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* Overhaul IR lowering of pointer types.
* Propagate address space in IRBuilder.
* Fixup.
* Fix.
* Fix.
* Change how Ptr type is printed to text.
* Fix.
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(#4618)
* Add `dev` cmake preset.
* Fix incorrect codegen when returning initializer list as existential value.
* Fix cmake.
* Fixup.
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* Handle type check cache update on extensions more gracefully.
* Correctness fix.
* Cache implcit cast overload resolution results.
* Fix.
* More optimizations.
* Cache implicit default ctor resolution.
* Disable redundancy removal.
* Fix.
* Fix test.
* Fix.
* Correctness fix.
* Fix.
* Fix,
* Fix test.
* Small tweak.
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* Allow bit operators on enum types.
* Fix.
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* Support mutable existential parameters.
* Update test.
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* Link-time constant and linkage API improvements.
* Fix.
* Allow module name to be empty.
* Fix.
* Fix.
* Fix compile error.
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* Add support for bitfields
Closes https://github.com/shader-slang/slang/issues/3559
* Set scopes for syntsized bitfield accessors
* Simplify generated code for bitfield accessors
* spelling
* regenerate vs project
* warnings
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* Support visibility control and default to `internal`.
* Fix wip.
* Fixes.
* Fix.
* Fix test.
* Add legacy language detection and compatibility for existing code.
* Add doc.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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* Support `constref` parameters passing.
* Fix.
* Fix.
* Add test and diagnostic on mix use of __constref and no_diff.
* check for [constref] on differentiable member method.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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* Incur l-value conversion cost during overload resolution.
* Fix compile error.
* cleanup.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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* Support per field matrix layout
* Fix warnings.
* Fix.
* Fix tests.
* Fix spiv gen.
* Fix.
* More test fixes.
* Fix.
* Run only GPU tests on self-hosted servers.
* Remove -use-glsl-matrix-layout-modifier.
* Fix.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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* Support implciit casted swizzled lvalue.
* Fix warnings.
* Fix.
* fix comment.
* Prefer mangled linkage name for global params.
* Update tests.
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Co-authored-by: Yong He <yhe@nvidia.com>
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* Redesign DeclRef + Deduplicate Val.
* Update project files
* Fix warning.
* Fix.
* Fix.
* Remove `Val::_equalsImplOverride`.
* Rmove `Val::_getHashCodeOverride`.
* Remove `semanticVisitor` param from `resolve`.
* Cleanups.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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* Create and cache flattened inheritance lists
The basic change here is to have a cached lookup that can map a `Type`,
or a `DeclRef` that might refer to a type or `extension`, to a list of
the *facets* that comprise it.
The notion of a *facet* here is similar to what the C++ standard calls
"sub-objects".
A declared type like a `struct` has:
* a facet for its own direct members
* one facet for each of its (transitive) base `struct` types
* one facet for each `interface` it conforms to
* one facet for each `extension` that applies to that type
The set of facets for a type is de-duplicated (so that "diamond"
inheritance patterns don't cause issues) and deterministically ordered,
using a variation of the C3 linearization algorithm.
The creation of a linearized list of facets should help the compiler
implementation in two key places:
* Testing if a type implements an interface (or inherits from a base
type) should now only take time linear in the number of (transitive)
bases of that type. We can simply scan the linearized facet list to
see if it contains a facet corresponding to the given base.
* Looking up the members of a type (or a value of a given type) should
be greatly simplified, since all of the members can be found in a
single linear scan of the facet list. In addition, those facets will
be ordered so that facets for "more derived" types will precede those
for "less derived" types, so that shadowing in the case of overrides
should be easier to implement.
This change only implements the first of these two improvements, since
there is already a *lot* of churn involved.
Notes and caveats:
* The handling of conjunction types (e.g., `IFoo & IBar`) complicates
the implementation, both because the simple approach to subtype
testing alluded to above is no longer complete, and also because
we need to be more careful about what forms of subtype witnesses
we construct, so that we can maintain the currently-required invariant
that two witnesses are only equal if they have matching structure.
* We don't implement the full/"proper" C3 algorithm here because it has
some failure cases that we'd still like to support. In particular if
we have both `IX : IA, IB` and `IY : IB, IA`, the C3 algorithm says it
is illegal to have `IZ : IX, IY` because the two bases it inherits
from disagree on the relative ordering of `IA` and `IB` in their
own linearizations. Handling such cases may make our implementation
less efficient, and it will also require testing of those corner
caes.
