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* SPIRV `Block` decoration fixes.
- SPIRV does not allow duplicate `Block` decorations. So we shouldn't be generating them.
- Also fixes duplication of OpName.
- SPIRV and HLSL do not allow ConstantBuffer with trailing unsized arrays. Added a check in the front-end against such code.
* Convert failing cross-compile tests to filecheck.
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Co-authored-by: Jay Kwak <82421531+jkwak-work@users.noreply.github.com>
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* Fix race-condition and visual artifacts issues
In PerformanceProfiler::getProfiler() we return a static object
for the profiler implementation, this is not thread-safe, so change
it to thead_local.
There is still some visual artifacts when using slang as the shading
language. We don't know the root cause yet, but found out it's related
to our loop inversion algorithm. So stage this feature for now, and turn
it into an internal option and default off. We will re-enable it after
more investigation on this optimization.
File an new issue 4151 to track it.
* Add '-loop-inversion' to the few tests
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* Fix fmod behavior targetting GLSL and SPIR-V
The default implementation of fmod was doing "Modulo" operation when
"fmod" in HLSL should do "remainder" operation.
* Fix a mistake in `fmod` GLSL target
When using __intrinsic_asm, the "if" logic wasn't emitted.
"__intrinsic_asm" had to be called from a new function and `fmod` had to
call it.
Alternatively, I am using `operator?()` to workaround.
A similar modification is made to `roundEven()` hoping for a better
performance.
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* Switch to direct-to-spirv backend as default.
* Fix slang-test.
* Fix.
* Fix.
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* Fix #3780.
* Fixers #3781.
* Add test for #3781.
* Diagnose error on unsupported builtin intrinsic types.
* Add check for recursion.
* Fix.
* Fix.
* Fix recursion detection.
* Fix.
* Fix.
* Fix recursion logic.
* More fix.
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* [SPIRV] fix code gen for `SV_Coverage`.
* Fix #3714, #3699.
* Fix.
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* Capability type checking.
* Fix.
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Co-authored-by: Yong He <yhe@nvidia.com>
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* [SPIRV] Support `globallycoherent` modifier.
* Fix.
* Disable executable cooperative vector tests.
* Update expected failure.
* [SPIRV] Emit varying output index decoration.
* Add test.
* Update tests.
* Fix test.
* Emit `SpvExecutionModeEarlyFragmentTests`.
* Lower `StructuredBuffer<bool>`.
* Support globallycoherent on ByteAddressBuffer.
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Co-authored-by: Yong He <yhe@nvidia.com>
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combined sampled image needs an OpImage to be generated. (#3424)
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* Unify Texture types in stdlib into 1 generic type.
* Fixes.
* Fix.
* Fixes.
* Fix reflection.
* Fix binding reflection.
* Add gather intrinsics.
* Fix gather intrinsics.
* Fix texture type toText.
* Fix intrinsic.
* fix cuda intrinsic.
* Fix project files.
* cleanup.
* Fix.
* Fix.
* Fix sampler feedback test.
* Fix getDimension intrinsics.
* Fix spirv sample image intrinsics.
* Fix test.
* Fix GLSL intrinsic.
* Cleanup.
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Co-authored-by: Yong He <yhe@nvidia.com>
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* Add SPIRV intrinsics for ShaderExecutionReordering.
* Add intrinsics for `Buffer` and `RWBuffer`.
* Various spirv fixes.
* Marshal bool vector type.
* Inline global constants + OpFOrdNotEqual->OpFUnordNotEqual.
* Fix.
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Co-authored-by: Yong He <yhe@nvidia.com>
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* Various SPIRV fixes.
- Geometry shader support (WIP).
- Fix texture get dimension and load.
- Fold global GetElement(MakeArray/MakeVector) insts.
- Call spvopt to inline all functions.
- Translate OpImageSubscript.
- Emit struct member names and global variable names.
- Fix lowering of OpBitNot -> OpNot, instead of OpBitReverse.
* Fix test.
* Fix geometry shader.
* Fix geometry shader emit.
* Add atomic Image access test.
* Fix tests.
* don't fail if spirv-opt fails.
* Update comments.
* Fix test.
* Cleanups.
