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* Use slang- prefix on slang compiler and core source (#973)jsmall-nvidia2019-05-31
| | | | | | | | | | | | * Prefixing source files in source/slang with slang- * Prefix source in source/slang with slang- prefix. * Rename core source files with slang- prefix. * Update project files. * Fix problems from automatic merge.
* WIP: Support for other source target language (#971)jsmall-nvidia2019-05-31
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * WIP: Setting up C/Cpp source compilation targets. * WIP: Emitting C/CPP. * WIP: Split out SourceSink, and use it for source output on emit. * SourceSink -> SourceStream * * Made SourceStream use m_ prefixing of members. * Make all methods use lower camel * Removed methods from SourceStream interface that are not used externally (use _ prefixing) * Improvements to documentation * EmitContext is now effectively empty, so just use SharedEmitContext as EmitContext. * SharedEmitContext -> EmitContext * Methods to LowerCamel in emit.cpp * Split out EmitContext and ExtensionUsageTracker into separate files. * Split out EmitVisitor into slang-c-like-source-emitter files. * EmitVisitor -> CLikeSourceEmitter * Tidy up around CLikeSourceEmitter - simplify header. * Small tidy up - removing repeated comments that are in header. * Remove EmitContext paramter threading. * Small tidy up. Use prefixed macros for slang-c-like-source-emitter.h * Small tidy up in slang-c-like-source-emitter.cpp * First pass at splitting out UnmangleContext. * MangledNameParser -> MangledLexer. * WIP making EmitOp (EOp) enum available outside of cpp * Generating EmitOpInfo from macro. * Split out emit precedence handling. Don't use kOp_ style anymore, just use an array indexed by EmitOp. * Disable C simple test for now. * Keep g++/clang happy with token pasting. * Fix win32 narrowing warning.
* Basic layout and reflection for specialized types (#970)Tim Foley2019-05-22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Basic layout and reflection for specialized types Suppose I have an interface, and a simple implementation of it: ```hlsl interface IModifier { float modify(float value); } struct Doubler : IModifier { float modify(float value) { return 2 * value; } } ``` SAnd now suppose I want to define an implementation that recursively uses the same interface: ```hlsl struct MultiModifier : IModifier { IModifier first; IModifier second; float modify(float value) { value = first.modify(value); value = second.modify(value); return value; } } ``` And now consider that I might have a generic entry point that uses the interface: ```hlsl void myShader<M : IModifier>( uniform M modifier, ... ) { ... } ``` I can easily specialize `myShader` for `M = Doubler`, but in order to specialze it for `M = MultiModifier` I need a way to specify what the types of `MultiModifier.first` and `.second` should be. That is what the `spReflection_specializeType` function is used to do: take a type like `MultiModifier` and specialize it for, say, `first : Doubler` and `second : Doubler`. That function creates an `ExistentialSpecializedType` that records the base type (`MultiModifier`) and the specialization arguments (the concrete types plus the witness tables that prove they implement the required interfaces). The change that introduced that logic neglected to include an implementation of type layout for `ExistentialSpecializedType`, and also didn't add any support for the new kind of type through the reflection API. That is what this change seeks to rectify. When it comes to layout, a specialized type neeeds to apply layout to its base type (e.g., `MultiModifier`) with the appropriate existential type "slot" arguments bound, which luckily is stuff that type layout already supporst (to handle specialization of interface-type shader parameters). Unlike the case for interface-type shader parameters where the "primary" and "pending" data for a type get propagated up the chain and allocated to different places, a specialized type should be allocated contiguously (e.g., `myShader<M>` is going to assume that the type `M` occupies a contiguous range in memory). The type layout for a specialized type thus computes a layout that is more-or-less a structure type consisting of the "primary" data followed by the "pending" data. This gets wrapped up in a new `ExistentialSpecializedTypeLayout` class. The reflection API then needs to expose an `ExistentialSpecializedTypeLayout` as a new kind of type, and then also provide access to the relevant pieces. For the "base" type, I went ahead and re-used the `getElementType` entry point, just for simplicity (we can debate whether that or a new entry point is more appropriate/convenient). For the actual layout, all that was needed was a way to query the offset for where the "pending" data gets placed, and that is already conveniently encoded as a `VarLayout` field in the `ExistentialSpecializedTypeLayout`. With this change, specialized types are closer to being truly usable, although there is still missing logic in IR lowering because we need to make sure that explicitly specialized types are represented differently from types that are specialized based on global shader parameters. * fixup: review feedback
* String/List closer to conventions, and use Index type (#959)jsmall-nvidia2019-04-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * List made members m_ Tweaked types to closer match conventions. * Use asserts for checking conditions on List. Other small improvements. * List<T>.Count() -> getSize() * List<T> Add -> add First -> getFirst Last -> getLast RemoveLast -> removeLast ReleaseBuffer -> detachBuffer GetArrayView -> getArrayView * List<T>:: AddRange -> addRange Capacity -> getCapacity Insert -> insert InsertRange -> insertRange AddRange -> addRange RemoveRange -> removeRange RemoveAt -> removeAt Remove -> remove Reverse -> reverse FastRemove -> fastRemove FastRemoveAt -> fastRemoveAt Clear -> clear * List<T> FreeBuffer -> _deallocateBuffer Free -> clearAndDeallocate SwapWith -> swapWith * List<T> SetSize -> setSize Reserve -> reserve GrowToSize growToSize * UnsafeShrinkToSize -> unsafeShrinkToSize Compress -> compress FindLast -> findLastIndex FindLast -> findLastIndex Simplify Contains * List<T> Removed m_allocator (wasn't used) Swap -> swapElements Sort -> sort Contains -> contains ForEach -> forEach QuickSort -> quickSort InsertionSort -> insertionSort BinarySearch -> binarySearch Max -> calcMax Min -> calcMin * Initializer::Initialize -> initialize List<T>:: Allocate -> _allocate Init -> _init IndexOf -> indexOf * * Put #include <assert.h> in common.h, and remove unneeded inclusions * Small refactor of ArrayView - remove stride as not used * getSize -> getCount setSize -> setCount unsafeShrinkToSize->unsafeShrinkToCount growToSize -> growToCount m_size -> m_count * Some tidy up around Allocator. * Use Index type on List. * Refactor of IntSet. First tentative look at using Index. * Made Index an Int Did preliminary fixes. Made String use Index. * Partial refactor of String. * String::Buffer -> getBuffer ToWString -> toWString * Small improvements to String. String:: Buffer() -> getBuffer() Equals() -> equals * Try to use Index where appropriate. * Fix warnings on windows x86 builds.
* Add the missing case for `AssocTypeDecl` in varying parameters' layout ↵Yong He2019-04-16
| | | | generation. (#947)
* Allow plugging in types with resources for interface parameters (#913)Tim Foley2019-03-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Allow plugging in types with resources for interface parameters The key feature enabled by this change is that you can take a shader declared with interface-type parameters: ```hlsl ConstantBuffer<ILight> gLight; float4 myShader(IMaterial material, ...) { ... } ``` and specialize its interface-type parameters to concrete type that can contain resources like textures, samplers, etc. The hard part of doing this layout is that we need to support signatures that include a mix of interface and non-interface types. Imagine this contrived example: ```hlsl float4 myShader( Texture2D diffuseMap, ILight light, Texture2D specularMap) { ... } ``` We end up wanting `diffuseMap` to get `register(t0)` and `specularMap` to get `register(t1)`, so that they have the same location no matter what we plug in for `light`. But if we plug in a concrete type for `light` that needs a texture register, we need to allocate it *somewhere*. We handle this by having the `TypeLayout` for `light` come back with a "primary" type layout that doesn't have any texture registers, but with a "pending" type layout that includes the texture register requirements of whatever concrete type we plug in. This split between "primary" and "pending" layout then needs to work its way up the hierarchy, so that an aggregate `struct` type with a mix of interface and non-interface fields (recursively), needs to compute an aggregate "primary type layout" and an aggregate "pending type layout," and then each field needs to be able to compute its offset in the primary/pending layout of the aggregate. A large chunk of the work in this PR is then just implementing the split between primary and pending data, and ensuring that layouts are computed appropriately. The next catch is that when a "parameter group" (either a parameter block or constant buffer) contains one or more values of interface type, then we can allow the parameter group to "mask" some of the resource usage of the concrete types we plug in, but others "bleed through." For example, if we have: ```hlsl struct MyStuff { float3 color; ILight light; } ConstantBuffer<MyStuff> myStuff; struct SpotLight { float3 position; Texture2D shadowMap; } `` If we plug in the `SpotLight` type for `myStuff.light`, then the `float3` data for the light can be "masked" by the fact that we have a constant buffer (we can just allocate the `float3` `position` right after `color`), but the `Texture2D` needed for `shadowMap` needs to "bleed through" and become "pending" data for the `myStuff` shader parameter. Adding support for that detail more or less required a full rewrite of the logic for allocating parameter group type layouts. The next detail is that when we go to legalize a declaration like the `myStuff` buffer, we will end up with something like: ```hlsl struct MyStuff_stripped { float3 color; } struct Wrapped { MyStuff_stripped primary; SpotLight pending; } ConstantBuffer<Wrapped> myStuff; ``` This "wrapped" version of the buffer type more accurately reflects the layout we need/want for the uniform/ordinary data, but in order to further legalize it and pull out the resource-type fields like `shadowMap` we need to have accurate layout information, and the problem is that layout information for the original buffer can't apply to this new "wrapped" buffer. The last major piece of this change is logic that runs during existential type legalization to compute new layouts for "wrapped" buffers like these that embeds correct offset/binding/register information for any resources nested inside them. A key challenge in that code is that existential legalization needs to erase any "pending" data from the program entirely, so that offset information that used to be relatie to the "pending" part of a surrounding type now needs to be relative to the primary part. The work here may not be 100% complete for all scenarios, but it does well enough on the new and existing tests that I want to checkpoint it. Note that a few other tests have had their output changed, but in all cases I've reviewed the diffs and determined that the change in observable behavior is consistent with what we intened Slang's behavior to be. Note that there is still one major piece of support for interface-type parameters that is missing here, and which might force us to revisit some of the decisions in this code: we don't properly support user-defined `struct` types with interface-type fields. * fixup: typos
* Improve support for interfaces as shader parameters (#886)Tim Foley2019-03-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Improve support for interfaces as shader parameters This change adds two main things over the existing support: 1. It is now possible to plug in concrete types that actually contain (uniform/ordinary) fields for the existential type parameters introduced by interface-type shader parameters. The `interface-shader-param2.slang` test shows that this works. 2. There is a limited amount of support for doing correct layout computation and generating output code that matches that layout, so that interface and ordinary-type fields can be interleaved to a limited extent. The `interface-shader-param3.slang` test confirms this behavior. There are several moving pieces in the change. * When it comes to terminology, we try to draw a more clear distinction between existial type parameters/arguments and existential/object value parametes/arguments. A simple way to look at it is that an `IFoo[3]` shader parameter introduces a single existential type parameter (so that a concrete type argument like `SomeThing` can be plugged in for the `IFoo`) but introduces three existential object/value parameters (to represent the concrete values for the array elements). * At the IR level, we support a few new operations. A `BindExistentialsType` can take a type that is not itself an interface/existential type but which depends on interfaces/existentials (e.g., `ConstantBuffer<IFoo>`) and plug in the concrete types to be used for its existential type slots. * Then a `wrapExistentials` instruction can take a type with all the existentials plugged in (possibly by `BindExistentialsType`) and wrap it into a value of the existential-using type (e.g., turn `ConstantBuffer<SomeThing>` into a `ConstantBuffer<IFoo>`). * The IR passes for doing generic/existential specialization have been updated to be able to desugar uses of these new operations just enough so that a `ConstantBuffer<IFoo>` can be used. * When we specialize an IR parameter of an interface type like `IFoo` based on a concrete type `SomeThing`, we turn the parameter into an `ExistentialBox<SomeThing>` to reflect the fact that we are conceptually referring to `SomeThing` indirectly (it shouldn't be factored into the layout of its surrounding type). * Parameter binding was updated so that it passes along the bound existential type arguments in a `Program` or `EntryPoint` to type layout, so that we can take them into account. The type layout code needs to do a little work to pass the appropriate range of arguments along to sub-fields when computing layout for aggregate types. * Type layout was updated to have a notion of "pending" items, which represent the concrete types of data that are logically being referenced by existential value slots. The basic idea is that these values aren't included in the layout of a type by default, but then they get "flushed" to come after all the non-existential-related data in a constant buffer, parameter block, etc. * The logic for computing a parameter group (`ConstantBuffer` or `ParameterBlock`) layout was updated to always "flush" the pending items on the element type of the group, so that the resource usage of specialized existential slots would be taken into account. * The type legalization pass has been adapted so that we can derive two different passes from it. One does resource-type legalization (which is all that the original pass did). The new pass uses the same basic machinery to legalize `ExistentialBox<T>` types by moving them out of their containing type(s), and then turning them into ordinary variables/parameters of type `T`. Big things missing from this change include: - Nothing is making sure that "pending" items at the global or entry-point level will get proper registers/bindings allocated to them. For the uniform case, all that matters in the current compiler is that we declare them in the right order in the output HLSL/GLSL, but for resources to be supported we will need to compute this layout information and start associating it with the existential/interface-type fields. - Nothing is being done to support `BindExistentials<S, ...>` where `S` is a `struct` type that might have existential-type fields (or nested fields...). Eventually we need to desugar a type like this into a fresh `struct` type that has the same field keys as `S`, but with fields replaced by suitable `BindExistentials` as needed. (The hard part of this would seem to be computing which slots go to which fields). As a practial matter, this missing feature means that interface-type members of `cbuffer` declarations won't work. The current tests carefully avoid both of these problems. They don't declare any buffer/texture fields in the concrete types, and they don't make use of `cbuffer` declarations or `ConstantBuffer`s over structure types with interface-type fields. * fixup: add override to methods * fixup: typos
* A small refactor to how implicit constant buffers are getting created. (#871)Tim Foley2019-03-01
| | | | | | | This affects layout computation for both the global and entry-point scopes, where multiple discrete shader parameters can be declared, but for layout purposes they must be treated as if they lived in the same `struct` type. If that `struct` type ends up consuming any "ordinary" data (`LayoutResourceKind::Uniform`) then an implicit constant buffer will be needed for that scope (e.g., the way fxc produces a `$Globals` constant buffer for the global scope). The logic for computing those scope layouts had a bug in it, in that the struct type was not being updated to have the right size for uniform data at the scope. That bug hasn't bitten anybody yet because no Slang users are relying on entry-point uniforms, and global-scope uniforms aren't fully implemented (and get diagnosed as an error elsewhere in the compiler). This change fixes that bug. This change also refactors things so that the logic for creating a constant buffer layout if and only if needed is moved into `type-layout.cpp` instead of relying on `parameter-binding.cpp` to compute whether or not it needs a block on its own. This is anticipating the rules for deciding whether or not a constant buffer is needed being slightly more thorny once interface types are in the mix.
