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* Immutable access qualifier for pointers and use `__ldg` on cuda. (#8710)Yong He2025-10-16
| | | | | | | | | | | | | | | | | | | | | | | | This PR implements `Access.Immutable` to allow pointers to immutable data. The new type `ImmutablePtr<T>` is defined as an alias of `Ptr<T, Address.Immutable>`. By forming a immutable pointer, the programmer is conveying to the compiler that the data at the pointer address will never change during the execution of the current program. Therefore loads from immutable pointers can be deduplicated by the compiler, and will translate to `__ldg` when generating code for CUDA. The SPIRV backend is not changed in this PR, since the current SPIRV spec makes it very difficult to specify loads from immutable address without generating tons of wrappers and boilerplate type declarations. We would like to see the spec evolved a bit to around its support of `NonWritable` physical storage pointers or immutable loads before we attempt to express such immutability in SPIRV. For now we simply emit ordinary pointers and loads when generating spirv. --------- Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
* Clean up Slang IR representation of undefined values (#8708)Theresa Foley2025-10-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Prior to this change, the Slang IR used a single opcode (`kIROp_Undefined`) to encode all cases of undefined values. The particular motivation for this change was a need to distinguish those undefined values that represent a load from an uninitialized memory location versus other sorts of undefined values. If transforming a variable into SSA form results in `undefined` values in cases where the a `load` was executed without a prior `store`, that represents an error on the programmer's part, and should be diagnosed. However, other cases of undefined values can arise during program transformation and optimization, and should not typically result in diagnostics being emitted. While it was not the original motivation for this change, it is also worth noting that the LLVM project has transitioned from initially using only a single `undef` instruction to having a more nuanced model, and the same factors that motivated their shift also apply to the Slang IR. Counter-intuitively, the semantics of undefined values actually need to be carefully defined. Concretely, this change splits the pre-existing `undefined` opcode into two sub-cases: - `kIROp_LoadFromUninitializedMemory`, to represent the case of loading from a memory location (such as a local variable) that has not been initialized. - `kIROp_Poison`, corresponding to the LLVM `poison` value. Our poison instruction is intended to have semantics comparable to LLVM's equivalent. Conceptually, any operation that is invoked with a poison value as input will (with a few exceptions) produce a poison value as output. One can think of the behavior of `poison` as similar to how not-a-number values propagate in floating-point computations: by default they "infect" the result of any computation they are involved in. This semantic choice helps to ensure that many optimizations end up being correct in the presence of undefined values, even if they did not specifically account for them. The `kIROp_LoadFromUninitializedMemory` case is comparable to the combination of `freeze` and `undef` in LLVM. An LLVM `undef` value has semantics that allow *each* use of that value to be replaced with a *different* arbitrary value; these semantics cause many optimizations to only be correct in the absence of undefined values. An LLVM `freeze` instruction can take an undefined value as input, and produces a single value that is still arbitrary, but must be consistent across all uses. The latter semantics are what we want, since a given `load` from an uninitialized memory location will yield an arbitrary-but-fixed value. Note that we intentionally do not have a direct analogue to LLVM's `undef` instruction, because of the way that `undef` causes so many complications when trying to write optimizations. We also do not add a `kIROp_Freeze` instruction in this change, but that is simply because we currently have no need for it. Existing code that was creating `IRUndefined` values has been updated to create either `IRPoison` or `IRLoadFromUninitializedMemory` values, as appropriate to the use case. Code that was checking for the `kIROp_Undefined` opcode has been updated to either check for both of the new opcodes (in the case of `switch` statements), or to use `as<IRUndefined>` to perform a dynamic cast to the common base type of the two new instructions. Note that this change does not alter the way that instructions representing undefined values are typically emitted as ordinary instructions in the block that produces an undefined value. While emitting `IRLoadFromUninitializedMemory` as an ordinary instruction is exactly what we want, the `IRPoison` case would actually be better represented in Slang IR as a "hoistable" instruction, so that there would only be a singular `poison` value of each type. Changing `IRPoison` to be hoistable would be a good follow-up change, but might run into more challenges depending on what assumptions (if any) the codebase is making about where undefined values get emitted. --------- Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
