && options.version < 440)
			require_extension_internal("GL_ARB_enhanced_layouts");

		set_extended_decoration(type.self, SPIRVCrossDecorationExplicitOffset);
		return "std430";
	}
	else if (buffer_is_packing_standard(type, BufferPackingStd140EnhancedLayout))
	{
		// Fallback time. We might be able to use the ARB_enhanced_layouts to deal with this difference,
		// however, we can only use layout(offset) on the block itself, not any substructs, so the substructs better be the appropriate layout.
		// Enhanced layouts seem to always work in Vulkan GLSL, so no need for extensions there.
		if (options.es && !options.vulkan_semantics)
			SPIRV_CROSS_THROW("Push constant block cannot be expressed as neither std430 nor std140. ES-targets do "
			                  "not support GL_ARB_enhanced_layouts.");
		if (!options.es && !options.vulkan_semantics && options.version < 440)
			require_extension_internal("GL_ARB_enhanced_layouts");

		set_extended_decoration(type.self, SPIRVCrossDecorationExplicitOffset);
		return "std140";
	}
	else if (options.vulkan_semantics && buffer_is_packing_standard(type, BufferPackingScalarEnhancedLayout))
	{
		set_extended_decoration(type.self, SPIRVCrossDecorationExplicitOffset);
		require_extension_internal("GL_EXT_scalar_block_layout");
		return "scalar";
	}
	else if (!support_std430_without_scalar_layout && options.vulkan_semantics &&
	         buffer_is_packing_standard(type, BufferPackingStd430))
	{
		// UBOs can support std430 with GL_EXT_scalar_block_layout.
		require_extension_internal("GL_EXT_scalar_block_layout");
		return "std430";
	}
	else if (!support_std430_without_scalar_layout && options.vulkan_semantics &&
	         buffer_is_packing_standard(type, BufferPackingStd430EnhancedLayout))
	{
		// UBOs can support std430 with GL_EXT_scalar_block_layout.
		set_extended_decoration(type.self, SPIRVCrossDecorationExplicitOffset);
		require_extension_internal("GL_EXT_scalar_block_layout");
		return "std430";
	}
	else
	{
		SPIRV_CROSS_THROW("Buffer block cannot be expressed as any of std430, std140, scalar, even with enhanced "
		                  "layouts. You can try flattening this block to support a more flexible layout.");
	}
}

void CompilerGLSL::emit_push_constant_block(const SPIRVariable &var)
{
	if (flattened_buffer_blocks.count(var.self))
		emit_buffer_block_flattened(var);
	else if (options.vulkan_semantics)
		emit_push_constant_block_vulkan(var);
	else if (options.emit_push_constant_as_uniform_buffer)
		emit_buffer_block_native(var);
	else
		emit_push_constant_block_glsl(var);
}

void CompilerGLSL::emit_push_constant_block_vulkan(const SPIRVariable &var)
{
	emit_buffer_block(var);
}

void CompilerGLSL::emit_push_constant_block_glsl(const SPIRVariable &var)
{
	// OpenGL has no concept of push constant blocks, implement it as a uniform struct.
	auto &type = get<SPIRType>(var.basetype);

	unset_decoration(var.self, DecorationBinding);
	unset_decoration(var.self, DecorationDescriptorSet);

#if 0
    if (flags & ((1ull << DecorationBinding) | (1ull << DecorationDescriptorSet)))
        SPIRV_CROSS_THROW("Push constant blocks cannot be compiled to GLSL with Binding or Set syntax. "
                            "Remap to location with reflection API first or disable these decorations.");
#endif