* When it comes time to revamp the implementation of lookup, we will
need to deal with the fact that a single linear list (seemingly)
cannot give us sufficient information to decide which of two members
of the same name should shadow the other, or if there is an ambiguity.
Or rather, it *can* give us that information if we are willing to
accept some very user-unfriendly behavior and simply say that
declarations earlier in the linearization always shadow later
declarations, even if the facets involved are not related by an
inheritance relationship of any kind.
* In order to remove one kind of vicious circularity from the approach,
the linearization that we are computing for `extension` declarations
will not be sufficient for lookups in the body of such an `extension`.
A future change may need to have support for creating and caching
two distinct linearizations for each `extension`: one that is to be
used when that `extension` is pulled into the linearization for a
type that it applies to, and another for when lookup will be performed
in the context of the `extension` itself.
* This change does *not* include the simple expedient of adding a direct
cache for subtype tests to the `SharedSemanticsContext`, although
adding such a cache would be a simple matter.
* This change introduces more deduplication for subtype witnesses,
which should enable more deduplication for other `Val`s (including
`Type`s), but it does not introduce any assumptions that equal
`Val`s or `Type`s must have identical pointer representations.
* Eventually we may find that, similar to the situation with `Type`s,
we will want to have a split between surface-level and canonicalized
versions of other `Val`s, including subtype witnesses.
* Fix clang error.
* remove debugging code.
---------
Co-authored-by: Yong He <yonghe@outlook.com>
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* Make DeclRefBase a Val, and DeclRef<T> a helper class.
* Fixes.
* Workaround gcc parser issue.
* Revert NodeOperand change.
* Fix.
* Fix clang incomplete class complains.
* Fix code review.
* Small cleanups and improvements.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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(#2958)
* Simplify type of diagnoseImpl
* Show source line for Note diagnostics, opting out of this where appropriate
* Make declared after use diagnostic clearer
* Fix erroneous error claiming variable is being used before its declaration
Closes https://github.com/shader-slang/slang/issues/2936
* Fix build on msvc
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Co-authored-by: jsmall-nvidia <jsmall@nvidia.com>
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* Bottleneck DeclRef creation through ASTBuilder.
* Fix clang error.
* Fix.
* Fix.
* More fix.
* Rebase on top of tree.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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* Be lenient on same-size unsigend->signed conversion.
* Fix tests.
* Use 250.
* wip
* Fix.
* Fix tests.
* Fix.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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* MVP for higher order functions
* Add shader subgroup partitioned glsl intrinsics
* Implement parsing and checking for tuple types
Currently there is no way to do anything useful with them from the source language however
* neaten
* Correct precedence of function type parsing
* neaten
* higher order function tests
* function types of any arity
* Inference for higher order functions
* Add second test for unsynchronized params
* regenerate vs projects
* dx11 -> dx12 for saturated cooperations tests
* Disable saturated cooperation tests on vulkan
They fail on release builds in CI, not essential for the higher order function work however
* remove saturated-cooperation tests
* Remove unnecessary assert and clarify control flow in AddDeclRefOverloadCandidates
* Add Tuple type name mangling
* Use functype keyword to introduce function types
* Add more inference tests for hof
---------
Co-authored-by: Yong He <yonghe@outlook.com>
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* #include an absolute path didn't work - because paths were taken to always be relative.
* WIP lowerCamel Dictionary.
* WIP more lowerCamel fixes for Dictionary.
* Add/Remove/Clear
* GetValue/Contains
* Fix tabs in dictionary.
Count -> getCount
* Fix fields with caps.
* Key -> key
Value -> value
Use m_ for members where appropriate.
Use lowerCamel in linked list.
* Some small fixes/improvements to Dictionary.
* Kick CI.
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* Warn on float-to-double coercion for arguments.
* Fix test.
* Rename.
* Fixup.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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(#2641)
Fixes https://github.com/shader-slang/slang/issues/2189
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stdlib. (#2615)
* Allow array parameters in forward diff.
* Use type canonicalization instead of coersion.
* Reimplement array type.
* Fix.
* Update test case.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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* Modified the new type system to support generic differentiable types and added support for differentiating overloaded functions.
* Changed a few asserts to release asserts to avoid unreferenced variable errors
* Fixed a naming issue with TypeWitnessBreadcumb::Flavor::Decl
* Added logic to avoid tracking differentiable types if the module does not use auto-diff or define differentiable types.
