| Age | Commit message (Collapse) | Author |
|---|
|
Fixes #23
Up to this point, the compiler has used the ordinary `String` type to represent declaration names, which means a bunch of lookup structures throughout the compiler were string-to-whatever maps, which can reduce efficiency.
It also means that things like the `Token` type end up carying a `String` by value and paying for things like reference-counting.
This change adds a `Name` type that is used to represent names of variables, types, macros, etc.
Names are cached and unique'd globally for a session, and the string-to-name mapping gets done during lexing.
From that point on, most mapping is from pointers, which should make all the various table lookups faster.
More importantly (possibly), this brings us one step closer to being able to pool-allocate the AST nodes.
|
|
This is in preparation for using `Name` as a type name.
|
|
- `ExpressionSyntaxNode` becomes `Expr`
- `StatementSyntaxNode` becomes `Stmt`
- `StructSyntaxNode` becomes `StructDecl`
- `ProgramSyntaxNode` becomes `ModuleDecl`
- `ExpressionType` becomes `Type`
- Existing fields names `Type` become `type`
- There might be some collateral damage here if there were, e.g., `enum`s named `Type`, but I can live with that for now and fix those up as a I see them
|
|
There were two main places where global variables were used in the Slang implementation:
1. The "standard library" code was generated as a string at run-time, and stored in a global variable so that it could be amortized across compiles.
2. The representation of types uses some globals (well, class `static` members) to store common types (e.g., `void`) and to deal with memory lifetime for things like canonicalized types.
In each case the "simple" fix is to move the relevant state into the `Session` type that controlled their lifetime already (the `Session` destructor was already cleaning up these globals to avoid leaks).
For the standard library stuff this really was easy, but for the types it required threading through the `Session` a bit carefully.
One more case that I found: there was a function-`static` variable used to generate a unique ID for files output when dumping of intermediates is enabled (this is almost strictly a debugging option).
Rather than make this counter per-session (which would lead to different sessions on different threads clobbering the same few files), I went ahead and used an atomic in this case.
Note that the remaining case I had been worried about was any function-`static` counter that might be used in generating unique names.
It turns out that right now the parser doesn't use such a counter (even in cases where it probably should), and the lowering pass already uses a counter local to the pass (again, whether or not this is a good idea).
This change should be a major step toward allowing an application to use Slang in multiple threads, so long as each thread uses a distinct `SlangSession`. The case of using a single session across multiple threads is harder to support, and will require more careful implementation work.
|
|
The catch with these operations is that they return a vector based on the scalar of the element type of the texture.
That is, given `Texture2D<float> t` the operation `t.GatherRed(...)` should return a `float4`.
The ideal way to solve this would use associated types, but we aren't there yet, so I am using extension declarations.
An extension can "capture" the identity of the element type, like so:
__generic<T, let N : int> __extension Texture2D<vector<T,N> > { ... }
That extension will match `Texture2D<float3>` and correctly capture `T == float`, so that we can use it in other operations.
Getting this working required a bunch of changes:
- Actually emit the relevant extension declarations in the stdlib
- Fix the parser to be able to parse `Texture2D<vector<T,N> >` (that is, a nested generic app).
- I actually went ahead and significantly overhauled the expression parser while I was there, because I just couldn't deal with the existing code any longer.
- Added support for general-case lookup to look through `__extension` declarations. I had logic in place to special-case this for looking up "constructors" but hadn't done anything for general member lookup yet.
- This required some annoying holes to be punched through the layers, because lookup might need to invoke semantic analysis to ensure that an extension has been checked.
- There is some first-pass code trying to support looking up a `typedef` nested inside the `vector` type. This is a nice idea in principle, but the problem is that the `Texture2D<T>` definition would be looking up `T.Element` and not `float4.Element`, and that means we'd need machinery for doing lookup *through* interface conformances for a type parameter like `T`
The big gotcha here is that none of this logic applies to `Texture2D<float>` (the original case I mentioned) because I am matching vector types and not scalars.
Matching scalars *should* be as easy as:
__generic<T : __BuitlinScalarType> __extension Texture2D<T> { ... }
But I'd need to confirm that interface constraints like that actually work, or else that extension would *also* apply to `Texture2D<float4>` and break everything.
|
|
For context: a `DeclRef` is supposed to capture both a pointer to a particualr declaration, and also any information needed to specialize that declaration for a context (e.g., generic parameter substitutions).
The existing approach had a hiearchy of specialized decl-ref types that mirrored the AST hierarchy, but that led to a lot of boilerplate where you had to recapitulate the exact same hierarchy.
The new appraoch basically treats `DeclRef<T>` as a sort of "smart pointer" in that it wraps a pointer to a `T` (the declaration), plus a side field for the specialization info, and then allows it to be cast as needed to other types (where the pointer cast would be allowed), while carrying along the side info.
To enable this, all the things that used to be member functions of declaration-reference types are now free functions that take a `DeclRef<T>` for some specific `T` as a parameter.
|
|
This gets rid of one unecessary namespace.
|
|
|
