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.
This allows shaders to declare and use pointer-type variables. Pointers
may be loaded and stored, be the result of an `OpSelect`, be passed to
and returned from functions, and even be passed as inputs to the `OpPhi`
instruction. All types of pointers may be used as variable pointers.
Variable pointers to storage buffers and workgroup memory may even be
loaded from and stored to, as though they were ordinary variables. In
addition, this enables using an interior pointer to an array as though
it were an array pointer itself using the `OpPtrAccessChain`
instruction.
This is a rather large and involved change, mostly because this is
somewhat complicated with a lot of moving parts. It's a wonder
SPIRV-Cross's output is largely unchanged. Indeed, many of these changes
are to accomplish exactly that! Perhaps the largest source of changes
was the violation of the assumption that, when emitting types, the
pointer type didn't matter.
One of the test cases added by the change doesn't optimize very well;
the output of `spirv-opt` here is invalid SPIR-V. I need to file a bug
with SPIRV-Tools about this.
I wanted to test that variable pointers to images worked too, but I
couldn't figure out how to propagate the access qualifier properly--in
MSL, it's part of the type, so getting this right is important. I've
punted on that for now.
Just like OpAccessChain we need to make use of the meta information
available to use from access_chain_internal as we can extract a packed
vector or transposed vector from a composite, not just memory load.
A block name cannot alias with any name in its own scope,
and it cannot alias with any other "global" name.
To solve this, we need to complicate the name cache updates a little bit
where we have a "primary" namespace and "secondary" namespace.
This is required to avoid relying on complex sub-expression elimination
in compilers, and generates cleaner code.
The problem case is if a complex expression is used in an access chain,
like:
Composite comp = buffer[texture(...)];
vec4 a = comp.a + comp.b + comp.c;
Before, we did not have common subexpression tracking for
OpLoad/OpAccessChain, so we easily ended up with code like:
vec4 a = buffer[texture(...)].a + buffer[texture(...)].b + buffer[texture(...)].c;
A good compiler will optimize this, but we should not rely on it, and
forcing texture(...) to a temporary also looks better.
The solution is to add a vector "implied_expression_reads", which works
similarly to expression_dependencies. We also need an extra mechanism in
to_expression which lets us skip expression read checking and do it
later. E.g. for expr -> access chain -> load, we should only trigger
a read of expr when using the loaded expression.
Avoids certain cases of variance between translation units by forcing
every dependent expression of a store to be temporary.
Should avoid the major failure cases where invariance matters.
Don't use `addsat()`/`subsat()`; that'll erroneously flag cases where
the sum is exactly the maximum integer value, or the difference is
exactly 0. Also, correct the condition for the `select()` function; it's
basically `mix()` with a boolean factor.
(What was I *thinking*?)
In GLSL, 8-bit types require GL_EXT_shader_8bit_storage. 16-bit types
can use either GL_AMD_gpu_shader_int16/GL_AMD_gpu_shader_half_float or
GL_EXT_shader_16bit_storage.
When trying to validate buffer sizes, we usually need to bail out when
using SpecConstantOps, but for some very specific cases where we allow
unsized arrays currently, we can safely allow "unknown" sized arrays as
well.
This is probably the best we can do, when we have even more difficult
cases than this, we throw a more sensible error message.
Previously, when generating non-Vulkan GLSL, each use of a spec constant
would be subsituted for its default value and the declaration of the constant
itself would be omitted completely.
This change slightly alters this behavior. The uses of the constant are kept,
as well as the declaration, although the latter is stripped of the layout
qualifier. The declaration is also prepended with the following code:
#ifndef <constant name>_value
#define <constant name> <default constant value>
#endif
and the constant itself now looks like
const <constant type> <constant name> = <constant name>_value;
The rationale for this change is that it gives the user a way to provide
custom values for specialization constants even when the target does not
support them.
- Add new Windows support
- Use CMake/CTest instead of Make + shell scripts
- Use --parallel in CTest
- Fix CTest on Windows
- Cleanups in test_shaders.py
- Force specific commit for SPIRV-Headers
- Fix Inf/NaN odd-ball case by moving to ASM
HLSL just picked the variable name which did not work as expected for
some users. Use the same logic as GLSL and set up declared_block_names,
so the actual name can be queried later.