* Moved the auto-diff passes to after the specialization step, added a more complex generics test
* Added a generics stress test and fixed AST-side logic. IR side needs some more work
* Added differential getter and setter logic, fixed multiple issues with DifferentiableTypeDictionary, added support for loops and conditions
* Changed differential getters to use pointer types, added getter type checking
* Fixed some bugs related to diff type registration and differential getters
* Removed some superfluous code
* Removed some more unused code.
* Fixed an issue with witness substitution
* Minor fix
Co-authored-by: Yong He <yonghe@outlook.com>
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* wip: dedup AST type nodes and cache lookup.
* Fix.
* Remove profiling.
* Fixes.
Co-authored-by: Yong He <yhe@nvidia.com>
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(#2388)
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* Warning on bool to float conversion.
* Fix test cases.
* Improve.
* LanguageServer: don't show constant value for non constant variables.
* Fix tests.
* Fix warnings in tests.
Co-authored-by: Yong He <yhe@nvidia.com>
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* Add `none` literal that is convertible to `Optional`.
* Fix cpu code gen.
* Include vk and cpu test for is-as operator test.
* Inline comparison operators.
Co-authored-by: Yong He <yhe@nvidia.com>
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* Major language server features.
* Include slangd in binary release.
* Fix compiler issues.
* Fix compiler error.
* Completion resolve.
* Various improvements.
* Update diagnostic test expected output.
* Bug fix for source locations.
* Adjust diagnostic update frequency.
* Update github actions to store artifacts.
* Fix infinite parser loop.
* Fix parser recovery.
* Fix parser recovery.
* Update test.
* Fix test.
* Disable IR gen for language server.
* Allow commit characters in auto completion.
* Fix lookup for invoke exprs.
* More parser robustness fixes.
* update solution file
Co-authored-by: Yong He <yhe@nvidia.com>
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* #include an absolute path didn't work - because paths were taken to always be relative.
* Use TerminatedUnownedStringSlice for literals in output C++.
* Remove Escape/Unescape functions used in slang-token-reader.cpp
Add target type of 'host-cpp' etc to map to the target types.
* Fix some corner cases around string encoding.
* Added unit test for string escaping.
Fixed some assorted escaping bugs.
* Updated test output.
* Added decode test.
* Stop using hex output, to get around 'greedy' aspect. Use octal instead.
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* Support `[DllImport]`
* Fix.
* Fix.
* Fix array type emit in cpp.
* Fix.
* Fix.
* Fix
Co-authored-by: Yong He <yhe@nvidia.com>
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Read/write resource types (what D3D/HLSL often refer to as UAVs) can be broadly categorized based on whether they require an underlying format (e.g., a `DXGI_FORMAT`) for reads, or not. D3D refers to the ones that require a format as "typed" UAVs (even though a `RWStructuredBuffer<MyData>` is clearly "typed" at the HLSL level). Vulkan refers to these cases as "storage images" and "storage texel buffers."
Under the D3D model, an application does not have to specify the exact format for a formatted/"typed" UAV in order for loads to work, but it *does* need to specify if an HLSL resource with a declared `float` or vector-of-`float` element type will be backed by data with a `*_UNORM` or `*_SNORM` format. This is where the `unorm` and `snorm` type modifiers come in.
Superficially, it might seem that adding this feature to the Slang compiler is "just" a matter of adding the two modifiers, which is easily done with a pair of one-line `syntax` declarations in `core.meta.slang` plus the corresponding AST node types.
Unfortunately the superficial view misses the detail that, to date, Slang has not had any support for *type modifiers* at all, and has only supported *declaration modifiers*. The distinction has so far not mattered, even with modifiers like `const` because, e.g., the difference between a "`const` array of `float`" and an "array of `const float`" doesn't really matter.
So, adding these two modifiers required introducing a lot of infrastructure along the way. Let's walk through what needed to happen:
* As described above, the actual `syntax` was added easily in the Slang stdlib
* I added a new subclass of `Modifier` for `TypeModifier`s in the AST, and added the AST nodes for `unorm` and `snorm` as subclasses of that.
* In order to syntactically support modifiers applied to types (e.g., `unorm float`), I needed to add a `ModifiedTypeExpr` subclass of `Expr` that represents a base type expression with one or more modifiers applied
* The parser needed some subtle new logic. There are two main cases where type modifiers will come up:
1. In contexts where we might be parsing a declaration (e.g., `const unorm float a`), we need to support a list of modifiers that might freely mix type modifiers and "declaration modifiers" which are not intended to apply to types. In this case we need to split the lis tof modifiers into the type-related ones and the declaration-related ones, and attach each subset to the appropriate place. This is very important for features like C-style pointers, where in `static const float* a;`, the `static` modifier applies to the entire declaration of `a`, but the `const` modifier *only* applies to the `float` type specifier, and *not* to the outer pointer type (the actual type of `a`).
