Some Metal devices have a bug where storage resources can still be
written to even if the fragment is discarded. This is obviously a bug in
Metal, but bothering Apple to fix it will only fix it for newer
versions; therefore, a workaround is needed for older versions. I have
made this an option so that, in case the bug is ever fixed, the
workaround can be disabled.
This workaround is simple: if a fragment shader may discard its fragment
and writes to a storage resource, a variable representing the
`HelperInvocation` built-in is created and passed to all functions. The
flag is checked on all resource writes; writes do not occur when
`HelperInvocation` is `true`. This relies on the earlier workaround to
update `HelperInvocation` when the fragment is discarded.
Fixes at least 3 failures in the CTS.
Some Metal devices have a bug where `simd_is_helper_thread()` won't
return true after a fragment has been discarded. We can work around this
by manually setting `gl_HelperInvocation` upon discarding a fragment.
This is fairly unintrusive, so it is enabled by default. I've made it an
option so that, when the bug is fixed, we can disable it.
restrict was supported, but it broke in MSL 3.0. __restrict works on all
versions, so opt for that instead.
Also check for RestrictPointer decoration and refactor to_restrict() to
not take optional parameter to make it more obvious when implied space
character is added.
Flattening doesn't play well with dynamic indices. In this case, it's
better to leave it as an array of structs.
(I wanted to do this for named blocks generally. Trouble is, the builtin
`gl_out` block is *also* a named block...)
Fixes six more CTS tests, under
`dEQP-VK.tessellation.user_defined_io.per_patch_block_array.*`.
Using vertex-style stage input is complex, and it doesn't support
nesting of structures or arrays. By using raw buffer input instead, we
get this support "for free," and everything becomes much simpler.
Arguably, this is the way I should've done this in the first place.
Eventually, I'd like to make this the default, and then remove the
option altogether. (And I still need to do that with
`multi_patch_workgroup`...)
Should help fix 66 tests in the Vulkan CTS, under the following trees:
- `dEQP-VK.pipeline.*.interface_matching.*`
- `dEQP-VK.tessellation.user_defined_io.*`
- `dEQP-VK.clipping.user_defined.*`
It is allowed to redeclare descriptors with different types in Vulkan.
MSL in general does not allow this, but for raw buffers, we can cast the
reference type at the very least.
For typed resources we are kinda hosed. Without descriptor indexing's
PARTIALLY_BOUND_BIT, descriptors must be valid if they are statically
accessed, so it would not be valid to access differently typed aliases
unless that flag is used. There might be a way to reinterpret cast
descriptors, but that seems very sketchy.
Implements support for:
- Single discrete descriptor
- Single argument buffer descriptor
- Array of argument buffer descriptors
Other cases are unimplemented for now since they are extremely painful
to unroll.
- Add CompilerMSL::emit_binary_ptr_op() and to_ptr_expression()
to emit binary pointer op. Compare matrix addresses without automatic
transpose() conversion, to avoid error taking address of temporary copy.
- Add Compiler::add_active_interface_variable() to also track active
interface vars in the entry point for SPIR-V 1.4 and above.
- For OpPtrAccessChain that ends in array element, use Element
as offset to existing index, otherwise it will access into
array dimension that doesn't exist.
- Dereference pointer function call arguments. Ultimately, this
dereferencing is actually backwards, and in future, we should aim
to properly support passing pointer variables between functions,
but such a refactoring was beyond the scope here.
- Use [] to declare array of pointers, as array<T*> is not supported in MSL.
- Add unit test shaders.
This is analogous to the existing support for fixing up shader inputs.
It is intended to be used with tessellation to add implicit builtins
that are read from a later stage, despite not being written in an
earlier stage. (Believe it or not, this is in fact legal in Vulkan.)
Helps fix 8 CTS tests under `dEQP-VK.pipeline.*.no_position`. (Eight
other tests work solely by accident without this change.)
The standard `matrix` type in MSL lacked a constructor in the
`threadgroup` AS. This means that it was impossible to declare a
`threadgroup` variable that contains a matrix. This appears to have been
an oversight that was corrected in macOS 13/Xcode 14 beta 4. This
workaround continues to be required, however, for older systems.
To avoid changing interfaces unnecessarily (which shouldn't be a problem
regardless because the old and new types take up the same amount of
storage), only do this for structs if the struct is positively
identified as being used for workgroup storage.
I'm entirely aware this is inconsistent with the way packed matrices are
handled. One of them should be changed to match the other. Not sure
which one.
Fixes 23 CTS tests under `dEQP-VK.memory_model.shared`.
Since `bool` is a logical type, it cannot be used in uniform or storage
buffers. Therefore, replacing it in structures should not change the
shader interface.
We leave it alone for builtins. (FIXME: Should we also leave it for
I/O varyings?)
Fixes 24 CTS tests under `dEQP-VK.memory_model.shared`.
