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* format
* Minor test fixes
* enable checking cpp format in ci
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* Misc. SPIRV Fixes, Part 2.
* Fix up.
* Fix.
* Add system smenatic values.
* 16 bit int and floats, matrix/vector reshape, bool ops.
* Fix.
* Fix.
* Allow push constant entry point params.
* entrypoint params.
* swizzleSet and swizzledStore.
* packoffset.
* string hash.
* Fix.
* Matrix arithmetics.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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Co-authored-by: Yong He <yhe@nvidia.com>
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* Cleanup refactoring work around the IR builder
We have some long-term goals for the IR that require a more centralized and disciplined set of rules for how IR instructions get created/emitted. I had been working on trying to set things up so that all IR instruction creation goes through a single bottleneck point, but the non-trivial work in that branch was getting drowned out by the sheer volume of cleanup and refactoring changes. This change tries to pull together several of the more important cleanups.
The big pieces are:
* `IRBuilder` and `SharedIRBuilder` now protect their data members and rely on users to initialize them more directly via constructor of an `init()` method. This change affects a *bunch* of sites where `IRBuilder`s were created. I changed use sites to use the constructors whenever possible, and to use `init()` in cases where we had longer-lived builders that needed to be initialized multiple times.
* The insertion location for the `IRBuilder` now uses an encapsulated type called `IRInsertLoc`. This new type can replace what used to be just two `IRInst*` fields in the builder, and also covers some new functionality (if we ever want to take advantage of it). Very little client code cares about this change, but it is still a nice cleanup in terms of making things more explicit.
* The creation of an `IRModule` has been moded *out* of `IRBuilder`, because in practice we `IRBuilder` always wants to be associated with a pre-existing `IRModule` at creation time (via its `SharedIRBuilder`). There is now an `IRModule::create()` operation instead. This required changing the sequencing at many `IRModule` creation sites, since most had been contriving to make an `IRBuilder` first. There were also several cleanups because code had been carelessly using non-reference-counted pointers for `IRModule`s in ways that broke now that `IRModule::create()` always returns a `RefPtr`.
* The core operations to actually allocate memory for IR instructions were moved into `IRModule` (since they interact with the memory pool that the module owns). These *were* called `createEmptyInst()` but have been renamed into `_allocateInst()`. In principle these seem like they should only be needed to be called by the `IRBuilder`, but in practice they are also needed by the IR deserialization logic.
* A few core operations for emitting IR instructions that were associted with `IRBuilder` were moved to actually be methods on `IRBuilder`. First is `_findOrEmitConstant` which is the primary bottleneck for creating simple scalar constant values. Another is `_createInst` (formerly part of the templated `createInstImpl` along with `createInstWithSizeImpl`) which is the main bottleneck for allocation and initialization of any instruction other than a constant (well, the `IRModuleInst` is the other exception...). Finally, there is also `_maybeSetSourceLoc()`, which is obvious to scope inside the `IRBuilder` once it is protecting the source-location info.
Notes:
* The `minSizeInBytes` parameter to `_createInst()` might not actually be needed at all. At this point any `IRInst` subtypes that need data allocated for things other than their operands already get created manually via `_allocateInst` or `_findOrEmitConstant`, so I *think* we could remove that part. I will handle that in a subsequent cleanup if it turns out to be the case.
* There is one IR pass (`slang-ir-string-hash.cpp`) that is using manual `_allocateInst()` instead of going through an `IRBuilder`. It could be easily cleaned up to not do so (and I will probably make that change down the line), but for now I wanted to avoid doing anything that wasn't close to pure refactoring if I could.
* At this point in our design an `IRBuilder` is a very lightweight thing - it basically just owns the insertion location plus a source location to write into instructions. A lot of our code currently treats `IRBuilder`s like they are expensive and/or need to be re-used (which leads to them being used in more mutable/stateful ways). It is quite likely that as we clean up other aspects of the implementation of IR creation/emission we can make `IRBuilder` use feel more lightweight in ways that can streamline and simplify code.
