Apoorv Ingle pushed to branch wip/spj-apporv-Oct24 at Glasgow Haskell Compiler / GHC Commits: 79816cc4 by Rodrigo Mesquita at 2025-09-02T12:19:59-04:00 cleanup: Move dehydrateCgBreakInfo to Stg2Bc This no longer has anything to do with Core. - - - - - 53da94ff by Rodrigo Mesquita at 2025-09-02T12:19:59-04:00 rts/Disassembler: Fix spacing of BRK_FUN - - - - - 08c0cf85 by Rodrigo Mesquita at 2025-09-02T12:19:59-04:00 debugger: Fix bciPtr in Step-out We need to use `BCO_NEXT` to move bciPtr to ix=1, because ix=0 points to the instruction itself! I do not understand how this didn't crash before. - - - - - e7e021fa by Rodrigo Mesquita at 2025-09-02T12:19:59-04:00 debugger: Allow BRK_FUNs to head case continuation BCOs When we start executing a BCO, we may want to yield to the scheduler: this may be triggered by a heap/stack check, context switch, or a breakpoint. To yield, we need to put the stack in a state such that when execution is resumed we are back to where we yielded from. Previously, a BKR_FUN could only head a function BCO because we only knew how to construct a valid stack for yielding from one -- simply add `apply_interp_info` + the BCO to resume executing. This is valid because the stack at the start of run_BCO is headed by that BCO's arguments. However, in case continuation BCOs (as per Note [Case continuation BCOs]), we couldn't easily reconstruct a valid stack that could be resumed because we dropped too soon the stack frames regarding the value returned (stg_ret) and received (stg_ctoi) by that continuation. This is especially tricky because of the variable type and size return frames (e.g. pointer ret_p/ctoi_R1p vs a tuple ret_t/ctoi_t2). The trick to being able to yield from a BRK_FUN at the start of a case cont BCO is to stop removing the ret frame headers eagerly and instead keep them until the BCO starts executing. The new layout at the start of a case cont. BCO is described by the new Note [Stack layout when entering run_BCO]. Now, we keep the ret_* and ctoi_* frames when entering run_BCO. A BRK_FUN is then executed if found, and the stack is yielded as-is with the preserved ret and ctoi frames. Then, a case cont BCO's instructions always SLIDE off the headers of the ret and ctoi frames, in StgToByteCode.doCase, turning a stack like | .... | +---------------+ | fv2 | +---------------+ | fv1 | +---------------+ | BCO | +---------------+ | stg_ctoi_ret_ | +---------------+ | retval | +---------------+ | stg_ret_..... | +---------------+ into | .... | +---------------+ | fv2 | +---------------+ | fv1 | +---------------+ | retval | +---------------+ for the remainder of the BCO. Moreover, this more uniform approach of keeping the ret and ctoi frames means we need less ad-hoc logic concerning the variable size of ret_tuple vs ret_p/np frames in the code generator and interpreter: Always keep the return to cont. stack intact at the start of run_BCO, and the statically generated instructions will take care of adjusting it. Unlocks BRK_FUNs at the start of case cont. BCOs which will enable a better user-facing step-out (#26042) which is free of the bugs the current BRK_ALTS implementation suffers from (namely, using BRK_FUN rather than BRK_ALTS in a case cont. means we'll never accidentally end up in a breakpoint "deeper" than the continuation, because we stop at the case cont itself rather than on the first breakpoint we evaluate after it). - - - - - ade3c1e6 by Rodrigo Mesquita at 2025-09-02T12:19:59-04:00 BRK_FUN with InternalBreakLocs for code-generation time breakpoints At the start of a case continuation BCO, place a BRK_FUN. This BRK_FUN uses the new "internal breakpoint location" -- allowing us to come up with a valid source location for this breakpoint that is not associated with a source-level tick. For case continuation BCOs, we use the last tick seen before it as the source location. The reasoning is described in Note [Debugger: Stepout internal break locs]. Note how T26042c, which was broken because it displayed the incorrect behavior of the previous step out when we'd end up at a deeper level than the one from which we initiated step-out, is now fixed. As of this commit, BRK_ALTS is now dead code and is thus dropped. Note [Debugger: Stepout internal break locs] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Step-out tells the interpreter to run until the current function returns to where it was called from, and stop there. This is achieved by enabling the BRK_FUN found on the first RET_BCO frame on the stack (See [Note Debugger: Step-out]). Case continuation BCOs (which select an alternative branch) must therefore be headed by a BRK_FUN. An example: f x = case g x of <--- end up here 1 -> ... 