2. In contexts where we are not parsing a declaration (e.g., a generic type argument), we need to support a list of modifiers and appy them *all* to the type specifier being parsed, even if some of them might not be appropriate.
* While working in the parser I implemented a certain amount of unrelated cleanup for code that was using raw `Modifier*`s to represent lists of modifiers, instead of the purpose-built `Modifiers` type.
* The `_parseGenericArg` case needed specific work, because it is an important case in the grammar where we need to parse *either* a type expression or a value exprssion, but cannot easily predict which we will see. The fix implemented for now is to always try to parse modifiers and, if we see any, to assume we are in the type case. Because of the rules for how modifiers in a C-like language inhere to the type specifier (and not necessarily the entire type), we need to refactor some of the type expression parsing routines to support parsing a "suffix" of a type expression.
* Note: I decided to be conservative and only make these changes in `_parseGenericArg` because that is place that is *needed* in order for user code with `unorm`/`snorm` to work, but in practice a user could still confuse our parser by using type modifiers as part of a cast (e.g., `x = (unorm float)y;`). While there is currently no reason why a user should want to do this, it *does* suggest that we need to be prepared to see type modifiers in other ambiguous "expression or type?" contexts. We have so far preferred to avoid looking up built-in syntax declarations like modifiers in expression contexts, because we want to allow users to create variable names that might conflict with some of the more surprising modifier keywords in HLSL (e.g., both `triangle` and `sample` are modifier keyword). A nuanced strategy may be required when we get around to closing this gap (which will be needed around when we want full pointer support, since a cast like `(const SomeType*)somePtr` is pretty common).
* In semantic checking, we now need a `visitModifiedTypeExpr`, which visits the base expression to produce a `Type` and then checks each of the `Modifier`s attached to it. During this process we need to translate the AST-level `Modifier`s into something that can exist properly in the universe of `Type`s. We introduce a `ModifiedType` subclass of `Type`, distinct from the `ModifiedTypeExpr` subclass of `Expr`. Furthermore, we introduce a `ModifierVal` subclass of `Val`, distinct from `Modifier`/`TypeModifier`.
* One unfortunate thing here is that it means we have both, e.g., `UNormModifier` to represent the parsed syntax, and `UNormModifierVal` to represent the `Type`/`Val`-level representation of the same concept. It is quite likely that we are near the point where we can/should consider having two distinct AST representations: one for freshly-parsed ASTs and one for semantically-checked ASTs. The `Type`/`Val` hierarchy clearly belongs to the latter.
* No actual semantic checking is currently being applied to the `unorm` and `snorm` modifiers, although we should in principle check that they are only being applied to `float` and vector-of-`float` types.
* In an attempt to simplify some of the creation logic and build a tiny bit of reusable infrastructure, I went ahead and added the skeleton of a dedupe-caching system in `ASTBuilder` so that we can easily ensure only a single `UNormModifierVal` and a single `SNormModifierVal` ever get created inside the scope of a single builder.
* TODO: Thinking about this, I'm now worried the deduplication does not mean I can make the simplifications I currently do in semantic checking by assuming that any two `UNormModifierVal`s will be pointer-identical. This is because we do not currently (IIRC) have the required "bottleneck" in the compiler where all ASTs get serialized after initial checking, and then deserialized when `import`ed into a downstream module, so that every AST node during a checking step comes from a single `ASTBuilder`. Hmm...
* If we can rely on deduplication to do its thing, then the `Val` and `Type` implementations of modifiers can be relatively simple.
* TODO: One issue here is that the equality comparison for `ModifiedType` currently checks for the same base type and the same modifiers in the same order. This works for now when we only have a small number of type modifiers and any given type will hae at most one, but in the longer run it relies on us to implement some kind of canonicalization scheme, which would both ensure that between `Modified(T, {A, B})` and `Modified(T, {B, A})` only one is allowed (that is, a canonical ordering on modifiers), and that we do not allow `Modified(Modified(T, {A}), {B})`.
* TODO: One other issues is that the `ModifiedType` case does not currently interact correctly with the `as()`-based casting for types (whereas that operation *does* interact in a semantically-correct fashion with `typedef`s). Fixing this issue in a robust way really depends on us re-architecting the `Type` system so that *any* `Type` can have modifiers attached, with modifiers affecting type identity/deduplication.