* indentation
---------
Co-authored-by: Yong He <yhe@nvidia.com>
Co-authored-by: Ellie Hermaszewska <ellieh@nvidia.com>
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* Add __truncate and __sampledType for spirv_asm
Allows some texture tests to start passing
* add __isVector
Currently unused
* Add 1-vector legalization pass (WIP)
* Add capabilities for image types
* neaten instruction dumping
* add 1-vector test
* Add a couple of cases to vec1 legalization
* Remove texture tests from expected failures
* comment
* regenerate vs projects
* Remove redundant define form synchapi emulation
* refactoring image methods
* All sample functions refactored
* Remove incorrect glsl intrinsics
Partially addresses https://github.com/shader-slang/slang/issues/3174
* __subscript image ops via writing funcs
* Extract texture struct writing from core.meta.slang
* Abstract out cuda intrinsic
* Remvoe erroneous call to opDecorateIndex
* spirv asm IR utils
* Correct position of loads for SPIR-V asm inst operands
* Raise constructors to global scope during spir-v legalization
* Correct snippet output
* Implement most texture sampling ops for SPIR-V
* Legalize 1-vectors for glsl too
* Make SPIR-V inst operands non-hoistable
* Better 1-vector legalization
* Put textures in ptrs for spirv
* insert missing break
* Add vec1 legalization test
* Add some missing pieces to slang-ir-insts
* Greatly neaten vec1 legalization
* a
* Neaten vec1 legalization
* Add image read and write intrinsics for spir-v
* Squash warnings
* regenerate vs projects
* Drop redundant guards
* Drop 5 tests from expected failure list
* Inst numbering changes to cross compile tests
* vec1 legalization tests only on vk
* Correct location of asm op emit
* Inline constant in spirv-asm
* Correct signedness for lane in wave intrinsics
* Extract element from float1 for cuda
* squash warnings
* Neaten spirv-emit
* dedupe more capabilities
* warnings
* neaten assert
* comments
* comments
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* Fix memory barrier intrinsics.
Makes them produce the same spirv code as dxc.
* Fix.
* filecheck barrier test for spirv backend.
* Fix glsl intrinsic definition.
* Fix intrinsics.
* Fix intrinsics.
* Fix.
* Fix.
---------
Co-authored-by: Yong He <yhe@nvidia.com>
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Co-authored-by: Yong He <yhe@nvidia.com>
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* Compile append and consume structured buffers to glsl.
* Fix.
* Update CI config.
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Co-authored-by: Yong He <yhe@nvidia.com>
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* fix block eater
* Be more careful about merge blocks during loop inversion
* Restrict loop inversion to loops without continue jumps
* Remove multiple back-edges from loops for SPIR-V
* Wiggle cross compile test output
* Make loop-inversion more conservative
* Allow loops on false side in cfg normalization
* Do not set loop continue block during inversion
* Add loop inversion test to failing test list for spirv
* Simplify single use continue blocks in spirv legalization
* wobble expected failure list
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Co-authored-by: Yong He <yonghe@outlook.com>
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* Generalize collectInductionValues
* Support affine transformations of loop index as induction variables
* Test for generalized induction value collection
* Neaten inductive variable finding
* Make types more specific
* Add loop inversion pass
* Test output changes after loop inversion
* Store the type of implication success when finding inductive variables
* Test that loop induction finding does not alway succeed
* Support chains of additions and branches of additions in induction variable finding
* Use c++17 for downstream compilers
* Wiggle expected output for cross compile test after loop inversion
* Add loop inversion test
* Simplify IfElse instructions with a single trivial block
* Invert loops with a user inserted break
* Limit loop inversion to loops with a 4 instruction or less comparison block
* regenerate vs projects
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* Add type layout for structured buffer
* Default to generating spirv directly
* vk test for compute simple
* Add spirv-dis as a downstream compiler
* Emit Array types in SPIR-V
* makevector for spirv
* Dump whole spirv module on validation failure
* register array types
todo, use emitTypeInst
* Neater formatting for unhandled inst printing
* break out emitCompositeConstruct
* Correct array type generation
* neaten
* Allow getElement for vector
* Remove unused
* Allow predicating target intrinsics on types
* Consider functions with intrinsics to have definitions