	// We're emitting the push constant block as a regular struct, so disable the block qualifier temporarily.
	// Otherwise, we will end up emitting layout() qualifiers on naked structs which is not allowed.
	bool block_flag = has_decoration(type.self, DecorationBlock);
	unset_decoration(type.self, DecorationBlock);

	emit_struct(type);

	if (block_flag)
		set_decoration(type.self, DecorationBlock);

	emit_uniform(var);
	statement("");
}

void CompilerGLSL::emit_buffer_block(const SPIRVariable &var)
{
	auto &type = get<SPIRType>(var.basetype);
	bool ubo_block = var.storage == StorageClassUniform && has_decoration(type.self, DecorationBlock);

	if (flattened_buffer_blocks.count(var.self))
		emit_buffer_block_flattened(var);
	else if (is_legacy() || (!options.es && options.version == 130) ||
	         (ubo_block && options.emit_uniform_buffer_as_plain_uniforms))
		emit_buffer_block_legacy(var);
	else
		emit_buffer_block_native(var);
}

void CompilerGLSL::emit_buffer_block_legacy(const SPIRVariable &var)
{
	auto &type = get<SPIRType>(var.basetype);
	bool ssbo = var.storage == StorageClassStorageBuffer ||
	            ir.meta[type.self].decoration.decoration_flags.get(DecorationBufferBlock);
	if (ssbo)
		SPIRV_CROSS_THROW("SSBOs not supported in legacy targets.");

	// We're emitting the push constant block as a regular struct, so disable the block qualifier temporarily.
	// Otherwise, we will end up emitting layout() qualifiers on naked structs which is not allowed.
	auto &block_flags = ir.meta[type.self].decoration.decoration_flags;
	bool block_flag = block_flags.get(DecorationBlock);
	block_flags.clear(DecorationBlock);
	emit_struct(type);
	if (block_flag)
		block_flags.set(DecorationBlock);
	emit_uniform(var);
	statement("");
}

void CompilerGLSL::emit_buffer_reference_block(uint32_t type_id, bool forward_declaration)
{
	auto &type = get<SPIRType>(type_id);
	string buffer_name;

	if (forward_declaration)
	{
		// Block names should never alias, but from HLSL input they kind of can because block types are reused for UAVs ...
		// Allow aliased name since we might be declaring the block twice. Once with buffer reference (forward declared) and one proper declaration.
		// The names must match up.
		buffer_name = to_name(type.self, false);

		// Shaders never use the block by interface name, so we don't
		// have to track this other than updating name caches.
		// If we have a collision for any reason, just fallback immediately.
		if (ir.meta[type.self].decoration.alias.empty() ||
		    block_ssbo_names.find(buffer_name) != end(block_ssbo_names) ||
		    resource_names.find(buffer_name) != end(resource_names))
		{
			buffer_name = join("_", type.self);
		}

		// Make sure we get something unique for both global name scope and block name scope.
		// See GLSL 4.5 spec: section 4.3.9 for details.
		add_variable(block_ssbo_names, resource_names, buffer_name);

		// If for some reason buffer_name is an illegal name, make a final fallback to a workaround name.
		// This cannot conflict with anything else, so we're safe now.
		// We cannot reuse this fallback name in neither global scope (blocked by block_names) nor block name scope.
		if (buffer_name.empty())
			buffer_name = join("_", type.self);

		block_names.insert(buffer_name);
		block_ssbo_names.insert(buffer_name);

		// Ensure we emit the correct name when emitting non-forward pointer type.
		ir.meta[type.self].decoration.alias = buffer_name;
	}
	else if (type.basetype != SPIRType::Struct)
		buffer_name = type_to_glsl(type);
	else
		buffer_name = to_name(type.self, false);

	if (!forward_declaration)
	{
		auto itr = physical_storage_type_to_alignment.find(type_id);
		uint32_t alignment = 0;
		if (itr != physical_storage_type_to_alignment.end())
			alignment = itr->second.alignment;

		if (type.basetype == SPIRType::Struct)
		{
			SmallVector<std::string> attributes;
			attributes.push_back("buffer_reference");
			if (alignment)
				attributes.push_back(join("buffer_reference_align = ", alignment));
			attributes.push_back(buffer_to_packing_standard(type, true));

