Torsten Schmits pushed to branch wip/torsten.schmits/mwb-26-01/mp-backports at Glasgow Haskell Compiler / GHC Commits: 2c9e7d5d by Jannis at 2026-07-08T18:23:59+02:00 Division by constants optimization - - - - - 84db06dd by Rodrigo Mesquita at 2026-07-08T18:23:59+02:00 determinism: Sampling uniques in the CG To achieve object determinism, the passes processing Cmm and the rest of the code generation pipeline musn't create new uniques which are non-deterministic. This commit changes occurrences of non-deterministic unique sampling within these code generation passes by a deterministic unique sampling strategy by propagating and threading through a deterministic incrementing counter in them. The threading is done implicitly with `UniqDSM` and `UniqDSMT`. Secondly, the `DUniqSupply` used to run a `UniqDSM` must be threaded through all passes to guarantee uniques in different passes are unique amongst them altogether. Specifically, the same `DUniqSupply` must be threaded through the CG Streaming pipeline, starting with Driver.Main calling `StgToCmm.codeGen`, `cmmPipeline`, `cmmToRawCmm`, and `codeOutput` in sequence. To thread resources through the `Stream` abstraction, we use the `UniqDSMT` transformer on top of `IO` as the Monad underlying the Stream. `UniqDSMT` will thread the `DUniqSupply` through every pass applied to the `Stream`, for every element. We use @type CgStream = Stream (UniqDSMT IO)@ for the Stream used in code generation which that carries through the deterministic unique supply. See Note [Deterministic Uniques in the CG] - - - - - c2f734ac by Rodrigo Mesquita at 2026-07-08T18:23:59+02:00 determinism: DCmmGroup vs CmmGroup Part of our strategy in producing deterministic objects, namely, renaming all Cmm uniques in order, depend on the object code produced having a deterministic order (say, A_closure always comes before B_closure). However, the use of LabelMaps in the Cmm representation invalidated this requirement because the LabelMaps elements would already be in a non-deterministic order (due to the original uniques), and the renaming in sequence wouldn't work because of that non-deterministic order. Therefore, we now start off with lists in CmmGroup (which preserve the original order), and convert them into LabelMaps (for performance in the code generator) after the uniques of the list elements have been renamed. See Note [DCmmGroup vs CmmGroup or: Deterministic Info Tables] and #12935. Co-authored-by: Matthew Pickering <matthewtpickering@gmail.com> - - - - - 52bbec84 by Rodrigo Mesquita at 2026-07-08T18:23:59+02:00 determinism: Cmm unique renaming pass To achieve object determinism, we need to prevent the non-deterministic uniques from leaking into the object code. We can do this by deterministically renaming the non-external uniques in the Cmm groups that are yielded right after StgToCmm. The key to deterministic renaming is observing that the order of declarations, instructions, and data in the Cmm groups are already deterministic (modulo other determinism bugs), regardless of the uniques. We traverse the Cmm AST in this deterministic order and rename the uniques, incrementally, in the order they are found, thus making them deterministic. This renaming is guarded by -fobject-determinism which is disabled by default for now. This is one of the key passes for object determinism. Read about the overview of object determinism and a more detailed explanation of this pass in: * Note [Object determinism] * Note [Renaming uniques deterministically] Significantly closes the gap to #12935 - - - - - 0f2bbced by Ben Gamari at 2026-07-08T18:23:59+02:00 Revert "Division by constants optimization" This appears to be responsible for the regression described in #25653. This reverts commit daff1e30219d136977c71f42e82ccc58c9013cfb. - - - - - a49a47f2 by Rodrigo Mesquita at 2026-07-08T18:23:59+02:00 hi: Stable sort avails Sorting the Avails in DocStructures is required to produce fully deterministic interface files in presence of re-exported modules. Fixes #25104 - - - - - 54ef9564 by Ian-Woo Kim at 2026-07-08T18:23:59+02:00 determinism: Interface re-export list det In 'DocStructureItem' we want to make sure the 'Avails' are sorted, for interface file determinism. This commit introduces 'DetOrdAvails', a newtype that should only be constructed by sorting Avails with 'sortAvails' unless the avails are known to be deterministically ordered. This newtype is used by 'DocStructureItem' where 'Avails' was previously used to ensure the list of avails is deterministically sorted by construction. Note: Even though we order the constructors and avails in the interface file, the order of constructors in the haddock output is still determined from the order of declaration in the source. This was also true before, when the list of constructors in the interface file <docs> section was non-deterministic. Some haddock tests