Making it easier to work with shaders https://git.yummers.dev/slang.git/atom?h=master 2025-09-30T00:45:08+00:00 2025-09-30T00:45:08+00:00 Yong He yonghe@outlook.com 2025-09-30T00:45:08+00:00 urn:sha1:a6deb5ed82cb8fc6b4f4c5c5fee264e09f97ff89 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> 2025-08-06T19:29:28+00:00 davli-nv davli@nvidia.com 2025-08-06T19:29:28+00:00 urn:sha1:5074c4948d73b451c74bd21ac139d69eaeb390f3 * Fix noperspective modifier for SV_Barycentrics in SPIRV and GLSL - Added test case with both regular and noperspective SV_Barycentrics inputs 🤖 Generated with [Claude Code](https://claude.ai/code) Co-authored-by: davli-nv <davli-nv@users.noreply.github.com> * fixup format * address review https://github.com/shader-slang/slang/pull/8067#pullrequestreview-3090037501 * address review https://github.com/shader-slang/slang/pull/8067#discussion_r2255818595 * add test case from review --------- Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: davli-nv <davli-nv@users.noreply.github.com> 2025-01-08T06:26:31+00:00 Yong He yonghe@outlook.com 2025-01-08T06:26:31+00:00 urn:sha1:c43f6fa55aca23365c86c6ec1737d42be74d9d3e * Add executable test on matrix-typed vertex input. * Fix emit logic of matrix layout qualifier. * Pass fragment shader varying input by constref to allow EvaluateAttributeAtCentroid etc. to be implemented correctly. 2024-06-12T20:38:23+00:00 ArielG-NV 159081215+ArielG-NV@users.noreply.github.com 2024-06-12T20:38:23+00:00 urn:sha1:8813c610562b1c30222ec3ef0734ef601d43b617 * capability upgrade warning/error adjusted implementation + tests to support a warning/error if capabilities are implicitly upgraded and test accordingly. * add glsl profile caps * add GLSL and HLSL capabilities to the associated capability * syntax error in capdef * only error if user explicitly enables capabilities 1. changed testing infrastructure to not set a `profile` explicitly, 2. Added tests to be sure this works as intended with user API and with slangc command line * Change capability atom definitions and how Slang manages them to fix errors 1. most `glsl_spirv` version atoms have been removed from `.capdef`, instead we will translate `spirv` version atoms into `glsl_spirv` since there is no point in writing the same code twice in `.capdef` files to define `spirv` versions. 2. add spirv version, and hlsl sm version (and equivlent) capability dependencies 3. removed some stage requirments which were set on objects, keep the wrapper capabilities. I am keeping the wrapper capabilities since I am unaware on if there are stage limitations (spec says code in practice does not work). * check internal version instead of version profile (_spirv_1_5 vs. spirv_1_5) * remove unused OpCapability. adjust SPIRV version'ing again for glsl_spirv * apply workaround for glslang bug with rayquery usage * ensure capabilities targetted by a profile and added together by a user are valid * remove additions to `spirv_1_*` wrapper * spirv_* -> glsl_spirv fix * fix bug where incompatable profiles would cause invalid target caps * try to avoid joining invalid capabilities * fix the warning/error & printing * run through tests to fix capability system and test mistakes many mistakes were mesh shaders doing `-profile glsl_450+spirv_1_4`. This is not allowed for a few reasons 1. the test tooling does not handle arguments the same as `slangc` 2. glsl_450 core profile does not support mesh shaders, nor does spirv_1_4. sm_6_5 does work in this senario * set some sm_4_1 intrinsics to sm_4_0 * replace `GLSL_` defs with `glsl_` * swap the unsupported render-test syntax for working syntax * set d3d11/d3d12 profile defaults this is required since sm version changes compiled code & behavior * adjusted nvapi capabilities with atomics + d3d11 set to use sm_5_0 as per default * cleanup * address review * incorrect styling * change `bitscanForward` to work as intended on 32 bit targets --------- Co-authored-by: Yong He <yonghe@outlook.com> 2023-09-20T10:30:27+00:00 Yong He yonghe@outlook.com 2023-09-20T10:30:27+00:00 urn:sha1:73292d9f3a1c790f72802dfe4cce57a1353dece6 * Direct SPIRV: Rasterization pipeline tests. * Fixup. * Fix. --------- Co-authored-by: Yong He <yhe@nvidia.com> 2021-03-03T19:45:39+00:00 Tim Foley tfoleyNV@users.noreply.github.com 2021-03-03T19:45:39+00:00 urn:sha1:13ff0bd345990c0fdfb7b52ebd5339cddb04889e This change allows varying fragment shader inputs to be declared in a way that allows the `GetAttributeAtVertex` operation to compile to valid code for both D3D and GLSL/SPIR-V/Vulkan. The key is that rather than just use ordinary `nointerpolation`-qualified inputs the code must declare these varying inputs with a new `pervertex` qualifier that marks them as *only* being usable with `GetAttributeAtVertex`. The `pervertex`-tagged inputs then translate to GLSL inputs using the `pervertexNV` qualifier Note that this change does *not* include any enforcement of the requirements around how these qualifiers are used (and the compiler doesn't have enforcement for the existing operations like `EvaluateAttributeAtCentroid`). The underlying problem is that the inerpolation-mode qualifiers and explicit interpolation functions in HLSL constitute a kind of rate-qualified type system, but without any systematic rules. It seems wasteful to encode a bunch of ad hoc rules for this stuff as special cases in the compiler when the clear right answer is to implement a systematic approach to rates. 2021-02-24T16:21:37+00:00 Tim Foley tfoleyNV@users.noreply.github.com 2021-02-24T16:21:37+00:00 urn:sha1:d66b30729029bdb43892e05c9c80fd56ac95a24f This operation was added along with the `SV_Barycentrics` system-value input, and allows for a `nointerpolation` varying input to a fragment shader to be fetched at a specific vertex index within the primitive that is causing the fragment shader to be invoked. This change adds support for the new operations in the standard library, and also includes a test case to make sure that we emit it correctly when producing HLSL/DXIL. This change also includes a small bug fix to our emission logic for function parameters so that we properly emit layout-related attributes for varying parameters declared directly on an entry point. (Note that most attribute end up being declared in `struct` types in existing HLSL shaders, and our IR passes produce only global variables for attributes on GLSL; the only case this affects is inidividual scalar/vector attributes declared declared as entry-point parameters, when outputting HLSL) Note that this change only adds support for the new function on the HLSL/DXIL path, and doesn't yet add any cross-compilation support for GLSL/SPIR-V. The reason for this is that the equivalent GLSL feature(s) appear to use a different model to the HLSL version, and we need to invent a suitable approach to align them to make portable code possible.