We need to specialize these if they are predicated on types
* Correct array type generation
* makeArray for spir-v
* replace getElement with getElementPtr for spirv
* Correct translation of field access for spirv
* Push layouts to types for spirv
* Spirv intrinsics * operator now makes a pointer
* Add structured buffer of struct test
* Preserve type layout in spirv structured buffer legalization
* neaten
* makeVectorFromScalar for SPIRV
* placeholder for layouts on param groups
* More type safe spirv op construction
* Know that constants and types only go in one section
* Remove emitTypeInst
* Add todo for spirv sampling
* Add links to spirv documentation on emit functions
* OpTypeImage support for SPIR-V
* Add simpler texture test for spirv
* s/spirv_direct/spirv/g
* Allow several string literals in target_intrinsic
* Handle global params without a var layour for SPIR-V
For example groupshared vars
* uint spirv asm type
* Add todo for isDefinition
It is currently too broad
* Some atomic op spirv intrinsics
* Strip ConstantBuffer wrappers for spirv
* Add todo for matrix annotations
* Do not associate decorations insts with spirv counterparts
* Correct entry point parameter generation
* Spelling
* Assert that fieldAddress is returning a pointer
* Add error for existential type layout getting to spir-v emit
* Add IRTupleTypeLayout
Unused so far
* Allow getElementPtr to work with vectors
* Correct target name in test
* Hide default spirv direct behind a premake option --default-spirv-direct=true
* Do not insert space at start of intrinsic def
* Correct asm rendering in tests
* remove redundant option
* Emit directly from direct test
* Add source language options for spirv-dis
* Add comments to spirv dis
* Add dead debug print for before spirv module
* Correct asm rendering in tests
* s/spirv_direct/spirv/g
* Only specialize intrinsic functions with predicates
* regenerate vs projects
* squash warnings
* squash warnings
* remove duplication
* Silence warnings from msvc
* squash warnings
* Overload for zero sized array
* More msvc warnings
* warnings
* Add spirv-tools to path for tests
* Do not be specific about dxc version for diag test
* Normalize line endings from spirv-dis
* Correct filecheck matches
* Temporarily disable two spirv tests
Failing on CI, undebuggable hang :/
* Do not emit storage class more than once for spirv snippet
* Do not pass spir-v to spirv-dis by stdin
* Do not get spirv-dis output via stream, use file
* normalize file endings in spirv-dis output
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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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Translates to textureQueryLod().x (with the Unclameped variant being returned in the .y component)
Co-authored-by: Yong He <yonghe@outlook.com>
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The translation to GLSL is incomplete as intrinsics only exist for some combination of comparison and channel (just channel 0)
Closes https://github.com/shader-slang/slang/issues/3021
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Co-authored-by: Yong He <yhe@nvidia.com>
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intrinsic (#2975)
* Correct glsl intrinsic for SampleCmpLevelZero without offset
* Add glsl intrinsic for SampleCmpLevelZero with offset
* Add test for samplecmplevelzero glsl translation
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Co-authored-by: Yong He <yonghe@outlook.com>
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* Work around for NonUniformResourceIndex with non integral types.
* Make the non integral NonUniformResourceIndex, inline early.
* Add a depreciated warning.
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* Various dxc/fxc compatibility fixes.
* Cleanup.
* Fix test cases.
* Fix comments.
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Co-authored-by: Yong He <yhe@nvidia.com>
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* Support GL_EXT_fragment_shader_barycentric
* Support pervertex with GL_EXT_fragment_shader_barycentric
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* Detect and deduplicate read-only resource access.
* Fix tests.
* Fix tests.
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Co-authored-by: Yong He <yhe@nvidia.com>
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* More control flow and Phi param simplifications.
* Fix.
* Fix gcc error.
* Fix.
* More IR cleanup.
* Fix bug in phi param dce + ifelse simplify.
* Propagate and DCE side-effect-free functions.
* Enhance CFG simplifcation to remove loops with no side effects.
* Fix.
* Fixes.
* Fix tests. Add [__AlwaysFoldIntoUseSite] for rayPayloadLocation.
* More cleanup.
* Fixes.
* Fix.