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.
Even as of Metal 2.1, MSL still doesn't support arrays of buffers
directly. Therefore, we must manually expand them. In the prologue, we
define arrays holding the argument pointers; these arrays are what the
transpiled code ends up referencing. We might be able to do similar
things for textures and samplers prior to MSL 2.0.
Speaking of which, also enable texture arrays on iOS MSL 1.2.
It'll be useful to have an "auxiliary buffer" for other builtins--e.g.
`DrawIndex` (which should be easier to implement now), or `ViewIndex`
when someone gets around to implementing multiview.
Pass this buffer to leaf functions as well.
Test that we handle this for integer textures as well.
It's intended to be used with MoltenVK to support arbitrary
`VkComponentMapping` settings. The idea is that MoltenVK will pass a
buffer (which it set to some buffer index that isn't being used)
containing packed versions of the `VkComponentMapping` struct, one for
each sampled image.
Yes, this is horribly ugly. It is unfortunately necessary. Much of the
ugliness is to support swizzling gather operations, where we need to
alter the component that the gather operates on--something complicated
by the `gather()` method requiring the passed-in component to be a
constant expression. It doesn't even support swizzling gathers on depth
textures, though I could add that if it turns out we need it.
This requires MSL 2.0+.
Also, force `ViewportIndex` and `Layer` to be defined as the correct
type, which is always `uint` in MSL.
Since Metal doesn't yet have geometry shaders, the vertex shader (or
tessellation evaluation shader == "post-tessellation vertex shader" in
Metal jargon) is the only kind of shader that can set this output. This
currently requires an extension to Vulkan, which causes validation of
the SPIR-V binaries for the test cases to fail. Therefore, the test
cases are marked "invalid", even though they're actually perfectly valid
SPIR-V--they just won't work without the
`SPV_EXT_shader_viewport_index_layer` extension.
Need some pretty hideous ladder variable system, but high level
languages do not support breaking out of a loop. break in switch blocks
and break in loops alias each other.
This is somewhat tricky, because in MSL this value is obtained through a
function, `get_sample_position()`. Since the call expression is an
rvalue, it can't be passed by reference, so functions get a copy
instead.
This was the last piece preventing us from turning on sample-rate
shading support in MoltenVK.
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.
We were passing a constant '1' to `emit_atomic_func_op()`--which caused
us to refer to SPIR-V value `%1`, which is almost certainly not what we
want! What we really want is to add/subtract the literal constant '1'
to/from the memory location.
This only affects the builtin when it is used, and not when it's passed
to a function. It's a lot cleaner than the way I was doing it before.
Remove the `to_expression()` hack.
In SPIR-V, builtin integral vectors can be either signed or unsigned,
but in MSL they're always unsigned. Unfortunately, the MSL spec forbids
implicit conversions between vector types--even if the corresponding
scalar types would implicitly convert. If you try, the result is a
cryptic error message such as:
```
program_source:37:60: error: cannot convert between vector values of different size ('int4' (aka 'vector_int4') and 'vector_uint4' (vector of 4 'unsigned int' values))
float4 r3 = as_type<float4>((as_type<int4>(r0) * gl_LocalInvocationID.xyyy) + as_type<int4>(r2));
~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~
```
Therefore, uses of these builtins must be explicitly cast, since the
rest of the binary likely assumes that the builtin is of its declared
type.
Two varyings (vertex outputs/fragment inputs) might have the same
location but be in different components--e.g. the compiler may have
packed what were two different varyings into a single varying vector.
Giving both varyings the same `[[user]]` attribute won't work--it may
yield unexpected results, or flat out fail to link. We could eventually
pack such varyings into a single vector, but that would require us to
handle the case where the varyings are different types--e.g. a `float`
and a `uint` packed into the same vector. For now, it seems most
prudent to give them unique `[[user]]` locations and let Apple's
compiler work out the best way to pack them.
In MSL, these only have an effect on fragment `[[stage_in]]` members.
They have no effect in vertex shaders. The Khronos front end doesn't
even emit the SPIR-V decorations for them.