- Assign ulongn physical type to buffer pointers in short arrays
when array stride is larger than pointer size.
- Support GL_EXT_buffer_reference_uvec2 casting
buffer reference pointers to and from uvec2 values.
- When packing structs, include structs inside physical buffers.
- Update mechanism for traversing pointer arrays when calculating type sizes.
- Added unit test shaders.
Fixes numerous CTS tests of types
dEQP-VK.pipeline.interface_matching.vector_length.member_of_*,
passing complex nested structs between stages as stage I/O.
- Make add_composite_member_variable_to_interface_block() recursive to allow
struct members to contain nested structs, building up member names and access
chains recursively, and only add the resulting flattened leaf members to the
synthetic input and output interface blocks.
- Recursively generate individual location numbers for the flattened members
of the input/output block.
- Replace to_qualified_member_name() with append_member_name().
- Update add_variable_to_interface_block() to support arrays as struct members,
adding a member to input and output interface blocks for each element of the array.
- Pass name qualifiers to add_plain_member_variable_to_interface_block() to allow
struct members to be arrays of structs, building up member names and access chains,
and adding multiple distinct flattened leaf members to the synthetic input and
output interface blocks.
- Generate individual location numbers for the individual array members
of the input/output block.
- SPIRVCrossDecorationInterfaceMemberIndex references the index of a member
of a variable that is a struct type. The value is relative to the variable,
and for structs nested within that top-level struct, the index value needs
to take into consideration the members within those nested structs.
- Pass var_mbr_idx to add_plain_member_variable_to_interface_block() and
add_composite_member_variable_to_interface_block(), start at zero for each
variable, and increment for each member or nested member within that variable.
- Add unit test shaders-msl/vert/out-block-with-nested-struct-array.vert
- Add unit test shaders-msl/vert/out-block-with-struct-array.vert
- Add unit test shaders-msl/tese/in-block-with-nested-struct.tese
We were passing arrays by value which the compiler fails to optimize,
causing abyssal performance. To fix this, we need to consider that
descriptors can be in constant or const device address spaces.
Also, lone descriptors are passed by value, so we explicitly remove address
space qualifiers.
One failure case is when shader passes a texture/sampler array as an
argument. It's all UniformConstant in SPIR-V, but in MSL it might be
thread, const device or constant, so that won't work ...
Global variable use works fine though, and that should cover 99.9999999%
of use cases.
Fragment shaders that require explicit early fragment tests are incompatible
with specifying depth and stencil values within the shader. If explicit early
fragment tests is specified, remove the depth and stencil outputs from the
output structure, and replace them with dummy local variables.
Add CompilerMSL:uses_explicit_early_fragment_test() function to consolidate
testing for whether early fragment tests are required.
Add two unit tests for depth-out with, and without, early fragment tests.
Promote to short instead and do simple casts on load/store instead.
Not 100% complete fix since structs can contain booleans, but this is
getting into pretty ridiculously complicated territory.
Add spvQuantizeToF16() family of synthetic functions to convert
from float to half and back again, and add function attribute
[[clang::optnone]] to honor infinities during conversions.
Adjust SPIRV-Cross unit test reference shaders to accommodate these changes.
Matching output/input struct member types between shader stages could fail if
a location is shared between members, each using different components of that
location, because the member vecsize was only stored once for the location.
Add MSLShaderInput::component member.
Use LocationComponentPair to key inputs_by_location, instead of just location.
ensure_correct_input_type() pass component value as well as location.
Vulkan specifies that the Sample Mask Test occurs before fragment shading.
This means gl_SampleMaskIn should be influenced by both sample-shading and
VkPipelineMultisampleStateCreateInfo::pSampleMask.
CTS tests dEQP-VK.pipeline.multisample_shader_builtin.* bear this out.
For sample-shading, gl_SampleMaskIn should only have a single bit set,
Since Metal does not filter for this, apply a bitmask based on gl_SampleID.
For a fixed sample mask, since Metal is unaware of
VkPipelineMultisampleStateCreateInfo::pSampleMask, we need to ensure that
we apply it to both gl_SampleMaskIn and gl_SampleMask. This has the side
effect of a redundant application of pSampleMask if the shader already
includes gl_SampleMaskIn when setting gl_SampleMask, but I don't see an
easy way around this.
Also, simplify the logic for including the fixed sample mask in gl_ShaderMask,
and print the fixed sample mask as a hex value for readability of bits.
We'll need to force a temporary and mark it as precise.
MSL is a little weird here, but we can piggyback on top of the invariant
float math option here to force fma() operations everywhere.
Firstly, never flatten inputs or outputs in multi-patch mode.
The main scenario where we do need to care is Block IO.
In this case, we should only flatten the top-level member, and after
that we use access chains as normal.
Using structs in Input storage class is now possible as well. We don't
need to consider per-location fixups at all here. In Vulkan, IO structs
must match exactly. Only plain vectors can have smaller vector sizes as
a special case.
