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2025-10-15Clean up Slang IR representation of undefined values (#8708)Theresa Foley
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>
2025-10-03Rename some symbols related to pointers types (#8592)Theresa Foley
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>
2025-07-01extend fiddle to allow custom lua splices in more places (#7559)Ellie Hermaszewska
* 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
2025-04-04Add a loop analysis step to infer the exit values of loop phi parameters. ↵Sai Praveen Bangaru
(#6696) * Initial loop analysis pass * More changes for a single-pass implication propagation * Update slang-ir-autodiff-loop-analysis.cpp * Cleanup + new system for loop analysis * Fixup bugs in loop analysis * Remove some relation types to simplify the analysis. Add test * Remove unused * Address comments * Fix issue with continue loops * Update reverse-loop-exit-value-inference-1.slang * Update reverse-continue-loop.slang
2025-02-25Fix a bug with hoisting 'IRVar' insts that are used outside the loop (#6446)Sai Praveen Bangaru
* Fix a bug with hoisting 'IRVar' insts that are used outside the loop - We introduce a 'CheckpointObject' inst and use that to split loop state insts into two pieces (one for within-loop uses and one for outside-loop uses. - This allows the two kinds of uses to be handled separately by the hoisting mechanism - CheckpointObject is then lowered to a no-op after hoisting is complete. * Update slang-ir-autodiff-primal-hoist.cpp * Update slang-ir-autodiff-primal-hoist.cpp
2025-02-25Fix `UseGraph::replace` (#6395)Sai Praveen Bangaru
* Fix `UseGraph::isTrivial()` test. * Fix. * Fix. * Refactor `UseGraph` and `UseChain` * Update slang-ir-autodiff-primal-hoist.cpp * Update all auto-diff locations that handle pointers to treat user pointers as regular values * Update test to use direct-SPIRV only --------- Co-authored-by: Yong He <yonghe@outlook.com>
2025-01-29Fix loophole in hoisting where an `OpVar`'s uses might not be properly ↵Sai Praveen Bangaru
registered for replacement (#6212) * ix loophole in hoisting where an IRVar's uses might not be properly registered for replacement * fix formatting
2025-01-09[Auto-diff] Overhaul auto-diff type tracking + Overhaul dynamic dispatch for ↵Sai Praveen Bangaru
differentiable functions (#5866) * Overhauled the auto-diff system for dynamic dispatch * More fixes * remove intermediate dumps * Update slang-ast-type.h * More fixes + add a workaround for existential no-diff * Update reverse-control-flow-3.slang * remove dumps * remove more dumps * Delete working-reverse-control-flow-3.hlsl * Cleanup comments + unused variables * More comment cleanup * Add support for lowering `DiffPairType(TypePack)` & `MakePair(MakeValuePack, MakeValuePack)` * Fix array of issues in Falcor tests. * Update slang-ir-autodiff-pairs.cpp * More fixes for Falcor image tests * Small fixups. --------- Co-authored-by: Yong He <yonghe@outlook.com>
2024-11-05Move switch statement bodies to their own lines (#5493)Ellie Hermaszewska
* Move switch statement bodies to their own lines * format --------- Co-authored-by: Yong He <yonghe@outlook.com>
2024-10-29formatEllie Hermaszewska
* format * Minor test fixes * enable checking cpp format in ci
2024-10-28Assorted auto-diff enhancements for increased performance & more streamlined ↵Sai Praveen Bangaru
auto-diff results (#5394) * Various AD enhancements * Fix issue with pt-loop test * Update pt-loop.slang * More fixes for perf. Final minimal context test now passes. * Fix issue with loop-elimination pass not running after dce * Try fix wgpu test by removing select operator * Disable wgpu * Delete out.wgsl * Remove comments * Update slang-ir-util.cpp * Fix header relative paths for slang-embed * Disbale wgpu for a few other tests * Better way of determining which params to ignore for side-effects * Update slang-ir-dce.cpp * Fix issue with circular reference from previous AD pass being left behind for the next AD pass * Update slang-ir-dce.cpp
2024-09-19Support `IDifferentiablePtrType` (#5031)Sai Praveen Bangaru