such as "ConstructorArgs" observe this (check the order of constructors in out/ConstructorArgs.html vs src/ConstructorArgs.hs vs its interface file) The updated tests are caused by haddock corners where the order in the source is not preserved (and was non-deterministic before this PR): * Module header in the latex backend * Re-export of pattern synonyms associated to a datatype (#25342) Fixes #25304 authored by Rodrigo Mesquita - - - - - aecd82b8 by Ian-Woo Kim at 2026-07-08T18:23:59+02:00 WIP: determinism: sort dependent file - sort on dependent_files - sort on fingerprint for usage - - - - - eb7033cf by Matthew Pickering at 2026-07-08T18:23:59+02:00 determinism: Use deterministic map for Strings in TyLitMap When generating typeable evidence the types we need evidence for all cached in a TypeMap, the order terms are retrieved from a type map determines the order the bindings appear in the program. A TypeMap is quite diligent to use deterministic maps, apart from in the TyLitMap, which uses a UniqFM for storing strings, whose ordering depends on the Unique of the FastString. This can cause non-deterministic .hi and .o files. Fixes #26846 - - - - - cd00672d by Matthew Pickering at 2026-07-08T18:23:59+02:00 determinism: Use a stable sort in WithHsDocIdentifiers binary instance `WithHsDocIdentifiers` is defined as ``` 71 data WithHsDocIdentifiers a pass = WithHsDocIdentifiers 72 { hsDocString :: !a 73 , hsDocIdentifiers :: ![Located (IdP pass)] 74 } ``` This list of names is populated from `rnHsDocIdentifiers`, which calls `lookupGRE`, which calls `lookupOccEnv_AllNameSpaces`, which calls `nonDetEltsUFM` and returns the results in an order depending on uniques. Sorting the list with a stable sort before returning the interface makes the output deterministic and follows the approach taken by other fields in `Docs`. Fixes #26858 - - - - - 82 changed files: - .gitlab/ci.sh - compiler/GHC/Cmm.hs - compiler/GHC/Cmm/BlockId.hs - compiler/GHC/Cmm/CLabel.hs - compiler/GHC/Cmm/Dataflow.hs - compiler/GHC/Cmm/Dataflow/Graph.hs - compiler/GHC/Cmm/Graph.hs - compiler/GHC/Cmm/Info.hs - compiler/GHC/Cmm/Info/Build.hs - compiler/GHC/Cmm/LayoutStack.hs - compiler/GHC/Cmm/Opt.hs - compiler/GHC/Cmm/Parser.y - compiler/GHC/Cmm/Pipeline.hs - compiler/GHC/Cmm/ProcPoint.hs - compiler/GHC/Cmm/Reducibility.hs - compiler/GHC/Cmm/Sink.hs - compiler/GHC/Cmm/Switch.hs - compiler/GHC/Cmm/Switch/Implement.hs - compiler/GHC/Cmm/ThreadSanitizer.hs - + compiler/GHC/Cmm/UniqueRenamer.hs - compiler/GHC/CmmToAsm.hs - compiler/GHC/CmmToAsm/AArch64/CodeGen.hs - compiler/GHC/CmmToAsm/AArch64/Instr.hs - compiler/GHC/CmmToAsm/BlockLayout.hs - compiler/GHC/CmmToAsm/Dwarf.hs - compiler/GHC/CmmToAsm/Monad.hs - compiler/GHC/CmmToAsm/PPC/Instr.hs - compiler/GHC/CmmToAsm/Reg/Graph.hs - compiler/GHC/CmmToAsm/Reg/Graph/Spill.hs - compiler/GHC/CmmToAsm/Reg/Linear.hs - compiler/GHC/CmmToAsm/Reg/Linear/Base.hs - compiler/GHC/CmmToAsm/Reg/Linear/State.hs - compiler/GHC/CmmToAsm/Reg/Liveness.hs - compiler/GHC/CmmToAsm/Wasm.hs - compiler/GHC/CmmToAsm/Wasm/FromCmm.hs - compiler/GHC/CmmToAsm/Wasm/Types.hs - compiler/GHC/CmmToAsm/X86/CodeGen.hs - compiler/GHC/CmmToAsm/X86/Instr.hs - compiler/GHC/CmmToLlvm.hs - compiler/GHC/CmmToLlvm/Base.hs - compiler/GHC/CmmToLlvm/CodeGen.hs - compiler/GHC/Core/Map/Type.hs - compiler/GHC/Data/Graph/Collapse.hs - compiler/GHC/Data/Stream.hs - compiler/GHC/Driver/CodeOutput.hs - compiler/GHC/Driver/Config/Cmm.hs - compiler/GHC/Driver/Config/StgToCmm.hs - compiler/GHC/Driver/Flags.hs - compiler/GHC/Driver/GenerateCgIPEStub.hs - compiler/GHC/Driver/Hooks.hs - compiler/GHC/Driver/Main.hs - compiler/GHC/Driver/Session.hs - compiler/GHC/Hs/Doc.hs - compiler/GHC/HsToCore/Docs.hs - compiler/GHC/HsToCore/Usage.hs - compiler/GHC/Iface/Make.hs - compiler/GHC/StgToCmm.hs - compiler/GHC/StgToCmm/CgUtils.hs - compiler/GHC/StgToCmm/Config.hs - compiler/GHC/StgToCmm/ExtCode.hs - compiler/GHC/StgToCmm/Foreign.hs - compiler/GHC/StgToCmm/Monad.hs - compiler/GHC/StgToCmm/Types.hs - compiler/GHC/Types/Avail.hs - compiler/GHC/Types/Unique.hs - compiler/GHC/Types/Unique/DFM.hs - + compiler/GHC/Types/Unique/DSM.hs - compiler/GHC/Types/Unique/Supply.hs - compiler/GHC/Utils/Monad/State/Strict.hs - compiler/GHC/Utils/Outputable.hs - compiler/GHC/Wasm/ControlFlow/FromCmm.hs - compiler/ghc.cabal.in - docs/users_guide/using-optimisation.rst - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - testsuite/tests/numeric/should_run/all.T - testsuite/tests/regalloc/regalloc_unit_tests.hs - testsuite/tests/showIface/DocsInHiFileTH.stdout - testsuite/tests/showIface/HaddockIssue849.stdout - testsuite/tests/showIface/NoExportList.stdout - testsuite/tests/wasm/should_run/control-flow/LoadCmmGroup.hs - testsuite/tests/wasm/should_run/control-flow/WasmControlFlow.hs The diff was not included because it is too large. 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