* The key place where `ModifiedType` creates a complication in semantic checking is type conversion/coercion. A user is likely to declare a `RWTexture2D<unorm float>`, fetch from it (producing a value of type `unorm float`) and then assign the result to a `float` variable, prompting for a conversion from `unorm float` to `float` (because they are distinct `Type`s).
* We handle this case in the core `_coerce()` operation by checking if either `toType` or `fromType` is a `ModifiedType`. If *either* one is a modified type, we apply logic to check for modifiers that are present on one and not the other. Basically we check which modifiers need to be "dropped" and which need to be "added" during conversion, and validate that these modifiers *can* be dropped/added without creating a semantic error. The only type modifiers we support right now *can* be dropped/added like this, so we are fine.
* TODO: When we add more complete pointer support, we could need logic here to validate when casts between, e.g., `const int*` and `int*` should/shouldn't be allowed.
* Note: Even opening the door to type modifiers at all creates the same kind of challenges for user-defined generic types (and functions!) since `MyType<int>` and `MyType<const int>` are distinct instantiations in a future where we support `const` as a type modifier. We *may* need to plan to restrict where modified types can be used, so that certain built-in generic types support modified types as arguments, but user-defined types don't (or at least might need to opt-in to get support).
* The result of a `_coerce()` that drops/adds modifiers is a `ModifierCastExpr`, which is a kind of no-op AST node that merely expresses that the conversion is allowed and valid.
* In IR lowering we currently do the simple thing and translate a `ModifiedType` to a distinct IR node called `AttributedType`.
* The change in terminology from "modifier" to "attribute" is to follow the way that these kinds of modifiers best map to the `IRAttr` case in the IR (rather than the `IRDecoration` case). We probably ought to do a careful terminology scrub here, because having this terminology mismatch between IR and AST could be a source of confusion.
* TODO: In principle, using `IRAttributedType` creates the same basic problems as using `ModifiedType`: code that is usin `as()` or similar operations to check for a specific subclass of `IRType` may not see the case they were looking for due to use of `IRAttributedType`.
* Initially I had hoped to avoid the problem by having the `IRAttr`s be attached directly as operands to an otherwise-ordinary `IRType`. E.g., a lowered `unorm float4` would be an `IRVectorType` with an "extra" operand that is an `IRUNormAttr`, something like: `Vector<Float, 4, UNorm>`. This sounds great (and looks great!), but runs into the problem that it is incompatible with the way we currently represent things like generic type parameters. A generic type parameter `T` is represented as an `IRParam`, and it does *not* make sense to have an additional `IRParam` to represent `const T` or `unorm T`, etc.
* The Right Way to solve this stuff at both the AST and IR levels is to avoid passing around bare `Type*` or `IRType*` in general, and instead use a value type that implements the needed policy more directly: something like a `TypeHolder` or `IRTypeHolder` (placeholder name). The `*Holder` type would abstract over the various "wrapper" nodes required to store all the additional data like attributes but, importantly, would *not* allow that extra information to be dropped or lost during operations like casting (e.g., note how the current `Type` implementation of `as()` loses information on `typedef` names, making our error messages slightly worse). This is actually quite similar to how we currently use the `DeclRef<T>` system to allow working with what is *usually* a `T*` under the hood, but in a way that ensures we don't lose track of any generic substitution information.
* During C-like code emit we have a process that turns an `IRType` into a chain of declarators as needed to emit a C-like declaration with pointers, arrays, etc. The `IRAttributedType` case needs to get folded into this logic. Basically, when we see an `IRAttributedType` we immediately emit any modifiers that are required to be in a prefix position, then recursively emit the underlying type with an extra layer of declarator that tracks the modifiers, so that we can emit any modifiers that should be placed in a postfix position *after* the type. As a specific example, our C/C++ back-end would want to use the postifx option to handle `const`, because then it can properly emit stuff like `int const * const *` and not the incorrect `const const int**`.
* The HLSL emit logic overrides the prefix case for handling type attributes, and uses it to emit `unorm` and `snorm` where they occur.
* One unfortunate detail is that (apparently) some downstream HLSL compilers do not allow the `unorm`/`snorm` modifiers to apply to `vector<float, *>` types, even though that should be semantically valid. Instead, they only support `float`, `float2`, `float3`, and `float4` explicitly. To work around this issue, we go ahead and change our HLSL emit logic so that when we encountered 1-to-4 component vectors of `float`, `int`, or `uint` we emit the type name using the typical HLSL shorthand. This is actually a signficicant change in our HLSL output, but it both seemed like a good fix to have anyway, and was also the only obvious way to address the downstream parser shortcomings without a massive kludge.