			auto flags = ir.get_buffer_block_type_flags(type);
			string decorations;
			if (flags.get(DecorationRestrict))
				decorations += " restrict";
			if (flags.get(DecorationCoherent))
				decorations += " coherent";
			if (flags.get(DecorationNonReadable))
				decorations += " writeonly";
			if (flags.get(DecorationNonWritable))
				decorations += " readonly";

			statement("layout(", merge(attributes), ")", decorations, " buffer ", buffer_name);
		}
		else if (alignment)
			statement("layout(buffer_reference, buffer_reference_align = ", alignment, ") buffer ", buffer_name);
		else
			statement("layout(buffer_reference) buffer ", buffer_name);

		begin_scope();

		if (type.basetype == SPIRType::Struct)
		{
			type.member_name_cache.clear();

			uint32_t i = 0;
			for (auto &member : type.member_types)
			{
				add_member_name(type, i);
				emit_struct_member(type, member, i);
				i++;
			}
		}
		else
		{
			auto &pointee_type = get_pointee_type(type);
			statement(type_to_glsl(pointee_type), " value", type_to_array_glsl(pointee_type), ";");
		}

		end_scope_decl();
		statement("");
	}
	else
	{
		statement("layout(buffer_reference) buffer ", buffer_name, ";");
	}
}

void CompilerGLSL::emit_buffer_block_native(const SPIRVariable &var)
{
	auto &type = get<SPIRType>(var.basetype);

	Bitset flags = ir.get_buffer_block_flags(var);
	bool ssbo = var.storage == StorageClassStorageBuffer || var.storage == StorageClassShaderRecordBufferKHR ||
	            ir.meta[type.self].decoration.decoration_flags.get(DecorationBufferBlock);
	bool is_restrict = ssbo && flags.get(DecorationRestrict);
	bool is_writeonly = ssbo && flags.get(DecorationNonReadable);
	bool is_readonly = ssbo && flags.get(DecorationNonWritable);
	bool is_coherent = ssbo && flags.get(DecorationCoherent);

	// Block names should never alias, but from HLSL input they kind of can because block types are reused for UAVs ...
	auto buffer_name = to_name(type.self, false);

	auto &block_namespace = ssbo ? block_ssbo_names : block_ubo_names;

	// Shaders never use the block by interface name, so we don't
	// have to track this other than updating name caches.
	// If we have a collision for any reason, just fallback immediately.
	if (ir.meta[type.self].decoration.alias.empty() || block_namespace.find(buffer_name) != end(block_namespace) ||
	    resource_names.find(buffer_name) != end(resource_names))
	{
		buffer_name = get_block_fallback_name(var.self);
	}

	// Make sure we get something unique for both global name scope and block name scope.
	// See GLSL 4.5 spec: section 4.3.9 for details.
	add_variable(block_namespace, resource_names, buffer_name);

	// If for some reason buffer_name is an illegal name, make a final fallback to a workaround name.
	// This cannot conflict with anything else, so we're safe now.
	// We cannot reuse this fallback name in neither global scope (blocked by block_names) nor block name scope.
	if (buffer_name.empty())
		buffer_name = join("_", get<SPIRType>(var.basetype).self, "_", var.self);

	block_names.insert(buffer_name);
	block_namespace.insert(buffer_name);

	// Save for post-reflection later.
	declared_block_names[var.self] = buffer_name;

	statement(layout_for_variable(var), is_coherent ? "coherent " : "", is_restrict ? "restrict " : "",
	          is_writeonly ? "writeonly " : "", is_readonly ? "readonly " : "", ssbo ? "buffer " : "uniform ",
	          buffer_name);

	begin_scope();

	type.member_name_cache.clear();

	uint32_t i = 0;
	for (auto &member : type.member_types)
	{
		add_member_name(type, i);
		emit_struct_member(type, member, i);
		i++;
	}