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Co-authored-by: Yong He <yhe@nvidia.com>
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* Overhaul global inst deduplication and cpp/cuda backend.
* Update IR documentation.
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Co-authored-by: Yong He <yhe@nvidia.com>
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* Reimplement address elimination pass.
* Fix error.
* Update test references.
Co-authored-by: Yong He <yhe@nvidia.com>
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Co-authored-by: Yong He <yhe@nvidia.com>
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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.
* Preliminary SER NVAPI support.
* Set the DXC compiler version.
Fix typo in premake5.lua
* Improve DXC version detection.
Enable HLSL2021 on late enough version of DXC.
* Fix typo.
* Fix launch.
* Test via DXIL output.
* Update dxc-error output.
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closes https://github.com/shader-slang/slang/issues/2410
Co-authored-by: Yong He <yonghe@outlook.com>
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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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See https://github.com/shader-slang/slang/issues/2213
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* Use IR pass to eliminate phi nodes
"Phi nodes" are one of the key contrivances that makes SSA (Static
Single Assignment) form work. Because SSA is so great for compiler
IRs, we kind of need to deal with phi nodes, but they also get in
the way because they don't have a direct analog in most lower-level
machine ISAs or execution models, nor in most of the high-level
languages a transpiler wants to emit. As a result a compiler like
ours needs to be able to eliminate the phi nodes from a program as
part of generating output code.
(For any clever people noting that SPIR-V supports phi nodes
directly: yes, it does. It doesn't need to and it probably *shouldn't*.
Anybody involved in the decision-making knows my reasoning, and
anybody else should feel free to ask me if they want the lecture.
Anyway...)
The basic idea of elimiating phi nodes is simple enough. We replace
each phi node with a temporary variable. Uses of the phi use values
loaded from the temporary. The operation of the phi itself
(assigning a value based on the branch taken) amounts to an assignment
into the temporary.
Previously, the Slang compiler dealt with phi nodes very late in
the process of generating code: in the middle of emitting strings
of source code in a high-level language like HLSL or GLSL. Doing the
work that late in compilation has two big drawbacks:
1. Our ability to emit clean and/or optimal code is limited because
we may not be able to make certain changes to the IR, or because we
cannot make use of additional information like a dominator tree that
might be available at other points in compilation.
2. Any other IR passes that relate to temporary variables won't be
able to see the variables that we generate for phi nodes. This could
raise issues with correctness (e.g., if we want to compute live-range
information for *all* temporary variables), or performance (we have no
way to run additional IR optimization passes after phis are eliminated).
This change addresses these problems by making the elimination of
phi nodes an explicit IR pass. Additional optimizations can easily be
run after this pass (although we'd need to be careful not to run
passes that could end up introducing new phis). The pass makes use
of the information available to it to try to produce code that will
emit to "clean" HLSL/GLSL.
The core of the pass is in `slang-ir-eliminate-phis.cpp`, and is
heavily commented, so I won't describe the approach in detail here.
There are two related issues that came up, though:
First, it turned out that our emit logic for local variables (`IRVar`
instructions) wasn't using the function we'd defined named `emitVar()`.
One worrying consequence of that oversight was that the `precise`
modifier would impact generated HLSL/GLSL for variables that turned
into SSA values (including phi nodes), but *not* for local variables
that had not been SSA'd (or that had been SSA'd and then de-SSA'd).
This change also fixes that bug; it is unclear how widespread the
impact of the original issue might be.
Second, generating explicit IR temporaries for phi nodes exposed a
pre-existing bug in the `slang-ir-restructure-scoping` pass. That pass
basically detects cases where we have an instruction `I` with a use
`U` such that the use follows the rules of SSA form ("def dominates
use," meaning `I` dominations `U`), but does not follow the more
restrictive scoping rules of high-level-language output (where a value
computed "inside" a loop is not automatically visible to code outside
the loop just because it dominates that code). That pass did not
correctly account for the case where `I` was a temporary variable.
It seems that case could not arise before now because we didn't have
any passes that would move `var`, `load`, or `store` operations out
of the basic block they started in. The fix for that pass was relatively
simple, and will make the whole thing more robust in case we add more
aggressive optimizations later.
