Metal 3.1 introduced a Metal regression bug which causes an infinite recursion
crash during Metal's analysis of an entry point input structure that itself
contains internal recursion. This patch works around this by replacing the
recursive input declaration with a alternate variable of type void*, and
then casting to the correct type at the top of the entry point function.
- Add CompilerMSL::Options::replace_recursive_inputs to enable
replacing recursive input.
- Add Compiler::type_contains_recursion() to determine if a struct
contains internal recursion, and add custom Decorations to mark
such structs, to short-cut future similar checks.
- Replace recursive input struct declarations with void*,
and emit a recast to correct type at top of entry function.
- Add unit test.
- Compiler::type_is_top_level_block() remove hardcode reference to spirv_cross
namespace, as it interferes with configurable namespaces (unrelated).
Normally, I wouldn't have bothered with this, given that we already
support the Vulkan 1.1 subgroup functionality, but a client asked for
the legacy extensions.
It is possible in SPIR-V to declare multiple specialization constants
with the same constant ID. The most common cause of this in GLSL is
defining a spec constant, then declaring the workgroup size to use that
spec constant by its ID. But, MSL forbids defining multiple function
constants with the same function constant ID. So, we must only emit one
definition of the actual function constant (with the
`[[function_constant(id)]]` attribute); but we can point the other
variables at this one definition.
Fixes three tests in the Vulkan CTS under
`dEQP-VK.compute.basic.max_local_size_*`.
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.
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.
- Determine sizing and alignments of pointers to types as
distinct from the size and alignment of the types themselves.
- Declare all buffer pointers in the MSL device address space.
- Support struct pointer recursion, where structs can
contain pointers to themselves or to a parent struct.
- Add SPIRType::was_forward_referenced to track if a type was forward
referenced, to help emit MSL structs in the correct dependency order.
- Handle pointers to pointers that are not just arrays of arrays.
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.
Here, the inline uniform block is explicit: we instantiate the buffer
block itself in the argument buffer, instead of a pointer to the buffer.
I just hope this will work with the `MTLArgumentDescriptor` API...
Note that Metal recursively assigns individual members of embedded
structs IDs. This means for automatic assignment that we have to
calculate the binding stride for a given buffer block. For MoltenVK,
we'll simply increment the ID by the size of the inline uniform block.
Then the later IDs will never conflict with the inline uniform block. We
can get away with this because Metal doesn't require that IDs be
contiguous, only monotonically increasing.
Rolled the hashes used for glslang, SPIRV-Tools, and SPIRV-Headers to
HEAD, which includes the update to 1.5.
Added passing '--amb' to glslang, so I didn't have to explicitly set
bindings in a large number of test shaders that currently don't, and
now glslang considers them invalid.
Marked all shaders that no longer pass spirv-val as .invalid.
Vulkan has two types of buffer descriptors,
`VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER_DYNAMIC` and
`VK_DESCRIPTOR_TYPE_STORAGE_BUFFER_DYNAMIC`, which allow the client to
offset the buffers by an amount given when the descriptor set is bound
to a pipeline. Metal provides no direct support for this when the buffer
in question is in an argument buffer, so once again we're on our own.
These offsets cannot be stored or associated in any way with the
argument buffer itself, because they are set at bind time. Different
pipelines may have different offsets set. Therefore, we must use a
separate buffer, not in any argument buffer, to hold these offsets. Then
the shader must manually offset the buffer pointer.
This change fully supports arrays, including arrays of arrays, even
though Vulkan forbids them. It does not, however, support runtime
arrays. Perhaps later.
Writable textures cannot use argument buffers on iOS. They must be
passed as arguments directly to the shader function. Since we won't know
if a given storage image will have the `NonWritable` decoration at the
time we encode the argument buffer, we must therefore pass all storage
images as discrete arguments. Previously, we were throwing an error if
we encountered an argument buffer with a writable texture in it on iOS.
This command allows the caller to set the base value of
`BuiltInWorkgroupId`, and thus of `BuiltInGlobalInvocationId`. Metal
provides no direct support for this... but it does provide a builtin,
`[[grid_origin]]`, normally used to pass the base values for the stage
input region, which we will now abuse to pass the dispatch base and
avoid burning a buffer binding.
`[[grid_origin]]`, as part of Metal's support for compute stage input,
requires MSL 1.2. For 1.0 and 1.1, we're forced to provide a buffer.
(Curiously, this builtin was undocumented until the MSL 2.2 release. Go
figure.)
This gets rather complicated because MSL does not support OpArrayLength
natively. We need to pass down a buffer which contains buffer sizes, and
we compute the array length on-demand.
Support both discrete descriptors as well as argument buffers.
Some support for subgroups is present starting in Metal 2.0 on both iOS
and macOS. macOS gains more complete support in 10.14 (Metal 2.1).
Some restrictions are present. On iOS and on macOS 10.13, the
implementation of `OpGroupNonUniformElect` is incorrect: if thread 0 has
already terminated or is not executing a conditional branch, the first
thread that *is* will falsely believe itself not to be. Unfortunately,
this operation is part of the "basic" feature set; without it, subgroups
cannot be supported at all.
The `SubgroupSize` and `SubgroupLocalInvocationId` builtins are only
available in compute shaders (and, by extension, tessellation control
shaders), despite SPIR-V making them available in all stages. This
limits the usefulness of some of the subgroup operations in fragment
shaders.
Although Metal on macOS supports some clustered, inclusive, and
exclusive operations, it does not support them all. In particular,
inclusive and exclusive min, max, and, or, and xor; as well as cluster
sizes other than 4 are not supported. If this becomes a problem, they
could be emulated, but at a significant performance cost due to the need
for non-uniform operations.