	// var.self can be used as a backup name for the block name,
	// so we need to make sure we don't disturb the name here on a recompile.
	// It will need to be reset if we have to recompile.
	preserve_alias_on_reset(var.self);
	add_resource_name(var.self);
	end_scope_decl(to_name(var.self) + type_to_array_glsl(type));
	statement("");
}

void CompilerGLSL::emit_buffer_block_flattened(const SPIRVariable &var)
{
	auto &type = get<SPIRType>(var.basetype);

	// Block names should never alias.
	auto buffer_name = to_name(type.self, false);
	size_t buffer_size = (get_declared_struct_size(type) + 15) / 16;

	SPIRType::BaseType basic_type;
	if (get_common_basic_type(type, basic_type))
	{
		SPIRType tmp;
		tmp.basetype = basic_type;
		tmp.vecsize = 4;
		if (basic_type != SPIRType::Float && basic_type != SPIRType::Int && basic_type != SPIRType::UInt)
			SPIRV_CROSS_THROW("Basic types in a flattened UBO must be float, int or uint.");

		auto flags = ir.get_buffer_block_flags(var);
		statement("uniform ", flags_to_qualifiers_glsl(tmp, flags), type_to_glsl(tmp), " ", buffer_name, "[",
		          buffer_size, "];");
	}
	else
		SPIRV_CROSS_THROW("All basic types in a flattened block must be the same.");
}

const char *CompilerGLSL::to_storage_qualifiers_glsl(const SPIRVariable &var)
{
	auto &execution = get_entry_point();

	if (subpass_input_is_framebuffer_fetch(var.self))
		return "";

	if (var.storage == StorageClassInput || var.storage == StorageClassOutput)
	{
		if (is_legacy() && execution.model == ExecutionModelVertex)
			return var.storage == StorageClassInput ? "attribute " : "varying ";
		else if (is_legacy() && execution.model == ExecutionModelFragment)
			return "varying "; // Fragment outputs are renamed so they never hit this case.
		else if (execution.model == ExecutionModelFragment && var.storage == StorageClassOutput)
		{
			uint32_t loc = get_decoration(var.self, DecorationLocation);
			bool is_inout = location_is_framebuffer_fetch(loc);
			if (is_inout)
				return "inout ";
			else
				return "out ";
		}
		else
			return var.storage == StorageClassInput ? "in " : "out ";
	}
	else if (var.storage == StorageClassUniformConstant || var.storage == StorageClassUniform ||
	         var.storage == StorageClassPushConstant)
	{
		return "uniform ";
	}
	else if (var.storage == StorageClassRayPayloadKHR)
	{
		return ray_tracing_is_khr ? "rayPayloadEXT " : "rayPayloadNV ";
	}
	else if (var.storage == StorageClassIncomingRayPayloadKHR)
	{
		return ray_tracing_is_khr ? "rayPayloadInEXT " : "rayPayloadInNV ";
	}
	else if (var.storage == StorageClassHitAttributeKHR)
	{
		return ray_tracing_is_khr ? "hitAttributeEXT " : "hitAttributeNV ";
	}
	else if (var.storage == StorageClassCallableDataKHR)
	{
		return ray_tracing_is_khr ? "callableDataEXT " : "callableDataNV ";
	}
	else if (var.storage == StorageClassIncomingCallableDataKHR)
	{
		return ray_tracing_is_khr ? "callableDataInEXT " : "callableDataInNV ";
	}

	return "";
}

void CompilerGLSL::emit_flattened_io_block_member(const std::string &basename, const SPIRType &type, const char *qual,
                                                  const SmallVector<uint32_t> &indices)
{
	uint32_t member_type_id = type.self;
	const SPIRType *member_type = &type;
	const SPIRType *parent_type = nullptr;
	auto flattened_name = basename;
	for (auto &index : indices)
	{
		flattened_name += "_";
		flattened_name += to_member_name(*member_type, index);
		parent_type = member_type;
		member_type_id = member_type->member_types[index];
		member_type = &get<SPIRType>(member_type_id);
	}

	assert(member_type->basetype != SPIRType::Struct);