2 -> ... g y = ... <--- step out from here - `g` will return a value to the case continuation BCO in `f` - The case continuation BCO will receive the value returned from g - Match on it and push the alternative continuation for that branch - And then enter that alternative. If we step-out of `g`, the first RET_BCO on the stack is the case continuation of `f` -- execution should stop at its start, before selecting an alternative. (One might ask, "why not enable the breakpoint in the alternative instead?", because the alternative continuation is only pushed to the stack *after* it is selected by the case cont. BCO) However, the case cont. BCO is not associated with any source-level tick, it is merely the glue code which selects alternatives which do have source level ticks. Therefore, we have to come up at code generation time with a breakpoint location ('InternalBreakLoc') to display to the user when it is stopped there. Our solution is to use the last tick seen just before reaching the case continuation. This is robust because a case continuation will thus always have a relevant breakpoint location: - The source location will be the last source-relevant expression executed before the continuation is pushed - So the source location will point to the thing you've just stepped out of - Doing :step-local from there will put you on the selected alternative (which at the source level may also be the e.g. next line in a do-block) Examples, using angle brackets (<<...>>) to denote the breakpoint span: f x = case <<g x>> {- step in here -} of 1 -> ... 2 -> ...> g y = <<...>> <--- step out from here ... f x = < ... 2 -> ...>> doing :step-local ... f x = case g x of 1 -> <<...>> <--- stop in the alternative 2 -> ... A second example based on T26042d2, where the source is a do-block IO action, optimised to a chain of `case expressions`. main = do putStrLn "hello1" <<f>> <--- step-in here putStrLn "hello3" putStrLn "hello4" f = do <> <--- step-out from here putStrLn "hello2.2" ... main = do putStrLn "hello1" <<f>> <--- end up here again, the previously executed expression putStrLn "hello3" putStrLn "hello4" doing step/step-local ... main = do putStrLn "hello1" f <> <--- straight to the next line putStrLn "hello4" Finishes #26042 - - - - - c66910c0 by Rodrigo Mesquita at 2025-09-02T12:19:59-04:00 debugger: Re-use the last BreakpointId whole in step-out Previously, to come up with a location to stop at for `:stepout`, we would store the location of the last BreakpointId surrounding the continuation, as described by Note [Debugger: Stepout internal break locs]. However, re-using just the location from the last source breakpoint isn't sufficient to provide the necessary information in the break location. Specifically, it wouldn't bind any variables at that location. Really, there is no reason not to re-use the last breakpoint wholesale, and re-use all the information we had there. Step-out should behave just as if we had stopped at the call, but s.t. continuing will not re-execute the call. This commit updates the CgBreakInfo to always store a BreakpointId, be it the original one or the one we're emulating (for step-out). It makes variable bindings on :stepout work - - - - - e4abed7b by sheaf at 2025-09-02T12:20:40-04:00 Revert accidental changes to hie.yaml - - - - - 003b715b by meooow25 at 2025-09-02T23:48:51+02:00 Adjust the strictness of Data.List.iterate' * Don't force the next element in advance when generating a (:). * Force the first element to WHNF like every other element. Now every element in the output list is forced to WHNF when the (:) containing it is forced. CLC proposal: https://github.com/haskell/core-libraries-committee/issues/335 - - - - - b2f6aad0 by Simon Hengel at 2025-09-03T04:36:10-04:00 Refactoring: More consistently use logOutput, logInfo, fatalErrorMsg - - - - - 60a16db7 by Rodrigo Mesquita at 2025-09-03T10:55:50+01:00 bytecode: Don't PUSH_L 0; SLIDE 1 1 While looking through bytecode I noticed a quite common unfortunate pattern: ... PUSH_L 0 SLIDE 1 1 We do this often by generically constructing a tail call from a function atom that may be somewhere arbitrary on the stack. However, for the special case that the function can be found directly on top of the stack, as part of the arguments, it's plain redundant to push then slide it. In this commit we add a small optimisation to the generation of tailcalls in bytecode. Simply: lookahead for the function in the stack. If it is the first thing on the stack and it is part of the arguments which would be dropped as we entered the tail call, then don't push then slide it. In a simple example (T26042b), this already produced a drastic improvement in generated code (left is old, right is with this patch): ```diff 3c3 < 2025-07-29 10:14:02.081277 UTC ---

