| Age | Commit message (Collapse) | Author |
|---|
|
More work on IR
|
|
- The changes introduced a new path where we don't even go through the current "lowering" (really an AST-to-AST legalization pass), but this exposed a few issues I didn't anticipate:
- First, we needed to make sure to pass in the computed layout information when emitting the original program (since the layout info is no longer automatically attached to AST nodes)
- Second, we needed to take the sample-rate input checks that were being done in lowering before, and move them to the emit logic (which is really ugly, but I don't see a way around it for GLSL).
|
|
With this change, basic generation of IR works for a trivial shader, and there is some basic support for dumping the generated IR in an assembly-like format.
As with the other IR change, the use of the IR is statically disabled for now, so that existing users won't be affected.
|
|
Add user-defined builtins to the "core" module
|
|
Starting to add intermediate representation (IR)
|
|
The Slang API allows an expert user to feed in source code that the compiler then treats as if it came from the Slang "standard library."
They can use this to introduce new builtin types, functions, etc. - so long as they are careful, and are willing to deal with the lack of any compatibility guarantees across versions.
At some point I split the Slang standard library into distinct modules, so that GLSL and HLSL builtins wouldn't pollute each other's namespace.
In that change, I had to decide what module any new user-defined builtins should get added to, and I apparently decided they should go into the module for the Slang language, which would only affect `.slang` files.
This doesn't work at all if the user wants to declare new HLSL builtins.
I've gone ahead and made user extensions add to the "core" module (which is used by all of HLSL, GLSL, and Slang), but a better long-term fix would be to let the user pick the module/language the new builtins should apply to.
|
|
Right now none of this is hooked up, but I want to get things checked in incrementally rather than have along long-lived branches.
- Added placeholder declarations for IR representation of instructions, basic blocks, etc.
- Start adding a `lower-to-ir` pass to translate from AST representation to IR
Again: none of this is functional, so it shouldn't mess with existing users of the compiler.
|
|
Improve diagnostics for overlapping/conflicting bindings
|
|
|
|
Closes #38
- Change overlapping bindings case from error to warning (it is *technically* allowed in HLSL/GLSL)
- Make diagnostic messages for these cases include a note to point at the "other" declaration in each case, so that user can more easily isolate the problem
- Unrelated fix: make sure `slangc` sets up its diagnostic callback *before* parsing command-line options so that error messages output during options parsing will be visible
- Unrelated fix: make sure that formatting for diagnostic messages doesn't print diagnostic ID for notes (all have IDs < 0).
- Note: eventually I'd like to not print diagnostic IDs at all (I think they are cluttering up our output), but doing that requires touching all the test cases...
|
|
Handle possibility of bad types in varying input/output signature.
|
|
Fixes #160
If the front-end runs into a type it doesn't understand in the parameter list of an entry point, it will create an `ErrorType` for that parameter, but then the parameter binding/layout rules will fail to create a `TypeLayout` for the prameter (and return `NULL`).
There were some places where the code was expecting that operation to succeed unconditionally, and so would crash when there was a bad type.
The specific case in the bug report was when the return type of a shader entry point was bad:
// `vec4` is not an HLSL type
vec4 main(...) { ... }
Note that the specific case in the buf report only manifests in "rewriter" mode (when the Slang compiler isn't allowed to issue error messages from the front-end), but the same basic thing would happen if the varying parameter/output had used a type that is invalid for varying input/output:
Texture2D main(...) { ... }
I'm not 100% happy with just adding more `NULL` checks for this, because there is no easy way to tell if they are exhaustive.
A better solution in the longer term might be to construct a kind of `ErrorTypeLayout` to represent cases where we wanted a type layout, but none could be constructed.
|
|
Name type
|
|
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.
|
|
Data-driven parsing of modifiers
|
|
Just like the previous change did for declaration keywords, this change uses the lexical environment to drive the lookup and dispatch of modifier parsing.
This allows us to easily add modifiers to Slang, even when they might conflict with identifiers used in user code (because the modifier names are no longer special keywords, but ordinary identifiers).
There was already some support for ideas like this with `__modifier` declarations (`ModifierDecl`) used to introduce some GLSL-specific keywords (so that they wouldn't pollute the namespace of HLSL files).
The new approach changes these to be actual `syntax` declarations (`SyntaxDecl`) with the same representation as those used to introduce declaration keywords.
Because many modifiers just introduce a single keyword that maps to a simple AST node (no further tokens/data), I modified the handling of syntax declarations so that they can take a user-data parameter, and this allows the common case ("just create an AST node of this type...") to be handled with minimal complications.
This also adds in a general-purpose string-based lookup path for AST node classes, that should support programmatic creation in more cases.
Statements are now the main case of keywords that need to be made table driven.
|
|
Look up declaration keywords using ordinary scoping.
|
|
The existing parser code was doing string-based matching on the lookahead token to figure out how to parse a declaration, e.g.:
```
if(lookAhead == "struct") { /* do struct thing */ }
else if(lookAhead == "interface") { /* do interface thing * }
...