* fixup: expected test output
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* Work to mitigate SPIR-V bloat
SPIR-V is not an especially compact format, but some patterns in how Slang generates code and then runs it through `spirv-opt` lead to many redundant field-by-field copy operations being emitted. This change attempts to address some of the resulting bloat from the Slang side of things.
Note: experimentation shows that the bloat is less pronounced when running either *no* SPIR-V optimizations or *full* SPIR-V optimizations, so it is also likely that the bloat should be addressed by changing which `spirv-opt` passes the Slang compiler runs in default (`-O1`) builds. Such changes should come as a distinct pull request.
This change primarily does two things:
First, the code generation strategy for passing arguments to `out` and `inout` parameters has been changed. In the past, the compiler would *always* copy the argument value into a temporary, then pass the address of the temporary, and then write back the value after the call. The new code generation strategy attempts to identify when an argument value already has a simple address in memory and passes that address directly when possible. This eliminates many copy operations that occur before/after calls to functions with `out`/`inout` parameters.
Second, we introduce an IR optimization pass that detects call sites where the entire contents of a buffer (usually a constant buffer) is being passed to a callee function, such that many bytes are loaded and then passed even if only very few are used in the callee. The pass moves the load operations from the caller to a specialized version of the the callee where possible (e.g., when the constant buffer in question is a global shader parameter). Doing this eliminates another major category of copies.
Notes:
* The IR lowering logic is complicated by the fact that several kinds of l-values (values that are usable as the desitnation of assignment, or for `out`/`inout` arguments) are not actually addressable. An easy example is a non-contiguous swizzle like `v.xwz` on a `float4`, where the value occupies 12 bytes, but not 12 consecutive bytes with a single address. There are many more corner cases like that and the IR lowering pass carries a lot of complexity to deal with them. A more systematic overhaul is due some time soon.
* The IR representation of `out` and `inout` parameters deserves some careful scrutiny when making these kinds of changes. The official semantics of `inout` in HLSL has been "copy in copy out" (and `out` is just "copy out") which is observably different from any solution that passes in the address of an l-value directly. By making this change we are saying that Slang's semantics are not precisely those of legacy HLSL, and that our semantics for `inout` parameters are closer to those of `inout` in Swift or of a mutable borrow in Rust. In the Swift case the implementation can freely pass the underlying storage of an l-value or the address of a temporary, and valid programs may not observe the different. It is thus illegal to observe the value in a storage local while a mutation to that location is "in flight." All of this is way more detailed and technical than 99% of Slang users will ever care about, but importantly it gives us semantic cover to eliminate these copies in the IR, and also to emit output C++ code that implements `out` and `inout` as by-reference parameter passing.
* There was an exsting generic pass for specializing functions based on call sites that uses a "template method" style of pattern to customize its behavior. That pass needed to be generalized to handle this use case because it had previously operated on the assumption that the "desire" to specialize a callee function must be driven by the parameter declarations of that function, and not on the argument values passed in. The code has been slightly refactored to allow the policy for specialization to consider both parameters and arguments.
* Unsurprisingly, a bunch of the GLSL (and thus SPIR-V) generated has changed with this work, so several baseline `.slang.glsl` files needed to be updated.
* This change is incomplete in that it does not address broader cases of buffer loads, including both partial loads from constant buffers (just loading one field, but a field that uses a "large" structure type), and loads from multi-element buffers (a lot from a structured buffer where the element type is "large"). The main question in each of those cases is how to define how "large" a structure needs to be before we decide to try and sink loads into callee functions like this. In the worst case, sinking loads in this way may actually create *more* memory traffic (because the same values get loaded in multiple callee functions).
* fixup: run premake
* fixup: typo
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* #include an absolute path didn't work - because paths were taken to always be relative.
* Fix issue with with SLANG_ENABLE_GLSLANG_SUPPORT
* Update expected output from glslang-error.glsl
* Fix bug in glsl dissassembly.
* Make ExtensionTracker available even if source is not emitted.
* Only explicitly set extension tracker based on capability bits, if we are in pass through.
* Small simplification of invoke sourceEmit.
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* #include an absolute path didn't work - because paths were taken to always be relative.
* WIP Fxc as downstream compiler.