	// We're overriding struct member names, so ensure we do so on the primary type.
	if (parent_type->type_alias)
		parent_type = &get<SPIRType>(parent_type->type_alias);

	// Sanitize underscores because joining the two identifiers might create more than 1 underscore in a row,
	// which is not allowed.
	ParsedIR::sanitize_underscores(flattened_name);

	uint32_t last_index = indices.back();

	// Pass in the varying qualifier here so it will appear in the correct declaration order.
	// Replace member name while emitting it so it encodes both struct name and member name.
	auto backup_name = get_member_name(parent_type->self, last_index);
	auto member_name = to_member_name(*parent_type, last_index);
	set_member_name(parent_type->self, last_index, flattened_name);
	emit_struct_member(*parent_type, member_type_id, last_index, qual);
	// Restore member name.
	set_member_name(parent_type->self, last_index, member_name);
}

void CompilerGLSL::emit_flattened_io_block_struct(const std::string &basename, const SPIRType &type, const char *qual,
                                                  const SmallVector<uint32_t> &indices)
{
	auto sub_indices = indices;
	sub_indices.push_back(0);

	const SPIRType *member_type = &type;
	for (auto &index : indices)
		member_type = &get<SPIRType>(member_type->member_types[index]);

	assert(member_type->basetype == SPIRType::Struct);

	if (!member_type->array.empty())
		SPIRV_CROSS_THROW("Cannot flatten array of structs in I/O blocks.");

	for (uint32_t i = 0; i < uint32_t(member_type->member_types.size()); i++)
	{
		sub_indices.back() = i;
		if (get<SPIRType>(member_type->member_types[i]).basetype == SPIRType::Struct)
			emit_flattened_io_block_struct(basename, type, qual, sub_indices);
		else
			emit_flattened_io_block_member(basename, type, qual, sub_indices);
	}
}

void CompilerGLSL::emit_flattened_io_block(const SPIRVariable &var, const char *qual)
{
	auto &var_type = get<SPIRType>(var.basetype);
	if (!var_type.array.empty())
		SPIRV_CROSS_THROW("Array of varying structs cannot be flattened to legacy-compatible varyings.");

	// Emit flattened types based on the type alias. Normally, we are never supposed to emit
	// struct declarations for aliased types.
	auto &type = var_type.type_alias ? get<SPIRType>(var_type.type_alias) : var_type;

	auto old_flags = ir.meta[type.self].decoration.decoration_flags;
	// Emit the members as if they are part of a block to get all qualifiers.
	ir.meta[type.self].decoration.decoration_flags.set(DecorationBlock);

	type.member_name_cache.clear();

	SmallVector<uint32_t> member_indices;
	member_indices.push_back(0);
	auto basename = to_name(var.self);

	uint32_t i = 0;
	for (auto &member : type.member_types)
	{
		add_member_name(type, i);
		auto &membertype = get<SPIRType>(member);

		member_indices.back() = i;
		if (membertype.basetype == SPIRType::Struct)
			emit_flattened_io_block_struct(basename, type, qual, member_indices);
		else
			emit_flattened_io_block_member(basename, type, qual, member_indices);
		i++;
	}

	ir.meta[type.self].decoration.decoration_flags = old_flags;

	// Treat this variable as fully flattened from now on.
	flattened_structs[var.self] = true;
}

void CompilerGLSL::emit_interface_block(const SPIRVariable &var)
{
	auto &type = get<SPIRType>(var.basetype);

	if (var.storage == StorageClassInput && type.basetype == SPIRType::Double &&
	    !options.es && options.version < 410)
	{
		require_extension_internal("GL_ARB_vertex_attrib_64bit");
	}