* initial diff-ref-type interface * Initial support for `IDifferentiablePtrType` * Fix unused vars * More tests + fix switch case fallthrough. * Update slang-ir-autodiff.cpp * Update diff-ptr-type-loop.slang * Add optimization to allow more complex pair types * Update slang-ir-autodiff-primal-hoist.cpp * Update diff-ptr-type-loop.slang * Update slang-ir-autodiff-primal-hoist.cpp * More fixes to address reviews * Update slang-check-expr.cpp * Optimizations + rename `differentiableRefInterfaceType` -> `differentiablePtrInterfaceType` * Move pair logic to ir-builder, unify the type dictionaries. --------- Co-authored-by: Yong He <yonghe@outlook.com>
2024-09-18Report AD checkpoint contexts (#5058)venkataram-nv
* Transferring source locations when creating phi instructions * Tracking for simple variables * Deriving source locations for loop counters * Printing checkpoint structure breakdown * More readable output format * Special behavior for loop counters * Writing report to file * Add slangc option to enable checkpoint reports * Display types of checkpointed fields * Message in case there are no checkpointing contexts * Catch source locations for function calls * Source cleanup * Fix compilation warnings * Remove stray dump() * Provide the report through diagnostic notes * Add missing path for sourceLoc during unzip pass * Add tests for reporting intermediates * Include more transfer cases for source locations * Fix ordering in address elimination * Fill in more holes with source location transfer * Remove debugging line * Reverting changes to diagnostic sink * Simplify address elimination using source location RAII contexts * Eliminating manual source loc transfers in forward transcription * Fix local var adaptation to use RAII location setter * Simplify primal hoisting logic for source location transfer * Simplify unzipping with RAII location scopes * Simplify transpose logic * Cleaning up for rev.cpp * Reverting spacing changes * Fix mistake with source loc RAII instantiation * Fix formatting issues
2024-07-25Overhaul IR lowering of pointer types. (#4710)Yong He
* Overhaul IR lowering of pointer types. * Propagate address space in IRBuilder. * Fixup. * Fix. * Fix. * Change how Ptr type is printed to text. * Fix.
2023-09-29Add `requirePrelude()` intrinsic function. (#3250)Yong He
* Add `requirePrelude()` intrinsic function. * Fix. --------- Co-authored-by: Yong He <yhe@nvidia.com>
2023-09-28Support `constref` parameters passing. (#3249)Yong He
* Support `constref` parameters passing. * Fix. * Fix. * Add test and diagnostic on mix use of __constref and no_diff. * check for [constref] on differentiable member method. --------- Co-authored-by: Yong He <yhe@nvidia.com>
2023-09-20Move force inlining step to before `processAutodiffCalls` (and run in loop) ↵Sai Praveen Bangaru
(#3217) * Move auto-diff force inlining step to before `processAutodiffCalls` * Fix `replaceUsesWith` to handle existing inst defined after current use. * Fix. --------- Co-authored-by: Yong He <yhe@nvidia.com>
2023-08-17Initial support for differentiating existential types (#3111)Sai Praveen Bangaru
* Merge * WIP: Complete auto-diff logic for existential types * Revert "Add compiler option for generating representative hash" This reverts commit 13b09ef4621e73844c96d64d9c111a8ed0d45aae. * More fixes for fwd-mode AD on existential types * Add anyValueSize inference pass * Fix checking of `Differential.Differential==Differential` * In-progress: infer any-value-size for existential types * Existentials now work in forward-mode * Overhaul handling of existential AD types. Fwd-mode works, reverse-mode requires front-end changes * Reverse-mode now works on existentials * Cleanup * Remove diff rules for create existential object for now * Revert treat-as-differentiable changes * Fixes * More fixes * Cleanup * more cleanup * signed/unsigned * Revert "Cleanup" This reverts commit e4f7d71f07bb207736f90708961eeecd09a1b652. * Cleanup (again) * Remove public/export/keep-alive on null differential after AD pass * Minor fix * Update dictionary accessors * Keep export decoration * More fixes + Support for `kIROp_PackAnyValue` * Merge upstream * Update expected-failure.txt
2023-08-16Use ankerl/unordered_dense as a hashmap implementation (#3036)Ellie Hermaszewska
