Structs are aligned as you would expect in MSL (maximum member
alignment), and it is not minimum 16 bytes like in std140.
Also rename the dummy "pad" members to a reserved naming scheme.
This is a fairly fundamental change on how IDs are handled.
It serves many purposes:
- Improve performance. We only need to iterate over IDs which are
relevant at any one time.
- Makes sure we iterate through IDs in SPIR-V module declaration order
rather than ID space. IDs don't have to be monotonically increasing,
which was an assumption SPIRV-Cross used to have. It has apparently
never been a problem until now.
- Support LUTs of structs. We do this by interleaving declaration of
constants and struct types in SPIR-V module order.
To support this, the ParsedIR interface needed to change slightly.
Before setting any ID with variant_set<T> we let ParsedIR know
that an ID with a specific type has been added. The surface for change
should be minimal.
ParsedIR will maintain a per-type list of IDs which the cross-compiler
will need to consider for later.
Instead of looping over ir.ids[] (which can be extremely large), we loop
over types now, using:
ir.for_each_typed_id<SPIRVariable>([&](uint32_t id, SPIRVariable &var) {
handle_variable(var);
});
Now we make sure that we're never looking at irrelevant types.
A lot of changes in spirv-opt output.
Some new invalid SPIR-V was found but most of them were not significant
for SPIRV-Cross, so just marked them as invalid.
Implement this by flattening outputs and unflattening inputs explicitly.
This allows us to pass down a single struct instead of dealing with the
insanity that would be passing down each flattened member separately.
Remove stage_uniforms_var_id.
Seems to be dead code. Naked uniforms do not exist in SPIR-V for Vulkan,
which this seems to have been intended for. It was also unused elsewhere.
Certain patterns with OpVectorShuffle (and probably others) will cascade
to so large, that they can cause OOM. After we have observed
force_recompile, don't spend unnecessary memory emitting code which will
never be used.