* The next step for this work is to identify the different paths that eventually lead to `_createInst()` being called, and unify them at a single bottleneck operation that can own the decisions around when to create an instruction vs. when to re-use an existing one (rather than those decisions being baked into the various `IRBuilder` subroutines that create instructions of the various subtypes).
* fixup: gcc/clang C++ spec details
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Overview
========
Prior to this change, we had two different code generation strategies for interface/existential types in Slang, that didn't always play nicely together:
* The "legacy" static specialization approach could handle plugging in an arbitrary concrete type for an existential type parameter (including types with resources, etc.), but wouldn't work well with things like a `StructuredBuffer<>` of an interface type, and requires somewhat counter-intuitive layout rules to make work.
* The new dynamic dispatch approach produces simpler, more easily understood layouts by assuming that values of interface type can fit into a fixed number of bytes. The tradeoff there is that it cannot handle types that include resources (only POD types).
The goal of this change is to make it so that the two strategies can co-exist. In particular, in cases where a shader is amenable to both static specialization and dynamic dispatch, the type layouts should agree.
In order to make the type layouts agree, we:
* Declare that *all* values of existential type reserve storage according to the dynamic-dispatch rules (so 16 bytes for the RTTI and witness-table information, plus whatever bytes are needed to story "any value" of a conforming type).
* Then we modify the "legacy" layout rules so that if a value of concrete type can fit in the reserved "any value" space for a given interface, then it is laid out there exactly like the dynamic dispatch rules would do. Otherwise, we fall back to the previous legacy rules (since we don't need to agree with the dynamic-dispatch layout on types that can't be used with dynamic dispatch).
Details
=======
* Renamed `ExistentialBox` to `BoundInterfaceType` to better clarify how it relates to `BindExistentialsType`
* Unconditionally apply the `lowerGenerics` pass during emit, since it is now responsible for aspects of the lowering of existential types when specialization is used.
* Made IR type layout take the target into account, so that the layout of resource types can vary by target (e.g., being POD on some targets, and invalid on others)
* Cleaned up some issues around using global shader parameters as the "key" for their layout information in the global-scope layout (only comes up when there are global-scope `uniform` parameters)
* Made there be a default any-value size (16) instead of making it be an error to leave out. This was the simplest option; we could try to go back to having an error, but we'd need to only issue it if we are sure a type/interface is being used with dynamic dispatch, since static dispatch doesn't have to obey the restrictions.
* Changed lowering of existential types to tuples so that bound interfaces where the concrete type won't fit use a "pseudo-pointer" instead of an "any-value" to hold the payload
* Changed IR type legalization to handle the "pseudo-pointer" case and apply layout information from an interface type over to the payload part when static specialization was used.
* Changed some details of how witness tables were being lowered, so that we didn't have to create "proxy" witness tables for the constraints on associated types (just use the actual requirement entries we generate)
* Changed witness tables so that they know the subtype doing the conforming
* Added logic so that we don't generate pack/unpack logic and witness table wrapper functions for types that are incompatible with any-value/dynamic dispatch for a given interface.
* Changed the core AST-level type layout logic to use the dynamic-dispatch layout in case things fit, and the legacy static specialization case when things don't (while also reserving space for the dynamic-dispatch fields)
* Changed a bunch of test cases for static specialization to properly use the new layout (which introduces new buffers in some cases, and moves data around in others).
Future Work
===========
The experience of trying to reconcile our older way of handling interface-type specialization with our newer model (that supports dynamic dispatch) makes it clear that we really need to make similar changes to our handling of generic type parameters on entry points and at the global scope.
A future change should make it so that a global type parameter is lowered with a type layout similar to a value parameter of interface type, including the RTTI and witness-table pieces, and just leaving out the "any value" piece. A similar translation strategy should apply to entry-point generic parameters (mirroring how we lower generic functions for dynamic dispatch already), and value specialization parameters.