* Simplify type layout (#867)Tim Foley2019-02-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Make vector/matrix type layouts include element type layouts Previously the `MatrixTypeLayout` class was a leaf node in the layout hierarchy, and vector types just used `TypeLayout` with no further refinement. This change adds a `VectorTypeLayout`, and makes all of vector, matrix, and array types inherit form a common base class for `SequenceTypeLayout`s. The actual layout computation logic was updated to compute layouts for the element types of vectors, and for the row (and element) types of matrices. Notes: * Because of the way varying input/output parameters are being handled, their type layouts won't include this new information, and they will just use `TypeLayout`. This was true even for the matrix case before. * I made the design choice in this change to have a matrix type always treat rows as the logical element type (since that is what is surfaced to ther user in the HLSL syntax). We could potentially make our lives easier during layout computation if we made the element type of a `MatrixTypeLayout` depend on the row-/column-major layout choice, but that would then require any algorithm that uses the new layout information to take row-vs-column-major into account. * No code is actually *using* this new information yet, although the work in `ir-union.cpp` could probably benefit from it. The main expected use case going forward is representing constant buffers as a "bag of bits." * Add a specialized type layout approach for varying parameters There is a lot of complexity in `GetLayoutImpl` because it needs to service both the "normal" case, which always wants a `TypeLayout` object to be returned, and the varying parameter case, where we currently don't care about getting back a `TypeLayout` object. Confusingly, the varying parameter layout logic actually *does* construct `TypeLayout` objects, and it just does it inside of `parameter-binding.cpp` rather than in `type-layout.cpp`. That logic cannot (easily) be shared with the `GetLayoutImpl` path because: * The varying case needs to deal with system-value semantics and also parameters that may be inputs, outputs, or both (so that they need to combine resource usage computed for inputs and outputs). * The varying case needs to special-case vectors (and to a lesser extent matrices) because of the quirks of uniform layout (e.g., four `float` varying inputs consume four `locations`, but a `float4` consumes only one location). This change introduces a customized layout function just for varying parameters, that only handles the scalar, vector, and matrix cases (since `parameter-binding.cpp` will have recursed through any strucures/arrays, and should error out on any other types that are illegal in varying parameter lists). In the long run we could consider trying to deduplicate code and share more of this logic with `GetLayoutImpl`, but that would require a more significant refactoring of type layout, which should probably wait until we are doing layout on IR types. * Rename CreateTypeLayout to createTypeLayout This is just a fixup to better reflect our established naming conventions. * Simplify type layout so that it always returns a layout object The core `GetLayoutImpl` routine included a fair bit of complexity to deal with the fact that its `outTypeLayout` parameter was optional. The caller could pass in null to say that it doesn't want a `TypeLayout` object to be constructed, and the routine would conditionalize a lot of its logic to deal with this case. This change simplifies the logic so that a `TypeLayout` is always constructed and returned. Instead of using a combination of a function result (for the `SimpleLayoutInfo`) and an output parameter (for the `TypeLayout`) we use a new `TypeLayoutResult` that acts as a tuple over the two. I had hoped for a more significant cleanup by also eliminating the need to return the `SimpleLayoutInfo` separately from the `TypeLayout`, but the simple layout info is what the underlying per-API/-context "rules" implementations use (so that they can avoid all the complexity of `TypeLayout`), and refactoring to derive the simple layout infor from a computed `TypeLayout` would be a bigger refactoring than I was ready for. * fixup: typos
* First steps toward supporting interface-type parameters on shaders (#852)Tim Foley2019-02-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * First steps toward supporting interface-type parameters on shaders What's New ---------- From the perspective of a user, the main thing this change adds is the ability to declare top-level shader parameters (either at global scope, or in an entry-point parameter list) with interface types. For example, the following becomes possible: ```hlsl // Define an interface to modify values interface IModifier { float4 modify(float4 val); } // Define some concrete implementations struct Doubler : IModifier { float4 modify(float4 val) { return val + val; } } struct Squarer : IModifier { ... } // Define a global shader parameter of interface type IModifier gGlobalModifier; // Define an entry point with an interface-type `uniform` parameter void myShader( unifrom IModifier entryPointModifier, float4 inColor : COLOR, out float4 outColor : SV_Target) { // Use the interface-type parameters to compute things float4 color = inColor; color = gGlobalModifier.modify(color); color = entryPointModifier.modify(color); outColor = color; } ``` The user can specialize that shader by specifying the concrete types to use for global and entry-point parameters of interface types (e.g., plugging in `Doubler` for `gGlobalModifier` and `Squarer` for `entryPointModifier`). The "plugging in" process is done in terms of a concept of both global and local "existential slots" which are a new `LayoutResourceKind` that represents the holes where concrete types need to be plugged in for existential/interface types. In simple cases like the above, each interface-type parameter will yield a single existential slot in either the global or entry-point parameter layout. Users can query the start slot and number of slots for each shader parameter, just like they would for any other resource that a parameter can consume. Before generating specialized code, the user plugs in the name of the concrete type they would like to use for each slot using `spSetTypeNameForGlobalExistentialSlot` and/or `spSetTypeNameForEntryPointExistentialSlot`. There are some major limitations to the implementation in this first change: * Parameters must be of interface type (e.g., `IFoo`) and not an array (`IFoo[3]`), or buffer (`ConstantBuffer<IFoo>`) over an interface type. Similarly, `struct` types with interface-type fields still don't work. * The work on interface-type function parameters still doesn't include support for `out` or `inout` parameters, nor for functions that return interface types (that isn't technically related to this change, but affects its usefullness). * No work is being done to correctly lay out shader parameters once the concrete types for existential slots are known, so that this change really only works when the concrete type that gets plugged in is empty. These limitations are severe enough that this feature isn't really usable as implemented in this change, and this merely represents a stepping stone toward a more complete implementation. Implementation -------------- The API side of thing largely mirrors what was already done to support passing strings for the type names to use for global/entry-point generic arguments, so there should be no major surprises there. The logic in `check.cpp` computes the list of existential slots when creating unspecialized `Program`s and `EntryPoint`s (this is logically the "front end" of the compiler), and then checks the supplied argument types against what is expected in each slot when creating specialized `Program`s and `EntryPoint`s. This again mirrors how generic arguments are handled. Type layout was extended to compute the number of existential slots that a type consumes, and will thus automatically assign ranges of slots to top-level and entry-point shader parameters in the same way it already allocates `register`s and `binding`s. The big missing feature is the ability to specialize a layout to account for the concrete types plugged into the existential-type slots. IR generation for specialized programs and entry points was slightly extended so that it attaches information about the concrete types plugged into the existential slots, and the witness tables that show how they conform to the interface for that slot. The linking step needed some small tweaks to make sure that information gets copied over to the target-specific program when we start code generation. The meat of the IR-level work is in `ir-bind-existentials.cpp`, which takes the information that was placed in the IR module by the generation/linking steps and uses it to rewrite shader parameters. For example, if there is a shader parameter `p` of type `IModifier`, and the corresponding existential slot has the type `Doubler` in it, we will rewrite the parameter to have type `Doubler`, and rewrite any uses of `p` to instead use `makeExistential(p, /*witness that Doubler conforms to IModifier*/)`. Once the replacement is done on the parameters, the existing work for specializing existential-based code when the input type(s) are known kicks in and does the rest. Testing ------- A single compute test is added to validate that this feature works. It is narrowly tailored to not require any of the features not supported by the initial implementation (e.g., all of the concrete types used have no members). The test case *does* include use of an associated type through one of these existential-type parameters, which has exposed a subtle bug in how "opening" of existential values is implemented in the front-end. Rather than fix the underlying problem, I cleaned up the code in the front-end to special case when the existential value being opened is a variable bound with `let`, to directly use a reference to that variable rather than introduce a temporary. Similarly, in the IR generation step, I added an optimization to make variables declared with `let` skip introducing an IR-level variable and just use the SSA value of their initializer directly instead. * fixup: missing files * fixup: incorrect type for unreachable return * fixup: actually comment ir-bind-existentials.cpp
* Split front- and back-ends (#846)Tim Foley2019-02-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Split front- and back-ends This change is a major refactor of several of the types that provide the behind-the-scenes implementation of the public C API. The goal of this refactor is primarily to allow for future API services that let the user operate both the front- and back-ends of the compiler in a more complex fashion. For example, as user should be able to compile a bunch of source code into modules, look up types, functions, etc. in those modules, specialize generic types/functions to the types they've looked up, and then finally request target code to be gernerated for specialized entry points. The back-end code generation they trigger should re-use the front-end compilation work (parsing, semantic checking, IR generation) that was already performed. The most visible change is that `CompileRequest` has been split up into several smaller types that take responsibility for parts of what it did: * The `Linkage` type owns the storage for `import`ed modules, and well as the `TargetRequest`s that represent code-generation targets. The intention is that an application could use a single `Linkage` for the duration of its runtime (so long as it was okay with the memory usage), so that each `import`ed module only gets loaded once. For now, this type needs to manage the search paths, file system, and source manager, because of its responsibility for loading files. * A `FrontEndCompileRequest` owns the stuff related to parsing, semantic checking, and initial IR generation. This most notably includes the `TranslationUnitRequest`s and the `FrontEndEntryPointRequest`s (which used to be just `EntryPointRequest`s). It's main job is to produce AST and IR modules for each translation unit, and to find and validate the entry points. The front-end request does *not* interact with generic arguments for global or entry-point generic parameters. * The main output of both `import` operations and front-end translation units is the `Module` type, which is just a simple container for both the AST module (to service the reflection/layout APIs, and also for semantic checking of code that `import`s the module) and the IR module (for linking and code generation). This type captures the commonalities between the old `LoadedModule` (which is now just an alias for `Module`) and `TranslationUnitRequest` (which now owns a `Module`). * The secondary output of front-end compilation is a `Program`, which comprises a list of referenced `Module`s and validated `EntryPoint`s that will be used together. Layout and code generation both need a `Program` to tell them what modules and entry points will be used together (we don't want to just code-gen everythin that has ever been loaded into the linakge). The `Program`s created by the front-end do not include generic arguments, so they may provide incomplete layout information and/or be unsuitable for code generation. * A `BackEndCompileRequest` owns stuff related to turning a `Program` into output kernels for the targets of a `Linkage`. Most of the data it owns beyond the `Program` to be compiled is minor, so this is a good candidate for demotion from a heap-allocated object to just a `struct` of options that gets passed around. * The `CompileRequestBase` type is an attempt to wrap up the common functionality of both front-end and back-end compile