```
That approach has some annoying down-sides:
- It is slower than it needs to be
- It is annoying to deal with cases where the available declaration keywords might differ by language
- Most importantly, it is not possible for us to introduce "extended" keywords that the user can make use of, but which can be ignored by the user and treated as an ordinary identifier.
That last part is important. Suppose the user wanted to have a local variable named `import`, but we also had a Slang extension that added an `import` keyword. Then a line of code like `import += 1` would lead to a failure because we'd try to parse an import declaration, even when it is obvious that the user meant their local variable. This would mean that Slang can't parse existing user code that might clash with syntax extensions. This issue is the reason why we currently have keywords like `__import`.
A traditional solution in a compiler is to map keywords to distinct token codes as part of lexing, which eliminates the first conern (performance) because now we can dispatch with `switch`. It can also aleviate the second concern if we add/remove names from the string->code mapping based on language (the rest of the parsing logic doesn't have to know about keywords being added/removed).
The solution we go for here is more aggressive.
Instead of mapping keyword names to special token codes during lexing, we instead introduce logical "syntax declarations" into the AST, which are looked up using the ordinary scoping rules of the language.
Depending on what code is imported into the scope where parsing is going on, different keywords may then be visible.
This solves our last concern, since a user-defined variable that just happens to use the same name as a keyword is now allowed to shadow the imported declaration for syntax (this is akin to, e.g., Scheme where there really aren't any "keywords").
This also opens the door to the possibility of eventually allowing user to define their own syntax (again, like Scheme).
For now I'm only using this for the declaration keywords.
With this change it should be pretty easy to also add statement keywords in the same fashion.
|
|
Make source location lightweight
|
|
Fixes #24
So far the code has used a representation for source locations that is heavy-weight, but typical of research or hobby compilers: a `struct` type containing a line number and a (heap-allocated) string.
This is actually very convenient for debugging, but it means that any data structure that might contain a source location needs careful memory management (because of those strings) and has a tendency to bloat.
The new represnetation is that a source location is just a pointer-sized integer.
In the simplest mental model, you can think of this as just counting every byte of source text that is passed in, and using those to name locations.
Finding the path and line number that corresponds to a location involves a lookup step, but we can arrange to store all the files in an array sorted by their start locations, and do a binary search.
Finding line numbers inside a file is similarly fast (one you pay a one-time cost to build an array of starting offsets for lines).
More advanced compilers like clang actually go further and create a unique range of source locations to represent a file each time it gets included, so that they can track the include stack and reproduce it in diagnostic messages.
I'm not doing anything that clever here.
|
|
Major naming overhaul:
|
|
Fix use of "pseudo-syntax" in current lowering pass
|
|
- `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
|
|
The so-called "lowering" pass (really a kind of AST-to-AST legalization pass right now) needs to handle some basic scalarization of structured types, and it does this by inventing what I call "pseuo-expressions" and "pseudo-declarations."
For example, there is a pseudo-expression node type that represents a tuple of N other expressions, and certain operations act element-wise over such tuples.
The problem was that the implementation introduced these out-of-band expression/declaration types into the existing AST hierarchy which led to a dilemma:
- If these new AST nodes were declared like all the others (and integrated into the visitor dispatch approach, etc.) then every pass would need to deal with them even though they are meant to be a transient implementation detail of this one pass
- But if the new nodes *aren't* declared like the others, then they can't meaningfully interact with visitor dispatch, and will just crash the compiler if they somehow "leak" through to latter passes. And because they are just ordinary AST nodes from a C++ type-system perspective, such leaking is entirely possible (if not probable)
Hopefully that setup helps make the solution clear: instead of having the "lowering" pass map an expression to an expression, it needs to map an expression to a new data type (here called `LoweredExpr`) that can wrap *either* an ordinary expression (the common case) or one of the new out-of-band values. Any code that accepts a `LoweredExpr` needs to handle all the cases, or explicitly decide that it can't/won't deal with anything other than ordinary expressions.
Most of the code changes are straightforward at that point, although the whole "lowering" approach is a bit fiddly right now, so gertting the tests passing took a bit of attention. I'm not sure our test coverage of all this code is great, so I wouldn't be surprised if some failures are lurking still.
|
|
Remove uses of global variables
|
|
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.
|
|
Typo fix.
|
|
Update documentation.
|
|
- Update readme to fill out some of the `TODO` sections
- Add an API user's guide that gives the basics of linking against Slang and using it to compile and reflect shaders
- Add a bit of usage info for the command-line `slangc` program
- Add an overview of the Slang language as it stands today
- Add an initial FAQ, mostly to help answer the "why should I use this?" question
|
|
Add Code of Conduct
|
|
|
|
Add a `-o` option to command-line `slangc`
|
|
Fixes #11
- This adds a `-o` command-line option for specifying an output file.
- The code tries to be a bit smart, to glean an output format from a file extension, and also to associate multiple `-o` options with multiple `-entry` options if needed.
