| Age | Commit message (Collapse) | Author |
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* Added ir-compression option.
* Fix issues around ir-compression.
* Fix typo in test name.
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* Initial work on direct emission of SPIR-V
This change adds a first vertical slice of support for emitting SPIR-V code directly from the Slang IR, instead of generating it indirectly via GLSL.
This work isn't usable for anything valuable right now; the goal is just to get something checked in that we can incrementally extend over time.
When invoking `slangc`, the `-emit-spirv-directly` option can be used to turn on the new code path.
I have not bothered to add an equivalent API option, because this flag is only intended to be used for testing in the immediate future.
The existing `emitEntryPoint()` function has become `emitEntryPointSource()` to more accurately reflect its role in a world where we can also emit entry points to a binary format.
Much of the logic that was inside `emitEntryPoint()` had to do with linking and then optimizing/transforming Slang IR code to get it ready for emission on a particular target.
This logic has been factored into a new `linkAndOptimizeIR()` function that can be shared between the path that emits source and the new one that emits SPIR-V.
The meat of the change is then the `emitSPIRVFromIR()` function in `slang-emit-spirv.cpp`, which is called *after* all the optimizations and transformations have been applied to the Slang IR to get it ready.
Rather than repeat myself here, I will try to make the comments in `slang-emit-spirv.cpp` usable as documentation of the approach being taken.
Smaller notes:
* I've included a test case that compares `slangc` output directly to expected SPIR-V. This is perhaps not an ideal plan for how to test SPIR-V emission going forward, but it suffices for now.
* The `external/` directory needed to be added to the include dirs for the `slang` project so that the new code can depend on the SPIR-V header.
* In `slang-ir-link`, the direct SPIR-V generation path means that we now link with a target of SPIR-V instead of GLSL. In principle this can be used to ensure that appropriate variants of intrinsics are selected based on the knowledge that we are emitting SPIR-V. In practice, that isn't being used at all.
* Fixup: path for SPIR-V headers
While working on this PR I used a copy of `spirv.h` that I placed into the repository tree manually, but since I started the work we ended up with SPIR-V headers in our tree anyway, albeit at a different path.
This change tries to fix things up so that my code uses the headers that were already placed in the repository.
* fixup; 64-bit build issue
* fixup: typo fixes based on review
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* Enable use of pre-built glslang binaries
This change uses an updated version of the `slang-binaries` submodule that includes pre-built versions of `slang-glslang.dll` and `libslang-glslang.so`, and enables the build of the main Slang project to rely on these binaries instead of building them from source.
An option to the premake build file can be used to generate the appropriate project files for `slang-glslang`, which should enable us to build updated binaries as needed. The default option is to *not* build those projects, so that we can reduce build times in the common case (and on CI).
* fixup: different copy commands per platform
* fixup
* fixup
* fixup: remove stray line added to premake file by accident
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* Added feature to repro manifest of approximation of command line that was used.
* Add missing slang-options.h
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The semantic checking logic was all inside `slang-check.cpp` and as a result this was a monster file that was extremely hard to follow. This change splits `slang-check.cpp` into several smaller files, although some of the resulting files are still quite large.
This change attempts to be a copy-paste job as much as possible and does *not* perform any cleanup on naming, structure, duplication, etc. in the code it deal with. No function bodies or signatures have been touched.
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* Strip IR after front-end steps are done
The main feature of this change is to unconditonally strip out the `IRHighLevelDeclDecoration`s in an IR module once the "mandatory" IR passes in the front end have run. This ensures that later IR passes (e.g., code emission) *cannot* rely on AST-level information to get their job done.
Since I was already writing a pass to remove some instructions at the end of the front-end passes, I went ahead and also made the `-obfuscate` flag apply to the front-end IR generation by causing it to strip `IRNameHintDecoration`s while it is doing the other stripping. With this, the main identifying information left in IR modules (other than semantics and entry-point names) is mangled name strings for imported/exported symbols.
A few other things got changes along the way:
* Removed the `.expected` file for one of the tests, where that file seemingly shouldn't have been checked in at all.
* Updated the signature of the DCE pass both so that it doesn't require a back-end compile request (it wasn't using it anyway), and so that it takes some options to decide whether to keep symbols marked `[export(...)]` alive (the front-end wants to keep these, while back-end passes currently need to be able to eliminate them).
* Moved the `obfuscateCode` flag from the back-end compile request to the base class shared between front- and back-end requests, and updated the options and repro logic to set both as needed. An obvious improvement in the future would be to have the front- and back-end requests share these settings by referencing a single common object in the end-to-end case, rather than each having their own copy.
* Removed logic that was keeping layout instructions alive in DCE, even if they weren't used. This seems to have been a vestige of an intermediate step between AST and IR layout.
* fixup: add the new files
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* WIP on serialize/save state.
* Relative string encoding.
* Added RelativeContainer unit test.
Split out RelativeContainer into core.
* Fix bug in RelativeString encoding.
* More work around relative container.
* Fix checks.
* Use RelativeBase for safe access.
Use malloc/free/realloc instead of List.
* Add natvis support for relative types.
* Setting up of state (not includes) writing of repro state.
* Capture after spCompile.
* Writing SourceFile and file system files.
Added -dump-repo
* First pass at loading state.
* First pass at reading repro.
* Small optimization around Safe32Ptr
* Refactor how repro data is stored - to make saving off the files more simple, by having all all backed by 'files'.
Make file loading always set up PathInfo so we get uniqueIdentifier info.
* Generate unique file names.
* Added RelativeFileSystem
Added saveFile to ISlangFileSystemExt and implemented for interfaces
Added mechanism to save of files (and manifest)
* Added ability to replace files in repo with directory holding their contents.
* Add support for entry points.
* Fix problem compiling on linux.
* Added SIMPLE_EX option, where everything on command line must be specified.
* Fix typo in unit test for relative container.
* Fix another typo in unit test for RelativeContainer.
* Fix small bugs.
* Fix release unused variable issue in slang-state-serialize.cpp
* Fix checking for SIMPLE_EX in testing, else broke COMMAND_LINE_SIMPLE.
* Fix warnings on 32 bit debug build.
* Added import-subdir-search-path-repro.slang test. Although disabled for now as writes to root of slang project.
* Remove wrong version of import-subdir-search-path-repro.slang
* Added import-subdir-search-path-repro.slang
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* Start exposing a new COM-lite API
This change is mostly about exposing a new API to the Slang compiler that allows more fine-grained control over the compilation flow. The basic concepts in the new API are:
* An `IGlobalSession` is the granularity at which we load/parse the Slang stdlib, and therefore gives applications a way to amortize startup cost for the library across multiple compiles. This is a concept that might be able to go away in a future version of Slang.
* An `ISession` owns all the code that gets loaded/compiled/generated. Any `import`ed modules are shared across everything in a session (we don't re-parse/-check the code when we see another `import` for the same module). Any generic- or interface-based code in the session can be specialized using types from the same session (but not necessarily across sessions).
* An `IModule` is the unit of code loading and scoping. It doesn't expose any API in this change, but would be the right scope for looking up types or entry points by name.
* An `IProgram` is a "linked" combination of modules and entry points from which code can be generated and reflection information queried.
This change re-uses the existing reflection API types, rather than introduce a new API that duplicates that functionality. That will probably change in a future revision.
There are two major pieces of functionality added here that aren't related to the new API:
* We now have an API concept of "entry point groups" which are one or more entry points that are intended to be used together so that they need to have non-overlapping parameters. For now this is being used to handle "hit groups" and local root signatures for ray tracing, but I'm not sure this is a concept we will keep in the long run.
* We have a very special-case (client-application-specific) flag that ascribes special meaning to the `shared` keyword, so that it can be attached to global parameters to indicate that they are actually to be part of the local root signature rather than the global one for DXR.
None of the API design (including naming) here is finalized; the only reason to check in the changes at this point to avoid having a long-running branch that leads to merge pain. Clients should *not* try to depend on the new API just yet, since it is still a work in progress.
* fixup: clang warning
* fixup: try to detect clang C++11 support
* fixup
* fixup
* fixup
* fixup
* fixup: review feedback
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* * Added SourceStyle to CLikeSourceEmitter, to limit cases to actual target types.
* Made Impl methods _ prefixed
* Small tidyup
* * SourceStream -> SourceWriter
* use slang-emit- prefix on SourceWriter file
* * Remove EmitContext -> merge into CLikeSourceEmitter
* slang-c-like-source-emitter -> slang-emit-source.cpp
* ExtensionUsageTracker -> GLSLExtensionTracker
slang-extension-usage-tracker.cpp/.h -> slang-emit-glsl-extension-tracker.cpp/.h
* emit-source.cpp.h -> emit-c-like.cpp/.h
* Small fix to move where some _ prefixed functions are declared in CLikeSourceEmitter.
* * CLikeSourceEmitter::CInfo -> Desc
* Functions to get and find CodeGenTarget by name
* Split out empty language impls
* Create an impl based on SourceStyle
* * CodeGenTarget conversion to and from string
* Move HLSL specific functions to HLSLEmitSource.