Co-authored-by: Yong He <yonghe@outlook.com>
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This change builds on previous work that moves toward a more IR-based representation of layout.
Those steps added some instructions for representing layout in the IR (initially just proxies for the AST layout objects), and an explicit lowering pass that could build a target-specific IR module that binds parameters and entry points to layout information.
This change aims to complete that work, in the sense that the IR representation of layout is now self-contained and does not rely on having pointers back into the AST-level representation.
Achieving this requires two main kinds of work:
1. Update any code that used layout information derived from the IR (most notably all the `slang-emit-*` code) to use the new IR representation and its accessors.
2. Update any code that *constructs* layouts using information derived from the IR to construct IR layouts instead.
The biggest new infrastructure feature in this change is support for "attributes" in the IR (I'd welcome feedback on the naming).
An attribute can either be thought of like key/value arguments that can be added to certain instructions to encode optional data, or alternatively like a decoration that is referenced as an operand instead of a child.
The value of attributes over decorations is that they can affect the hash/identity of an instruction (which decorations can't), while the advantage of decorations is that they can easily be added/removed over the lifetime of an instruction (which attributes can't).
We mostly use them here to represent operands that are logically optional.
Once attributes are available, the encoding of layout information into the IR is mostly straightforward:
* An `IRVarLayout` has a fixed operand for its type layout, and can accept a few different attributes
* Zero or more `IRVarOffsetAttr`s that specify the offset of the variable for a given resource kind. These are equivalent to the `VarLayout::ResourceInfo`s at the AST level.
* An optional `IRUserSemanticAttr` and `IRSystemValueSemanticAttr` to represent the (possibly derived) semantic of a varying input/output parameter.
* An option `IRStageAttr` to represent the known stage for a parameter.
* An `IREntryPointLayout` has a var layout for the entry point parameters (logically grouped in to a struct) and another var layout for the result parameter.
* There is a small type hierarchy rooted at `IRTypeLayout` where each subtype can add fixed operands and attributes that are expected to appear. It also supports `IRTypeSizeAttr`s that serve a similar role to the `IRVarOffsetAttr`s.
* Structure types maintain the mapping of fields to their var layouts using `IRStructFieldLayoutAttr`s.
With the encoding in place, most of the changes in category (1) (code that just *uses* rather than *creates* layouts) was straightforward. The biggest different beyond name changes was that everything needs to be fetched using accessors instead of bare fields. It would have been possible to stage this commit and make the diffs smaller by first introducing mandatory acessors to the AST layout types.
The changes in category (2) were more involved. There were a lot of places in the existing code where a `TypeLayout` or `VarLayout` would be created, and then initialized piecemeal over several lines of code (and sometimes even across functions). Because of the way that layouts need to support many optional properties, it did not seem practical to just have monolithic factory functions that took all the options as arguments, so I instead opted for a builder approach.
The builders for `IRVarLayout` and `IREntryPointLayout` are both straightforward, and honestly there is no realy need for a builder for entry point layouts right now, but I was trying to future-proof in case we decidd to add some optional attributes to them.
The builders for type layouts are more involved because of the inheritance hierarchy. Each concrete sub-type of type layout needs to define its own builder type that customizes the opcode, operands, and attributes of the final instruction.
The refactoring that had to go into this change was a nice excuse to clean up a few ugly warts in the AST layout code that were largely there to support IR use cases. While this change adds a lot of new infrastructure code to the IR, most of the client code has stayed the same or gotten simpler.
One annoying wart that remains with this change is the notion of an "offset element type layout" for parameter group types. That idea was added to deal with a legacy feature in the reflection API that we realized was a mistake, but unfortunately having that "offset" layout handy made writing a few other pieces of code simpler so that there are use cases of the feature even in the IR. Removing those uses is do-able, but requires careful refactoring so it is best left to a follow-on change.