2025-07-29 10:50:36.560949 UTC 160,161c160 < PUSH_L 0 < SLIDE 1 2

SLIDE 1 1

164,165d162 < PUSH_L 0 < SLIDE 1 1 175,176c172 < PUSH_L 0 < SLIDE 1 2 ---

SLIDE 1 1

179,180d174 < PUSH_L 0 < SLIDE 1 1 206,207d199 < PUSH_L 0 < SLIDE 1 1 210,211d201 < PUSH_L 0 < SLIDE 1 1 214,215d203 < PUSH_L 0 < SLIDE 1 1 218,219d205 < PUSH_L 0 < SLIDE 1 1 222,223d207 < PUSH_L 0 < SLIDE 1 1 ... 600,601c566 < PUSH_L 0 < SLIDE 1 2 ---

SLIDE 1 1

604,605d568 < PUSH_L 0 < SLIDE 1 1 632,633d594 < PUSH_L 0 < SLIDE 1 1 636,637d596 < PUSH_L 0 < SLIDE 1 1 640,641d598 < PUSH_L 0 < SLIDE 1 1 644,645d600 < PUSH_L 0 < SLIDE 1 1 648,649d602 < PUSH_L 0 < SLIDE 1 1 652,653d604 < PUSH_L 0 < SLIDE 1 1 656,657d606 < PUSH_L 0 < SLIDE 1 1 660,661d608 < PUSH_L 0 < SLIDE 1 1 664,665d610 < PUSH_L 0 < SLIDE 1 1 ``` I also compiled lib:Cabal to bytecode and counted the number of bytecode lines with `find dist-newstyle -name "*.dump-BCOs" -exec wc {} +`: with unoptimized core: 1190689 lines (before) - 1172891 lines (now) = 17798 less redundant instructions (-1.5% lines) with optimized core: 1924818 lines (before) - 1864836 lines (now) = 59982 less redundant instructions (-3.1% lines) - - - - - 8b2c72c0 by L0neGamer at 2025-09-04T06:32:03-04:00 Add Control.Monad.thenM and Control.Applicative.thenA - - - - - 39e1b7cb by Teo Camarasu at 2025-09-04T06:32:46-04:00 ghc-internal: invert dependency of GHC.Internal.TH.Syntax on Data.Data This means that Data.Data no longer blocks building TH.Syntax, which allows greater parallelism in our builds. We move the Data.Data.Data instances to Data.Data. Quasi depends on Data.Data for one of its methods, so, we split the Quasi/Q, etc definition out of GHC.Internal.TH.Syntax into its own module. This has the added benefit of splitting up this quite large module. Previously TH.Syntax was a bottleneck when compiling ghc-internal. Now it is less of a bottle-neck and is also slightly quicker to compile (since it no longer contains these instances) at the cost of making Data.Data slightly more expensive to compile. TH.Lift which depends on TH.Syntax can also compile quicker and no longer blocks ghc-internal finishing to compile. Resolves #26217 ------------------------- Metric Decrease: MultiLayerModulesTH_OneShot T13253 T21839c T24471 Metric Increase: T12227 ------------------------- - - - - - bdf82fd2 by Teo Camarasu at 2025-09-04T06:32:46-04:00 compiler: delete unused names in Builtins.Names.TH returnQ and bindQ are no longer used in the compiler. There was also a very old comment that referred to them that I have modernized - - - - - 41a448e5 by Ben Gamari at 2025-09-04T19:21:43-04:00 hadrian: Pass lib & include directories to ghc `Setup configure` - - - - - 46bb9a79 by Ben Gamari at 2025-09-04T19:21:44-04:00 rts/IPE: Fix compilation when zstd is enabled This was broken by the refactoring undertaken in c80dd91c0bf6ac034f0c592f16c548b9408a8481. Closes #26312. - - - - - 138a6e34 by sheaf at 2025-09-04T19:22:46-04:00 Make mkCast assertion a bit clearer This commit changes the assertion message that gets printed when one calls mkCast with a coercion whose kind does not match the type of the inner expression. I always found the assertion message a bit confusing, as it didn't clearly state what exactly was the error. - - - - - 