Simon Peyton Jones pushed to branch wip/T26989 at Glasgow Haskell Compiler / GHC Commits: 710a4f21 by Simon Peyton Jones at 2026-05-13T11:48:30+01:00 Major refactor of the Simplifier The main payload of this patch is to refactor the Simplifer to avoid repeated simplification when using Plan (AFTER) for rule rewrites. The need for this was shown up by #26989. See Note [Avoid repeated simplification] in GHC.Core.Opt.Simplify.Iteration. Related refactoring: * Refactor the two fields `sc_dup` and `sc_env` in `ApplyToVal` into one, `sc_env`. Reason: the envt is irrelevant in the "simplified" case, so the data type describes the possiblitiies much more accurately now. * Some refactoring in `knownCon` to split off `wrapDataConFloats`. * Refactor `lookupRule` and its auxiliary functions to return `RuleMatch`, a new data type. See Note [data RuleMatch] in GHC.Core. Ditto for BuiltinRule. This RuleMatch returns fragments of the target in rm_args and rm_floats, leaving `rm_rhs` to be the stuff from the RULE itself. Doing this has routine consequences in GHC.Core.Opt.ConstantFold. Many changes there but all routine. * When doing occurrence analysis on RULEs, make the occ-info on the rule binders relate just to the RHS, not the LHS. See (OUR1) in Note Note [OccInfo in unfoldings and rules] This means that Lint must not complain about the fact that the patterns in the RULE mentions binders that are marked dead. See Note [Dead occurrences] in GHC.Core.Lint. I changed the Core pretty-printer so that it didn't suppress dead binders, else I can't see those binders in RULEs. That led to quite a lot of testsuite wibbles. * Refactor FloatBinds, so that it is used both by `exprIsConApp_mabye` and by `lookupRule` * Move the definition of FloatBinds out of GHc.Core.Make, into GHC.Core. * Add FloatTick as an extra constructor. * Refactor `lookupRule` to use `FloatBinds` instead of `BindWrapper`. This refactor just shares more code. (Rename GHC.Core.Opt.FloatOut.FloatBinds to FloatLets, to avoid gratuitious name clash with GHC.Core.FloatBinds.) Corecion optimisation * In simpleOpt, when composing coercions, call new function `optTransCo`. This is much lighter weight than full blown coercion optimisation. * Make `GHC.Core.Opt.Arity.pushCoValArg` and `pushCoTyArg` return the coercionLKind of the coercion. This saves recomputing that coercionLKind at the key call sites in GHC.Core.Opt.Simplify.Iteration.pushCast. * Rename `addCoerce` in GHC.Core.Simplify.Iteration to become `pushCast`. * In the `ApplyToVal` case of `pushCast` we had a very unsavoury call to `simplArg`. I eliminated it by adding a field `sc_cast` to `ApplyToVal` that records any pending casts. Much nicer now. See Note [The sc_cast field of ApplyToVal]. * Don't optimise coercions if the type-substitution is empty. See Note [Optimising coercions] in GHC.Core.Opt.Simplify.Iteration. The fix for #26838 is dramatic. For the test in perf/compiler/T26839 we have Compiler allocs: Before: 7,363M After: 688M Compile time goes down generally. Here are compiler-alloc changes over 0.5%: CoOpt_Read(normal) 729,184,920 -0.7% CoOpt_Singletons(normal) 666,916,960 -4.6% GOOD LargeRecord(normal) 1,227,056,876 +1.1% T12227(normal) 256,827,604 -4.6% GOOD T12425(optasm) 76,879,410 -0.8% T12545(normal) 787,826,918 -10.8% GOOD T12707(normal) 775,186,464 -0.9% T13253(normal) 318,599,596 -0.8% T14766(normal) 685,857,320 -1.0% T15304(normal) 1,123,333,422 -2.2% T15630(normal) 123,142,330 -2.6% T15630a(normal) 