Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: e8d1a0d6 by Bernhard M. Wiedemann at 2026-08-10T21:31:23-04:00 driver: Link object files in a deterministic order The object files handed to the linker come from the HomePackageTable, which is ordered by the order in which modules finished compiling. With -j1 that is the build plan order, with -jN it is whatever the scheduler produced, so the same sources can link to different (but equivalent) binaries. The order reaches the output: .text and .rodata contributions are concatenated in link order, so e.g. building the hdav executable of the DAV package twice, once with -j1 and once with -j4, yields two binaries that differ in ~100kB of section contents. Sort the home modules by module before collecting their linkables, guarded under `Opt_ObjectDeterminism` . Fixes #27612 Signed-off-by: Bernhard M. Wiedemann <bwiedemann@suse.de> - - - - - 556db2f3 by sheaf at 2026-08-10T21:32:06-04:00 Reduce SpecConstr threshold in GHC.Tc.Solver.Rewrite As remarked in #27628, this module currently sits on a knife's edge: if the body of 'simplifyArgsWorker' is made even a tiny bit smaller, then SpecConstr suddenly kicks in and causes disastrous reboxing of the LiftingContext argument. To make this less likely to happen, this commit lowers the SpecConstr threshold. - - - - - d9c3e8a6 by sheaf at 2026-08-10T22:10:21-04:00 Allow rewriting in RuntimeReps for newtype ConPats This commit implements PHASE 2 of the FixedRuntimeRep plan described in Note [The Concrete mechanism] in GHC.Tc.Utils.Concrete for newtype constructor patterns. In short, GHC now accepts programs of the form f (MkN x) = ... in which the argument 'x' of the newtype constructor pattern 'MkN x' has a representation that is not syntactically concrete, e.g. it can be 'Id IntRep' reducing to 'IntRep'. See T20363{,b,c} for examples. There are two main parts to the implementation: 1. Typechecking, in GHC.Tc.Gen.Pat.tcDataConPat. See Note [Typechecking newtype constructor patterns] in GHC.Tc.Gen.Pat. 2. Desugaring. We restructure the code for desugaring pattern matches by allowing the scrutinised match variable to be casted. This allows us to accumulate coercions and avoids creating binders at intermediate types tha don't have a fixed RuntimeRep. See the revamped Note [Match Ids] in GHC.HsToCore.Monad. Fixes #20363 ------------------------- Metric Increase: InstanceMatching ------------------------- - - - - - b33992b6 by Wolfgang Jeltsch at 2026-08-10T22:10:22-04:00 Add support for textual output of bytecode file content - - - - - 35823b6f by sheaf at 2026-08-10T22:10:27-04:00 Avoid wasteful allocations in mkTyConAppCo The idiom "traverse isReflCo_maybe" followed by "map fst" used in 'GHC.Core.Coercion.mkTyConAppCo' was allocating a lot of waste. This commit uses 'GHC.Data.Unboxed.traverseMaybeUB' to avoid all these unnecessary intermediate allocations. In a quick microbenchmark for 'mkTyConAppCo', this change resulted in: - refl case (all argument coercions are reflexive): - -60% runtime - -80% allocations - non-refl case: - from 0% to -12% runtime (depending on which argument is non-refl) - from 0% to -70% allocations ( -- '' -- ) Fixes #27648 ------------------------- Metric Decrease: FamAppCachePerf SimplCastPerf T12425 T15703 T26426 T3064 T9872b_defer T9872d T5321Fun T9020 T9630 ------------------------- - - - - - 54 changed files: - + changelog.d/T20363 - + changelog.d/link-deterministic-order - + changelog.d/show-byte-code - compiler/GHC/ByteCode/Serialize.hs - + compiler/GHC/ByteCode/Show.hs - compiler/GHC/Core/Coercion.hs - compiler/GHC/Data/Unboxed.hs - compiler/GHC/Driver/Pipeline.hs - compiler/GHC/Hs/Pat.hs - compiler/GHC/HsToCore/Match.hs - compiler/GHC/HsToCore/Match.hs-boot - compiler/GHC/HsToCore/Match/Constructor.hs - compiler/GHC/HsToCore/Match/Literal.hs - compiler/GHC/HsToCore/Monad.hs - compiler/GHC/HsToCore/Utils.hs - compiler/GHC/Tc/Gen/Pat.hs - compiler/GHC/Tc/Gen/Sig.hs - compiler/GHC/Tc/Solver/Rewrite.hs - compiler/GHC/Tc/Types/Evidence.hs - compiler/GHC/Tc/Utils/Concrete.hs - compiler/GHC/Types/Id/Make.hs - compiler/ghc.cabal.in - docs/users_guide/using.rst - ghc/GHC/Driver/Session/Mode.hs - ghc/Main.hs - testsuite/tests/corelint/T21115b.stderr - testsuite/tests/count-deps/CountDepsParser.stdout - testsuite/tests/dmdanal/should_compile/T23398.stderr - testsuite/tests/numeric/should_compile/T23907.stderr - testsuite/tests/rep-poly/RepPolyRecordPattern.hs - testsuite/tests/rep-poly/RepPolyRecordPattern.stderr - testsuite/tests/rep-poly/RepPolyRecordUpdate.stderr - testsuite/tests/rep-poly/T20113.stderr - − testsuite/tests/rep-poly/T20363.stderr - − testsuite/tests/rep-poly/T20363_show_co.hs - − testsuite/tests/rep-poly/T20363_show_co.stderr - − testsuite/tests/rep-poly/T20363b.stderr - + testsuite/tests/rep-poly/T20363c.hs - testsuite/tests/rep-poly/all.T - + testsuite/tests/show-bytecode/Example.hs - + testsuite/tests/show-bytecode/Makefile - + testsuite/tests/show-bytecode/all.T - + testsuite/tests/show-bytecode/normalize - + testsuite/tests/show-bytecode/show-bytecode-breakpoints.stdout - + testsuite/tests/show-bytecode/show-bytecode-breakpoints.stdout-javascript-unknown-ghcjs - + testsuite/tests/show-bytecode/show-bytecode-hpc.stdout - + testsuite/tests/show-bytecode/show-bytecode-vanilla.stdout - + testsuite/tests/show-bytecode/show-bytecode-vanilla.stdout-javascript-unknown-ghcjs - testsuite/tests/simplCore/should_compile/T24229a.stderr - testsuite/tests/simplCore/should_compile/T24229b.stderr - testsuite/tests/simplCore/should_compile/T3717.stderr - testsuite/tests/simplCore/should_compile/T3772.stdout - testsuite/tests/simplCore/should_compile/T4081.stderr - testsuite/tests/simplCore/should_compile/T4908.stderr The diff was not included because it is too large. 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