	// Either make it plain in/out or in/out blocks depending on what shader is doing ...
	bool block = ir.meta[type.self].decoration.decoration_flags.get(DecorationBlock);
	const char *qual = to_storage_qualifiers_glsl(var);

	if (block)
	{
		// ESSL earlier than 310 and GLSL earlier than 150 did not support
		// I/O variables which are struct types.
		// To support this, flatten the struct into separate varyings instead.
		if (options.force_flattened_io_blocks || (options.es && options.version < 310) ||
		    (!options.es && options.version < 150))
		{
			// I/O blocks on ES require version 310 with Android Extension Pack extensions, or core version 320.
			// On desktop, I/O blocks were introduced with geometry shaders in GL 3.2 (GLSL 150).
			emit_flattened_io_block(var, qual);
		}
		else
		{
			if (options.es && options.version < 320)
			{
				// Geometry and tessellation extensions imply this extension.
				if (!has_extension("GL_EXT_geometry_shader") && !has_extension("GL_EXT_tessellation_shader"))
					require_extension_internal("GL_EXT_shader_io_blocks");
			}

			// Workaround to make sure we can emit "patch in/out" correctly.
			fixup_io_block_patch_primitive_qualifiers(var);

			// Block names should never alias.
			auto block_name = to_name(type.self, false);

			// The namespace for I/O blocks is separate from other variables in GLSL.
			auto &block_namespace = type.storage == StorageClassInput ? block_input_names : block_output_names;

			// Shaders never use the block by interface name, so we don't
			// have to track this other than updating name caches.
			if (block_name.empty() || block_namespace.find(block_name) != end(block_namespace))
				block_name = get_fallback_name(type.self);
			else
				block_namespace.insert(block_name);

			// If for some reason buffer_name is an illegal name, make a final fallback to a workaround name.
			// This cannot conflict with anything else, so we're safe now.
			if (block_name.empty())
				block_name = join("_", get<SPIRType>(var.basetype).self, "_", var.self);

			// Instance names cannot alias block names.
			resource_names.insert(block_name);

			const char *block_qualifier;
			if (has_decoration(var.self, DecorationPatch))
				block_qualifier = "patch ";
			else if (has_decoration(var.self, DecorationPerPrimitiveEXT))
				block_qualifier = "perprimitiveEXT ";
			else
				block_qualifier = "";

			statement(layout_for_variable(var), block_qualifier, qual, block_name);
			begin_scope();

			type.member_name_cache.clear();

			uint32_t i = 0;
			for (auto &member : type.member_types)
			{
				add_member_name(type, i);
				emit_struct_member(type, member, i);
				i++;
			}

			add_resource_name(var.self);
			end_scope_decl(join(to_name(var.self), type_to_array_glsl(type)));
			statement("");
		}
	}
	else
	{
		// ESSL earlier than 310 and GLSL earlier than 150 did not support
		// I/O variables which are struct types.
		// To support this, flatten the struct into separate varyings instead.
		if (type.basetype == SPIRType::Struct &&
		    (options.force_flattened_io_blocks || (options.es && options.version < 310) ||
		     (!options.es && options.version < 150)))
		{
			emit_flattened_io_block(var, qual);
		}
		else
		{
			add_resource_name(var.self);

			// Legacy GLSL did not support int attributes, we automatically
			// declare them as float and cast them on load/store
			SPIRType newtype = type;
			if (is_legacy() && var.storage == StorageClassInput && type.basetype == SPIRType::Int)
				newtype.basetype = SPIRType::Float;

			// Tessellation control and evaluation shaders must have either
			// gl_MaxPatchVertices or unsized arrays for input arrays.
			// Opt for unsized as it's the more "correct" variant to use.
			if (type.storage == StorageClassInput && !type.array.empty() &&
			    !has_decoration(var.self, DecorationPatch) &&
			    (get_entry_point().model == ExecutionModelTessellationControl ||
			     get_entry_point().model == ExecutionModelTessellationEvaluation))
			{
				newtype.array.back() = 0;
				newtype.array_size_literal.back() = true;
			}

			statement(layout_for_variable(var), to_qualifiers_glsl(var.self),
			          variable_decl(newtype, to_name(var.self), var.self), ";");
		}
	}
}