123,092,100 -2.6% T15703(normal) 299,751,682 -2.9% GOOD T17516(normal) 964,072,280 +1.0% T18223(normal) 367,016,820 -6.2% GOOD T18730(optasm) 130,643,770 -3.3% GOOD T20261(normal) 535,608,584 -0.7% T21839c(normal) 340,340,436 -0.9% T24984(normal) 85,568,392 -1.9% T3064(normal) 174,631,992 -1.2% T3294(normal) 1,215,886,432 -0.7% T5030(normal) 141,449,704 -17.2% GOOD T5321Fun(normal) 258,484,744 -1.9% T8095(normal) 770,532,232 -2.7% T9630(normal) 858,423,408 -14.5% GOOD T9872c(normal) 1,591,709,448 +0.7% info_table_map_perf(normal) 19,700,614,458 -1.3% geo. mean -0.7% minimum -17.2% maximum +1.1% Metric Decrease: CoOpt_Singletons T12227 T12545 T15703 T18223 T18730 T21839c T5030 T9630 - - - - - 55 changed files: - compiler/GHC/Core.hs - compiler/GHC/Core/Coercion.hs - compiler/GHC/Core/Coercion/Opt.hs - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Make.hs - compiler/GHC/Core/Opt/Arity.hs - compiler/GHC/Core/Opt/ConstantFold.hs - compiler/GHC/Core/Opt/FloatIn.hs - compiler/GHC/Core/Opt/FloatOut.hs - compiler/GHC/Core/Opt/OccurAnal.hs - compiler/GHC/Core/Opt/Simplify/Env.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Core/Opt/Simplify/Utils.hs - compiler/GHC/Core/Opt/SpecConstr.hs - compiler/GHC/Core/Opt/Specialise.hs - compiler/GHC/Core/Ppr.hs - compiler/GHC/Core/Rules.hs - compiler/GHC/Core/SimpleOpt.hs - compiler/GHC/Core/TyCo/Subst.hs - compiler/GHC/CoreToStg/Prep.hs - compiler/GHC/Data/List/SetOps.hs - compiler/GHC/Driver/Config/Core/Lint.hs - compiler/GHC/HsToCore/Pmc/Solver.hs - compiler/GHC/IfaceToCore.hs - compiler/GHC/Types/Id/Make.hs - testsuite/tests/codeGen/should_compile/T25177.stderr - testsuite/tests/deSugar/should_compile/T13208.stdout - testsuite/tests/linters/notes.stdout - testsuite/tests/numeric/should_compile/T15547.stderr - testsuite/tests/numeric/should_compile/T20347.stderr - testsuite/tests/numeric/should_compile/T20374.stderr - testsuite/tests/numeric/should_compile/T20376.stderr - + testsuite/tests/perf/compiler/T26989.hs - + testsuite/tests/perf/compiler/T26989a.hs - testsuite/tests/perf/compiler/all.T - testsuite/tests/printer/T18052a.stderr - testsuite/tests/simplCore/should_compile/DsSpecPragmas.stderr - testsuite/tests/simplCore/should_compile/RewriteHigherOrderPatterns.stderr - testsuite/tests/simplCore/should_compile/T15205.stderr - testsuite/tests/simplCore/should_compile/T18668.stderr - testsuite/tests/simplCore/should_compile/T19246.stderr - testsuite/tests/simplCore/should_compile/T19599.stderr - testsuite/tests/simplCore/should_compile/T19599a.stderr - testsuite/tests/simplCore/should_compile/T21917.stderr - testsuite/tests/simplCore/should_compile/T23074.stderr - testsuite/tests/simplCore/should_compile/T24359a.stderr - testsuite/tests/simplCore/should_compile/T25160.stderr - testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-32 - testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-64 - testsuite/tests/simplCore/should_compile/T26051.stderr - testsuite/tests/simplCore/should_compile/T26116.stderr - testsuite/tests/simplCore/should_compile/T8331.stderr - testsuite/tests/simplCore/should_compile/T8848a.stderr - testsuite/tests/simplCore/should_compile/spec004.stderr - testsuite/tests/typecheck/should_compile/T13032.stderr The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/710a4f21b994c26970ff7b817124fc31... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/710a4f21b994c26970ff7b817124fc31... You're receiving this email because of your account on gitlab.haskell.org.