* Emitting texture and image types.
* Move move GLSL specific functionality to GLSLSourceEmitter
* Split more out of slang-emit-c-like
* Refactor more out of slang-emit-c-like
* * tryEmitIRInstExprImpl(IRInst* inst, IREmitMode mode, const EmitOpInfo& inOuterPrec)
* Fix bug around output of uintBitsToFloat
* More work refactoring out target specifics from slang-emit-c-like
* Move functions that are only implemented once in GLSL impl into their Impl method.
* Move rate qualification out of slang-emit-c-like
* * Added getEmitOpForOp - allows for table usage so different ops can be dealt with the same way
* Moved vector comparison to slang-emit-glsl
*
* * Use EmitOpInfo to control output in slang-emit-c-like.cpp for unary ops
* Move more functionality from CLikeSourceEmitter to HLSLSourceEmitter
* Make output of parameters implementaion specific.
* Extracted interpolation modifiers.
* Remove IR from methods that don't need them.
* Remove IR from method names.
* Refactor handling of output of types - to make the impls implement the full path without lots of cases for specific impls
* Add variable declaration modifiers and matrix layout to larget specific in slang-emit.
* Make target specific internal functions _ prefixed.
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(#974)
* * Added SourceStyle to CLikeSourceEmitter, to limit cases to actual target types.
* Made Impl methods _ prefixed
* Small tidyup
* * SourceStream -> SourceWriter
* use slang-emit- prefix on SourceWriter file
* * Remove EmitContext -> merge into CLikeSourceEmitter
* slang-c-like-source-emitter -> slang-emit-source.cpp
* ExtensionUsageTracker -> GLSLExtensionTracker
slang-extension-usage-tracker.cpp/.h -> slang-emit-glsl-extension-tracker.cpp/.h
* emit-source.cpp.h -> emit-c-like.cpp/.h
* Small fix to move where some _ prefixed functions are declared in CLikeSourceEmitter.
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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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* 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.
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* * Remove Makefile
* Document how to create build using premake5
* Added support for finding the executable path
* If binDir not set on command line use the executable path
* Fix getting exe path on linux.
* Removed CalcExecutablePath from Path:: interface, made implementation internal.
* Documentation improvements.
* Fixes based on review
* Fix some typos
* Removed unused/needed global
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* Add better control over image formats for GLSL/SPIR-V targets
Currently Slang emits GLSL code assuming all R/W images need to have explicit formats, and thus we try to infer a format from the element type of the image.
E.g., given a `RWTexture2D<half4>` we might infer that a qualifier of `layout(rgba16f)` should be used.
This strategy has two notable shortcomings:
* Sometimes the user will want a format that doesn't match an existing HLSL type. E.g., if they want the equivalent of `layout(r11f_g11f_b10f)`, then what should they put in their `RWTexture2D<...>` to make the inference do what they need?
* Sometimes the user knows that they don't need to specify a format *at all*, because using the `GL_EXT_shader_image_load_formatted` extension, they can still perform non-atomic load/store on images with no format specified in the SPIR-V.
This change adds two features directed at these challenges.
First, we add an explicit `[format(...)]` attribute that can be used to specify an explicit image format, including ones that don't match any HLSL type.
An example of using this new attribute is:
```hlsl
[format("r11f_g11f_b10f")]
RWTexture2D<float3> myImage;
```
For simplicity in initial bring-up, the new formats all use the same naming as formats in GLSL (this should make it easy for a programmer who knows what they expect to get in the GLSL output). We can change the naming convention for formats at a later time, so long as we keep these existing names in as a compatibility feature.
Note that this is *not* given a `vk::` prefix since the attribute should signal the programmer's intent to provide an image with that format on *all* targets (although only some targets might act on that information).
Also note that the attribute takes a string (`[format("rgba8")`) instead of a bare identifier (`[format(rgba8)]`) because this is consistent with the existing convention for attributes in HLSL.
When `[format(...)]` is left off, the default compiler behavior will still be to infer a format, but this behavior can be overidden for a single image using an explicit format of `"unknown"`:
```hlsl
[format("unknown")]
RWTexture2D<float4> mysteryMachine;
```
The second new feature is that if a user knows they are coding for a GPU that supports the `"unknown"` format in all non-atomic cases, then they can opt into making that the default for images without an explicit `[format(...)]`, using the new `-default-image-format-unknown` command-line option for `slangc`.
The new test case included with this change confirms that we correctly see the explicit formats in the output GLSL and *no* formats for images without explicit `[format(...)]` when using the new command-line option. The test stresses images declared at global scope, in parameter blocks, and in entry-point parameter lists, to try and make sure that all the relevant IR passes in the compiler preserve the format information.
* fixup: missing file
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lines (#885)
* * Check for inconsistent command line options for renderer
* Moved RenderApiUtil into core so can be used in slang-test
* Make it use the ShaderdLibrary for API testsing
* Added some simplifying functions to StringUtil for spliting/comparisons
* Refactored the synthesis of rendering tests so that inconsistent combinations are not produced
* Add missing slang-render-api-util.cpp & .h
* Stop warning on linux about _canLoadSharedLibrary not being used.
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* Added CombinationUtil to produce combinations of flags
Used in Dx11 device creation making it fall back to release driver if debug driver is not found
* Made dx12 renderer startup similar to dx11 - testing multiple configs.
* Small improvements in naming.
* * Moved functionality to gfx from core
* Use FlagCombiner to simplify construction, and can be iterated over, without need for array
* Share DeviceCheckFlags
* Improve comments.
* Re-add the comment about combinations tested to set up dx11 device.
* More comment improvements.
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* First steps toward supporting interface-type parameters on shaders
What's New
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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
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* Initial support for uniform parameters on entry points
The basic feature this work adds is the ability to define a shader entry point like:
```hlsl
[shader("fragment")]
float4 main(
uniform Texture2D t,
uniform SamplerState s,
float2 uv : UV)
{
return t.Sample(s,uv);
}
```
In this example, the `uniform` keyword is used to mark that the given entry point parameters are *not* varying input/output flowing through the pipeline, but rather uniform shader parameters that should function as if the shader was declared more like:
```hlsl
Texture2D t,
SamplerState s,
[shader("fragment")]
float4 main(
float2 uv : UV)
{
return t.Sample(s,uv);
}
```
Allowing `uniform` parameters on entry points makes it easier to define multiple entry points in one file without accidentally polluting the global scope with shader parameters that only certain entry points care about.
This feature is also more or less a prerequisite for allowing generic type parameters directly on entry point functions, since the main use case for those type parameters is for determining what goes in various `ConstantBuffer`s or `ParameterBlock`s.
There are two main pieces to the implementation.
First, we need to be able to compute appropriate layout information for entry points that include `uniform` parameters.
Second, we need to transform the entry point function to move any `uniform` parameters to be ordinary global-scope shader parameters, to make sure that all other back-end passes don't need to worry about this special case.
The latter piece of the implementation is, relatively speaking, simpler.
The pass in `ir-entry-point-uniforms.{h,cpp}` converts entry point parameters that are determined to be uniform (using the already-computed layout information) into fields of a `struct` type and then declares a global shader parameter based on that `struct` type (and applies already-computed layout information to that parameter).
After that, the remaining IR passes (notably including type legalization) will handle things just as for any other global shader parameter.
The changes to the layout step are more significant, but most of the changes are just cleanups and fixes to enable the feature.
The two major changes that enable entry-point `uniform` parameters are:
* In `collectEntryPointParameters` we now dispatch out to a new `computeEntryPointParameterTypeLayout` function, which decided whether to compute the type layout for a `uniform` parameter, or for a varying parameter (what used to be the default behavior handled by `processEntryPointParameterDecl`).
* The main `generateParameterBindings` routine was extended so that it allocates registers/bindings to the resources required by each entry point (using `completeBindingsForParameter`) after it has allocated registers/binding to all of the global-scope parameters (this addition is mirrored in `specializeProgramLayout`).
The effect of these changes is that the `uniform` parameters of any entry points specified in a compile request will be laid out after the global-scope parameters, in the order the entry points were specified in the compile request.
A bunch of smaller changes were made around parameter layout that are worth enumerating so that the diffs make some sense:
* The `EntryPointLayout` type was changed so that instead of trying to *be* a `StructTypeLayout`, it instead *owns* one, in the same fashion as `ProgramLayout`. This commonality was factored into a base class `ScopeLayout`, and a bunch of edits followed from that change.
* Because `uniform` parameters are moved out of the entry point parameter list early in the IR transformations, the logic in `ir-glsl-legalize.cpp` that tried to look up parameter layout information by index would no longer work if the entry point parameter list had been altered. Instead, that logic now looks for the decorations directly on the parameters.