* Addition of `Load`/`Store` coherent operations (#8395)16-Bit-Dog2025-10-10
| | | | | | | | | | | | | | | | | | | | | | | | Fixes: https://github.com/shader-slang/slang/issues/7634 Duplicate of PR https://github.com/shader-slang/slang/pull/8052 Primary Changes: * Added `storeCoherent` and `loadCoherent` for coherent load/store via pointers. This is backed by `IRMemoryScopeAttr` which is an `IRAttr` attached to `IRLoad` and `IRStore` * Logic in `source\slang\slang-emit-spirv.cpp` for load/store emitting has been reworked to be less messy and more maintainable * Add to `hlsl.meta.slang` coop vector and coop matrix coherent load/store operations Secondary Changes: * Added a missing load/store test for coop matrix: `tests\cooperative-matrix\load-store-pointer.slang` --------- Co-authored-by: ArielG-NV <aglasroth@nvidia.com> Co-authored-by: ArielG-NV <159081215+ArielG-NV@users.noreply.github.com> Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com> Co-authored-by: Nathan V. Morrical <natemorrical@gmail.com>
* Update debug var when in-param proxy var is being updated. (#8671)Yong He2025-10-10
| | | | | | | | | | | | | | | | | | | | | | | Closes #8664. The problem is that when there is an `in` parameter, Slang will create a local variable to proxy the parameter, copy the value of the parameter into the proxy variable, and replace all uses of the parameter in the function body to use the proxy variable instead. This way all writes to the parameter become writes to the proxy variable. However, when there is debug info enabled, we are also going to create a "debugVariable" corresponding to the parameter, but this debugVariable isn't updated when the proxy variable is updated. The fix is to map the proxy var instead of the original param to the debug var during the `insertDebugValueStore` pass, so that any changes to the proxy var will result in additional stores being inserted to the debug var. Allowing function body to modify an `in` parameter is a bad legacy behavior we inherited from HLSL that we should really be moving away from. I would like us to completely treat an `in` parameter as immutable by default in the next language version (Slang 2026), and make it an error if the user tries to do so. This will allow us to generate much cleaner code and in many cases would help with performance.
* Use symbol alias instead of wrapper synthesis to implement link-time types. ↵Yong He2025-10-07
| | | | | | | | | | | | | | | | | | | | | | | | | | (#8603) This change achieves link-time type resolution with a different mechanism. For `extern struct Foo : IFoo = FooImpl;`, instead of synthesizing a wrapper type `Foo` that has a `FooImpl inner` field and dispatches all interface method calls to `inner.method()`, this PR completely removes this synthesis step, and instead just lower such `extern`/`export` types as `IRSymbolAlias` instructions that is just a reference to the type being wrapped. Then we extend the linker logic to clone the referenced symbol instead of the SymbolAlias insts itself during linking. By doing so, we greatly simply the logic need to support link-time types, and achieves higher robustness by not having to deal with many AST synthesis scenarios. Closes #8554. --------- Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
* Fix legalization crash when processing metal parameter blocks. (#8591)Yong He2025-10-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Closes #7606. When Slang compile for a bindful target, we will run the resource type legalization pass to hoist resource typed struct fields outside of the struct type and define them as global parameters and passing them around via dedicated function parameters. When we compile for a bindless target, we don't run this pass. However, Metal is a hybrid bindful and bindless target. We need to run type legalization for the constant buffer, but skip type legalization for parameter block. The previous attempt to support this behavior is to hack the type legalization pass to return `LegalVal::simple` when it sees a `ParameterBlock<T>`. However, whenever the code is accessing `parameterBlock.someNestedField`, the type of the nested field may get a `LegalType::tuple`, and now we will run into inconsistent scenarios where we have a `LegalVal::simple` on the operand val, and but the legalization logic is expecting that val to be a `LegalType::tuple`. This breaks a lot of assumptions and invariants in the type legalization pass, resulting unstable/fragile behavior. To systematically solve this problem, this change generalizes the existing legalize buffer element type pass to translate `ParameterBlock<Texture2D>` (and similar cases) to `ParameterBlock<Texture2D.Handle>`. So that such parameter block will always be legalized to `LegalType:::simple` during type legalization, and we will never run into any inconsistent cases. This allowed us to get rid of the hacky logic in the type legalization pass to try to workaround the inconsistencies.