- There is a restriction that all the output files need to agree on the code generation target. This is reasonable for now, but might be something to lift eventualy
- There is a restriction that only one output file is allowed per entry point
- Together with the previous item this means you can't output both a `.spv` and a `.spv.asm` in one pass, even though both should be possible
- There is currently a restriction that output paths only apply to entry points
- This means there is no way to output reflection JSON to a file with `-o` (but that is mostly just a debugging feature for now)
- This also means we don't support any "container" formats that can encapsulate multiple compiled entry points
|
|
Fixup for the glslang bug workaround
|
|
There was a bug where the intialization expression for a variable was being lowered after the declaration was added to the output code, so that any sub-expressions that get hoisted out actually get computed *after* the original variable. This obviously led to downstream compilation failure.
I've updated the test case to stress this scenario.
|
|
Work around glslang issue 988
|
|
The basic bug there is that if you have a member of `struct` type in a `uniform` block and then pass a reference to that member directly to a call:
```
struct Foo { vec4 bar; };
uniform U { Foo foo; };
void main() { doSomething(foo); }
```
then glslang generates invalid SPIR-V which seems to cause an issue for some drivers.
This change works around the problem by detecting cases where an argument to a function call is a reference to `uniform` block member (of `struct` type) and then rewrites the code to move that value to a temporary before the call.
|
|
Make the "hack" sampler explicit for now
|
|
- We use this to work around the fact that, e.g., `Texture2D.Load` doesn't take a sampler, but the equivalent GLSL operation `texelFetch` requires one
- Previously we tried to hide the sampler from the user, hoping that glslang would drop it and we could just ignore it, but that doesn't work
- For now we'll go ahead and explicitly show the sampler in the reflection info so that an app can react appropriately
- We also generate a unique binding for the sampler, instead of the old behavior that fixed it with `binding = 0`
- We still fix it with `set = 0`, so it might still surprise users
|
|
Map HLSL `frac()` to GLSL `fract()`
|
|
|
|
Don't add `flat` qualifier to integer fragment output
|
|
Fixes #133
We already had logic to skip adding `flat` to a vertex input, and this just extends it to not adding `flat` to a fragment output.
Note that explicit qualifiers in the input HLSL/Slang will still be carried through to the output, so it is still possible for a Slang user to shoot themself in the foot with interpolation qualifiers.
|
|
Add an API option to control emission of `#line` directives
|
|
- API users can use this to get "clean" output to aid with debugging Slang issues
- Also changes the prefix on intermediate files that Slang dumps, to make them easier to ignore with a regexp
|
|
Require extension when using `gl_Layer` in VS
|
|
The requirements for using `gl_Layer` differ by stage, and so we need to pick an appropriate GL version based on the target stage, and then also require a specific extension for anything other than geometry or fragment.
|
|
Translate NV single-pass stereo extension from Slang to GLSL
|
|
- The easy part here is treating `NV_` prefixed semantics as another case of "system-value" semantics
- Mapping the new semantics (`NV_X_RIGHT` and `NV_VIEWPORT_MASK`) to their GLSL equivalents is harder
- Instead of a single "right-eye vertex" output, GLSL defines an array of per-view positions
- Instead of a vector of masks, GLSL defines an array of per-view masks
- Another point here is that a lot of semantics that appear as `uint` in HLSL are `int` in GLSL, which can lead to conversion issues.
- The approach here is to have the lowering pass introduce a notion of assignment with "fixups," which will try to cast things as needed
- When assigning to a simple value with the "wrong" type, introduce a cast
- When assigning to an array from a vector, break out multiple assignments of individual vector/array elements
- In order to facilitate the above, I needed to add actual types to the magic expressions I introduce to represent GLSL builtin variables. These were taken by scanning the online documentation for GL, so they might not be perfect.
- Major issues with the approach in this change:
- No attempt is being made here to check that the original declaration used a type appropriate to the semantic. The assumption is that this logic only ever triggers for Slang entry points, or GLSL entry points using a Slang `struct` type for input/output (and for right now Slang code is only ever written by "understanding" developers)
- In the case of a Slang entry point, we always copy varying parameters in/out around the call to `main_`, so this approach should handle calls to functions with `out` or `in out` parameters okay, but it is *not* robust to cases where we don't want to copy in all the entry point parameters first thing (e.g., a GS), so that will have to change
- In the GLSL case (or if we revise the approach to Slang entry points), there is going to be a problem if these converted varying parameters are ever passed as arguments to `out` or `in out` parameters. In these cases we need to do more sleight-of-hand to reify a temporary variable and do the necessary copy-in/copy-out. Being able to do that logic relies on having correct information about callees, which requires having robust semantic analysis of the function body. There is only so much we can do...
- A better long-term approach would not rely on an ad-hoc "fixup" conversion during assignment, but would instead implement the GLSL builtin variables as, effectively, global "property" declarations that have both `get` and `set` accessors, and then tunnel a reference to such a property down through lowering, where it can lower to uses of the "getter" or "setter" as appropriate in context (and the result type of the getter/setter can be what we'd want/expect).
|