* First pass FXC downstream compiler working.
* GCC compile fix.
* Fix FXC parsing issue.
* Special case filesystem access.
* Use StringUtil getSlice.
* Fix isses with not emitting source for FXC.
* WIP on DXC.
* Small fixes for DXBC handling.
* Removed DXC from ParseDiagnosticUtil (can use generic)
Try to improve output for notes from DXC.
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* #include an absolute path didn't work - because paths were taken to always be relative.
* WIP Fxc as downstream compiler.
* First pass FXC downstream compiler working.
* GCC compile fix.
* Fix FXC parsing issue.
* Special case filesystem access.
* Use StringUtil getSlice.
* Fix isses with not emitting source for FXC.
* Small fixes for DXBC handling.
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This change converts a large number of our existing tests to use the `ShaderObject` support that was added to the `gfx` layer.
In many cases, tests were just updated to pass `-shaderobj` and the result Just Worked.
In other cases, a `name` attribute had to be added to one or more `TEST_INPUT` lines.
For tests that did not work with shader objects "out of the box," I spent a little bit of time trying to get them work, but fell back to letting those tests run in the older mode.
Future changes to the infrastructure will be needed to get those additional tests working in the new path.
Along with the changes to test files, the following implementation changes were made to get additional tests working:
* Because the shader object mode uses explicit register bindings (from reflection), the hacky logic that was offseting `u` registers for D3D12 based on the number of render targets gets disabled (by another hack).
* The "flat" reflection information coming from Slang was not correctly reporting "binding ranges" for things that consumed only uniform data (which would be everything on CUDA/CPU), so it was refactored to properly include binding ranges for anything where the type of the field/variable implied a binding range should be created (even if the `LayoutResourceKind` was `::Uniform`).
* A few fixes were made to the CUDA implementation of `Renderer`, in order to get additional tests up and running. Most of these changes had to do with texture bindings, which hadn't really been tested previously.
In addition, a few changes were made that were attempts at getting more tests working, but didn't actually help. These could be dropped if requested:
* As a quality-of-life feature (not being used) the `object` style of `TEST_INPUT` line is upgraded to support inferring the type to use from the type of the input being set.
* Any `object` shader input lines get ignored in non-shader-object mode.
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* Add basic GLSL support for SV_Barycentrics
This change allows for fragment shader varying inputs marked with the `SV_Barycentrics` semantic to be mapped to GLSL code using the `gl_BaryCoordNV` builtin variable (from he `GL_NV_fragment_shader_barycentric` extension).
This is the simplest possible change to get the functionality up and running, and it leaves out many things that could be desired in a more feature-complete version of the feature later:
* There is no support for alternative extensions that provide similar functionality. Selection of which extension to favor could eventually be based on the "capability" work that has been put in place.
* There is no attempt made to check that the input has the expected type (or to coerce it if it doesn't), so for now this is only going to be guaranteed to work for a `float3` input.
* This change does not expose the `pervertexNV` qualifier added in the `GL_NV_fragment_shader_barycentric` extension, which can be used by a shader to access the uninterpolated vertex inputs.
The last issue is an important one, since the HLSL `GetAttributeAtVertex` function seems to be defiend to work with *any* incoming varying parameter that was marked with `nointerpolation`. When we have a `nointerpolation` input, it would seem that we need to know whether it will be used with `GetAttributeAtVertex` (in which case it should be declared as a `pervertexNV` array input in GLSL) or not (in which case it should be declared as a `nointerpolation` input, without an array).
* fixup: missing file
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* Enable all dynamic dispatch tests on CUDA.
* Fix expected cross-compile test results.
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* Adding support for global uniform shader parameters
This change adds support for Slang programmers to declare shader parameters of "ordinary" types at global scope:
```hlsl
uniform float gScaleFactor;
void main() { ... *= gScaleFactor; ... }
```
The generated HLSL/GLSL/DXIL/SPIR-V output will be something along the lines of:
```hlsl
struct GlobalParams
{
float gScaleFactor;
}
cbuffer globalParams
{
GlobalParams globalParams;
}
void main() { ... *= globalParams.gScaleFactor; ... }
```
The binding information used for the implicit `globalParams` constant buffer will be determined by the existing implicit parameter binding logic (which already had support for this kind of transformation).