requests. Most of it is just exposing the availability of a linkage and `DiagnosticSink`, so this type is a good candidate for subsequent removal. The main interesting thing it has is the flags related to dumping and validation of IR, so there is probably a good refactoring still to be made around deciding how options should be handled going forward. * Behind the scenes, the `Program` type is set up to handle some level of on-line compilation and layout work. The `Program` knows the `Linkage` it belongs to, and allows for a `TargetProgram` to be looked up based on a specific `TargetRequest`. A `TargetProgram` then allows layout information and compiled kernel code to be asked for on-demand, in order to support eventual "live" compilation scenarios. * The `EndToEndCompileRequest` type is a composition/coordination type that replaces the old `CompileRequest` in a way that uses the services of the various other types. It owns a few pieces of state that only make sense in the context of an end-to-end compile (e.g., there is really no way to "pass through" code when the front- and back-ends are run separately) or a command-line compile (everything to do with specifying output paths for files is really just for the benefit of `slangc`, and might even be moved there over time). * One important detail is that the `EndToEndCompilRequest` owns all of the string-based generic arguments for both global and entry-point generic parameters. The logic in `check.cpp` for dealing with those arguments has been heavily refactored to separate out the parsings steps that are specific to end-to-end compilation with string-based type arguments, and the semantic checking steps that result in a specialized `Program` (which can be exposed through new APIs that aren't tied to end-to-end compilation). It is perhaps not surprising that this change had a lot of consequences, so I'll briefly run over some of the main categories of changes required: * I changed the way that global generic arguments are passed via API (use `spSetGlobalGenericArgs` instead of the generic arguments for `spAddEntryPointEx`, which are not just for entry-point generics), which has been a change that we've needed for a long time. This is technically a breaking API change, although we should have very few client applications that care about it. * A bunch of places that used to take "big" objects like `CompileRequest` now just take the sub-pieces they care about (e.g., a function might have only needed a `Linkage` and a `DiagnosticSink`). This makes many subroutines or "context" struct types more generally useful, at the cost of taking more parameters. * In a few cases the conceptually clean separation of the layers breaks down (often for edge-case or compatibility features), and so we may pass along additional objects that are allowed to be null, but are used when present. A big example of this is how the back-end code generation routines accept an `EndToEndCompileRequest` that is optional, and only used to check whether "pass through" compilation is needed. We should probably look into cleaning this kind of logic up over time so that we don't need to violate the apparent separation of phases of compilation. * In cases where separation of layers was being broken for the sake of GLSL features, I went ahead and ripped them out, since all of that should be dead code anyway. * In many cases I increased the encapsulation of data in the core types to help track down use sites and make sure they are following invariants better. * In cases where code was doing, e.g., `context->shared->compileRequest->session->getThing()` I have tried to introduce convenience routines so that the usage site is just `context->getThing()` to improve encapsulation and allow changes to be made more easily going forward. * The `noteInternalErrorLoc` functionality was moved off of the compile request and into `DiagnosticSink`, since that is the one type you can rely on having around when you want to note an internal error. We may consider going forward if (and how) it should reset the counter used for noting locations on internal errors. * A few APIs now take `DiagnosticSink*` arguments where they didn't before, and as a result some public APIs need to create `DiagnosticSink`s to pass in, before going ahead and ignoring the messages. In the future there should be variations of these APIs that accept an `ISlangBlob**` parameter for the output. * fixup: missing include for compilers with accurate template checking (non-VS) * fixup: review feedback
* Feature/casting tidyup (#822)jsmall-nvidia2019-02-04
| | | | | | | | | | * Use 'is' over 'as' where appropriate. * dynamic_cast -> dynamicCast * Replace 'dynamicCast' with 'as' where has no change in behavior/ambiguity. * Replace dynamicCast with as where doesn't change behavior/non ambiguous.
* Feature/as refactor (#817)jsmall-nvidia2019-01-31
| | | | | | | | | | | | | | | | | | | | | | | | * Made dynamicCast a free function. * Replace As with as or dynamicCast depending on if it is a type. * Fix problem with using non smart pointer cast. * Removed legacy asXXXX methods. * Remove As from Type. * Removed As from Qual type -> made coercable into Type*, such that can just use free 'as'. * Remove left over QualType::As() impl. * Remove As from SyntaxNodeBase. * Made as for instructions implemented by dynamicCast. * Replace As on DeclRef. Use the global as<> to do the cast. * Add const safe versions of dynamicCast and as for IRInst
* Initial support for dynamic dispatch using "tagged union" types (#772)Tim Foley2019-01-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Initial support for dynamic dispatch using "tagged union" types Suppose a user declares some generic shader code, like the following: ```hlsl interface IFrobnicator { ... } type_param T : IFrobincator; ParameterBlock<T : IFrobnicator> gFrobnicator; ... gFrobincator.frobnicate(value); ``` and then they have some concrete implementations of the required interface: ```hlsl struct A : IFrobnicator { ... } struct B : IFrobnicator { ... } ``` The current Slang compiler allows them to generate distinct compiled kernels for the case of `T=A` and the case of `T=B`. This means that the decision of which implementation to use must be made at or before the time when a shader gets bound in the application. This change adds a new ability where the Slang compiler can generate code to handle the case where `T` might be *either* `A` or `B`, and which case it is will be determined dynamically at runtime. This means a single compiled kernel can handle both cases, and the decision about which code path to run can be made any time before the shader executes. This new option is supported by defining a *tagged union* type. Via the API, the user specifies that `T` should be specialized to `__TaggedUnion(A,B)` (the double underscore indicates that this is an experimental and unsupported feature at present). We refer to the types `A` and `B` here as the "case" types of the tagged union. Conceptually, the compiler synthesizes a type something like: ```hlsl struct TU { union { A a; B b; } payload; uint tag; } ``` The user can then allocate a constant buffer to hold their tagged union type, and when they pick a concrete type to use (say `B`), they fill in the first `sizeof(B)` bytes of their buffer with data describing a `B` instance, and then set the `tag` field to the appopriate 0-based index of the case type they chose (in this case the `B` case gets the tag value `1`). Actually implementing tagged unions takes a few main steps: * Type parsing was extended to special-case `__TaggedUnion` as a contextual keyword. This is really only intended to be used when parsing types from the API or command-line, and Bad Things are likely to happen if a user ever puts it directly in their code. Eventually construction of tagged unions should be an API feature and not part of the language syntax. * Semantic checking was extended to recognize that a tagged union like `__TaggedUnion(A,B)` shoud support an interface like `IFrobnicator` whenever all of the case types suport it, as long as the interface is "safe" for use with tagged unions (which means it doesn't use a few of the advancd langauge features like associated types). * The IR was extended with instructions to represent tagged union types and to extract their tag and the payload for the different cases as needed. * IR generation was extended to synthesize implementations of interface methods for any interface that a tagged union needs to support. Right now the implementation is simplistic and only handles simple method requirements, which it does by emitting a `switch` instruction to pick between the different cases. * A new IR pass was introduced to "desugar" any tagged union types used in the code. The downstream HLSL and GLSL compilers don't support `union`s, so we have to instead emit a tagged union as a "bag of bits" and implement loading the data for particular cases from it manually. * Final code emit mostly Just Works after the above steps, but we had to introduce an explicit IR instruction for bit-casting to handle the output of the desugaring pass. There are a bunch of gaps and caveats in this implementation, but that seems reasonable for something that is an experimental feature. The various `TODO` comments and assertion failures in unimplemented cases are intended, so that this work can be checked in even if it isn't feature-complete. * fixup: missing files * fixup: typos
* Fix some subtle bugs in D3D constant buffer layout (#771)Tim Foley2019-01-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Fix some subtle bugs in D3D constant buffer layout The root of the issue here is that the D3D constant buffer layout rules require 16-byte alignment for arrays and structures, but they do *not* round up the size of an array/structure type to account for that alignment. That means that in cases like the following: ```hlsl cbuffer C0 { float3 a[2]; float c0; } struct A { float4 x; float3 y; }; cbuffer C1 { A a; float c1; } ``` The `c0` and `c1` fields get an offset of 28 and not 32 like you might expect if the preceding array/structure field `a` had been padded out to match its 16-byte alignment. The actual fix here is relatively simple, and mostly amount to shuffling around some code in `type-layout.cpp` to ensure that the D3D constant buffer layout don't inherit the logic that was rounding up array/structure sizes. Along the way I took the opportunity to clean up the inheritance hierarchy by making the GLSL-family layout rules not try to share anythign with the D3D family (not that there is very little to share), which in turn allowed for some simplification of the GLSL side of things. Fixing this behavior changed the output of a few reflection tests. In the case of `tests/reflection/arrays.hlsl` the output confirmed that we had been producing bad reflection information in these kinds of cases. The output for `tests/reflection/matrix-layout.slang` also showed some bugs in our reflection, but these were overall more minor: we mis-reported the size of certain matrices as 64 bytes instead of 60, and as a result also computed the size of the overall constant buffer as 4 bytes bigger than needed. In all of these cases I double-checked the expected output against dxc to make sure that the new offsets/sizes are what we should have been producing in the first place. I also updated the reflection test harness to start outputting layout information for the element type of a structured buffer, which changed the output of `tests/reflection/structured-buffer.slang`, but this didn't show any change in what we reported: it is just information that wasn't in the output to begin with. Finally, I added two new tests around these subtle cases of buffer layout behavior (especially subtle because it varies across target APIs). The `tests/compute/buffer-layout.slang` test simply sets up a type to ilustrate the troublesome scenarios and then embeds it in both a constant buffer and structured buffer that will be backed by memory with sequential `int` values. We then read out the value of a field as a way to probe its de facto *offset* at runtime. This test doesn't really stress the Slang compiler (except for our ability to pass through the same type declarations to downstream compilers), but it is useful to confirm our expectations about where things land in memory. The `tests/reflection/buffer-layout.slang` test then uses the reflection test infrastructure to confirm that the same type declarations used in the compute test produce the expected offsets in our reported reflection information. Before the fixes in this change this test showed us producing dangerously incorrect results in our D3D reflection information, which has now been fixed to match the empirically-determined offsets from the compute test. * fixups based on review feedback
