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* SPIRVToMSLConverter.h
* Copyright (c) 2014-2018 The Brenwill Workshop Ltd. (
* 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#ifndef __SPIRVToMSLConverter_h_
#define __SPIRVToMSLConverter_h_ 1
#include "spirv.hpp"
#include <string>
#include <vector>
#include <unordered_map>
namespace mvk {
#pragma mark -
#pragma mark SPIRVToMSLConverterContext
/** Options for converting SPIR-V to Metal Shading Language */
typedef struct SPIRVToMSLConverterOptions {
std::string entryPointName;
spv::ExecutionModel entryPointStage = spv::ExecutionModelMax;
uint32_t mslVersion = makeMSLVersion(2);
uint32_t texelBufferTextureWidth = 4096;
uint32_t auxBufferIndex = 0;
bool shouldFlipVertexY = true;
bool isRenderingPoints = false;
bool isRasterizationDisabled = false;
bool needsAuxBuffer = false;
* Returns whether the specified options match this one.
* It does if all corresponding elements are equal.
bool matches(const SPIRVToMSLConverterOptions& other) const;
bool hasEntryPoint() const {
return !entryPointName.empty() && entryPointStage != spv::ExecutionModelMax;
void setMSLVersion(uint32_t major, uint32_t minor = 0, uint32_t point = 0) {
mslVersion = makeMSLVersion(major, minor, point);
bool supportsMSLVersion(uint32_t major, uint32_t minor = 0, uint32_t point = 0) const {
return mslVersion >= makeMSLVersion(major, minor, point);
static uint32_t makeMSLVersion(uint32_t major, uint32_t minor = 0, uint32_t patch = 0) {
return (major * 10000) + (minor * 100) + patch;
} SPIRVToMSLConverterOptions;
* Defines MSL characteristics of a vertex attribute at a particular location.
* The isUsedByShader flag is set to true during conversion of SPIR-V to MSL
* if the shader makes use of this vertex attribute.
typedef struct MSLVertexAttribute {
uint32_t location = 0;
uint32_t mslBuffer = 0;
uint32_t mslOffset = 0;
uint32_t mslStride = 0;
bool isPerInstance = false;
bool isUsedByShader = false;
* Returns whether the specified vertex attribute match this one.
* It does if all corresponding elements except isUsedByShader are equal.
bool matches(const MSLVertexAttribute& other) const;
} MSLVertexAttribute;
* Matches the binding index of a MSL resource for a binding within a descriptor set.
* Taken together, the stage, desc_set and binding combine to form a reference to a resource
* descriptor used in a particular shading stage. Generally, only one of the buffer, texture,
* or sampler elements will be populated. The isUsedByShader flag is set to true during
* compilation of SPIR-V to MSL if the shader makes use of this vertex attribute.
typedef struct MSLResourceBinding {
spv::ExecutionModel stage;
uint32_t descriptorSet = 0;
uint32_t binding = 0;
uint32_t mslBuffer = 0;
uint32_t mslTexture = 0;
uint32_t mslSampler = 0;
bool isUsedByShader = false;
* Returns whether the specified resource binding match this one.
* It does if all corresponding elements except isUsedByShader are equal.
bool matches(const MSLResourceBinding& other) const;
} MSLResourceBinding;
/** Context passed to the SPIRVToMSLConverter to map SPIR-V descriptors to Metal resource indices. */
typedef struct SPIRVToMSLConverterContext {
SPIRVToMSLConverterOptions options;
std::vector<MSLVertexAttribute> vertexAttributes;
std::vector<MSLResourceBinding> resourceBindings;
/** Returns whether the vertex attribute at the specified location is used by the shader. */
bool isVertexAttributeLocationUsed(uint32_t location) const;
/** Returns whether the vertex buffer at the specified Metal binding index is used by the shader. */
bool isVertexBufferUsed(uint32_t mslBuffer) const;
* Returns whether this context matches the other context. It does if the respective
* options match and any vertex attributes and resource bindings used by this context
* can be found in the other context. Vertex attributes and resource bindings that are
* in the other context but are not used by the shader that created this context, are ignored.
bool matches(const SPIRVToMSLConverterContext& other) const;
/** Aligns certain aspects of this context with the source context. */
void alignWith(const SPIRVToMSLConverterContext& srcContext);
} SPIRVToMSLConverterContext;
* Describes one dimension of the workgroup size of a SPIR-V entry point, including whether
* it is specialized, and if so, the value of the corresponding specialization ID, which
* is used to map to a value which will be provided when the MSL is compiled into a pipeline.