* As a result of this change the `half-texture.slang` test broke, since it was using raw HLSL as the expected output. I changed the test to do a DXIL comparison instead, which is our preferred way of testing cross-compilation behavior (since it is more robust in the face of small changes to our source output).
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If the user has a derived `struct` type:
```hlsl
struct Base { int b = 1; }
struct Derived : Base { int d = 2; }
```
Then it is still reasonable for them to want to use initializer lists when declaring variables using the `Derived` type:
```hlsl
Derived x = {};
Derived y = { 7, 8 };
```
This change implements two missing pieces of functionality in the Slang compiler to allow this case:
* First, when the front-end semantic checks are applied to an initializer list, if the type being initialized is a derived `struct` type it always expects to find initialization arguments for its base type before those for its fields.
* Second, when lowering an initializer-list expression from the AST to the IR, the compiler expects the first argument in the list to be the initial value for the base field (if any). This also applies to default-initialization of fields/variables.
This change slightly entangles front-end logic with the logic for how struct inheritance is lowered to the IR, but the behavior is unlikely to confuse users who expect C++-like layout.
It is worth noting that with this change it should be possible to initialize the base type using either a nested initializer list or flat arguments:
```hlsl
struct BigBase { int x; int y; int z; }
struct BigDerived : BigBase { int w; }
BigDerived a = { {1,2,3}, 4 };
BigDerived b = { 1, 2, 3, 4 };
```
This behavior should Just Work because of the existing C-like rules for initializer lists where an aggregate can be initialized by either a `{}`-enclosed block or distinct values for its leaf fields.
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* Another fix for overriding property decls
The central problem we keep running into with `property` decls in `interface`s comes down to two choices:
1. When a member lookup `obj.someName` or a simple lookup for `someName` produces an overloaded result, we make no attempt to resolve the overloading right away, and instead postpone disambiguation until the point where that expression gets *used*, in case the context where it gets used can help in disambiguation (a notable case being when there is a call expression `obj.someName(...)` or `someName(...)`).
2. When looking up members in a the scope of a type (either for `obj.someName` or `someName` in the context of a method), we include all results from base types in the set of overloads returned, even in cases where the type has a direct member that "overrides" the inherited one.
The combination of these factors means that when a `struct` type implements a `property` to satisfy a requirement of an inherited `interface`, then references to `obj.someProp` end up being ambiguous between the property in the concrete `struct` type and the property it inherits through the `interface`.
There is no quick fix possible for issue (2). It might seem that we could just skip over members inherited through `interface`s when doing lookup in a type, but that solution wouldn't apply to inheritance from another `struct` type, or any future scenario where we support default implementations of methods in interfaces. The simple idea of saying that a derived-type member named `M` hides all inherited members named `M` is possible, but would lead to a bad user interface when a type wants to support both a core "bottleneck" method and a bunch of convenience overloads with the same name.
That leaves us with issue (1), and trying to find a reasonable fix for it. The common case is that any expression `e` eventually gets used in a context where it will be be subject to disambiguation:
* If we form a call expression `e(...)`, then the overload resolution logic will (obviously) work to disambiguate which `e` was meant.
* If `e` is used as an argument to another call (`f(... e ...)` or `... + e`), then `e` will be coerced to the expected parameter type for its argument position, and that coercion will disambiguate it (this is the bit that was fixed in #1501)
* If `e` is used in another context where a type is expected/known, it will also be coerced: `if(e)`, `int v = e`, etc.
The problem case that is left behind is any scenario where `e` is not subject to one of the above resolution cases, which mostly amounts to cases where an expression is never coerced to a single fixed type. There are a few important cases where this occurs today:
* When the expression is used as the left-hand side of an assignement (`e = ...`).
* When an expression is used to initialize a variable with an implicit type (`let v = e`).
* When inferring generic arguments from the value arguments at a call site (`f(e)` where `f` is defined as `f<T>(T v)`)
The key connecting thread in each of these cases is that the front-end needs to determine the type of `e` to make progress.