* Running tests in slang-test process (#740)jsmall-nvidia2018-12-12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * First pass at having an interface to write text to that can be replaced. Simplifed and made more rigerous the interface used to write formatted strings. * Added AppContext to simplify setting up and parsing around of streams. * Added more simplified way to get the std error/out from AppContext. * Work in progress using dll for tools to speed up testing. * First pass at ISlangWriter interface. * Added support for writing VaArgs. Added NullWriter. * Use ISlangWriter for output. * Use ISlangWriter for output - replacing OutputCallback. Make IRDump go to ISlangWriter * SlangWriterTargetType -> SlangWriterChannel Improvements around AppContext * Shared library working with slang-reflection-test. * Dll testing working for render-test. * Include va_list definintion from header. * Fix errors from clang. * Fix typo for linux. * Added -usexes option * Fix typo. * Fix arguments problem on linux. * Fix typo for linux. * Add windows tool shared library projects. * Fix warning from x86 win build. Fix signed warning from slang-test/main.cpp * First attempt at getting premake to work on travis, and run tests. * Try moving build out into script. * Invoke bash scripts so they don't have to be executable. * Drive configuration/tests from env parameters set by travis * Try using source to run travis tests. * Remove the build.linux directory - but doing so will overwrite Makefile. * Made -fno-delete-null-pointer-checks gcc only. * Try to fix warning from -fno-delete-null-pointer-checks * Turn of warnings for unknown switches. * Try to make premake choose the correct tooling. * Disabled missing braces warning. * Disable -Wundefined-var-template on clang. * -Wunused-function disabled for clang. * Fix typo due to SlangBool. * Remove this nullptr tests. * "-Wno-unused-private-field" for clang. * Added "-Wno-undefined-bool-conversion" * Add DominatorList::end fix. * Split scripts into travis_build.sh travis_test.sh * Fix gcc/clang template pre-declaration issue around QualType. * Fix premake to build such that pthread correctly links with slang-glslang
* Change how buffers are emitted (#741)Tim Foley2018-12-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Change how buffers are emitted This is a change with a lot of pieces, which can't always be separated out cleanly. I'm going to walk through them in what I hope is a logical order. The main goal of this change was to allow arrays of structured buffers to translate to Vulkan. Consider two declarations of structured buffers in HLSL/Slang: ```hlsl StructuredBuffer<X> single; StructuredBuffer<Y> multiple[10]; ``` The current translation logic was handling `single` by translating it into an *unnamed* GLSL `buffer` block like: ```glsl layout(std430) buffer _S1 { X single[]; }; ``` That syntax allows an expression like `single[i]` in Slang to be translated simply as `single[i]` in GLSL. But that naive translating doesn't work for `multiple`, since we need to declare a array of blocks in GLSL, which requires giving the whole thing a name: ```glsl layout(std430) buffer _S2 { Y _data[]; } multiple[10]; ``` Now a reference to `multiple[i][j]` in Slang needs to become `multiple[i]._data[j]` in GLSL. To avoid having way too many special cases around single structured buffers vs. arrays, it makes sense to allows emit things in the latter form, so that we instead lower `single` as: ```glsl layout(std430) buffer _S1 { X _data[]; } single; ``` So that now a reference to `single[i]` becomes `single._data[i]` in GLSL. Most of that can be handled in the standard library translation of the structured buffer indexing operations. The only wrinkle there is that there were some *old* special-case instructions in the IR intended to handle buffer load/store operations (these were added back when I was trying to keep the "VM" path working). These aren't really needed to have structured-buffer operations work; they can be handled as ordinary functions as far as the stdlib is concerned. I removed the old instructions. Along the way, it became clear that a few other cases follow the same pattern. Byte-addressed buffers are an obvious case. We were lowering HLSL/Slang: ```hlsl ByteAddressBuffer b; ... uint x = b.Load(0); ``` to GLSL like: ```glsl layout(std430) buffer _S1 { uint b[]; }; ... uint x = b[0]; ``` That logic would fail for arrays the same way that the structured buffer case was failing. The fix is the same: use named `buffer` blocks and then introduce an explicit `_data` field: ```glsl layout(std430) buffer _S1 { uint _data[]; } b; ... uint x = b._data[0]; ``` Just like with structured buffers, all of the VK translation for operations on byte-addressed buffers can be implemented directly in teh stdlib, so once the emit logic was changed it was just a matter of adding `._data` to a bunch of VK tranlsations. It turns out that arrays of constant buffers have more or less the same problem, and furthermore we have some problems with any code that directly uses the modern HLSL `ConstantBuffer<T>` type. Note: the emit logic around constant buffers sometimes refers to "parameter groups" because that is being used in the compiler as a catch-all term for constant buffers, texture buffers, and parameter blocks. The existing code was going out of its way to reproduce the way that constant buffer declarations are implicitly referenced in HLSL: ```hlsl cbuffer C { float f; } ... float tmp = f; // No reference to `C` here ``` This can be seen in the emit logic with the `isDerefBaseImplicit` function, which is used to take the internal IR representation for a reference to `f` (which is closer to the expression `(*C).f` or `C->f`) and leave off any reference to `C` so that we emit just `f`. That kind of logic just flat out doesn't work in some important cases. Arrays of constant buffers are a clear one: ```hlsl ConstantBuffer<X> cbArray[3]; ... X x = cbArray[0]; ``` There is no way to translate that to an ordinary `cbuffer` declaration at all. The same problem can be created without arrays, though: ```hlsl ConstantBuffer<X> singleCB; ... X x = singleCB; ``` The current strategy for translating constant buffers was translating `singleCB` into a `cbuffer` declaration that reproduced the fields of `X` as its members, which just wouldn't work: ```hlsl cbuffer singleCB { float f; // field of `X` } ... X x = singleCB; // ERROR: there is nothing named `singleCB` in this HLSL ``` The new strategy is more consistent. We still generate a `cbuffer` declaration for a single constant buffer, but we always give it a single field of the chosen element type: ```hlsl cbuffer singleCB { X singleCB; } ... X x = singleCB; // this works fine! ``` And in the array case we generate code that uses the explicit `ConstantBuffer<T>` type: ```hlsl ConstantBuffer<X> cbArray[3]; ... X x = cbArray[0]; ``` The GLSL output is more complicated because unlike with HLSL there is no implicit conversion from a uniform block to its element type (there is no notion of an element type). The array case thus needs a `_data` field similar to what we do for structured buffers: ```glsl layout(std140) uniform _S3 { X _data; } cbArray[3]; ... X x = cbArray[0]._data; ``` And then the non-array case needs to have a similar `_data` field for consistency: ```glsl layout(std140) uniform _S1 { X _data; } singleCB; ... X x = singleCB._data; ``` This is handled by inserting the necessary reference to `_data` whenever we dereference a constant buffer, either as part of a load instruction (loading from the whole CB as a pointer), or an `IRFieldAddress` instruction which forms a pointer into the CB (e.g., `&(singleCB->f)` becomes `singleCB._data.f`). The current emit logic handles `ParameterBlock<X>` differently from `ConstantBuffer<X>`, but really only to allow parameter blocks to be explicitly named in the output, while constant buffers were left implicit by default. Thus the only difference was a legacy one (from back when trying to exactly reproduce the HLSL text we got as input was considered an important goal), and the new approach to emitting constant buffers would get rid of it. I removed the separate logic for emitting `ParameterBlock<X>` and just let the handling for constant buffers deal with it. Note that any resource types inside of a `ParameterBlock<X>` would have been moved out as part of legalization, so that a parameter block is 100% equivalent to a constant buffer when it comes time to emit code. Unsurprisingly, changing the way we generate HLSL and GLSL output for all these buffer types meant that any tests that were directly comparing the output of `slangc` against `fxc`, `dxc`, or `glslang` broke. The basic approach to fixing the breakage in GLSL tests was to update the GLSL baseline to reflect the new output startegy. In some cases I used macros to name the various `_S<digits>` temporaries so that future renaming will hopefully be easier (it would be great if we auto-generated temporary names with a bit more context). There was one GLSL test (`tests/bugs/vk-structured-buffer-binding`) that was using raw GLSL expected output, and this was changed to use a GLSL baseline to generate SPIR-V for comparison. For HLSL tests we were sometimes running the same input file through `slangc` and `fxc`/`dxc`, and in these cases I macro-ized the various `cbuffer` declarations to generate different declarations depending on the compiler. I completely dropped the tests coming from the D3D SDK because they aren't providing much coverage, and updating them would change them so far from the original code that the purported benefit (using a body of existing shaders) would be lost. I also dropped the explicit matrix layout qualifiers in the `matrix-layout` test because the new output strategy breaks those for GLSL (you can't put matrix layout qualifiers on `struct` fields, and now the body of every constant buffer is inside a `struct`). This isn't as big of a loss as it seems, because our handling of those qualifiers wasn't really right to begin with. Slang users should only be setting the matrix layout mode globally (and we should probably switch to error out on the explicit qualifiers for now). The other thing that got dropped is tests involving `packoffset` modifiers. Slang already warns that it doesn't support these, and the way they were used in the test cases is actually misleading. For the binding/layout-related tests, the goal was to show that Slang reproduces the same layout as fxc, in which case explicitly enforcing a layout via `packoffset` seems like cheating (are we sure we enforced the layout fxc would have produced?). The real reason was that Slang used to emit explicit `packoffset` on *every* field of a `cbuffer` it would output, because of an `fxc` bug where you couldn't use `register` on textures/samplers declared inside a `cbuffer` unless *every* field in the `cbuffer` used a `register` or `packoffset` modifier. Slang hasn't required that behavior in a while because it now splits textures and samplers, and the one test case where we needed `packoffset` to work around the `fxc` bug in the baseline HLSL has been macro-ified even more to work around the bug. The amount of churn in the test cases is unfortunate, but it continues to point at the weakness of any testing strategy that checks for exact equivalent between Slang's output and that of other compilers. We need to keep working to replace these tests with better alternatives. In `check.cpp` there is logic to perform implicit dereferencing, so that if you write `obj.f` where `obj` is a `ConstantBuffer<X>` (or some other "pointer-like" type) and `f` is a field in `X`, then this effectively translates as `(*obj).f`. That is, we dereference the value of type `ConstantBuffer<X>` to get a value of type `X`, and then refer to the field of the `X` value. There was a problem where the logic to insert that kind of implicit dereference operation was using a reference (`auto& type = ...`) for the type of the expression being dereferenced, and then clobbering it. This would mean that an expression of type `ConstantBuffer<X>` would have its type overwritten to be just `X` and then codegen would break later on. I'm not sure how we haven't run into that before. The `array-of-buffers` test case was added to confirm that we now support arrays of constant, structured, and byte-address buffers for both DXIL and SPIR-V output. Okay, so that was a lot of stuff, but hopefully it is clear how this all works to make the output of the compiler more consistent and explicit, while also supporting the required new functionality. * fixup: review feedback
* Add support for Vulkan raytraicng "shader record" (#735)Tim Foley2018-11-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The syntax for this is a placeholder for now, since we will probably want to migrate to whatever gets decided on for dxc. To declare that some data should be part of the "shader record" use `layout(shaderRecordNV)` to mirror the GLSL raytracing extension: ```hlsl layout(shaderRecordNV) cbuffer MyShaderRecord { float4 someColor; uint someValue; } ``` The intention (not enforced) is that an application would map `MyShaderRecord` to "root constants" in the "local root signature" when compiling for DXR, while the output code in GLSL will always map to the shader record in Vulkan raytracing: ```glsl layout(shaderRecordNV) buffer MyShaderRecord { float4 someColor; uint someValue; }; ``` This change does *not* support declaring a global value of `struct` type with `layout(shaderRecordNV)` (or a `ParameterBlock` with the modifiers, although that would be a nice-to-have feature) and it does *not* support having the contents of the shader record be mutable (even if GLSL/Vulkan allows it). Those can/should be added in future changes. In terms of implementation, this closely mirrors the way that `layout(push_constant)` buffers were being handled, where the data inside the `ConstantBuffer<X>` (the value of type `X`) gets laid out using ordinary rules (and consuming ordinary `UNIFORM` storage, while the buffer itself is given a different layout resource to reflect that fact that it does not consume a VK `binding` any more, but a different conceptual resource. Note: an alternative design here (that might actually be preferrable) would be to have both push-constant and shader-record buffers be handled as alternative aliases for `ConstantBuffer` (or maybe `ParameterBlock`) so that you have, e.g.: ```hlsl PushConstantBuffer<X> myPushConstants; ShaderRecord<Y> myShaderRecord; ``` This alternative design avoids API-specific decorations on the declarations, and reflects the intent of the programmer very directly, even when they are compiling for a target like D3D that doesn't reflect these choices at the IL level (it could still be exposed through the Slang reflection API).