* Rename some symbols related to pointers types (#8592)Theresa Foley2025-10-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Note that while this change touched a large numer of files, there are no changes to functionality being made here. The only things being done are renaming various symbols and, in a few cases, updating or adding comments for consistency with the new names. The core of the naming changes are: * Most things named to refer to `OutType` (e.g., `IROutType`, `IRBuilder::getOutType()`, etc.) have been consistently renamed to refer to `OutParamType`, to emphasize that the relevant AST/IR node types are only intended for use to represent `out` parameters. * The same change as described above for `OutType` is also made for `RefType`, which becomes `RefParamType` in most cases. One mess that this exposes is the way that the `ExplicitRef<T>` type in the core module currently lowers to `IRRefParamType`. This change sticks to the rule of not making functional changes, so that mess is left as-is for now. * Names referring to `InOutType` have been changed to instead refer to `BorrowInOutType`. The intention with this naming change is to emphasize that the Slang rules for `inout` are semantically those of a borrow (or at least our interpretation of what a borrow means). * Names referring to `ConstRefType` have been changed to instead refer to `BorrowInType`. This change starts work on clarifying that the existing `__constref` modifier was never intended to be a read-only analogue of `__ref`, and instead is the input-only analogue of `inout`. * The `ParameterDirection` enum type has been changed to `ParamPassingMode`, to reflect the fact that the concept of "direction" fails to capture what is actually being encoded, particularly once we have modes beyond simple `in`/`out`/`inout`. While this change does not alter behavior in any case (the user-exposed Slang language is unchanged), it is intended to set up subsequence changes that will work to make the handling of these types in the compiler more nuanced and correct. Breaking this part of the change out separately is primarily motivated by a desire to minimize the effort for reviewers. --------- Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
* Rewriting the lower-buffer-element-type pass to avoid unnecessary ↵Yong He2025-09-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | packing/unpacking. (#8526) Part of the effort to improve the performance of generated SPIRV code. The existing lower-buffer-element-type pass works by loading the entire buffer element content from memory, and translate it to logical type stored in a local variable at the earliest reference of a buffer handle. This means that is can generate inefficient code that reads more than necessary. Consider this example: ``` struct BigStruct { bool values[1024]; } ConstantBuffer<BigStruct> cb; void test(BigStruct v) { if (v.values[0]) { printf("ok"); } } [numthreads(1,1,1)] void computeMain() { test(cb); } ``` In IR, the `computeMain` function before lower-buffer-element-type pass is something like following: ``` func test: %v = param : BigStruct %barr = fieldExtract(%v, "values") %element = elementExtract(%barr, 0) ... // uses %element func computeMain: %v = load(cb) call %test %v ``` The existing lower-buffer-element-type pass will rewrite the bool array in `BigStruct` into `int` array so it is legal in SPIRV. However, it does so by inserting the translation on the first `load` of the constant buffer: ``` struct BigStruct_std430 { int values[1024]; } var cb : ConstantBuffer<BigStruct_std430>; func computeMain: %tmpVar : var<BigStruct> call %unpackStorage(%tmpVar, cb) %v : BigStruct = load %tmpVar call %test %v ``` This means that the entire array will be loaded and translated to int, before calling `test`, which only uses one element. It turns out that the downstream compiler isn't always able to optimize out this inefficient translation/copy. This PR completely rewrites the way buffer-element-type lowering is handled to avoid producing this inefficient code. It works in two parts: first we turn on the `transformParamsToConstRef` pass for SPIRV target as well, so we will translate the `test` function to take the `v` parameter as `constref`. The second part is a redesigned buffer-element-type pass that defers the storage-type to logical-type translation until a value is actually used by a `load` instruction. In this example, after `transformParamsToConstRef`, the IR is: ``` func test: %v = param : ConstRef<BigStruct> %barr = fieldAddr(%v, "values") %elementPtr = elementAddr(%barr, 0) %element = load(%elementPtr) ... // uses %element func computeMain: call %test %cb ``` The new `buffer-element-type-lowering` pass will take this IR, and insert translation at latest possible time across the entire call graph, and translate the IR into: ``` func test: %v = param : ConstRef<BigStruct_std430> %barr = fieldAddr(%v, "values") %elementPtr : ptr<int> = elementAddr(%barr, 0) %element_int = load(%elementPtr) %element = cast(%element_int) : %bool ... // uses %element func computeMain: call %test %cb ``` In this new IR, there is no longer a load and conversion of the entire array. See new comment in `slang-ir-lower-buffer-element-type.cpp` for more details of how the pass works. This PR also address many other issues surfaced by turning on `transformParamsToConstRef` pass on SPIRV backend. --------- Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