* The `UsedRange` type in `parameter-binding.cpp` was tracking the existing parameter associated with a range using a `ParameterInfo*` (which accounts for the possibility of multiple `VarDecl`s mapping to the same logical shader parameter), when just using a `VarLayout*` is sufficient for all current use cases. The overhead of allocating a `ParameterInfo` seems like overkill for entry-point parameters, where there can't possibly be multiple declarations of the "same" parameter, so avoiding these overheads was a focus when trying to deduplicate code between the global and entry-point parameter cases.
* A bunch of parameter binding logic that was specific to GLSL input has been deleted completely. There was no way to even execute this code in the compiler today, and there is pretty much zero chance of us needing (or wanting) to deal with GLSL input in the future. This includes custom `UsedRangeSet`s specific to each translation unit, which were only needed for global-scope `in` and `out` varying declarations in GLSL.
* A bunch of functions with `EntryPointParameter` in their names were renamed to use `EntryPointVaryingParameter` to help distinguish that they only apply to the varying case, while entry point `uniform` parameters are handled elsewhere.
* The `completeBindingsForParameter` function was re-worked into something that can be used for both global-scope shader parameters (where we have a `ParameterInfo` and possibly explicit bindings) and entry-point parameters (where we expect to have neither). This helps unify the (fairly subtle) logic for how we allocate and assign bindings for resources, constant buffers, parameter blocks, etc.
* A small change was made so that the entry-point stage is attached directly to top-level parameters of the entry point, and *not* recursively to every field along the way. This could be a breaking change for some applications, but it makes more logical sense (to me); we'll have to check if this affects Falcor. This change produces different output for several of the reflection tests, but the changes are consistent with no longer attaching stage information to sub-fields of varying `struct`-type parameters.
* Because there is a bunch of repeated logic in `parameter-binding.cpp` that has to do with computing a `struct` layout for ordinary/uniform data, I tried to factor that into a single `ScopeLayoutBuilder` type, which handles computing the offsets for any parameters with ordinary data, and then also handles wrapping up the layout in a constant buffer layout if there was any ordinary data at the end.
* A similar convenience routine `maybeAllocateConstantBufferBinding` was added because I noticed multiple places in `parameter-binding.cpp` that were trying to allocate a constant buffer binding for global uniforms, and they were wildly inconsistent (and in most cases used logic that would only work for D3D).
* The main `generateParameterBindings` routine is significantly shortened by using all of these utilities that were introduced. I tried to comment the places that changed to explain the overall flow correctly.
* The `specializeProgramLayout` routine (used to take a `ProgramLayout` from `generateParameterBindings` and specialize it based on knowledge of global generic arguments) had basically been rewritten with more explicit commenting/rationale for what happens in each step. It makes use of the same shared utilities as `generateParameterBindings` and `collectEntryPointParameters`.
In terms of testing:
* I added a test case to specifically test the new behavior, and in particular I made sure to include a mix of both global and entry-point parameters and also to have entry-point parameters of both ordinary and resource/object types.
* I tweaked an existing test for global type parameters to use an entry-point `uniform` parameter instead of a global one, in an effort to migrate it toward being able to use an explicitly generic entry point.
* fixups from merge
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* Support function parameters of existential (interface) type
The basic idea here is that you can define a function that takes an interface-type parameter:
```hlsl
interface IThing { void doSOmething(); }
void coolFunction(IThing thing) { ... thing.doSomething() ... }
```
and call it with a concrete value that implements the given interface:
```hlsl
struct Stuff : IThing { void doSomething() { /* secret sauce */ } }
...
Stuff stuff;
coolFunction(stuff);
```
The compiler implementation will specialize `coolFunction` based on the concrete type that was actually passed in, resulting in output code along the lines of:
```hlsl
struct Stuff { ... }
void Stuff_doSomething(Stuff this) { /* secret sauce */ }
void coolFunction_Stuff(Stuff thing) { ... Stuff_doSomething(thing); }
```
In terms of implementation the new specialization approach has been integrated into the existing pass for generic specialization (which has been refactored significantly along the way), because generic specialization can open up opportunities for existential/interface simplification and vice versa, so there is no fixed interleaving of the two passes that can clean up everything.
The new logic therefore subsumes the old code for simplifying existential types (which only worked on local variables) in `ir-existential.{h,cpp}`. The local simplification rules from that implementation have become part of the core specialization pass instead, so that they can open up further transformation opportunities enabled by existential-type simplifications.
This code in place right now only handles the basic case of a function parameter that directly uses an interface type, and not one that wraps up an interface type in an array, structure, etc. Additional simplifications need to be introduced to deal with those cases as well.
* fixup: typos
|
|
* 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
|
|
* Remove AppContext. Use StdChannels to hold writers, and TestToolUtil to hold test tool specific functionality.
* StdChannels -> StdWriters
* getStdOut -> getOut, getStdError -> getError
|
|
* Refactor several IR passes
This change takes some IR passes that lived together in `ir.cpp` and moves them into their own files to improve clarity.
In most cases these were passes introduced early in the life of the IR, so that it didn't seem like a big deal to have them all in one file, but now that `ir.cpp` has grown unwieldly this seems like an important cleanup to make.
To give a quick rundown of the passes involved:
* The IR "linking" step has been pulled out to `ir-link.{h,cpp}`. This code for this pass is pretty much identical to what was in `ir.cpp`, and no attempt has been made to clean up or refactor it in the current change.
* The GLSL legalization step has been pulled out to `ir-glsl-legalize.{h,cpp}`. This used to be invoked directly from the linking step, but has been made a new top-level pass invoked from `emit.cpp`. Just like with the linking, the code in the new file is just a copy-paste of what was in `ir.cpp`, and no attempt at cleanup has been made. Also note that it might be a good idea to move this pass later in the overall sequence, but this PR doesn't attempt to do that as it could change results.
* The generic specialization step has been pulled out to `ir-specialize.{h,cpp}`. The file name does not explicitly reference *generic* specialization because I anticipate this pass having to perform other kinds of specialization as well. The code in this case amounts to a heavy cleanup/refactoring pass and thus deserves careful scrutiny. The reason for the cleanup is that the generic specialization step used to be part of the "linking" step long ago, and continued to share infrastructure with it long after that stopped making sense. The newly cleaned up pass has much simpler logic that should be easy enough to follow from the comments.
* In order to reduce code dulication, the IR "cloning" part of the `ir-specialize-resources.{h,cpp}` pass was pulled into its own files (`ir-clone.{h,cpp}`) that both the generic specialization step and the resource-based specialization step now share.
The remaining changes then pertain to deleting a bunch of code out of `ir.cpp` and adding the new files to the build.
The only test that needed updating was `vkray/raygen`, where some subtle ordering change in the refactored generic specialization logic has lead to the relative order of the specialized `TraceRay` and `saturate` functions beind reversed.
* fixup: typo in assert
* fixup: typos in comments
|
|
* First step toward supporting use of interfaces as existential types
Traditional generics involve universal quantification. E.g., a declaration like:
```
void drive<T : IVehicle>(T vehicle);
```
indicates for *for all* types `T` that implement the `IVehicle` interface, the `drive()` function is available.
In contrast, whend directly using an interface type like:
```
IVehicle v = ...;
v.doSomething();
```
we only know that there *exists* some concrete type (we could call it `E`) such that `v` refers to a value of type `E`, and `E` implements the `IVehicle` interface. In order to perform an operation like `v.doSomething()` we need to "open" the existential value so that we can look at the concrete type and how it implements the `IVehicle.doSomething` requirement.
This change adds a very explicit representation of existentials to Slang's IR. An operation like `e = makeExistential(v, w)` creates a value of some existential type (interfaces being our only existential types for now), by wrapping a concrete value `v` (the type of `v` can be seen as an implicit operand) and a witness table `w` showing that the type of `v` implements the requirements of the chosen interface type.
In turn, opening of an existential is handled with operations `extractExistential{Value|Type|WitnessTable}` which pull the corresponding piece of information out of a value of existential type (which somewhere in the code had to have been created with `makeExistential`).
The change includes a trivial simplification pass that can detect cases where an `extractExistential*` operation is applied direclty to a `makeExistential` operation, so that there is only one possible result that could be extracted. This allows for simplification of existential types used in trivial ways for local variables (this is mostly so I can check in a functional test, rather than to actually support useful code involving interfaces right now).
The logic in the semantic checking phase of the compiler is comparatively more complex.
When we are about to perform member lookup given an expression like `obj.member` we will first check if `obj` has an existential type, and if it does we will construct a suitable local context in which we extract the value, type, and witness table from the existential (these all become explicit AST expression nodes), and then use the extracted value as the base of the lookup operation.
The nature of existential values is that two different values with the same existential (interface) type could wrap concrete values with differnt types, so that we need to carefully refer only to the extracted type/value/witness-table of specific *values*. We handle this right now by conceptually moving the existential-type value into a local variable (by introducing a `LetExpr` that amounts to `let v = <init> in <body>`) and then require that the extract expressions must refer to the (immutable) variable declaration from which they are extracting a value.
(Eventually we should expand this so that when using an immutable local variable of existential type we just use that variable as-is rather than introduce a new temporary)
A simple test case is included that uses an interface type in an almost trivial way for a local variable; this test can be run and produces the expected results.