* Allow parameter blocks to be explicitly bound to spaces (#736)Tim Foley2018-11-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Don't look at VK bindings when compiling for D3D and vice versa The compiler had been looking at all the modifiers on a declaration when piecing together binding information, whether or not those modifiers should apply on the chosen target API. This was working in practice because the "layout resource kinds" used by each API target were disjoint, for the most part. This change ensures that we don't even look at modifiers that don't apply on the chosen target, and furthermore adds a new warning that applies if the user is compiling a shader with explicit `register` bindings for Vulkan, if there are no corresponding `[[vk::binding(...)]]` attributes (under the assumption that if they want to be explicit in one case, they probably want to be explicit in all cases). * Allow explicit space/set bindings on parameter blocks The syntax for the D3D case is to specify a `space` in a `register` modifier, without any other register class: ```hlsl ParameterBlock<X> myBlock : regsiter(space999); ``` In the Vulkan case, the user must apply the `[[vk::binding(...)]]` attribute and is expected to use a `binding` of zero: ```hlsl [[vk::binding(0,999)]] ParameterBlock<X> myBlock; ``` This change includes a reflection test for the new capability (where we also confirm that it produces the expected output when compared with fxc), and a test for the diagnostic messages when the user messes up bindings for Vulkan. The implementation itself is fairly straightforward, since the compiler already treats registe spaces/sets as a resource that parameters can consume directly. Note: the test case for explicit parameter block space/set bindings includes some commented out code that lead to a compiler crash. I would like to fix the underlying issue, but it seemed sensible to keep the bug fix out of a change like this that is adding functionality.
* Use register spaces by default for D3D12 targets (#734)Tim Foley2018-11-30
| | | | | | | | | The change here is that the logical that used to be controlled by `-parameter-blocks-use-register-spaces` is now turned on unconditionally, meaning that a `ParameterBlock<X>` will get its own register `space` by default when targetting D3D Shader Model 5.1 and later. I had originally made this feature optional because I wasn't sure whether Shader Model 5.1 should default to using register spaces or not, because D3D 11 doesn't support spaces at the API level and MSDN documetnation made it sound like SM5.1 was available for D3D11 as well. Subsequent reading has led me to understand that MSDN is wrong on this front, and SM5.1 and later are D3D12-only, so it is always safe to use spaces. The new logic is now that we automatically use spaces for parameter blocks any time it is possible (SM5.1+ and any Vulkan target), and otherwise fall back to not using spaces (SM5.0 and earlier). I updated a reflection test case that was covering parameter blocks to confirm the output differs between SM5.0 and 5.1.
* Add support for unbounded arrays as shader parameters (#725)Tim Foley2018-11-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Add support for unbounded arrays as shader parameters With this change, Slang shaders can use unbounded-size arrays as parameters, e.g.: ```hlsl Texture2D t[] : register(t3, space2); SamplerState s[]; ``` As shown in the above example, Slang supports both explicit `register` declarations on unbounded-size arrays and also implicit binding. When doing automatic parmaeter binding, Slang will allocate a full register space to an unbounded-size array of textures/smaplers, starting at register zero. Note that for the Vulkan target, an array of descriptors of any size (including unbounded size) consumes only a single `bindign`, so much of this logic is specific to D3D targets. Details on the changes made: * The single biggest change is a new `LayoutSize` type that is used to store a value that can either be a finite unsigned integer or a dedicated "infinite" value (which is stored as the all-bits-set `-1` value). This is used in places where a size could either be a finite value or an "unbounded" value, to both try to make standard math robust against the infinite case, and also to force code to deal with both the finite and infinite cases more explicitly when they care about the difference. * The public API was documented so that unbounded-size arrays report their size as `-1`. We should probably change this function to return a signed value instead of `size_t`, but that would technically be a source-breaking change, so we want to make sure we stage it appropriately. * The code that invokes fxc was updated so that it passes the appropriate flag to enable unbounded arrays of descriptors. I haven't looked yet at whether dxc needs such a flag, so there may need to be a follow-on change to add that. * The logic in the `UsedRanges::Add` method for tracking what registers have been claimed was rewritten because the previous version had some subtle bugs. The new version includes more detailed comments that attempt to explain why I think the new logic works. * The top-level logic for auto-assigning bindings to parameters has been overhauled to deal with the fact that a parameter that needs "infinite" amounts of a resource should be claiming a full register space for those resources instead. Whenever a parameter allocates any register spaces we want them all to be contiguous, so we have a loop that counts the requirements and allocates the spaces before we go along and dole them out. * When computing the layout for an array type, we need to carefully deal with unbounded-size arrays. In the case of an unbounded array of a "simple" resource type (e.g., `Texture2D[]`), we opt to expose the type layout as consuming an infinite number of the appropriate register, while in the case of a complex type (say, a `struct` with two texture fields), we need to instead allocate whole spaces for those fields. The logic here is more subtle than I would like, and interacts with the existing code that "adjusts" the element type of an array in order to make standard indexing math Just Work. * Similarly, when a `struct` type has unbounded-array fields, then we need to transform any field with infinite register requirements to instead consume a space in the resulting aggregate type. This case is comparatively easier than the array case. * The test case for unbounded arrays covers both explicit and implicit bindings, and also the case of an unbounded array over a `struct` type (it does not cover the case of a `struct` contianing unbounded arrays, so that will need to be added later). For this test we are both validation the output reflection data and that we produce the same code as fxc (with explicit bindings in the fxc case). * The reflection test app was modified to use the new API contract and detect when a parameter consumes `SLANG_UNBOUNDED_SIZE` resources. * Fixup: ensure unbounded size is defined at right bit width
* Add callable shader support for Vulkan ray tracing (#718)Tim Foley2018-11-12
| | | | | | | | | | | | | | | | | | * Add callable shader support for Vulkan ray tracing This change extends the previous work to update Vulkan ray tracing support for the finished `GL_NV_ray_tracing` spec. One of the features missing in the experimental extension that was added to the final spec is "callable shaders," which allow ray tracing shaders to call other shaders as general-purpose subroutines. Most of the implementation work here mirrors what was done for the `TraceRay()` function to map it to `traceNV()`. We map the generic `CallShader<P>` function to the non-generic `executeCallableNV`, with a payload identifier that indicates a specific global variable of type `P` (the global variable being generated from a `static` local in `CallShader`). A new modifier is added to identify the payload structure, and the parameter binding/layout logic introduces a new resource kind for callable-shader payload data (where previously the logic had assumed ray and callable payloads should use the same resource kind). Two test shaders are included: one for the callable shader (`callable.slang`) and one for a ray generation shader that calls it (`callable-caller.slang`). Just for kicks, the payload data type is defined in a shared file so that we can be sure the two agree (trying to emulate what might be good practice, and ensure that ray tracing support works together with other Slang mechanisms). * Typo fix: assocaited->associated One instance was found in review, but I went ahead and fixed a bunch since I seem to make this typo a lot. * Typo fix: defintiion->definition
* Support cross-compilation of ray tracing shaders to Vulkan (#663)Tim Foley2018-10-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Move to newer glslang * Support cross-compilation of ray tracing shaders to Vulkan This change allows HLSL shaders authored for DirectX Raytracing (DXR) to be cross-compiled to run with the experimental `GL_NVX_raytracing` extension (aka "VKRay"). * The GLSL extension spec is marked as experimental, so that any shaders written using this support should be ready for breaking changes when the spec is finalized. * "Callable shaders" are not exposed throug the GLSL extension, so this feature of DXR will not be cross-compiled. * The experimental Vulkan raytracing extension does not have an equivalent to DXR's "local root signature" concept. This does not visibly impact shader translation (because the local/global root signature mapping is handled outside of the HLSL code), but in practice it means that applications which rely on local root signatures on their DXR path will not be able to use the translation in this change as-is; more work will be needed. The simplest part of the implementation was to go into the Slang standard library and start adding GLSL translations for the various DXR operations. In some cases, like mapping `IgnoreHit()` to `ignoreIntersectionNVX()` this is almost trivial. The various functions to query system-provided values (e.g., `RayTMin()`) were also easy, with the only gotcha being that they map to variables rather than function calls in GLSL, and our handling of `__target_intrinsic` assumes that a bare identifier represents a replacement function name, and not a full expression, so we have to wrap these definitions in parentheses. The tricky operations are then `TraceRay<P>()` and `ReportHit<A>()`, because these two are generics/templates in HLSL. GLSL doesn't support generics, even for "standard library" functions, so the raytracing extension implements a slightly complex workaround: the matching operations `traceNVX()` and `reportIntersectionNVX()` pass the payload/attributes argument data via a global variable. That is, shader code for the GLSL extensions writes to the global variable and then calls the intrinsic function. The linkage between the call site and the global is established by a modifier keyword (`rayPayloadNVX` and `hitAttributeNVX`, respectively) and in the case of ray payload also uses `location` number to identify which payload global to use (since a single shader can trace rays with multiple payload types). Our translation strategy in Slang tries to leverage standard language mechanisms instead of special-case logic. For example, to translate the `ReportHit<A>()` function, we provide both a default declaration that will work for HLSL (where the operation is built-in with the signature given), and a *definition* marked with the `__specialized_for_target(glsl)` modifier. The GLSL definition declares a function `static` variable that will fill the role of the required global, and then does what the GLSL spec requires: assigns to the global, and then calls the `reportIntersectionNVX` builtin (which we declare as a separate builtin). Our ordinary lowering process will turn that `static` variable into an ordinary global in the IR, and the `[__vulkanHitAttributes]` attribute on the variable will be emitted as `hitAttributeNVX` in the output. There is no additional cross-compilation logic in Slang specific to `ReportHit<A>()` - the target-specific definition in the standard library Just Works. The case for `TraceRay<P>()` is a bit more complicated, simply because the GLSL `traceNVX()` function needs to be passed the `location` for the payload global. We implement the payload global as a function-`static` variable, with the knowledge that every unique specialization of `TraceRay<P>()` will generate a unique global variable of type `P` to implement our function-`static` variable. We then add a slightly magical builtin function `__rayPayloadLocation()` that can map such a variable to its generated `location`; the logic for this is implemented in `emit.cpp` and described below. We also changed the `RayDesc` and `BuiltinTriangleIntersectionAttributes` types from "magic" intrinsic types over to ordinary types (because the GLSL output needs to declare them as ordinary `struct` types). This ends up removing some cases in the AST and IR type representations. By itself this change would break HLSL emit, because in that case the types really are intrinsic. We added a `__target_intrinsic` modifier to these types to make them intrinsic for HLSL, and then updated the downstream passes to handle the notion of target-intrinsic types. The logic for binding/layout of entry point inputs and outputs was updated so that raytracing stages don't follow the default logic for varying input/output parameters. This is because the input/output parameters of a raytracing entry point aren't really "varying" in the same sense as those in the rasterization pipeline. In particular, the SPIR-V model for raytracing input and output treats "ray payload" and "hit attributes" parameters as being in a distinct storage class from `in` or `out` parameters. We also detect cases where a ray tracing stage declares inputs/outputs that it shouldn't have. This logic could conceivably be extended to other stages (e.g., to give an error on a compute shader with user-defined varying input/output). The type layout logic added cases for handling raytracing payload and hit-attribute data, but this is currently just a stub implementation that follows the same logic as for varying `in` and `out` parameters (it cannot give meaningful byte sizes/offsets right now). To my knowledge the GLSL spec doesn't currently specify anything about layout, and I haven't read the DXR spec language carefully enough to know what it says about layout. A future change should update the layout logic to allow for byte-based layout of ray payloads, etc. so that we can query this information via reflection. The GLSL legalization logic in `ir.cpp` was updated to factor out the per-entry-point-parameter code into its own function, and then that function was updated to special-case the input/output of a ray-tracing shader. While for rasterization stages we typically want to take the user-declared input/output and "scalarize" it for use in GLSL (in part to deal with language limitations, and in part to tease system values apart from user-defined input/output), the GLSL spec for raytracing requires payload and hit attribute parameters to be declared as single variables. There is also the issue that even for an `in out` parameter, a ray payload parameter should only turn into a single global, whereas the handling for varying `in out` parameters generates both an `in` and an `out` global for the GLSL case. Other than the handling of entry point parameters, the GLSL legalization pass doesn't need to do anything special for ray tracing shaders. The trickiest change in the `emit.cpp` logic is that we now generate `location`s for ray payload arguments (the outgoing from a `TraceRay()` call) on demand during code generation. This is a bit hacky, and it would be nice to handle it as a separate pass on the IR rather than clutter up the emit logic, but