typedef struct {
uint32_t size = 1;
uint32_t specializationID = 0;
bool isSpecialized = false;
} SPIRVWorkgroupSizeDimension;
* Describes a SPIRV entry point, including the Metal function name (which may be
* different than the Vulkan entry point name if the original name was illegal in Metal),
* and the size of each workgroup, if the shader is a compute shader.
typedef struct {
std::string mtlFunctionName = "main0";
struct {
SPIRVWorkgroupSizeDimension width;
SPIRVWorkgroupSizeDimension height;
SPIRVWorkgroupSizeDimension depth;
} workgroupSize;
} SPIRVEntryPoint;
/** Special constant used in a MSLResourceBinding descriptorSet element to indicate the bindings for the push constants. */
static const uint32_t kPushConstDescSet = std::numeric_limits<uint32_t>::max();
/** Special constant used in a MSLResourceBinding binding element to indicate the bindings for the push constants. */
static const uint32_t kPushConstBinding = 0;
#pragma mark -
#pragma mark SPIRVToMSLConverter
/** Converts SPIR-V code to Metal Shading Language code. */
class SPIRVToMSLConverter {
/** Sets the SPIRV code. */
void setSPIRV(const std::vector<uint32_t>& spirv);
* Sets the SPIRV code from the specified array of values.
* The length parameter indicates the number of uint values to store.
void setSPIRV(const uint32_t* spirvCode, size_t length);
/** Returns a reference to the SPIRV code, set by one of the setSPIRV() functions. */
const std::vector<uint32_t>& getSPIRV();
* Converts SPIR-V code, set using setSPIRV() to MSL code, which can be retrieved using getMSL().
* The boolean flags indicate whether the original SPIR-V code, the resulting MSL code,
* and optionally, the original GLSL (as converted from the SPIR_V), should be logged
* to the result log of this converter. This can be useful during shader debugging.
bool convert(SPIRVToMSLConverterContext& context,
bool shouldLogSPIRV = false,
bool shouldLogMSL = false,
bool shouldLogGLSL = false);
* Returns the Metal Shading Language source code most recently converted
* by the convert() function, or set directly using the setMSL() function.
const std::string& getMSL() { return _msl; }
/** Returns information about the shader entry point. */
const SPIRVEntryPoint& getEntryPoint() { return _entryPoint; }
* Returns whether the most recent conversion was successful.
* The initial value of this property is NO. It is set to YES upon successful conversion.
bool getWasConverted() { return _wasConverted; }
* Returns a human-readable log of the most recent conversion activity.
* This may be empty if the conversion was successful.
const std::string& getResultLog() { return _resultLog; }
/** Sets MSL source code. This can be used when MSL is supplied directly. */
void setMSL(const std::string& msl, const SPIRVEntryPoint* pEntryPoint) {
_msl = msl;
if (pEntryPoint) { _entryPoint = *pEntryPoint; }
void logMsg(const char* logMsg);
bool logError(const char* errMsg);
void logSPIRV(const char* opDesc);
bool validateSPIRV();
void writeSPIRVToFile(std::string spvFilepath);
void logSource(std::string& src, const char* srcLang, const char* opDesc);
std::vector<uint32_t> _spirv;
std::string _msl;
std::string _resultLog;
SPIRVEntryPoint _entryPoint;
bool _wasConverted = false;
#pragma mark Support functions
/** Appends the SPIR-V in human-readable form to the specified log string. */
void logSPIRV(std::vector<uint32_t>& spirv, std::string& spvLog);
/** Converts the SPIR-V code to an array of bytes (suitable for writing to a file). */
void spirvToBytes(const std::vector<uint32_t>& spv, std::vector<char>& bytes);
/** Converts an array of bytes (as read from a file) to SPIR-V code. */
void bytesToSPIRV(const std::vector<char>& bytes, std::vector<uint32_t>& spv);
* Ensures that the specified SPIR-V code has the correct endianness for this system,
* and converts it in place if necessary. This can be used after loading SPIR-V code
* from a file that may have been encoded on a system with the opposite endianness.
* This function tests for the SPIR-V magic number (in both endian states) to determine
* whether conversion is required. It will not convert arrays of uint32_t values that
* are not SPIR-V code.
* Returns whether the endianness was changed.
bool ensureSPIRVEndianness(std::vector<uint32_t>& spv);