Our semantic checking logic already has functions that try to draw a distinction between the two cases:
* The `CheckTerm()` operation is supposed to be used when we expect that we will eventually coerce or otherwise diambiguate the term, and also in cases where we don't yet know if a term should name a type or a value
* The `CheckExpr()` operation is supposed to be used when we do not expect that we will apply coercion/disambiguation to a term, and need to have assurances that it has been coerced into a non-overloaded expression with a reasonable type
The simple part of the fix made here is to make `CheckExpr()` actually do part of what it is suppsoed to (attempt to disambiguate overloaded terms), and then audit all the call sites to `CheckExpr()` to make sure they are actually ones that intend to opt into that logic.
The messier part of the fix is dealing with generic argument inference, because we need to extract the type of the disambiguated expression for the purposes of inference, but we don't want to disturb the actual argument list at a call site (because type coercion of the arguments is supposed to handle the disambiguation). This part is done with a bit of special-casing in the overload-resolution context, by adding a method that gets the type or an argument after disambiguation (when possible).
* fixup
Co-authored-by: Yong He <yonghe@outlook.com>
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Our current lookup process always finds *all* members of a type, which can include both an inherited member (e.g., from an `interface`) and one that logically overrides/implements it. If something downstream doesn't filter this result down and favor the derived member, then an ambiguity error will result.
To date, this has mostly been a non-issue because we haven't emphasized inheritance, and the main case we did support (`struct` types implemented `interface` methods) gets disambiguated as part of overload resolution for function calls.
Recent changes to support `property` declarations to `interface`s add the possibility for ambiguity between a "base" and "derived" declaration that can't rely on overload resolution for disambiguation.
The approach in this PR is to add disambiguation logic to the other main place where the results of lookup get used. If a lookup result is being assigned to a variable, passed to a function, or otherwise used in a case where a value of a specific type is needed, it will be "coerced" to the desired type. This change makes it so that the first step in the coercion logic is to try to disambiguate the expression that is being coerced.
In order to ensure that an overloaded expression can be detected and resolved even when just checking if coercion is possible, I needed to update the `canCoerce*()` functions to also take the expression that is being tested for coercibility, and not just its type. There is only one case (that I saw) where coercion checks were being made without an expression value available, and that case didn't actually need/want to handle overloading.
In order to test the fixes here, I added logic to the `property`-in-`interface` test to make sure that the critical cases work as expected (references to a derived member using "dot syntax" and "implicit `this`" syntax).
Alternatives Considered
-----------------------
The first attempt at this fix took a simpler approach: I added the disambiguation logic as a post-process on member lookup. That is, given `obj.foo` I would take the `LookupResult` for `foo` and immediately try to filter it to include only the most-derived members. This approach has the major benefit of catching even more use cases of values (and thus helping to ensure that we don't spend forever chasing down more of these ambiguity errors), but it also has two critical problems:
1. If we only trigger disambiguation when looking up `obj.foo`, then we can't do anything to help when `foo` is looked up as an ordinary identifier, but is actually equivalent to `this.foo`. A full fix would require doing this disambiguation on *every* name lookup, which leads to the second issue:
2. It is important that for a method call like `obj.m(...)` we do *not* disambiguate when looking up `obj.m`, and instead let the overload resolution for the call resolve things. That choice is what makes it possible to call an inherited `m` declaration even when there is a derived `m` with a different signature.
Issue (1) is covered by the test case that was added here, but we should probably have a test case for (2) to make sure we don't break that use case.
Caveats
-------
An important case that we don't solve in this PR is when the result of a lookup is captured in a variable without an explicit type:
let f = obj.foo;
That case also needs disambiguation, and should be addressed in a later change.
A secondary issue is that our approach to prioritizing declarations during lookup is still quite naive. We really need a way for lookup to attach information about nesting of scopes to results (to be clear that results from inner scopes should be preferred over those from outer scopes), as well as have a robust mechanism for comparing the priority of members based on the inheritance graph of a type. This change doesn't do anything to make the situation better or worse.
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* Add a ASTBuilder to a Module
Only construct on valid ASTBuilder (was being called on nullptr on occassion)
* Add nodes to ASTBuilder.
* Compiles with RefPtr removed from AST node types.
* Initialize all AST node pointer variables in headers to nullptr;
* Initialize AST node variables as nullptr.
Make ASTBuilder keep a ref on node types.
Make SyntaxParseCallback returns a NodeBase
* Don't release canonicalType on dtor (managed by ASTBuilder).
* Give ASTBuilders a name and id, to help in debugging.
For now destroy the session TypeCache, to stop it holding things released when the compile request destroys ASTBuilders.
* Moved the TypeCheckingCache over to Linkage from Session.
* NodeBase no longer derived from RefObject.
* Only add/dtor nodes that need destruction.
First pass compile on linux.