* Add SPV_NV_bindless_texture support (#8534)Lujin Wang2025-09-26
| | | | | | | | | | | | | Treat DescriptorHandle as uint64_t instead of uint2. Implement target-specific SPIR-V emission with the bindless texture support. For OpImageTexelPointer, Image must have a type of OpTypePointer with Type OpTypeImage. Fix the issue by using [constref] in __subscript. Add a test coverage for various texture/sampler handle types. --------- Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
* Fix DebugCompilationUnit to reference main shader file instead of header ↵Lujin Wang2025-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | files (#7957) This PR implements the requested fix for issue #7923 where DebugCompilationUnit incorrectly referenced header files instead of the main shader file. ## Summary - Modified IRDebugSource to include isIncludedFile flag as third operand - Updated emitDebugSource function to accept and pass the included file flag - Updated call sites to use source->isIncludedFile() from SourceFile class - Modified SPIR-V emission to only create DebugCompilationUnit for non-included files ## Test Results The fix has been verified with the provided reproducer code. The SPIR-V output now correctly shows DebugCompilationUnit referencing the main shader file instead of header files. Generated with [Claude Code](https://claude.ai/code) --------- Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Lujin Wang <lujinwangnv@users.noreply.github.com> Co-authored-by: Claude Code <claude@anthropic.com> Co-authored-by: slangbot <ellieh+slangbot@nvidia.com> Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
* Introduce CDataLayout & -fvk-use-c-layout (#8136)Julius Ikkala2025-08-21
| | | | | | | | | | | | | | | | Closes #8112. ~~The issue asks for a "C layout", but in this PR I use the term "CPU layout" because this naming was pre-existing in the codebase as `kCPULayoutRulesImpl_`. The primary purpose of this layout is to match CPU-side struct definitions with the shader side. I'm open to better naming suggestions, though.~~ Edit: switched back to using `CDataLayout` & `-fvk-use-c-layout`, as the CPU target depends on the object layout rules of existing CPU layout rules, but they're incompatible with actual shaders. So a new `kCLayoutRulesImpl_` was needed anyway. --------- Co-authored-by: Ellie Hermaszewska <ellieh@nvidia.com>
* slang: Add support for generating getters for IR struct defs. (#7725)Sruthik P2025-07-17
| | | | | | | | | | | | This change expands the IR struct definition generation logic in slang-ir.h.lua to code generate the getters for the operands of an IR. To facilitate the above, the schema for the IR definitions in slang-ir-insts.lua is updated to allow for explicit specification of the operands of an IR, with Fiddle code generating the getters for them. slang-ir.h is updated to remove the hardcoded getters of the IRs since they are now generated by Fiddle. Fixes part of #7185
* Perf improvements to IR serialization (#7751)Ellie Hermaszewska2025-07-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * option to use riff as serialization backend * option to use riff as serialization backend * perf * shuffle code * perf improvements to deserialization * formatting * remove bit_cast * correct IR verification * neaten serialized format * fix peek module info * formatting * remove temporary profiling code * cleanup * fix wasm build * more explicit sizes * deserialize via fossil on 32 bit wasm * Make serialized modules Int size agnostic * reorder stable names to allow range based check for 64 bit constants * format * review comments * fix build * fix * c++17 compat slang-common.h
* Document IR changes (#7781)Ellie Hermaszewska2025-07-17
| | | | | * Document IR changes * Remove duplication
* Stable names and backwards compat for serialized IR modules (#7644)Ellie Hermaszewska2025-07-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | * stable names * tests, options and ci for stable names * Add back compat design document * fix warnings * formatting * comment * neaten * regenerate command line reference * consolidate ci scripts * faster ci * remove libreadline * Move new function to end of interface --------- Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
* extend fiddle to allow custom lua splices in more places (#7559)Ellie Hermaszewska2025-07-01
* Add fkYAML submodule * Generate slang-ir-inst-defs.h from slang-ir-inst-defs.yaml * generate ir-inst-defs.h * neaten things * neaten inst def parser * add rapidyaml submodule * remove fkyaml * remove fkyaml submodule * remove use of ir-inst-defs.h * format and warnings * fix wasm build * tidy * remove rapidyaml * Extend fiddle to allow custom splices in more places * Use lua to describe ir insts * fix * neaten * neaten * neaten * spelling * neaten * comment comment out assert * merge