A more complex test case that passes an existential into a function is included, but left disabled because a more aggressive simplification approach is required to generate working code from it.
* Add missing file for expected test output
* Fixups for merge from top-of-tree
|
|
* Specialize away resource-type function parameters
Work on #397.
Introduction
------------
Suppose a user writes a function that takes a resource type as a parameter:
```hlsl
float4 getThing(RWStructuredBuffer<float4> buffer, int index)
{
return buffer[index];
}
```
This function creates challenges when generating code for GLSL-based targets, because a global shader parameter of type `RWStructuredBuffer`:
```hlsl
RWStructuredBuffer<float4> gBuffer;
```
translates to a global GLSL `buffer` declaration:
```hlsl
buffer _S0
{
float4 _data[];
} gBuffer;
```
There is no equivalent to that `buffer` declaration that can be used in function parameter position, and it is illegal in GLSL to pass `gBuffer` into a function.
(Aside: yes, we could in principle translate a function parameter like `RWStructuredBuffer<float4> buffer` to `float4 buffer[]`, but that will not in turn generalize to arrays of structured buffers; it is a dead-end strategy)
The solution employed by many shader compilers is to "inline everything" to eliminate the need for parameters of resource types, and then rely on dataflow optimization to eliminate locals of resource types. This strategy can of course lead to an increase in code size, and it also means that call stacks are lost when doing step-through debugging. Another serious issue is that an "early `return`" from a function can turn into the equivalent of a multi-level `break` when inlined, and not all of our targets support multi-level `break`.
The solution implemented in this change works around some, but not all, of the problems with full inlining.
The approach here generates specialized versions of a function like `getThing`, adapted to the actual arguments provided at different call sites.
Thus if we have code like:
```hlsl
RWStructuredBuffer<float4> gA;
RWStructuredBuffer<float4> gB[10];
...
getThing(gA, x);
getThing(gA, y);
getThing(gB[someVal], z);
```
we will generate two specializations of `getThing`: one specialized for the `buffer` parameter being `gA` and the other for `gB`:
```hlsl
float4 getThing_gA(int index) { return gA[index]; }
float4 getThing_gB(int _val, int index) { return gB[_val][index]; }
```
and the call sites will change to match:
```hlsl
getThing_gA(x);
getThing_gA(y);
getThing_gB(someVal, z);
```
Note how in the case where the argument being passed in was obtained by indexing into an array of resources, the callee is specialized to the identity of the global shader parameter (`gB`), and now accepts a new parameter to indicate the array index into it.
While this description motivates the change based on GLSL output, the same basic issue can arise for other targets.
For example, while current HLSL has added the `ConstantBuffer<T>` type, it is not supported on older targets, and it turns out that even dxc does not allow functions to have `ConstantBuffer<T>` parameters.
Longer-term, we will likely need to do even more aggressive specialization both in order to generate SPIR-V output directly, and also to deal with function that have return values or `out` parameters of resource types.
Implementation
--------------
The meat of the change is in `ir-specialize-resources.{h,cpp}`, where we have a pass that looks at all call sites (`IRCall` instructions) in the program, and attempts to replace them with calls to specialized functions, where the specializations are generated on-demand.
The code in this pass is heavily commented, so hopefully it serves to explain itself all right.
After specialization is complete, we may still have functions like the original `getThing` that will produce invalid code when emitted as GLSL, so we need a way to make sure they don't appear in the output.
To date we've had some very ad hoc approaches for ignoring IR constructs that we don't want to affect emitted code, but this change goes ahead and adds a more real dead code elimination (DCE) pass in `ir-dce.{h,cpp}`.
This pass follows a straightforward approach of tagging instructions that are "live" and then propagating liveness through the whole program, before making a single pass to delete anything that isn't live.
When I first added the DCE pass it eliminated *everything* because there were no "roots" for liveness.
I solved this for now by adding a new decoration, `IREntryPointDecoration`, to mark shader entry points in the IR which should always be live (as should anything they depend on).
A secondary problem that arose was that for GLSL ray tracing shaders it is possible for the incoming/outgoing payload or attributes parameters to be unused, but eliminating them as dead would change the signature of a shader an potential break the rules for how ray tracing programs communicate.
I added a very simple `IRDependsOnDecoration` that allows one IR instruction to keep another alive *as if* it used it, without actually using it.
There's also a fixup in the IR dumping logic where I was forgetting to store anything in the mapping from instruction to their names, so that the name of an instruction was getting incremented each time it was referenced.
Testing
-------
There are three different tests added as part of this change:
* The `compute/func-resource-param` test covers the basic `RWStructuredBuffer` case above, which we expect to work fine for D3D11/12, but fail for Vulkan without specialization.
* The `cross-compile/func-resource-param-array` test covers the case where we don't just have one resource, but an array of them. This is not an end-to-end compute test primarily because our `render-test` application doesn't yet handle arrays of resources correctly in its binding logic.
* The `compute/func-cbuffer-param` test covers the case of a function with a `ConstantBuffer<T>` parameter, which requires specialization to become valid for any of our targets.
* fixup: warnings/errors from other compilers
* fixup: typos and cleanup
* fixup: typos
|
|
Before this change, global shader parameters were represented in the IR as just being ordinary global variables.
The only indication that a particular global represented a parameter was when it got a layotu attached to it (as part of back-end processing), and we've had a number of bugs related to layouts being dropped so that what should have been a shader parameter turned into an ordinary global variable in the output.
This change is more strongly motivated by the fact that making shader parameters look like globals means that we cannot easily reason about their value when doing IR transformations.
If we see two `load`s from the same global variable can we assume they yield the same value?
In the general case we cannot, and this means that any transformation that wants to rely on the fact that an input `Texture2D` shader parameter can't actually change over the life of the program needs to do extra work.
The fix here is to introduce a new kind of IR instruction that represents a global shader parameter directly (not a pointer to it as a global would), at which point there isn't even such a notion as a "load" from the parameter, since it represents the value directly.
In several cases logic that used to apply to global variables in case they were shader parameters (by looking for a layout) is now moved to apply to these global parameters.
The biggest source of issues in this change was that switching from pointers to plain values to represent these shader parameters stresses different cases in type legalization. I also had to deal with the case of legalization for GLSL where we actually *do* need global shader parameters that are writable (since varying output goes in the global scope), but in that case I borrowed the use of pointer-like `Out<...>` and `InOut<...>` types to represent that intent, which we were already using for function parameters representing outputs.
A few tests started failing because the changes lead to a slightly different order of code emission, which in some HLSL tests resulted in a function parameter named `s` getting emitted before a global parameter named `s`, leading to the latter getting the name `s_1` instead of `s_0`.
A few SPIR-V tests started failing because the new approach means that we no longer end up performing a load from all varying input parameters at the start of `main` and instead reference the varying inputs directly. The resulting code is more idomatic, but it differed from the baselines for those tests.
|
|
* Remove the "VM" and "bytecode" features
The "bytecode" in `bc.{h,cpp}` was an initial attempt at a serialized encoding for the Slang IR, but we now have the `ir-serialize.{h,cpp}` approach which was has been kept up to date much better.
Similarly, the "VM" in `vm.{h,cpp}` was intended to be a system for interpreting Slang code in the bytecode format directly (so that you could load and evaluate code in a Slang module in a lightweight fashion). This never got used past a single test, which we eventually disabled.
There are good ideas in some of this code, but at this point the implementations have bit-rotted to a point where trying to maintain it is more costly than it would be to re-created it if/when we ever decide these features are important again.
* fixup: remove slang-eval-test from Makefile
|
|
* First pass at caching file system.
* default-file-system -> slang-file-system
fix problem with location("build.linux") confusing windows build for now.
* Added CompressedResult
Fix problem in Result construction with it being unsigned
* Add support for Path simplification.
* Testing for Path::Simplify.
* Refactored CacheFileSystem - automatically handles ISlangFileSystem or ISlangFileSystemExt appropriately.
Removed WrapFileSystem - because wasn't possible to emulate some of the behavior if just loadFile is implemented.
Split out StringBlob - so that no need to convert between ISlangBlob and String repeatidly.
* Remove unwanted code in ~CompileRequest
|
|
Improvements in 'singleton'ness of DefaultFileSystem
Made WrapFileSystem a stand alone type - to remove 'odd' aspects of deriving from DefaultFileSystem (such as inheriting getSingleton method/fixing ref counting)
Simplified CompileRequest::loadFile - becauce fileSystemExt is always available.
|
|
* Refactor of path handling.
* Added PathInfo
* Changed ISlangFileSystem - such that has separate concepts of reading a file, getting a relative path and getting a canonical path
* Added support for getting a canonical path for windows/linux
* Made maps/testing around canonicalPaths
* User output remains around 'foundPath' - which is the same as before
* Small improvements around PathInfo
* Added a type and make constructors to make clear the different 'path' uses
* Fixed bug in findViewRecursively
* Checking and reporting for ignored #pragma once.