* Correct namespace for getClockFrequency * missing const * Add missing assignment operator * Remove unused variables * Return correct modified variable * Use stable hash code for file system identity * terse static_assert * Structured binding for map iteration * Make (==) and getHashCode const on many structs * Add ConstIterator for LinkedList * Replace uses of ItemProxy::getValue with Dictionary::at * Extract list of loads from gradientsMap before updating it * Const correctness in type layout * Add unordered_dense hashmap submodule * Use wyhash or getHashCode in slang-hash.h * refactor slang-hash.h * Use ankerl/unordered_dense as a hashmap implementation Notable changes: - The subscript operator returns a reference directly to the value, rather than a lazy ItemProxy (pair of dict pointer and key) slang-profile time (95% over 10 runs): - Before: 6.3913906 (±0.0746) - After: 5.9276123 (±0.0964) * 64 bit hash for strings So they have the same hash as char buffers with the same contents * Narrowing warnings for gcc to match msvc * revert back to c++17 * Correct c++ version for msvc * Use path to unordered_dense which keeps tests happy * Do not assign to and read from map in same expression * Remove redundant map operations in primal-hoist * Split out stable hash functions into slang-stable-hash.h * 64 bit hash by default * regenerate vs projects * Correct return type from HashSetBase::getCount() * correct width for call to Dictionary::reserve * Use stable hash for obfuscated module ids * Signed int for reserve * clearer variable naming * Parameterize Dictionary on hash and equality functors * Allow heterogenous lookup for Dictionary * missing const * Use set over operator[] in some places * Remove unused function * s/at/getValue
2023-08-01Generalize collectInductionValues (#3031)Ellie Hermaszewska
* Generalize collectInductionValues * Support affine transformations of loop index as induction variables * Test for generalized induction value collection * Neaten inductive variable finding * 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
2023-06-07AD: Fix out-of-scope indexing rules for insts in loop header blocks during ↵Sai Praveen Bangaru
the primal-inst availability pass (#2918) * add test case * Fix out-of-scope indexing rules for loop header blocks --------- Co-authored-by: Yong He <yhe@nvidia.com> Co-authored-by: Yong He <yonghe@outlook.com>
2023-05-09Fix function side-effectness prop logic. (#2875)Yong He
2023-05-07Optimize logic around indexed temporary variables (#2873)Sai Praveen Bangaru
2023-05-06Don't store loop induction values + fix minor issue (#2872)Sai Praveen Bangaru
2023-04-28SSA Register Allocation improvements. (#2857)Yong He
* SSA Register Allocation improvements. * Fix. * Rename `Use`->`UseOrPseudoUse`. --------- Co-authored-by: Yong He <yhe@nvidia.com>
2023-04-28Fix handling of `[PreferRecompute]`. (#2855)Sai Praveen Bangaru
Co-authored-by: Yong He <yhe@nvidia.com> Co-authored-by: Yong He <yonghe@outlook.com>
2023-04-27Small fixes to autodiff pass. (#2852)Yong He
* Remove obsolete assert in `extractPriamlFunc`. * Fix `findUniqueStoredVal` to ignore diff uses. --------- Co-authored-by: Yong He <yhe@nvidia.com>
2023-04-27Prevent storing loads of global parameters. (#2850)Yong He
Co-authored-by: Yong He <yhe@nvidia.com>
2023-04-26Fix most of the disabled warnings on gcc/clang (#2839)Ellie Hermaszewska
2023-04-25Support recomputing phi params in bwd prop func. (#2841)Yong He
2023-04-25Cleanup checkpointing policy impl. (#2837)Yong He
* Cleanup checkpointing policy impl. * More cleanup. --------- Co-authored-by: Yong He <yhe@nvidia.com>
2023-04-25Dictionary using lowerCamel (#2835)jsmall-nvidia
* #include an absolute path didn't work - because paths were taken to always be relative. * WIP lowerCamel Dictionary. * WIP more lowerCamel fixes for Dictionary. * Add/Remove/Clear * GetValue/Contains * Fix tabs in dictionary. Count -> getCount * Fix fields with caps. * Key -> key Value -> value Use m_ for members where appropriate. Use lowerCamel in linked list. * Some small fixes/improvements to Dictionary. * Kick CI.
2023-04-24Change AD checkpointing policy to recompute more. (#2836)Yong He
Co-authored-by: Yong He <yhe@nvidia.com>
2023-04-21Refactor checkpointing policy and availability pass. (#2826)Yong He
Co-authored-by: Yong He <yhe@nvidia.com>
2023-04-12Combine lookupWitness lowering with specialization. (#2794)Yong He
2023-03-29Update checkpoint policy to make obvious recompute decisions. (#2753)Yong He
* Update checkpoint policy to make obvious recompute decisions. Also adds an optimization to fold updateElement chains on the same array or struct into a single makeArray or makeStruct. * Bug fixes around array types with different int typed count. * change test. * Fix. --------- Co-authored-by: Yong He <yhe@nvidia.com>
2023-03-15AD: Primal-Hoisting Rework + Checkpoint Policy Framework (#2702)Sai Praveen Bangaru