void CompilerGLSL::emit_uniform(const SPIRVariable &var)
{
	auto &type = get<SPIRType>(var.basetype);
	if (type.basetype == SPIRType::Image && type.image.sampled == 2 && type.image.dim != DimSubpassData)
	{
		if (!options.es && options.version < 420)
			require_extension_internal("GL_ARB_shader_image_load_store");
		else if (options.es && options.version < 310)
			SPIRV_CROSS_THROW("At least ESSL 3.10 required for shader image load store.");
	}

	add_resource_name(var.self);
	statement(layout_for_variable(var), variable_decl(var), ";");
}

string CompilerGLSL::constant_value_macro_name(uint32_t id)
{
	return join("SPIRV_CROSS_CONSTANT_ID_", id);
}

void CompilerGLSL::emit_specialization_constant_op(const SPIRConstantOp &constant)
{
	auto &type = get<SPIRType>(constant.basetype);
	add_resource_name(constant.self);
	auto name = to_name(constant.self);
	statement("const ", variable_decl(type, name), " = ", constant_op_expression(constant), ";");
}

int CompilerGLSL::get_constant_mapping_to_workgroup_component(const SPIRConstant &c) const
{
	auto &entry_point = get_entry_point();
	int index = -1;

	// Need to redirect specialization constants which are used as WorkGroupSize to the builtin,
	// since the spec constant declarations are never explicitly declared.
	if (entry_point.workgroup_size.constant == 0 && entry_point.flags.get(ExecutionModeLocalSizeId))
	{
		if (c.self == entry_point.workgroup_size.id_x)
			index = 0;
		else if (c.self == entry_point.workgroup_size.id_y)
			index = 1;
		else if (c.self == entry_point.workgroup_size.id_z)
			index = 2;
	}

	return index;
}

void CompilerGLSL::emit_constant(const SPIRConstant &constant)
{
	auto &type = get<SPIRType>(constant.constant_type);

	SpecializationConstant wg_x, wg_y, wg_z;
	ID workgroup_size_id = get_work_group_size_specialization_constants(wg_x, wg_y, wg_z);

	// This specialization constant is implicitly declared by emitting layout() in;
	if (constant.self == workgroup_size_id)
		return;

	// These specialization constants are implicitly declared by emitting layout() in;
	// In legacy GLSL, we will still need to emit macros for these, so a layout() in; declaration
	// later can use macro overrides for work group size.
	bool is_workgroup_size_constant = ConstantID(constant.self) == wg_x.id || ConstantID(constant.self) == wg_y.id ||
	                                  ConstantID(constant.self) == wg_z.id;

	if (options.vulkan_semantics && is_workgroup_size_constant)
	{
		// Vulkan GLSL does not need to declare workgroup spec constants explicitly, it is handled in layout().
		return;
	}
	else if (!options.vulkan_semantics && is_workgroup_size_constant &&
	         !has_decoration(constant.self, DecorationSpecId))
	{
		// Only bother declaring a workgroup size if it is actually a specialization constant, because we need macros.
		return;
	}

	add_resource_name(constant.self);
	auto name = to_name(constant.self);

	// Only scalars have constant IDs.
	if (has_decoration(constant.self, DecorationSpecId))
	{
		if (options.vulkan_semantics)
		{
			statement("layout(constant_id = ", get_decoration(constant.self, DecorationSpecId), ") const ",
			          variable_decl(type, name), " = ", constant_expression(constant), ";");
		}
		else
		{
			const string &macro_name = constant.specialization_constant_macro_name;
			statement("#ifndef ", macro_name);
			statement("#define ", macro_name, " ", constant_expression(constant));
			statement("#endif");

			// For workgroup size constants, only emit the macros.
			if (!is_workgroup_size_constant)
				statement("const ", variable_decl(type, name), " = ", macro_name, ";");
		}
	}
	else
	{
		statement("const ", variable_decl(type, name), " = ", constant_expression(constant), ";");
	}
}

void CompilerGLSL::emit_entry_point_declarations()
{
}

void CompilerGLSL::replace_illegal_names