* Removed SLANG_PATH_TYPE_NONE as doesn't serve any useful purpose.
* Improve comments in slang.h aroung ISlangFileSystem
* Remove the need for <windows.h> in slang-io.cpp
* Ran premake5.
* Improvements and fixes around PathInfo.
* Fix typo on linix GetCanonical
* Make the ISlangFileSystem the same as before, and ISlangFileSystem contain the new methods.
Internally it always uses the ISlangFileSystemExt, and will wrap a ISlangFileSystem with WrapFileSystem, if it is determined (via queryInterface) that it doesn't implement the full interface.
|
|
* Add a warning on missing return, and initial SCCP pass
The user-visible feature added here is a diagnostic for functions with non-`void` return type where control flow might fall off the end. This *sounds* like a trivial diagnostic to add as part of the front-end AST checking, but that can run afoul of really basic stuff like:
```hlsl
int thisFunctionisOkay(int a)
{
while(true)
{
if(a > 10) return a;
a = a*2 + 1;
}
// no return here!
}
```
This function "obviously" doesn't need to have a `return` statement at the end there, but realizing this fact relies on the compiler to understand that the `while(true)` loop can't exit normally, and doesn't contain any `break` statement. One can write "obvious" examples that need more and more complex analysis to rule out.
The answer Slang uses for stuff like this is to do the analysis at the IR level right after initial code generation (this would be before serialization, BTW, so that attached `IRHighLevelDeclDecoration`s can be used).
When lowering the AST to the IR, we always emit a `missingReturn` instruction (a subtype of `IRUnreachable`) at the end of its body if it isn't already terminated. The IR analysis pass to detect missing `return` statements is then as simple as just walking through all the functions in the module and making sure they don't contain `missingReturn` instructions.
For that simple pass to work, we first need to make some effort to remove dead blocks that control flow can never reach. This change adds a very basic initial implementation of Spare Conditional Constant Propagation (SCCP), which is a well-known SSA optimization that combines constant propagation over SSA form with dead code elimination over a CFG to achieve optimizations that are not possible with either optimization along.
For the moment, we don't actually implement any constant *folding* as part of the SCCP pass, so we can eliminate the dead block in a case like the function above (and those in the test case added in this change), but will not catch things like a `while(0 < 1)` loop. Handling more "obvious" cases like that is left for future work.
* fixup: warning on unreachable code
* Handle case where user of an inst isn't in same function/code
The code as assuming any instruction in the SSA work list has to come from the function/code being processed, but this misses the case where an instruction in a generic has a use inside the function that the generic produces.
This change adds code to guard against that case.
|
|
* * Remove the need for IRHighLevelDecoration in Emit
* Use the IRLayoutDecoration for GeometryShaderPrimitiveTypeModifier
* Initial look at at variable byte encoding, and simple unit test.
* Fixing problems with comparison due to naming differences with slang/fxc.
* * More tests and perf improvements for byte encoding.
* Mechanism to detect processor and processor features in main slang header.
* Split out cpu based defines into slang-cpu-defines.h so do not polute slang.h
* Support for variable byte encoding on serialization.
* Removed unused flag.
* Fix warning.
* Fix calcMsByte32 for 0 values without using intrinsic.
* Fix a mistake in calculating maximum instruction size.
* Introduced the idea of SourceUnit.
* Small improvements around naming.
Add more functionality - including getting the HumaneLoc.
* Add support for #line default
* Compiling with new SourceLoc handling.
* Fix off by one on #line directives.
* Can use 32bits for SourceLoc. Fix serialize to use that.
* Small fixes and comment on usage.
* Premake run.
* Fix signed warning.
* Fix typo on StringSlicePool::has found in review.
|
|
* * Change the layout of IROp such that 'main' IROps are 0-x.
* Removed MANUAL_RANGE instuction types, as no longer needed.
* Work in prog on optimizing.
* * Constant time lookup for IROpInfo
* Refactor and document a little more the IROp layout
* Mark ops that use 'other' bits
* Fix typo in definition of kIROpFlag_UseOther
* First pass at working out serialization structure.
* Work in progress on ir-serialize
* Storing strings in IRSerialInfo
Split out IRSerialInfo from the IRSerializer - to make more explicit what is actually saved.
* First pass at serializing out data.
* First pass at serialize reading.
* Fix riff fourcc mark order.
* First pass at reconstructing IRInst / IRDecoration from serialized data.
* Handling of TextureBaseType
* Deserializing of constants.
* Small changes around ir serialization.
* Changed StringIndex indexing to not be an offset into the m_strings array, but an index into strings in order. Doing so makes cache lookup much faster, and makes the 'indicies' themselves smaller and therefore more compressible.
* Removed the need for m_arena in IRSerialWriter. Previously it's purpose was to store the string contents that were being used to lookup UnownedStringSlice.
Now we keep the StringRepresentation in scope and reference that, and so don't need the copy.
* Don't need to construct the IRModuleInst as is created and set on createModule call.
* Remove test code for testing serialization.
* Fix problem with release build in ir-serialize causing warning.
* Use SLANG_OFFSET_OF for offsets in non pod classes to avoid gcc/clang warning.
Give storage to integral static variables to avoid linkage problems with gcc/clang.
* Fix warnings under x86 win32 debug.
|
|
* Update glslang version
* Fix build for new glslang
The latest glslang required a few changes to our manual build for their code (because we are *not* taking a dependency on CMake).
* Rebuild project files using premake, which picks up a few files added to glslang, but also a few diffs in Slang's own project files in cases where they were edited manually instead of using premake.
* Fix up the declaration our our device limits (which are inentionally set to *not* limit what code passes through our glslang), because the underlying structure definition in glslang has changed. This is a kludgy bit of glslang's design, but it doesn't make sense for us to invest in a more serious workaround.
* Remove the "hack sampler" workaround
When the `GL_KHR_vulkan_glsl` spec was introduced to allow GLSL to be compiled for Vulkan SPIR-V, it made an annoying mistake by leaving a few builtins as taking `sampler2D`, etc. when the equivalent SPIR-V operations only require a `texture2D`, etc. The relevant builtins are:
* `textureSize`
* `textureQueryLevels`
* `textureSamples`
* `texelFetch`
* `texelFetchOffset`
This means that shader code that wanted to use those operations needed to conspire to have a `sampler` handy so they could write, e.g.:
```glsl
vec4 val = texelFetch(sampler2D(myTexture, someRandomSampler), p, lod);
```
when what they really wanted was this:
```glsl
vec4 val = texelFetch(myTexture, p, lod);
```
That is annoying but probably something each to work around for a GLSL programmer, but when cross-compiling from HLSL, you might have an operation like:
```hlsl
float4 val = myTexure.Load(p);
```
in which case a cross-compiler needs to manufacture a sampler out of thin air. If the shader happened to use a sampler for something else you could snag that, but in the worse case you had to cross-compile to GLSL that declared a new sampler.
Slang did this by declaring a sampler called `SLANG_hack_samplerForTexelFetch` (because `texelFetch` is the operation that first surfaced the issue). For complex reasons we *always* define this sampler, even if we turn out not to need it in a particular output kernel. This choice has a bunch of annoying consequences:
* There is *always* a sampler defined in descriptor set zero, because that's where we put the hack sampler, so a user-defined parameter block always has a set number of 1 or greater (see #646).
* The hack sampler shows up in reflection output because users need to size their descriptor sets appropriately to pass along this sampler that won't actually be used if they don't want to get debug spew from the validation layers.
We filed an issue on glslang about this problem, and eventually some kind folks from the gamedev community (who also saw the same problem) defined an extension spec (`GL_EXT_samplerless_texture_functions`) to fix the underlying issue and contributed a patch to glslang to make it support that extension.
This change just backs the hack out of Slang now that we have a glslang version that supports the extension to get past the defect in the original GLSL-for-Vulkan definition. Besides yanking out the code for the hack, we also change the relevant builtins to declare that they require this new GLSL extension (so that we properly request it from glslang when the builtins are used), and fix some reflection test cases that exposed the existence of the "hack sampler."
* Fixup: syntax error in stdlib generator files
* Remove more code for hack sampler
There was logic to ensure we always have a "default" register space/set when cross-compiling, because the hack sampler would need it. This is no longer necessary once we remove the hack sampler.
* Fix expected test output.
Fixing the root cause of issue #646 means that one of our test cases that tickles that issue now produces different output (luckily it can now be used as a regression test for the issue).
|
|
* * Remove dispose from IRInst
* Use MemoryArena instead of MemoryPool
* Make all IRInst not require Dtor - by having ref counted array store ptrs that need freeing
* Increase block size - typically compilation is 2Mb of IR space(!)
* Fix issues around StringRepresentation::equal because null has special meaning.
* Don't bother to construct as String to compare StringRepresentation, just used UnownedStringSlice.
* Added fromLiteral support to UnownedStringSlice and use instead of strlen version.
* Use more conventional way to test StringRepresentation against a String.
* Fix gcc/clang template problem with cast.