Another thing that could be considered for a follow-on change is how much information should be specified when constructing a `Builder` for an IR type layout, and how much should be allowed to be specified statefully/piecemeal. It would be nice to force all the required operands to be specified up front, but `IRParameterGroupTypeLayout::Builder` doesn't currently work that way because so much of the client code that needs it involved a lot of stateful setting and would need to be refactored heavily to provide the necessary information up front.
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* Initial work on representing layout at IR level
This change starts the process of making the back-end of the compiler independent of the AST-level layout information (`TypeLayout`, `VarLayout`, etc.) so that it instead only relies on layout information that is embedded into IR modules. This brings us incrementally closer to a world in which the back-end could be run without the AST-level structures even existing (e.g., for an application that just wants to ship IR without any AST information for IP protection, while still supporting some amount of linking and specialization).
The main parts of the change are:
* There is a bunch of incidental churn related to specifying entry points by index instead of the `EntryPoint` object for certain operations. This ends up being a better choice because we can use the index to look up side-band information about the entry point that might not be stored on the `EntryPoint` object itself. In particular...
* We expand the `ComponentType` interface to support looking up the mangled name of an entry point by index. In common cases (no generic/interface specialization) this would be the same as asking the `EntryPoint` for its mangled name, but in cases where we have specialized a generic entry point, the mangled name would include speicalization arguments that are only available on the `SpecializedComponentType` that wraps the entry point. This part of the change isn't ideal and there might be a better solution waiting to be invented. Note that we store mangled entry point names as strings rather than using `DeclRef`s because that ensures that the information could be serialized and deserialized without a dependence on the AST.
* The `TargetProgram` type (which represents binding a specific `ComponentType` for a shader program to a specific `TargetRequest` that represents the target platform) is expanded to include an `IRModule` that represents layout information, in addition to the AST-level `ProgramLayout` it already contained. We create both of these objects at the same time (on-demand) to simplify the overall flow (so that any code that triggers creation of the AST-level layout will also ensure that the IR-level layout exists).
* A bunch of code in the emit passes that was passing down layout-related objects has been eliminated. It appears that most of those objects weren't actually being used, so this is just a cleanup, but it helps ensure that the back-end steps are "clean" and don't depend on the AST-level information. The one big exception here is that the emit logic needs to know the stage for the entry point being emitted (to deal with one wrinkle in translating DXR to VKRT).
* A big change (actually introduced by @jsmall-nvidia in a branch that this change copied and then built from) is to introduce some more explicit IR instructions to represent layout information, notably an `IRTypeLayout` and an `IRVarLayout`. For now these objects still reference their AST equivalents, but the separation gives us an incremental path to move information from the AST-level objects over to the IR ones. This work includes logic in `IRBuilder` to construct the IR-level layout objects from the AST-level ones on-demand, so that the existing code paths that try to attach AST-level layout will continue to work for now.
* Because layout information is now embedded in the IR, the `slang-ir-link.cpp` logic loses a lot of cases that used to deal with attaching AST-level layout objects to IR-level instructions during the linking process. Instead, the linker now assumes that one (or more) of the input IR modules will have layout information associated with it, and the linker makes sure to copy layout decorations (and the instructions they reference) from the input IR module(s) to the output using its more ordinary mechanisms.
* Inside `slang-lower-to-ir.cpp`, we add logic to construct an IR module in a `TargetProgram` that simply references the global shader parameters, entry points, etc. and attaches IR layout decorations to them. This is akin to the existing pass in the same file that constructs IR to represent specialization information, and both of these passes share infrastructure with the main AST->IR lowering pass. Eventually, it is expected that this pass will encompass more of the logic for copying AST-level layout information over to IR-level equivalents.