this approach was expedient. Basically, any of the global variables that got generated from the `static` declarations in the standard library implementation of `TraceRay()` will trigger the logic to assign them a `location`. The logic for emitting intrinsic operations added a few new `$`-based escape sequences. The `$XP` case handles emitting the location of a generated ray payload variable; this is how we emit the matching location at the site where we call `traceNVX`. The `$XT` case emits the appropriate translation for `RayTCurrent()` in HLSL, because it maps to something different depending on the target stage. All of the test cases here consist of a pair of an HLSL/Slang shader written to the DXR spec, plus a matching GLSL shader for a baseline. The GLSL shaders are carefully designed so that when fed into glslang they will produce the same SPIR-V as our cross-compilation process. This kind of testing is quite fragile, but it seems to be the best we can do until our testing framework code supports *both* DXR and VKRay. A bunch of the core changes ended up being blocked on issues in the rest of the compiler, so some additional features go implemented or fixed along the way: The first big wall this work ran into was that the `__specialized_for_target` modifier hasn't actually been working correctly for a while. It turns out that for the one function that is using it, `saturate()`, we have been outputting the workaround GLSL function in *all* cases (including for HLSL output) rather than only on GLSL targets. The problem here is that for a generic function with a `__specialized_for_target` modifier or a `__target_intrinsic` modifier, the IR-level decoration will end up attached to the `IRFunc` instruction nested in the `IRGeneric`, but the logic for comparing IR declarations to see which is more specialized (via `getTargetSpecializationLevel()`) was looking only at decorations on the top-level value (the generic). The quick (hacky) fix here is to make `getTargetSpecializationLevel()` try to look at the return value of a generic rather than the generic itself, so that it can see the decorations that indicate target-specific functions. A more refined fix would be to attach target-specificity decorations to the outer-most generic (to simplify the "linking" logic). The only reason not to fold that into the current fix is that the `__target_intrinsic` modifier currently serves double-duty as a marker of target specialization *and* information to drive emit logic. The latter (the emit-related stuff) currently needs to live on the `IRFunc`, and moving it to the generic could easily break a lot of code. This needs more work in a follow-on fix, but for now target specialization should again be working. The other big gotcha that the simple "just use the standard library" strategy ran into was that function-`static` variables weren't actually implemented yet, and in particular function-`static` variables inside of generic functions required some careful coding. The logic in `lower-to-ir.cpp` has this `emitOuterGenerics()` function that is supposed to take a declaration that might be nested inside of zero or more levels of AST generics, and emit corresponding IR generics for all those levels. This is needed because two different AST functions nested inside a single generic `struct` declaration should turn into distinct `IRFunc`s nested in distinct `IRGeneric`s. The tricky bit to making that all work is that the same AST-level generic type parameter will then map to *different* IR-level instructions (the parameters of distinct `IRGeneric`s) when lowering each function. The existing logic handled this in an idiomatic way by making "sub-builders" and "sub-contexts." This change refactors some of the repeated logic into a `NestedContext` type to help simplify the pattern, and applies it consistently throughout the `lower-to-ir.cpp` file. Besides that cleanup, the major change is `lowerFunctionStaticVarDecl` which, unsurprisingly, handles lower of function-`static` variables to IR globals. The careful handling of nested contexts here is needed because if we are in the middle of lowering a generic function, then a `static` variable should turn into its *own* `IRGeneric` wrapping an `IRGlobalVar`. The body of the function should refer to the global variable by specializing the global variable's `IRGeneric` to the parameters of the *functions* `IRGeneric`. This tricky detail is handled by `defaultSpecializeOuterGenerics`. An additional subtlety not actually required for this raytracing work (and thus not properly tested right now) is handling function-`static` variables with initializers. These can't just be lowered to globals with initializers, because HLSL follows the C rule that function-`static` variables are initialized when the declaration statement is first executed (and this could be visible in the presence of side-effects). The lowering strategy here translates any `static` variable with an initializer into *two* globals: one for the actual storage, plus a second `bool` variable to track whether it has been initialized yet. There are some opportunities to optimize this case, especially for `static const` data, but that will need to wait for future changes. We've slowly been shifting away from the model where a user thinks of a "profile" as including both a stage and a feature level. Instead, the user should think about selecting a profile that only describes a feature level (e.g., `sm_6_1`, `glsl_450`, etc.), and then separately specifying a stage (`vertex`, `raygeneration, etc.) for each entry point. The challenge here is that the command-line processing still only had a single `-profile` switch, and no way to specify the stage. Adding the `-stage` option was relatively easy, but making it work with the existing validation logic for command-line arguments was tricky, because of the complex model that `slangc` supports for compiling multiple entry points in a single pass. * In `slang.h` add new reflection parameter categories for ray payloads and hit attributes, as part of entry point input/output signatures. * A previous change already updated our copy of glslang to one that supports the `GL_NVX_raytracing` extension, so in `slang-glslang.cpp` we just needed to map Slang's `enum` values for the raytracing stage names to their equivalents in the glslang code. * Moved the logic for looking up a stage by name (`findStageByName()`) out of `check.cpp` and into `compiler.cpp`, with a declaration in `profile.h` * Added a `$z` suffix to the GLSL translation of `Texture*.SampleLevel()`, to handle cases where the texture element type is not a 4-component vector. Note that this fix should actually be applied to *all* these texture-sampling operations, but I didn't want to add a bunch of changes that are (clearly) not being tested right now. * The layout logic for entry points was updated to correctly skip producing a `TypeLayout` for an entry point result of type `void`, which meant that the related emit logic now needs to guard against a null value for the result layout. * In `ir.cpp`, dump decorations on every instruction instead of just selected ones, so that our IR dump output is more complete. * Added a command-line `-line-directive-mode` option so that we can easily turn off `#line` directives in the output when debugging. Not all cases where plumbed through because the `none` case is realistically the most important. * Parser was fixed to properly initialize parent links for "scope" declarations used for statements, so that we can walk backwards from a function-scope variable (including a `static`) and see the outer function/generics/etc. * Added GLSL 460 profile, since it is required for ray tracing. Also updated the logic for computing the "effective" profile to use to recognize that GLSL raytracing stages require GLSL 460. * Added some conventional ray-tracing shader suffixes to the handling in `slang-test`. This code isn't actually used, but was relevant when I started by copy-pasting some existing VKRay shaders as the starting point for my testing. * Fixup: typos
* Improve support for non-32-bit types. (#643)Tim Foley2018-09-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | The main change here is to fill out the `BaseType` enumeration so that it covers the full range of 8/16/32/64-bit signed and unsigned integers, as well as 16/32/64-bit floating-point numbers, and then propagate that completion through various places in the code. More details: * The current `half`, `float`, `double`, `int`, and `uint` types are still the default names for their types, so things like `float16_t` and `int32_t` were added as `typedef`s. * We still need to generate the full gamut of vector/matrix `typedef`s for the new types, so that things like `float16_t4x3` will work (yes, I know that is ugly as sin, but that's the HLSL syntax...). * A few pieces of dead code from earlier in the compiler's life got removed, since I did a find-in-files for `BaseType::` and tried to either update or delete every site. * A few call sites that were enumerating integer base types in an ad-hoc fashion were changed to use a single `isIntegerBaseType()` function that I added in `check.cpp` * When compiling with dxc for shader model 6.2 and up, we enable the compiler's support for native 16-bit types via a flag. * The public API enumeration for reflection of scalar types added cases for 8- and 16-bit integers (it already exposed the other cases we need) * The lexer was updated to be extremely liberal in what kinds of suffixes it allows on literals. I also removed the logic that was treating, e.g., `0f` as a floating-point literal (it doesn't seem to be the right behavior). That would now be an integer literal with an invalid suffix. * The logic in the parser that applies types to literals was updated to handle a few more cases: `LL` and `ULL` for 64-bit integers, and `H` for 16-bit floats. * The mangling logic needed to be updated to handle the new cases, and I consolidated the handling of those types in their front-end and IR forms. * Removed the explicit `BasicExpressionType::ToString` logic, since all basic types are `DeclRefType`s in the front end, and we can just print them out as such. * As a bit of a gross hack, fudged the conversion costs so that `int` to `int64_t` conversion is a bit more costly. The problem there is that given an operation like `int(0) + uint(0)`, the best applicable candidates ended up being `+(uint,uint)` and `+(int64_t,int64_t)` because the cost of a single `int`-to-`uint` conversion was the same as the sum of the cost of an `int`-to-`int64_t` and a `uint`-to-`int64_t`. A better long-term fix here is to completely change our overload resolution strategy, but that is obviously way too big to squeeze into this change. * Type layout computation was updated to handle all the new types and give them their natural size/alignment. Note that this does *not* work for down-level HLSL where `half` is treated as a synonym for `float`. It also doesn't deal with the fact that many of these types aren't actually allowed in constant buffers for certain shader models. A future change should work to add error messages for unsupported stuff during type layout (or just make the types themselves require support for certain capabilities)
* Add support for more RasterizerOrdered types (#628)Tim Foley2018-08-21
| | | | | | | | | | | | | | Fixes #627 The front-end has support for `RasterizerOrderedBuffer` and `RasterizerOrderedTexture*`, but left out support for: * `RasterizerOrderedByteAddressBuffer` * `RasterizerOrderedStructuredBuffer` [Nitpick: these tyeps are all amazingly annoying to type. It is easy to want to write `RasterOrdered` instead of the bulkier `RasterizerOrdered`, and almost everybody does in casual speech. There's already the issue of wanting to type `StructureBuffer` (a buffer of structures) instead of `StructuredBuffer` (a buffer that is... structured?). Then you have `ByteAddressBuffer` which is just adding to the confusion because it is nominally a "byte addressable" buffer (so that `ByteAddressedBuffer` would actually make sense), but then actually *isn't* byte addressable in practice.] There were a few `TODO` comments related to this already, and this change was mostly a matter of doing a find-in-files for `RWByteAddressBuffer` and `RWStructuredBuffer` and adding matching `RasterizerOrdered` cases. The test I added just checks that these types make it through the front-end, and doesn't do any actual confirmation that they work as intended. It is worth noting that the handling of ordering in GLSL/VK is different from in HLSL ("pixel shader interlock" instead of "rasterizer ordered views"), so coming up with a cross-compilation story would need to be a later step.
* Add options to control matrix layout rules (#583)Tim Foley2018-05-31
| | | | | | | | | | | | | | | | | | | | | * Add options to control matrix layout rules Up to this point, the Slang compiler has assumed that the default matrix layout conventions for the target API will be used. This means column-major layout for D3D, and *row major* layout for GL/Vulkan (note that while GL/Vulkan describe the default as "column major" there is an implicit swap of "row" and "column" when mapping HLSL conventions to GLSL). This commit introduces two main changes: 1. The default layout convention is switched to column-major on all targets, to ensure that D3D and GL/Vulkan can easily be driven by the same application logic. I would prefer to make the default be row-major (because this is the "obvious" convention for matrices), but I don't want to deviate from the defaults in existing HLSL compilers. 2. Command-line and API options are introduced for setting the matrix layout convention to use (by default) for each code generation target. It is still possible for explicit qualifiers like `row_major` to change the layout from within shader code. I also added an API to query the matrix layout convention that was used for a type layout (which should be of the `SLANG_TYPE_KIND_MATRIX` kind), but this isn't yet exercised. I added a reflection test case to make sure that the offsets/sizes we compute for matrix-type fields are appropriately modified by the flag that gets passed in. In a future change we could possibly switch the default convention to row-major, if we also changed our testing to match, since there are currently not many clients to be adversely impacted by the change. * Fixup: silence 64-bit build warning
* Fix bug around arrays of structs of resources (#352)Tim Foley2018-01-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Should fix #351 The basic problem is that the type layout logic in Slang isn't taking into account the way that resource-type fields in aggregate types get split. When you just have a bare aggregate, this oversight doesn't cause a problem, but once you put those aggregates into an array, the problems become clear. Given: ```hlsl struct Test { Texture2D a; Texture2D b; }; Test test[8]; ``` The default type-layout algorithm gives `Test::a` an offset of zero, and `Test::b` an offset of one. However, after splitting, we have something like: ```hlsl Texture2D test_a[8]; Texture2D test_b[8]; ``` It is clear in this case that `test_b` can't start at an offset of one relative to `test_a` - it needs to start at `register(t8)`. This change handles things by adjusting the layout of an array type to account for this detail as soon as it is created. The alternative would have been to not change layout rules at all, but to instead try to adjust things at the point where types get split (and the layout for the un-split case gets applied to the split variable). The reason for doing it the way it is in this change is that the reflection API will hopefully provide accurate information. Related to reflection information, one thing that is missing here is proper computation of the "stride" for an array like this. We'll see if that needs to be addressed in a follow-up.