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* render-test should not fail on HLSL compiler *warnings*
The logic in `render-test` that invokes `D3DCompile` was causing a test to fail if it produced any warnings (not just if compilation fails).
Warning output can be dealt with by the test runner, since it will compare output between runs anyway, and it is useful to be able to run something through `render-test` that compiles with warnings.
* Be more careful about deleting IR instructions
There was an `IRInst::deallocate()` method that had a precondition that the instruction should already be removed from its parent and clear out all its operands before calling, but it wasn't checking this and the few call sites weren't doing things right either.
I consolidated things on `IRInst::removeAndDeallocate()` which does all the things: removes from the parent, clear out operands, and then deallocates.
I also made sure to clear out the type operand.
This clears up some crashing issues where passes were removing instructions but those instructions would still show up as users of other instructions.
* Don't emit bitwise not for non-Boolean types
It seems like the logic in `emit.cpp` messed things up and decided that `Not` (the IR instruction that is equivalent to `!` in the AST) should emit as `!` for Boolean types and `~` for other types, but this makes no sense (e.g., `~(a & 1)` is very different from `!(a & 1)`, even when interpreted as a condition).
It seems like this logic was intended for the `BitNot` case, where `~a` and `!a` are actually equivalent for Boolean values (but a target language might not like `~a` on `bool` values).
Maybe the original plan was that the `Not` instruction should only apply to Boolean values in the first place, and that other values should be converted to `bool` (or a vector of `bool`) before applying `Not`, but even in that case the emit logic makes no sense.
This caused an actual problem for one of my test cases, so it was important to fix it now.
* Fix issue with cached resolution for overoaded operators
The basic problem was that the lookup logic was forming a key based on the *first* definition it found for the overloaded operator, but that means that when processing a prefix `++a` call we might look up the *postfix* definition of `operator++` and decide to use its opcode as the key.
This "fixes" the logic by looking for the first definition with a "compatible" definition (e.g., a `__prefix` function if we are checking a `PrefixExpr`), and then uses its opcode.
A better fix in the long run would be to make the cache just be keyed on the operator name and the "fixity" of the expression (prefix, postfix, or infix).
* Introduce an intermediate structured control-flow representation
The code previously used a single function called `emitIRStmtsForBlocks` in `emit.cpp` that would take a logical sub-graph of the CFG and emit it as high-level statements.
It would do this by recognizing operations like coniditional branches that it could turn into high-level `if` statements, etc.
The main problem with this function was that it mixed together the logic for how we restructure the program with the logic for how we emit high-level code from that structure.
This change splits those two parts of the algorithm by introducing an intermediate data structure: a tree of `Region`s, which represent single-entry regions of the CFG.
There are subclasses of `Region` corresponding to various structured control-flow constructs, and then a leaf case that wraps a single `IRBlock`.
The new function `generateRegionsForIRBlocks()` (in `ir-restructure.cpp`) now handles the restructuring work, by building one or more `Region`s to represent a sub-graph, while `emitRegion()` handles emitting HLSL/GLSL source code from a region.
Splitting things in this way opens up some opportunities for future changes:
* We can expand the set of IR control-flow constructs allowed, so long as we can still generate structure `Region`s from them, without having to mess with the emit logic (e.g., we could start to support multi-level `break` by introducing temporaries as needed). In the limit we can generate our `Region`s using something like the "Relooper" algorithm.
* We can emit to other representations while retaining the same control-flow restructuring support. E.g., if we drop the structured information from the IR, then emitting to SPIR-V for Vulkan would require us to use the strucured control-flow information from these `Region`s.
* We can do analysis that needs to understand `Region` structure. This is relevant to issue #569, which was what prompted me to start on this work. Now that we have a representation of the nesting of `Region`s, we can use it to reason about visibility of values between blocks.
During development of this change I ran into a gotcha, in that I had been assuming each IR block would map to a single `Region`, forgetting that our current lowering of "continue clauses" in `for` loops leads to them being duplicated. The `Region` representation handles this by having a linked-list struct mapping IR blocks to the `SimpleRegion`s that represent them. I added a test case that includes a `for` loop with a continue clause that is reached along multiple paths just to make sure that we continue to support that case.
The compiler output should not change as a result of this work; this is supposed to be a pure refactoring change.
* Add a pass to resolve scoping issues in generated code
Fixes #569
The basic problem arises because the structured control flow that we output in high-level HLSL/GLSL doesn't match the "scoping" rules of an SSA IR.
In particular, SSA says that a value can be used in any block that is dominated by the definition, but in the presence of `break` and `continue` statements it is easy to construct cases where a block dominates something that is not in its scope for structured control flow. Consider:
```hlsl
for(;;) {
int a = xyz;
if(a) { int b = a; break; }
int c = a;
}
int d = b;
```
This program is invalid as HLSL, because the variable `b` is referenced outside of its scope, but if we look at the CFG for this function, it is clear that the block that computes `b` dominated the block that computes `d`. IR optimizations can easily create code like this, so we need to be ready for it.
The previous change added an explicit `Region` structure to represent the structured control flow that we re-form out of the IR, and this change adds a pass that exploits the structuring information to detect cases like the above and introduce temporaries to fix the scoping issue. For example, the pass would change the earlier code block into something like:
```hlsl
int tmp;
for(;;) {
int a = xyz;
if(a) { int b = a; tmp = b; break; }
int c = a;
}
int d = tmp;
```
That is, we introduce a new `tmp` variable at a scope "above" both the definition and use of `b`, and then we copy `b` into that temporary right where it is computed, and then use the temporary instead of the original `b` at the use site.
A few details that came up during the implementation:
* Downstream compilers may get confused by code like the above, and complain that `tmp` may be used before it is initialized, even though the very definition of dominators in a CFG means we don't have to worry about it. Still, I introduced some one-off code to initialize the temporaries just to silence spurious warnings coming from fxc.
* We need to be careful not to apply this logic to "phi nodes" (the parameters of basic blocks) since they will already be turned into temporaries by the emit logic, and trying to introduce temporaries with this pass led to broken code (I still need to investigate why). It may be that a future version of this pass should also take the code out of SSA form, so that we can introduce both kinds of temporaries in a single pass (and maybe eliminate some unnecessary variables by doing basic register allocation).
There is another transformation that could fix some issues of this kind, by moving code out of a structured control-flow construct and to the "join point" after it. For example, we could turn our loop from the start of this commit message into:
```hlsl
for(;;) {
int a = xyz;
if(a) { break; }
int c = a;
}
int b = a;
int d = b;
```
Moving the definition of `b` to after the loop is possible because there is no way to get out of the loop without executing that code anyway. Now the scoping issue for `d`'s use of `b` has gone away, but of course we've introduced a *new* scoping issue for `a`, when it gets used by `b`.
Adding a pass to re-arrange control flow like this could reduce the cases where we have to apply the current pass, but it wouldn't eliminate them entirely. That means such a pass can be deferred to future work.
This change includes a test case the reproduces the original issue, so that we can confirm the fix works.
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* Generate Visual Studio projects using Premake
This change adds a `premake5.lua` file that allows us to generate our Visual Studio solution using Premake 5 (https://premake.github.io/).
The existing Visual Studio solution/projects are now replaced with the Premake-generated ones, and project contributors will be expected to update these by running premake after adding/removing files.
I have *not* changed the Linux `Makefile` build at all, because that file is also used for things like running our tests, so that clobbering it with a premake-generated `Makefile` would break our continuous testing.
Hopefully future changes can switch to a generated `Makefile` and perhaps even add an XCode project as well.
Notes:
* The `build/slang-build.props` file is no longer needed/used, so it has been removed.
* The `slang-eval-test` test fixture wasn't following our naming conventions for its directory path, so it was updated to streamline the Premake build configuration work. This required changes to the `Makefile` as well
* Some seemingly unncessary preprocessor definitions that were specified for `core` and `slang-glslang` have been dropped. We will see if anything breaks from that.
* Possible fixup for Premake vpath issue
Premake's `vpath` feature seems to be nondeterministic about the order it applies filters (because Lua isn't deterministic about the order of entries in a key/value table), and as a result we can end up in a weird case where it decides that a `foo.cpp.h` file matches the `**.cpp` filter (I'm not sure why) before it tests against the `**.h` filter.
This change uses an (undocumented) Premake facility to set `vpath` using a list of singleton tables, which seems to fix the order in which things get tested.
* Remove support for "single-file" build of Slang
The `hello` example was the only bit of code that uses the "single-file" way of building Slang, and this had already run up against limitations of the Visual Studio compilers in its Debug|x64 build.
Rather than mess with Premake to make it pass through the `/bigobj` linker flag that is needed to work around the issue, it makes more sense just to stop using/supporting the feature since we wouldn't want users to depend on it anyway (our documentation no longer refers to it).
While I was at it I went ahead and made sure that the `SLANG_DYNAMIC` flag doesn't need to be set manually, so that instead there is a non-default `SLANG_STATIC` option (not that we have a static-library build of Slang at the moment).
