Support Workgroup (threadgroup) variables.
Mark if SPIRConstant is used as an array length, since it cannot be specialized.
Resolve specialized array length constants.
Support passing an array to MSL function.
Support emitting GLSL array assignments in MSL via an array copy function.
Support for memory and control barriers.
Struct packing enhancements, including packing nested structs.
Enhancements to replacing illegal MSL variable and function names.
Add Compiler::get_entry_point_name_map() function to retrieve entry point renamings.
Remove CompilerGLSL::clean_func_name() as obsolete.
Fixes to types in bitcast MSL functions.
Add Variant::get_id() member function.
Add CompilerMSL::Options::msl_version option.
Add numerous MSL compute tests.
They might potentially be used as part of OpStore in the SPIRV-Tools
inliner in some cases.
Implement these as declared variables but without any initializer.
CompilerGLSL type_to_glsl() and image_type_glsl() functions support optional object ID.
Add SPIRType::Image::access member to support SPIR-V OpTypeImage access qualifier.
Remove SPIRType::Image::is_read and ::is_written members.
Use DecorationNonReadable and DecorationNonWritable to mark read/write access for image variables.
CompilerMSL emit access qualifiers per image variable, instead of per image type.
CompilerGLSL and CompilerHLSL behaviour is unchanged.
Add bool members is_read and is_written to SPIRType::Image.
Output correct texture read/write access by marking whether textures
are read from and written to by the shader.
Override bitcast_glsl_op() to use Metal as_type<type> functions.
Add implementations of SPIR-V functions inverse(), degrees() & radians().
Map inverseSqrt() to rsqrt().
Map roundEven() to rint().
GLSL functions imageSize() and textureSize() map to equivalent
expression using MSL get_width() & get_height() functions.
Map several SPIR-V integer bitfield functions to MSL equivalents.
Map SPIR-V atomic functions to MSL equivalents.
Map texture packing and unpacking functions to MSL equivalents.
Refactor existing, and add new, image query functions.
Reorganize header lines into includes and pragmas.
Simplify type_to_glsl() logic.
Add MSL test case vert/functions.vert for added function implementations.
Add MSL test case comp/atomic.comp for added function implementations.
test_shaders.py use macOS compilation for MSL shader compilation validations.
This is kinda tricky, because if we only conditionally write to a
function parameter variable it is implicitly preserved in SPIR-V, so we must force
an in qualifier on the parameter to get the same behavior in GLSL.