* More fixups for Vulkan parameter block bindings (#309)Tim Foley2017-12-14
| | | | | | | | | I'm adding a small cross-compilation test to try to make sure that we are testing the binding generation for GLSL output. We probably still need a more complex test that uses multiple blocks, plus variables not in a block. The big changes here are: - Change the `containerTypeLayout` field to a `containerVarLayout` in the `ParameterGroupTypeLayout`, so that we can store the base offsets for the fields in a uniform fashion (even though these will all be zero). - Switch the emit logic to carefully use either the container or element var layout depending on what they are emitting bindings for. This involved adding something akin to the "reflection path" notion that Falcor has to use, but only for the emit step.
* Fix parameter block binding for Vulkan (#308)Tim Foley2017-12-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fixes #307 This ends up being a major overhaul over how type layout computation is structured and exposed. The big problems all arise around cases where both the "container" for a parameter block or CB, and the "element" type both use the same kind of resource. E.g., if you define a CB with a texture in it, then in Vulkan both the CB and the texture use the same kind of resource, and so if you query the CB's resource usage it will just tell you it uses two descriptor-table slots, but nothing more than that. Similar confusion still arises in the HLSL case, when a CB with a texture in it reports its parameter category as "mixed" so that a user might query for a category they didn't mean to. There were also cases in the existing code where a parameter block might expose *both* a register-space usage and another concrete resource type, which isn't right. The most important changes here are: - A `ParameterGroupTypeLayout` now has a more refined internal structure, consisting of: - A `containerTypeLayout`, which represents the resource usage of the buffer/block itself (e.g., if a constant buffer had to be allocated) - An `elementVarLayout` which stores the offsets that need to be applied to get from the `VarLayout` for an instance of this parameter-group type to the offsets of its elements. The `TypeLayout` for this variable layout should be the "raw" type of the block/CB element. - The `offsetElementTypeLayout` (formerly just `elementTypeLayout`) which represents the element type, but in the case of a `struct` element type, will have fields offset similar to the `elementVarLayout`. This is what all the old code used to use, so we need to keep it for compatibility. - When doing reflection on a `ParameterGroupTypeLayout`, we now only report the resource usage of the `containerTypeLayout`. This is technically a potentially breaking change in the public API, but I don't think Falcor will mind, since they actually want something closer to this behavior. - Add a new public API for querying the element variable layout of a parameter block of constant buffer. This could be used by savvy applications to fold the handling of CB element offsetting into some notion of a "reflection path." This would be required for applications that want to handle CBs or parameter blocks where the element type is *not* a `struct` type. - Remove old logic for applying an offset when creating a type layout for constant buffer element, and instead perform offsetting more uniformly later, by constructing the `offsetElementTypeLayout` from the `rawElementTypeLayout`. This is useful both because we want to keep both (the "raw" type layout becomes the type layout of the `elementVarLayout`), and also because we can decide later whether we even want to allocate a CB register for a buffer, based on whether it actually contains any uniform data. - Fix cases where we might end up with a parameter block type reporting both that it uses a whole register space (and thus should not expose the resource usage of the container/element type) *and* a constant-buffer register/slot. The latter should be hidden inside the regsiter space. - Clean up the `spReflectionParameter_GetBinding{Index,Space}` functions to just route to `spReflectionVariableLayout_Get{Offset,Space}`, using the "default" category of the parameter - Try to make the `GetSpace` query take into account cases where a variable also has an explicit `RegisterSpace` allocation. - This probably still needs some cleanup, since ideally we'd just move things into the `space` field on the `ReosurceInfo` and have an invariant that a variable *either* has a `RegisterSpace` allocation, or it has other resource infos, but never both... - Add some ad-hoc logic so that if the user queries for a binding index/space using a parameter category that doesn't actually apply (e.g., they query for a D3D `t` register when using Vulkan), we can optionally remap it to the resource type they "probably" meant. This is a mess of Do What I Mean code, but it is also what our users want right now. - Fix various bits of emit logic so that if a parameter block has a register space/set allocated to it, we properly output that as part of the binding information for it. - This is another thing that might be cleaned up if we rationale the way that things get split during legalization. - Add a GLSL case for emitting a parameter block variable as a `cbuffer`.
* Add support for global generic parameters (#285)Yong He2017-11-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Add support for global generic parameters (In-progress work) This commit include: 1. Update Slang API to allow specification of generic type arguments in an `EntryPointRequest` 2. Add parsing of `__generic_param` construct, which becomes a GlobalGenericParamDecl, contains members of `GenericTypeConstraintDecl`. 3. Semantics checking will check whether the provided type arguments conform to the interfaces as defined by the generic parameter, and store SubtypeWitness values in the EntryPointRequest, which will be used by `specializeIRForEntryPoint` when generating final IR. 4. Add a new type of substitution - `GlobalGenericParamSubstitution` for subsittuting references to `__generic_param` decls or to its member `GenericTypeConsraintDecl` with the actual type argument or witness tables. 5. Update `IRSpecContext` to apply `GlobalGenericParamSubstitution` when specializing the IR for an EntryPointRequest. 6. Update `render-test` to take additional `type` inputs, which specifies the type arguments to substitute into the global `__generic_param` types. This commit does not include ProgramLayout specialization. * IR: pass through `[unroll]` attribute (#284) The initial lowering was adding an `IRLoopControlDecoration` to the instruction at the head of a loop, but this was getting dropped when the IR gets cloned for a particular entry point. The fix was simply to add a case for loop-control decorations to `cloneDecoration`. * fix warnings * IR: support `CompileTimeForStmt` (#286) This statement type is a bit of a hack, to support loops that *must* be unrolled. The AST-to-AST pass handles them by cloning the AST for the loop body N times, and it was easy enough to do the same thing for the IR: emit the instructions for the body N times. The only thing that requires a bit of care is that now we might see the same variable declarations multiple times, so we need to play it safe and overwrite existing entries in our map from declarations to their IR values. Of course a better answer long-term would be to do the actual unrolling in the IR. This is especially true because we might some day want to support compile-time/must-unroll loops in functions, where the loop counter comes in as a parameter (but must still be compile-time-constant at every call site). * Add support for global generic parameters (In-progress work) This commit include: 1. Update Slang API to allow specification of generic type arguments in an `EntryPointRequest` 2. Add parsing of `__generic_param` construct, which becomes a GlobalGenericParamDecl, contains members of `GenericTypeConstraintDecl`. 3. Semantics checking will check whether the provided type arguments conform to the interfaces as defined by the generic parameter, and store SubtypeWitness values in the EntryPointRequest, which will be used by `specializeIRForEntryPoint` when generating final IR. 4. Add a new type of substitution - `GlobalGenericParamSubstitution` for subsittuting references to `__generic_param` decls or to its member `GenericTypeConsraintDecl` with the actual type argument or witness tables. 5. Update `IRSpecContext` to apply `GlobalGenericParamSubstitution` when specializing the IR for an EntryPointRequest. 6. Update `render-test` to take additional `type` inputs, which specifies the type arguments to substitute into the global `__generic_param` types. progress on parameter binding * Add a more contrived test case for specializing parameter bindings * update render-test to align buffers to 256 bytes (to get rid of D3D complains on minimal buffer size). * adding one more test case for parameter binding specialization. * Cleanup according to @tfoleyNV 's suggestions. * fix a bug introduced in the cleanup
* Parameter block work (#276)Tim Foley2017-11-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | * Don't auto-enable IR use for compute tests The `COMPARE_COMPUTE` and `COMPARE_RENDER_COMPUTE` test fixtures were set up to always enable the `-use-ir` flag on Slang, which precludes having any tests that confirm functionality on the old non-IR path (which is still required by our main customer). This change adds the `-xslang -use-ir` flags explicitly to any compute test cases that left them out, and makes the fixture no longer add it by default. * Continue building out parameter block support The initial front-end logic for parameter blocks was already added, but they are still missing a bunch of functionality. This change addresses some of the known issues: - Bug fix: don't try to emit HLSL `register` bindings for variables that consume whole register spaces/sets - Overhaul type layout logic so that it can make decisions based on a given code generation target (currently passed in as a `TargetRequest`), which allows us to decide whether or not a parameter block should get its own register set on a per-target basis. - Always use a register space/set for Vulkan - Never use a register space/set for HLSL SM 5.0 and lower - By default, don't use register spaces/sets for HLSL output - Add a command-line flag and some "target flags" to enable register-space usage for D3D targets - Hackily add initial support for parameter blocks in the AST-to-AST path - This just blindly lowers `ParameterBlock<T>` to `T`, which shouldn't quite work - A more complete overhaul will probably need to wait until the AST-to-AST legalization is changed to use the `LegalType`s from the IR legalization pass. - Add a compute-based test case to actually run code using parameter blocks - This file runs test cases both with and without the IR
* Parameter blocks (#245)Tim Foley2017-11-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * Rename existing ParameterBlock to ParameterGroup We are planning to add a new `ParameterBlock<T>` type, which maps to the notion of a "parameter block" as used in the Spire research work. Unfortunately, the compiler codebase already uses the term `ParameterBlock` as catch-all to encompass all of HLSL `cbuffer`/`tbuffer` and GLSL `uniform`/`buffer`/`in`/`out` blocks (all of which are lexical `{}`-enclosed blocks that define parameters...). This change instead renames all of the existing concepts over to `ParameterGroup`, which isn't an ideal name, but at least doesn't directly overlap the new terminology or any existing terminology. The new `ParameterBlockType` case will probably be a subclass of `ParameterGroupType`, since it is a logical extension of the underlying concept. * Add Shader Model 5.1 profiles The HLSL `register(..., space0)` syntax is only allowed on "SM5.1" and later profiles (which is supported by the newer version of `d3dcompiler_47.dll` that comes with the Win10 SDK, but not the older version of `d3dcompiler_47.dll` - good luck figuring out which you have!). This change adds those profiles to our master list of profiles, and nothing else. * First pass at support for `ParameterBlock<T>` - Add the type declaration in stdlib - Add a special case of `ParameterGroupType` for parameter blocks - Handle parameter blocks in type layout (currently handling them identically to constant buffers for now, which isn't going to be right in the long term) - Add an IR pass that basically replaces `ParameterBlock<T>` with `T` - Eventually this should replace it with either `T` or `ConstantBuffer<T>`, depending on whether the layout that was computed required a constant buffer to hold any "free" uniforms - Add first stab at an IR pass to "scalarize" global variables using aggregate types with resources inside. - This currently only applies to global variables, so it won't handle things passed through functions, or used as local variables - It also only supports cases where the references to the original variable are always references to its fields, and not the whole value itself - Add a single test case that technically passes with this level of support, but probably isn't very representative of what we need from the feature * Fold parameter-block desugaring into a more complete "type legalization" pass The basic problem that was arising is that once you desugar `ParameterBlock<T>` into `T`, you then need todeal with splitting `T` into its constituent fields if it contains any resource types. Handling those transformations by following the usual use-def chains wasn't really helping, because you might need systematic rewriting that can really only be handled bottom-up. This change adds a new pass that is intended to perform multiple kinds of type "legalization" at once: - It will turn `ParameterBlock<T>` into `T` - It may at some point also convert `ConstantBuffer<T>` into `T` as well - It will turn an value of an aggregate type that contains resources into N different values (one per field) - As a result of this, it will also deal with AOS-to-SOA conversion of these types Legalization is applied to *every* function/instruction/value, so that it can make large-scale changes that would be tough to manage with a work list. This pass needs to be run *after* generics have been fully specialized, so that we know we are always dealing with fully concrete types, so that their legalization for a given target is completely known. This is still work in progress; there's more to be done to get this working with all our test cases, and finish the remaining `ParameterBlock<T>` work. * Improve binding/layout information when using parameter blocks - When doing type layout for a parameter block, don't include the resources consumed by the element type in the resource usage for the parameter block - Note that this is pretty much identical to how a `ConstantBuffer<T>` does not report any `LayoutResourceKind::Uniform` usage, except that `ParameterBlock<T>` is *also* going to hide underlying texture/sampler reigster usage - The one exception here is that any nested items that use up entire `space`s or `set`s those need to be exposed in the resource usage of the parent (I don't have a test for this) - When type legalization needs to scalarize things, it must propagate layout information down to the new leaf variables. In general, the register/index for a new leaf parameter should be the sum of the offsets for all of the parent variables along the "chain" from the original variable down to the leaf (we aren't dealing with arrays here just yet). - When type legalization decides to eliminate a pointer(-like) type (e.g., desugar `ParameterBlock<T>` over to `T`), actually deal with that in terms of the `LegalVal`s created, so that we can know to turn a `load` into a no-op when applied to a value that got indirection removed. - Hack up the "complex" parameter-block test so that it actually passes (the big hack here is that the HLSL baseline is using names that are generated by the IR, and are unlikely to be stable as we add/remove transformations). - Note: I can't make these be compute tests right now, because regsiter spaces/sets are a feature of D3D12/Vulkan, and our test runner isn't using those APIs.