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This code is currently not used by anything, but I wanted to check in a first pass at an implementation of dominator tree construction so that we don't have to keep avoiding implementing algorithms that rely on having dominator information available.
The algorithm used to construct the dominator tree is taken from "A Simple, Fast Dominance Algorithm" by Keith D. Cooper, Timothy J. Harvey, and Ken Kennedy.
This is not the "best" algorithm in terms of asymptotic performance, but it is among the simplest algorithms for computing a dominator tree that still outperforms naive iterative set-based methods.
The actual data structure and API for the dominator tree has a bit of "cleverness" in it to try to make the common queries reasonably fast (e.g., you can check whether A dominates B in constant time).
My hope is that even if we implement a more advanced algorithm for constructing the dominator tree, we can retain compatibility with passes that might make use of this API.
Because no code is currently using this logic, I have done only minimal testing by stepping through this code and validating the results on paper for some very small CFGs.
More serious testing/debugging may need to wait until we have an optimization pass that needs the dominator tree we compute here.
One open question I have is how best to introduce traditional unit testing into Slang, since this is an example of code that would benefit greatly from being unit tested.
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* Cleanup: remove unused files from project
* Cleanup: move IRModule forward declaration into correct namespace
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* Introduce an IR-level type system
Up to this point, the Slang IR has used the front-end type system to represent types in the IR.
As a result (but ultimately more importantly) the IR representation of generics and specialization has used AST-level concepts embedded in the IR.
For example, to express the specialization of `vector<T,N>` to a concrete type `float` for `T`, we needed an IR operation that could represent the specialization, with operands that somehow represented the type argument `float`.
The whole thing was very complicated.
The big idea of this change is to introduce a new representation in which types in the IR are just ordinary instructions, so that using them as operands makes sense. The hierarchy of IR types closely mirrors the AST-side hierarchy for now, and that will probably be something we should maintain going forward.
In order to make these changes work, though, I also had to do major overhauls of things like the way substitutions are performed, how we check interface conformances, the way lookup through interface types is done, etc. etc. This is a big change, and unfortunately any attempt to summarize it in the commit message wouldn't do it justice.
* Fix 64-bit build warning
* Fix up some clang warnings/errors
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Fixes #350
When the Slang project forked off from the Spire research effort, we renamed things as we went, but many cases seem to have slipped through the cracks.
The two biggest diffs here are:
- The `hello` example program was incorrectly talking about what was in the shader file (Slang no longer supports the "module" or "pipeline" constructs from Spire), and so it wasn't just a simple rename.
- The files under `tests/bindings` were mistakenly using `__SPIRE__` as a preprocessor guard, which means that they weren't actually testing what they meant to. Luckily, it looks like the relevant functionality didn't regress while these tests were unintentionally deactivated.
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The main practical change here is that things that used to be `IRValue`s, like literals, are now being expressed as instructions in the global scope.
In order to validate that things are actually being handled correctly, this change introduces an explicit "validation" pass that can be run on the IR to check for different invariants (although it doesn't check many of the important ones right now). I've left the validation pass turned off by default, but with a command-line flag to enable it. We may want to make it be on by default in debug builds, just to keep us honest. The main invariant for the moment is that when on IR instruction is used as an operand to another, it had better come from the same IR module.
Some of the existing passes were violating this rule, in particular when it came to cloning of witness tables related to global generic parameter substitution. Those features can in theory be handled better now by allowing `specialize` instructions at other scopes, but I didn't want to over-complicate this change, so I make just enough fixes to ensure that these steps always clone witness tables they get from the "symbols" on an IR specialization context. In order for this to work when recursively specializing, I had to ensure that the logic for generic specialization had a notion of a "parent" specialization context that it would fall back to to perform cloning when necessary.
This change keeps the logic that was caching and re-using the instructions for literal values within a module, but adds some logic that isn't really being tested right now for picking the right parent instruction to insert a constant instruction into. This logic doesn't trigger right now because all of the cases we are using it on have zero operands (and so they always get "hoisted" to the global scope), but eventually for things like types we want to be able to support instructions with operands (e.g., `vector<float, 4>`) and handle the case where some of those operands come from different scopes (e.g., when nested inside a generic).
The final change here is mostly cosmetic: the `IRBuilder` is now more abstract about where insertion occurs: it tracks a single `IRParentInst` to insert into, and then an optional `IRInst` to insert before. In the common case, that parent is an `IRBlock`, but it could conceivably also be the global scope, or a witness table, etc. Use sites where we used to change those fields directly now use distinct methods `setInsertInto(parent)` and `setInsertBefore(inst)` which capture the two cases we care about. Accessors are also defined to extract the current block (if the current parent is a block), and the current "function" (global value with code, if the current parent is a global value with code, or a block inside one).
With this work in place, it should be possible for a follow-on change to start putting `specialize` instructions at the global scope and thus clean up some of the on-the-fly specialization work. This work should also help with some of the requirements around a distinct IR-level type system and more explicit generics.
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Pull BaseType, TextureFlavor and SamplerStateFlavor enums and helper functions into a shared file "type-system-shared.h".
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* Initial work on validating "constexpr"-ness in IR
The underlying issue here is that certain operations in the target shading languages constrain their operands to be compile-time constants. A notable example is the optional texel offset parameter to the `Texture2D.Sample` operation.
When calling these operations in GLSL, the user is required to pass a "constant expression," and any variables in that expression must therefore be marked with the `const` qualifier (and themselves be initialized with constant expressions). Any GLSL output we generate must of course respect these rules.
When calling these operations in HLSL, the user is not so constrained. Instead, they can pass an arbitrary expression, which may involve ordinary variables with no particular markup, and then the compiler is responsible for determining if the actual value after simplification works out to be a constant. In some cases, the requirement that a value be constant might actually trigger things like loop unrolling. Also, it is okay to use a function parameter to determine such a constant expression, as long as the argument turns out to be a constant at all call sites.
The way we have decided to tackle these challenges in Slang is that we we propagate a notion of `constexpr`-ness through the IR. This is currently being tackled in `ir-constexpr.cpp` with a combination of forward and backward iterative dataflow:
* When the operands to an instruction are all `constexpr`, and the opcode is one we believe can be constant-folded, then we infer that the instruction *can* be evaluated as `constexpr`
* When instruction is required to be `constexpr`, then we infer that all of its operands are also required to be `constexpr`.
If this process ever infers that a function parameter is required to be `constexpr`, then we might have to continue propagation at all the call sites to that function.
If after all the propagation is done, there are any cases where an instruction is *required* to be `constexpr`, but it *can't* be `constexpr` (we weren't able to infer `constexpr`-ness for its operands), then we issue an error.
This implementation encodes the idea of `constexpr`-ness in the IR as part of the type system, using a simplified notion of rates. This change adds a `RateQualifiedType` that can represent `@R T`, and then introduces a `ConstExprRate` that can be used for `R`. Many accessors for the type information on IR nodes were updated to distinguish when one wants the "full" type of an IR value (which might include rate information) vs. just the "data" type.
A `constexpr` qualifier was added in the front-end, and is being used to decorate the texel offset parameter for `Texture2D.Sample`. Lowering from AST to IR looks for this qalifier and infers when a function parameter must be typed as `@ConstExpr T` instead of just `T`.
There are lots of limitations and gotchas in the implementation so far:
* The `@ConstExpr` rate is the only one added in this change, but it seems clear that the conceptual `ThreadGroup` rate that was added to represent `groupshared` should probably get folded into the representation.
* I'm not 100% pleased with how many places in the IR I have to special-case for rate-qualified types. At the same type, pulling out rate as a distinct field on `IRValue` would probably require that we pay attention to rate everywhere.
* I've added a test case to show that we can issue errors when users fail to provide a constant expression for the texel offset, but the actual error message isn't great because it doesn't indicate *why* a constant expression was required. Realistically the "initial IR" should contain a few more decorations we can use to relate error conditions back to the original code (even if this is in a side-band structure).
* I've added a test case that is supposed to show that we can back-propagate `constexpr`-ness to local variables, and I've manually confirmed that it works for Vulkan/SPIR-V output, but the level of Vulkan support in `render_test` today means I can't enable the test for check-in.
* While I'm attempting to propagate `@ConstExpr` information from callees to callers, I haven't implemented any logic to specialize callee functions based on values at call sites.
* In a similar vein, there is no handling of control-flow dependence in the current code. If we infer that a phi (block parameter) needs to be `@ConstExpr`, then it isn't actually enough to require that the inputs to the phi (arguments from predecessor blocks) are all `@ConstExpr` because we also need any control-flow decisions that pick which incoming edge we take to be `@ConstExpr` as well.
* As a practical matter, implicit propagation of `@ConstExpr` from a function body to a function parameter should only be allowed for functions that are "local" to a module. Any function that might be accessed from outside of a module should really have had its `@ConstExpr` parameter marked manually, and our pass should validate that they follow their own rules. Right now we have no kind of visibility (`public` vs `private`) system, so I'm kind of ignoring this issue.
While that is a lot of gaps, this is also just enough code to get the Falcor MultiPassPostProcess example working, so I'm inclined to get it checked in.