* One small wrinkle with this change was that the output for an HLSL generation test case changed some of its `#line` directives. The old code was actually more inaccurate than the new, so this change just updated the baseline. It also added some logic in the linker to make sure that when an IR instruction has multiple definitions, we try to pick up a source location from any of them, in case the "main" one somehow didn't get a location.
* Another small fix was that the key/value map in `StructTypeLayout` for mapping fields/members to their layouts was keyed on `Decl*` when it really should have been `VarDeclBase*`.
This change should in principle be a pure refactoring with no functionality changes, so no new tests were added. It is unfortunately also a change that has a high probability of breaking at least *some* client code, so we may want to be defensive and mark this with a new major version number (well, a new *minor* version number since we are pre-`1.0`) to give us some room for releasing hotfixes to the old version if needed.
* fixup: infinite recursion bug detected by clang
* fixup: remove commented-out code
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* Revise new COM-lite API
This change revises the "COM-lite" API that was recently introduced to try to streamline it and introduce some missing central/base concepts.
The central new abstraction in the API is the notion of a "component type," which is a unit of shader code composition. A component type can have:
* IR code for some number of functions/types/etc.
* Zero or more global shader parameters
* Zero or more "entry point" functions at which execution can start
* Zero or more "specialization" parameters (types or values that must be filled in before kernel code can be generated)
* Zero or more "requirements" (dependencies on other component types that must be satisfied before kernel code can be generated)
Both individual compiled modules, and validated entry points are then examples of component types, and we additionally define a few services that apply to all component types:
* We can take N component types and compose them to create a new component type that combines their code, shader parameters, entry points, and specialization parameters. A composed component type may also include requirements from the sub-component types, but it is also possible that by composing thing we satisfy requirements (if `A` requires `B`, and we compose `A` and `B`, then the requirement is now satisfied, and doesn't appear on the composite).
* We can take a component type with N specialization parameters, and specialize it by giving N compatible specialization arguments. The result of specialization is a new component type with zero specialization parameters. Under the right circumstances the specialzed component type will be layout compatible with the unspecialized one.
* One more example that isn't exposed in the public API today is that we can take a component with requirements and "complete" it by automatically composing it with component types that satisfy those requirements. This can be seen as a kind of linking step that pulls together the transitive closure of dependencies.
* We can query the layout for the shader parameters and entry points of a component type, for a specific target.
* We can query compiled kernel code for an entry point in a component type (for a specific target). This only works for component types with zero specialization parameters and zero requirements.
The idea is that by giving users a fairly general algebra of operations on component types, they can compose final programs in ways that meet their requirements. For example, it becomes possible to incrementally "grow" a component type to represent the global root signature for ray tracing shaders as new entry points are added, in such a way that it always stays layout-compatible with kernels that have already been compiled.
Much of the implementation work here is in implementing the unifying component type abstraction, and in particular re-writing code that used to assume a program consisted of a flat list of modules and entry points to work with a hierarchical representation that reflects the underlying algebra (e.g., with types to represent composite and specialized component types).
There's also a hidden "legacy" case of a component type to deal with some legacy compiler behaviors that can't be directly modeled on top of the simple algebra with modules and entry points.
This API is by no means feature-complete or fully developed. It is expected that we will flesh it out more when bringing up application code (e.g., Falcor) on top of the revamped API.
One notable thing that went away in this change is explicit support for "entry point groups" and notions of local root signatures (especially the Falcor-specific handling of the `shared` keyword, which a previous change turned into an explicitly supported feature). With the new "building blocks" approach, it should be possible for a DXR application to deal with local root signatures as a matter of policy (on top of the API we provide). If/when we need to provide some kind of emulation of local root signatures for Vulkan (and/or if Vulkan is extended with an explicit notion of local root signatures), we might need to revisit this choice.
* Fix debug build
There was invalid code inside an `assert()`, so the release build didn't catch it.
* fixup: warnings
* fixup: more warnings-as-errors
* fixup: review notes
* fixup: use component type visitors in place of dynamic casting
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* 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.
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