The reason this change is being pursued right now is because it is one step toward removing the implicit `KernelContext` type that is used to wrap the generated code for our CPU and CUDA C++ targets. Handling global-scope parameters of ordinary type requires an IR pass that synthesizes the `GlobalParams` structure type above, and that step ends up removing the need for the similar `UniformState` structure that was being used in the CPU/CUDA emit logic.
A more detailed guide to the changes included follows:
* The diagnostic for a global-scope variable that is implicitly a shader parameter was kept, but changed to a warning. Users can opt out of the warning by decorating their parameter as a `uniform` (since that keyword is already being used to mark entry-point parameters that should be treated as uniform shader parameters).
* To simplify the task of finding the global shader parameters, the `CLikeSourceEmitter` type has been given an `m_irModule` member. The previous emit logic for `UniformState` was having to do a roundabout solution involving the `EmitAction`s to deal with not having direct access to the module.
* Removed a few dead declarations in the emit logic (related to a much earlier point where emit was based on the AST instead of the IR).
* Made the computation of type names in C++ emit take into account `ConstantBuffer<T>` and `ParameterBlock<T>`. As far as I can tell, these were being handled with some special-case hacks in the emit logic instead of being supported more fundamentally. It might actually be good to pass these through as `ConstantBuffer<T>` and `ParameterBlock<T>` in the C++ output, and allow the prelude to customize their translation (defaulting to defining them as `T*`).
* Removed the special-case C++ emit logic for references to global shader parameters. There are now at most two global shader parameters to deal with, and the default emit logic (referring to them by name) does the Right Thing.
* Changed the handling of entry points for C++ (both CPU and CUDA) so that it handles the bundled-up shader paameters for the global and entry-point scopes the same way. The main complication here is OptiX, where parameter data is passed very differently than it is for CUDA compute kernels.
* Reverted changes to `ir-entry-point-uniforms` that had made its logic depend on the compilation target. The parameter binding logic was already responsible for deciding if a given target needed to wrap up its entry-point parameters in a constant buffer, and the IR pass was respecting that layout information. The current workaround had been removing the `ConstantBuffer<T>` indirection from this IR pass for CPU/CUDA, but then reintroducing the same indirection later on in the emit step.
* Added an explicit IR pass with the task of collecting global-scope parameters of uniform/ordinary type and packaging them up into a `struct`, and then optionally packaging that `struct` up in a constant buffer. This pass bases its decisions on the IR layout information that was already computed, so it should match whatever policy choices were made at the layout level.
* Changed the "key" operand on IR `struct` layout information to not assume an `IRStructKey`. The problem here is that the global scope gets a `StructTypeLayout` to represent its members, and this is convenient (rather than having to always special-case logic that handles the global scope), but the "fields" of that struct are global variables which do not have `IRStructKey`s associated with them. The simplest solution is to use the variables themselves as the keys, which required removing the assumption in the IR encoding.
* Updated the IR layout process to compute a layout for the global scope of an entire program, and to attach that to the `IRModule` via a decoration. Updated the IR linking process to carry through that decoration to the linked output. This is necessary so that the IR pass that transforms global parameters can access the global-scope layout information.
An important concern with this approach is that the contents and layout of the monolithic `GlobalParams` structure depends on the exact set of modules that were linked (and the order in which they were specified, in some cases). This isn't really a new thing with this change, but it becomes more important as we start to think of how to generalize things to better support separate compilation and linking.
There are changes that can (and should) be made to the way that IR layouts are computed for programs (e.g., so that we compute layout per-module and then combine them rather than as a whole-program step). In this case, the problem of forming the combined/linked global layout can be moved down the IR level and not be reliant on AST-level information.
Just changing the way layout and linking interact would not change the fundamental problem that global shader parameters as they currently exist in Slang/HLSL/GLSL are not readily compatible with true separate compilation. We either need to find a solution strategy that we can apply to allow existing shaders to work with separate compilation *or* we need to incrementally work toward removing support for global-scope shader parameters in favor of explicit entry-point parameters in all cases.
* fixup: missing files
* fixup: comment the new code
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