* fixed all warningsYong He2017-11-04
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* fix all unreachable code warningsYong He2017-11-04
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* Allow use of dxc compiler for DXIL generation (#241)Tim Foley2017-11-01
| | | | | | | | | | | | | | | | - Add shader model 6.0, 6.1, and 6.2 targets - Add DXIL and DXIL assembly as output formats - Add header for DXC API to `external/` - Add `dxc-support.cpp` that wraps usage of the API - Add `-pass-through dxc` option, equivalent to what we have for `fxc` Notes: * This does *not* include any logic to add `dxcompiler.dll` to our build process; that is way out of scope for the build complexity I'm ready to deal with * For right now, the use of `dxcompiler.dll` is hard-coded, and it must be discoverable in the current executable's search path; options to customize can come later * The `-pass-through` option is kind of silly because the code doesn't actually pay attention to the value (just whether it is set). If you set it to `fxc` but ask for DXIL, we pass through `dxc` anyway.
* Implement notion of a "container format" (#213)Tim Foley2017-10-16
| | | | | | | | | | | The big addition here is that the Slang "bytecode" is no longer treated as just a "code generation target" (`CodeGenTarget`) akin to DX bytecode (DXBC) or SPIR-V, but instead is a `ContainerFormat` that can be used to emit all the results of a compile request (well, currently just the IR-as-BC, but the intention is there). Getting to this goal involved some prior checkins that eliminated bogus "targets" that weren't really akin to SPIR-V or DXBC: `-target slang-ir-asm` and `-target reflection-json`. Those targets were really in place to support testing, and so they've been made more explicit testing/debug options. This change eliminates `-target slang-ir` and instead tries to allow the user to specify `-o foo.slang-module` as an output file name, that indicates the intention to output a "container" file that will wrap up all the generated code. I've also gone ahead and generalized the existing `-target` option so that we are actually building up a *list* of code generation targets. This is largely just a cleanup, since it forces code to be more aware of when it is doing something target-specific vs. target independent. For example, reflection layout information lives on a requested target, and not on the compile request as a whole, and similarly output code is per-target, per-entry-point. As a cleanup, I eliminated support for per-translation-unit output. This was vestigial code from back when I used to try and do HLSL generation for a whole translation unit instead of per-entry-point (which turned out to be a lot of complexity for little gain), and it was only being used in the `hello` example and the `render-test` test fixture - in both cases fixing it up was easy enough. I've stubbed out the old `spGetTranslationUnitSource` API, but haven't removed it yet.
* Get rid of the `-slang-ir-asm` target (#212)Tim Foley2017-10-13
| | | | | | | | * Get rid of the `-slang-ir-asm` target This is really only useful for debugging, so I've replaced the functionality with a `-dump-ir` command line option (which dump's the IR for an entry point before doing codegen). * fixup: use HLSL target, not DXBC, so test can run on Linux
* First attempt at a Linux build (#193)Tim Foley2017-09-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * First attempt at a Linux build - Fix up places where C++ idioms were written assuming lenient behavior of Microsoft's compiler - Add a few more alternatives for platform-specific behavior where Windows was the only platform accounted for. - Add a basic Makefile that can at least invoke our build, even if it isn't going good dependency tracking, etc. - Build `libslang.so` and `slangc` that depends on it, using a relative `RPATH` to make the binary portable (I hope) - Add an initial `.travis.yml` to see if we can trigger their build process. * Fixup: const bug in `List::Sort` I'm not clear why this gets picked up by the gcc *and* clang that Travis uses, but not the (newer) gcc I'm using on Ubuntu here, but I'm hoping it is just some missing `const` qualifiers. * Fixup: reorder specialization of "class info" Clang complains about things being specialized after being instantiated (implicilty), and I hope it is just the fact that I generate the class info for the roots of the hierarchy after the other cases. We'll see. * Fixup: add `platform.cpp` to unified/lumped build * Fixup: Windows uses `FreeLibrary` and not `UnloadLibrary` * Fixup: fix Windows project file to include new source file This obviously points to the fact that we are going to need to be generating these files sooner or later.
* IR: handle control flow constructs (#186)Tim Foley2017-09-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * IR: handle control flow constructs This change includes a bunch of fixes and additions to the IR path: - `slang-ir-assembly` is now a valid output target (so we can use it for testing) - This uses what used to be the IR "dumping" logic, revamped to support much prettier output. - A future change will need to add back support for less prettified output to use when actually debugging - IR generation for `for` loops and `if` statements is supported - HLSL output from the above control flow constructs is implemented - Revamped the handling of l-values, and in particular work on compound ops like `+=` - Add basic IR support for `groupshared` variables - Add basic IR support for storing compute thread-group size - Output semantics on entry point parameters - This uses the AST structures to find semantics, so its still needs work - Pass through loop unroll flags - This is required to match `fxc` output, at least until we implement unrolling ourselves. * Fixup: 64-bit build issues. * fixup for merge
* Get IR working for `AdaptiveTessellationCS40/Render` testTim Foley2017-09-12
| | | | | | | | | | | | | | | | | | | | I had expected this to be the first case where control-flow instructions were needed, but it turns out that we aren't testing that entry point right now. The real work/fix here ended up being handling of the `row_major` layout qualifier on a matrix inside a `cbuffer`. The existing AST-based code was passing it through easily (although I don't believe it was handling the layout rules right). Getting it working in the IR involved beefing up the type-layout behavior so that it can handle explicit layout qualifiers (at least for matrix layout) which should also improve the layout computation for non-square matrices with nonstandard layout in the AST-based path. There are still some annoying things left to do: - The `row_major` and `column_major` layout qualifiers in HLSL/GLSL mean different things (well, they mean the reverse of one another) so I need to validate that the GLSL case is working remotely correctly. - The layout logic isn't handling other explicit-layout cases as supported by GLSL (but of course GLSL is a far lower priority than HLSL/Slang) - There is currently no way to pass in an explicit matrix layout flag to Slang to control the default behavior. - Any client who was using Slang for HLSL pass-through and then applying a non-default flag on their HLSL->* compilation will get nasty unexpected behavior when the IR goes live - and they are already dealing with nasty behavior around non-square matrices not matching layout between Slang and the downstream. - The logic that gleans layout modes from a variable declaration is currently only being applied for fields of structure types (which applies to `cbuffer` declarations as well), and not to global-scope uniform variables. - We need test cases for all of this.
* Major naming overhaul:Tim Foley2017-08-09
| | | | | | | | | | - `ExpressionSyntaxNode` becomes `Expr` - `StatementSyntaxNode` becomes `Stmt` - `StructSyntaxNode` becomes `StructDecl` - `ProgramSyntaxNode` becomes `ModuleDecl` - `ExpressionType` becomes `Type` - Existing fields names `Type` become `type` - There might be some collateral damage here if there were, e.g., `enum`s named `Type`, but I can live with that for now and fix those up as a I see them
* Try to improve handling of failures during compilationTim Foley2017-07-19
| | | | | | | The change is mostly about trying to make sure the compiler "fails safe" when it encounters an internal assumption that isn't met. Most internal errors will now throw exceptions (yes, exceptions are evil, but this will work for now), and these get caught in `spCompile` so that they don't propagate to the user (they just see a message that compilation aborted due to an internal error). Subsequent changes are going to need to work on diagnosing as many of these situations as possible, so that users can at least know what construct in their code was unexpected or unhandled by the compiler.
* Handle `Buffer` types more like texturesTim Foley2017-07-17
| | | | | | | | Fixes #94 We'd been handling HLSL `Buffer` and `RWBuffer` in a one-off fashion, and that led to a lot of code duplication, and also to the issue that we weren't handling `RasterizerOrderedBuffer` at all. This change basically folds `Buffer` in so that it is conceptually a texture type (just with a unique shape). Hopefully all the other logic still works.
* Adjust type layout when parameter block constains member using the same resourceTim Foley2017-07-14
| | | | | | | | | | | | | | | | | | If we have something like to following in HLSL: cbuffer C { Texture2D t; ... } and we are compiling to GLSL, then both `C` and `C.t` consume the same kind of resource (a descriptor-table slot). The way reflection was working right now, querying the index of `C` would return its binding (let's say it is `4` just to be concrete) and then a query on `C::t` would give its offset, which was being computed as `0` because it is the first field in the logical `struct` type. That obviously leads to bad math and requires some subtle `+1`s in cases to get things right (e.g., when scalaring during lowering, I had to carefully add one in some cases). It is unreasonable to expect users to deal with this. This commit changes it so that the offset of field `C::t` is `1` so that hopefully more things Just Work. The special-case logic in lowering is now gone. One important catch here is that this pretty much only works in the case where the element type of a parameter block is a `struct` type (which is really all that makes sense right now). If we ever want to generalize this in the future, then it will probably be necessary to change the `TypeLayout` case for parameter blocks to store a `VarLayout` for the element, rather than just a `TypeLayout`.
* Don't assign a `binding` to a `push_constant` bufferTim Foley2017-07-14
| | | | | | | | | | | | Fixes #12 - This was a latent issue, but the previous commit brought it to the front. - As indicated in #12, I don't allocate a descriptor-table slot to the block - Instead I allocate a `PushConstantBuffer` - Unlike what #12 asks for, I don't use a different resource type for the contents of the block - Pretty much all the logic is easiest if these continue to be just plain `Uniform` data
* An array of resources in Vulkan only consumes one bindingTim Foley2017-07-13
| | | | | | | | Fixes #84 - When computing resource usage for an array type, don't multiply the resource usage of the element type by the element count foor descriptor-table-slot resources. - When reporting the "stride" of an array type through reflection, report the stride for descriptor table slots as zero, always.
* Try to be more robust against un-checked types during lowering, etc.Tim Foley2017-07-10
| | | | | | | | - Try to handle `ErrorType` gracefully when computing type layouts - When outputting a `TypeExp`, if the type part is errorneous (or missing), try to use the expression part - Make sure to lower the expressions side of a `TypeExp` during lowering
* Pick layout rules based on target languge, not source.Tim Foley2017-07-09
| | | | The tricky bit here was that the `reflection-json` output format isn't really a code generation target like the others, and we need to be able to have multiple "targets" active to make sense of it. This needs cleaning-up.
* Fix support for `std430` layoutTim Foley2017-07-07
| | | | | | Fixes #57 There were a bunch of issues in how `std430` was being implemented, largely due to just stubbing it in without any test cases. This commit adds a reasonably good test case to ensure that we've got things basically working.
* Fix alignment computation for `std140` uniformsTim Foley2017-07-07
| | | | | | Fixes #55 I was incorrectly computing alignment as `elementSize * elementAlignment`, rounded up to a power of two (which works out to be `elementSize` squared), when I should have been using `elementSize * elementCount`, rounded up to a power of two.