* Fixup: missing expected output for test
* Fixup: disable test that relies on [unroll] for now
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1, make IRModule class own a memory pool for all IR object allocations
2. For now, we allow IR objects to own other (externally) heap allocated objects, such as String, List and RefPtrs by tracking all IR objects that has been allocated for the IRModule in a list named `IRModule::irObjectsToFree`. and call destructor for all these objects upon the destruction of the IRModule. In the long term, we should eliminate the use of all these externally allocated types in IR system and get rid of this tracking and explicit destructor calls.
3. remove non-generic `createValueImpl` functions and retain only generic versions in IRBulider so we can properly call the constructor of the IR types to set up virtual tables correctly for destructor dispatching.
4. add `MemoryPool` class for allocation of the IR objects.
5. Make sure we are disposing IRSpecContexts when we are done with the specialized IR module.
6. Add `_CrtDumpMemoryLeaks()` calls to check memory leaks upon destruction of a Slang session. If we are to support multiple sessions at a time, this call should probably be replaced with the more advanced MemoryState versions of the memory leak checker.
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* Generate SSA form for IR functions
The basic idea here is simple: in the front-end after we have lowered the AST to initial IR we will apply a set of "mandatory" optimization passes. The first of these is to attempt to translate the all functions into SSA form so that they are amenable to subsequent dataflow optimizations. Eventually, the mandatory optimization passes would include diagnostic passes that make sure variables aren't used when undefined, etc.
Just doing basic SSA generation already cleans up a lot of the messiness in our IR today, because constructs that used to involve many local variables can now be handled via SSA temporaries.
The implementation of SSA generation is in `ir-ssa.cpp`, and it follows the approach of Braun et al.'s "Simple and Efficient Construction of Static Single Assignment Form." I used this instead of the more well-known Cytron et al. algorithm because Braun's algorith mis very simple to code, and does not require auxiliary analyses to generate the dominance frontier.
The main wrinkle in our SSA representation right now is that instead of using ordinary phi nodes, we instead allow basic blocks to have parameters, where predecessor blocks pass in different parameter values. This encodes information equivalent to traditional phi nodes, but has two (small) benefits:
1. There is no fixed relationship between the order of phi operands and predecessor blocks, so we don't have to worry about breaking the phis when we alter the order in which predecessors are stored. This is important for us because predecessors are being stored implicitly.
2. It is easy to operationalize a "branch with arguments" either when lowering to other languages, or when interpreting the IR. A branch with arguments is implemented as a sequence of stores from the arguments to the parameters of the target block (very similar to a call), followed by a jump to the block.
Relevant to the above, this change also adds an interface for enumerating the predecessors or successors of a block in our CFG. Rather than use an auxliary structure, we directly use the information already encoded in the IR:
* The sucessors of a block are the target label operands of its terminator instruction. In our IR this is a contiguous range of `IRUse`s, possible with a stride (to account for the way `switch` interleaves values and blocks).
* The predecessors of a block are a subset of the uses of the block's value. Specifically, they are any uses that are on a terminator instruction, and within the range of values that represent the successor list of that instruction.
One important limitation of the "blocks with arguments" model for handling phis is that it is really only convenient to stash extra arguments on an unconditional terminator instruction. This change works around this prob lem by breaking any "critical edges" - edges between a block with multiple successors and one with multiple predecessors. We assume that "phi" nodes will only ever be needed on a block with multiple predecessors, and because critical edges are broken, each of these predecessors will then have only a single successor, so its branch instruction can handle the extra arguments.
This change introduces a notion of an "undefined" instruction in the IR. This is handled as an instruction rather than a value because I anticipate that we will want to distinguish different undefined values when it comes time to start issuing error messages (those messages will need to point to the variable that was used when undefined).
* Fix expected test output.
Another change was merged that enabled the `glsl-parameter-blocks` test, and its output is affected by our IR optimization work.
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The basic change is simple: remove support for all code generation paths other than the IR.
There is a lot of vestigial code left, but the main logic in `ast-legalize.*` is gone.
Doing this breaks a *lot* of tests, for various reasons:
- We can no longer guarantee exactly matching DXBC or SPIR-V output after things pass through out IR
- Many builtins don't have matching versions defined for GLSL output via IR (even when they had versions defined via the earlier approach that worked with the AST)
- A lot of code creates intermediate values of opaque types in the IR, which turn into opaque-type temporaries that aren't allowed (this breaks many GLSL tests, but also some HLSL)
I implemented some small fixes for issues that I could get working in the time I had, but most of the above are larger than made sense to fix in this commit.
For now I'm disabling the tests that cause problems, but we will need to make a concerted effort to get things working on this new substrate if we are going to make good on our goals.
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* Add core.natvis file to Slang DLL build
It seems that when `slang.dll` gets loaded into a user's project, the debugger is able to pick up the custom visualizers implemented in `slang.natvis` (which is directly added to the DLL project) but not `core.natvis` (which is added to a static library project that the DLL project references). Adding `core.natvis` to the DLL project directly seems to resolve this and greatly improve the debugging experience when in user code.
* Bug fix: emit type of CB before CB when using IR
The problem here was the logic for emitting types used by an IR declaration before the declaration.
I refactored it to share logic between variables with initializers and functions, but in doing so failed to have an ordinary variable (which includes constant buffers) ensure that its own type was emitted before the variable.
This is a one-line fix.
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* Make AST and IR share type legalization code
A previous change already made it so that the AST-to-AST lowering/legalization pass could work together with IR-based lowering of `import`ed code, but that change didn't take into account the case where a function written in the AST needed to call an IR function and pass in a type that required legalization.
Both the IR-based and AST-based passes had their own approaches to type legalization, that mostly agreed on the desired output, but they ended up creating their own representations for legalized types which would mean that for a function call the caller and callee might end up legalizing the parameter list to use different types.
This change tries to fix this issue (and adds a new test case that relies on the fix) by massively overhauling the AST-based legalization pass so that it uses the same type legalization code as the IR. The shared code has been moved out into `legalize-types.{h,cpp}`.
Notes:
- I eliminated the `FilteredTupleType` type, since it was starting to cause code duplication in a lot of places. Instead, type legalization just creates new `struct` types to represent the result of filtering.
- One big consequence of this is that the `LegalType::pair` case needs to remember for each field in the original type which field (if any) in the new `struct` type it maps to
- A big source of complexity (and probably bugs) in this code is trying to figure out how to parent these new `struct` definitions effectively. A good follow-on change would be something that outputs declarations on-demand during the AST emit logic (as we do for the IR), just to avoid some of this song and dance.
- The old AST type legalization had a notion of both a "tuple" type and a "varying tuple" type. The "tuple" case was quite complex, and combined behavior currently handled by `LegalType::pair` (for splitting into ordinary and special sides) and `LegalType::tuple` (for holding multiple distinct elements to represent the fields of an aggregate). The "varying tuple" case was closer to `LegalType::tuple`, so I tried to just re-use the existing logic for that too. The one place this potentially gets messy is in `reifyTuple()`.
- The messiest bit of handling the "varying tuple" concept (which is used for GLSL shader inputs/outputs since they have to be scalarized) is that when passing them as function arguments we need to reify the tuple back into a structured value. Because the `LegalExpr` hierarchy doesn't have type information, but constructing a value of the "original" type requires such information, things get a little messy.
- I did *not* try to deal with any of the logic related to handling system inputs/outputs for cross-compilation purposes. Of course, the long-term goal is that any actual cross-compilation is handled via the IR, but this change can't afford to break the AST-based path just yet. As a result, there is still quite a bit of complexity in the handling of assignment, to deal with cases where "fixups" are required.
* fixup: bad code in macro, not caught by Visual Studio compiler
* fixup: more stuff missed by VS compiler
* fixup: VS continutes to miss stuff in UNREACHABLE_RETURN
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* Rename `lower.{h,cpp}` to `ast-legalize.{h,cpp}`
This pass isn't really performing lowering akin to `lower-to-ir.{h,cpp}` so the file name is misleading.
By renaming this pass we emphasize its role as an AST-related pass.
Also update the comment at the top of `ast-legalize.h` to reflect the intended purpose of this pass in a world where we have the IR up and running.
* Allow `import` as an alias for `__import`
The use of double underscores to mark our new syntax has so far had two purposes:
1. It helps identify syntax that isn't meant to be exposed to users in its current form (e.g., `__generic` gets a double underscore because we want users to have a more pleasant surface syntax for generics that they write). This rationale doesn't apply to `__import`, which is a major language feature that users need to interact with.
2. It helps avoid the problem where the compiler treats something as a keyword that isn't supposed to be reserved in HLSL/GLSL and so causes existing user code to fail to parse (e.g., when the user tries to write a function called `import`). This no longer matters because we look up almost all of our keywords using the existing lexical scoping in the language (so the user can shadow almost any keyword with a local declaration).
So, neither of the original two reasons applies to `__import`, and it makes sense to expose it as `import`.
Doing so is a one-line change.
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