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* First steps toward inheritance for struct types
This change adds the ability for a `struct` type to declare a base type that is another `struct`:
```hlsl
struct Base
{
int baseMember;
}
struct Derived : Base
{
int derivedMember;
}
```
The semantics of the feature are that code like the above desugars into code like:
```hlsl
struct Base
{
int baseMember;
}
struct Derived
{
Base _base;
int derivedMember;
}
```
At points where a member from the base type is being projected out, or the value is being implicitly cast to the base type, the compiler transforms the code to reference the implicitly-generated `_base` member. That means code like this:
```hlsl
void f(Base b);
...
Derived d = ...;
int x = d.baseMember;
f(d);
```
gets transformed into a form like this:
```hlsl
void f(Base b);
...
Derived d = ...;
int x = d._base.baseMember;
f(d._base);
```
Note that as a result of this choice, the behavior when passing a `Derived` value to a function that expects a `Base` (including to inherited member functions) is that of "object shearing" from the C++ world: the called function can only "see" the `Base` part of the argument, and any operations performed on it will behave as if the value was indeed a `Base`. There is no polymorphism going on because Slang doesn't currently have `virtual` methods.
In an attempt to work toward inheritance being a robust feature, this change adds a bunch of more detailed logic for checking the bases of various declarations:
* An `interface` declaration is only allowed to inherit from other `interface`s
* An `extension` declaration can only introduce inheritance from `interface`s
* A `struct` declaration can only inherit from at most one other `struct`, and that `struct` must be the first entry in the list of bases
This change also adds a mechanism to control whether a `struct` or `interface` in one module can inherit from a `struct` or `interface` declared in another module:
* If the base declaration is marked `[open]`, then the inheritance is allowed
* If the base declaration is marked `[sealed]`, then the inheritance is allowed
* If it is not marked otherwise, a `struct` is implicitly `[sealed]`
* If it is not marked otherwise, an `interface` is implicitly `[open]`
These seem like reasonable defaults. In order to safeguard the standard library a bit, the interfaces for builtin types have been marked `[sealed]` to make sure that a user cannot declare a `struct` and then mark it as a `BuiltinFloatingPointType`. This step should bring us a bit closer to being able to document and expose these interfaces for built-in types so that users can write code that is generic over them.
There are some big caveats with this work, such that it really only represents a stepping-stone toward a usable inheritance feature. The most important caveats are:
* If a `Derived` type tries to conform to an interface, such that one or more interface requirements are satisfied with members inherited from the `Base` type, that is likely to cause a crash or incorrect code generation.
* If a `Derived` type tries to inherit from a `Base` type that conforms to one or more interfaces, the witness table generated for the conformance of `Derived` to that interface is likely to lead to a crash or incorrect code generation.
It is clear that solving both of those issues will be necessary before we can really promote `struct` inheritance as a feature for users to try out.
* fixup: trying to appease clang error
* fixups: review feedback
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* Small improvements to documentation and code around DiagnosticSink
* Made methods/functions in slang-syntax.h be lowerCamel
Removed some commented out source (was placed elsewhere in code)
* Making AST related methods and function lowerCamel.
Made IsLeftValue -> isLeftValue.
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* Compiles.
* Small tidy up around session/ASTBuilder.
* Tests are now passing.
* Fix Visual Studio project.
* Fix using new X to use builder when protectedness of Ctor is not enough.
Substitute->substitute
* Add some missing ast nodes created outside of ASTBuilder.
* Compile time check that ASTBuilder is making an AST type.
* Moced findClasInfo and findSyntaxClass (essentially the same thing) to SharedASTBuilder from Session.
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* Fields from upper to lower case in slang-ast-decl.h
* Lower camel field names in slang-ast-stmt.h
* Fix fields in slang-ast-expr.h
* slang-ast-type.h make fields lowerCamel.
* slang-ast-base.h members functions lowerCamel.
* Method names in slang-ast-type.h to lowerCamel.
* GetCanonicalType -> getCanonicalType
* Substitute -> substitute
* Equals -> equals
ToString -> toString
* ParentDecl -> parentDecl
Members -> members
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* * Added MemberFilterStyle - controls action of FilteredMemberList and FilteredMemberRefList
* Splt out template implementations
* Use more standard method names dofr FilteredMemberRefList
* Added reflect-static.slang test
* Added isNotEmpty/isEmpty to filtered lists
* Added ability to index into filtered list (so not require building of array)
* Default MemberFilterStyle to All.
* Remove explicit MemberFilterStyle::All
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