9d626be1 by sheaf at 2025-09-04T19:22:46-04:00 Simplifier/rules: fix mistakes in Notes & comments - - - - - f7c556cc by Apoorv Ingle at 2025-09-07T14:55:06-05:00 This commit: - Streamlines implementations of `tcExpr` and `tcXExpr` to work on `XExpr` Calls `setInGeneratedCode` everytime the typechecker goes over an `XExpr` - Kills `VACtxt` (and its associated VAExpansion and VACall) datatype, it is subsumed by simply a SrcSpan. - Kills the function `addHeadCtxt` as it is now mearly setting a location - The function `tcValArgs` does its own argument number management - Makes `splitHsApps` not look through `XExpr` - `tcExprSigma` is called if the head of the expression after calling `splitHsApps` turns out to be an `XExpr` - Removes location information from `OrigPat` payload - Removes special case of tcBody from `tcLambdaMatches` - Removes special case of `dsExpr` for `ExpandedThingTc` - Moves `setQLInstLevel` inside `tcInstFun` - Rename `HsThingRn` to `SrcCodeCtxt` - Kills `tcl_in_gen_code` and `tcl_err_ctxt`. It is subsumed by `ErrCtxtStack` - Kills `ExpectedFunTyOrig`. It is subsumed by `CtOrigin` - Fixes `CtOrigin` for `HsProjection` case in `exprCtOrigin`. It was previously assigned to be `SectionOrigin`. It is now just the expression - Adds a new `CtOrigin.ExpansionOrigin` for storing the original syntax - Adds a new `CtOrigin.ExpectedTySyntax` as a replacement for `ExpectedTySyntaxOp`. Cannot kill the former yet because of `ApplicativeDo` - Renames `tcMonoExpr` -> `tcMonoLExpr`, `tcMonoExprNC` -> `tcMonoLExpr` - Renames `EValArg`, `EValArgQL` fields: `ea_ctxt` -> `ea_loc_span` and `eaql_ctx` -> `eaql_loc_span` Notes added [Error Context Stack] Notes updated Note [Expanding HsDo with XXExprGhcRn] ------------------------- Metric Decrease: T9020 ------------------------- - - - - - 143 changed files: - compiler/GHC/Builtin/Names/TH.hs - compiler/GHC/ByteCode/Asm.hs - compiler/GHC/ByteCode/Breakpoints.hs - compiler/GHC/ByteCode/Instr.hs - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Opt/Simplify.hs - compiler/GHC/Core/Opt/SpecConstr.hs - compiler/GHC/Core/Rules.hs - compiler/GHC/Core/Utils.hs - compiler/GHC/CoreToIface.hs - compiler/GHC/Data/IOEnv.hs - compiler/GHC/Driver/CodeOutput.hs - compiler/GHC/Driver/Pipeline/Execute.hs - compiler/GHC/Hs.hs - compiler/GHC/Hs/Expr.hs - compiler/GHC/Hs/Instances.hs - compiler/GHC/HsToCore/Expr.hs - compiler/GHC/HsToCore/Match.hs - compiler/GHC/HsToCore/Pmc.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/HsToCore/Ticks.hs - compiler/GHC/Iface/Load.hs - compiler/GHC/Linker/Loader.hs - compiler/GHC/Rename/Expr.hs - compiler/GHC/Rename/Splice.hs - compiler/GHC/Runtime/Debugger/Breakpoints.hs - compiler/GHC/Runtime/Eval.hs - compiler/GHC/Stg/Lint.hs - compiler/GHC/StgToByteCode.hs - compiler/GHC/Tc/Errors.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Gen/App.hs - + compiler/GHC/Tc/Gen/App.hs-boot - compiler/GHC/Tc/Gen/Do.hs - compiler/GHC/Tc/Gen/Expr.hs - compiler/GHC/Tc/Gen/Expr.hs-boot - compiler/GHC/Tc/Gen/Head.hs - compiler/GHC/Tc/Gen/Match.hs - compiler/GHC/Tc/Gen/Pat.hs - compiler/GHC/Tc/Gen/Splice.hs - compiler/GHC/Tc/Gen/Splice.hs-boot - compiler/GHC/Tc/Instance/Class.hs - compiler/GHC/Tc/Types/ErrCtxt.hs - compiler/GHC/Tc/Types/LclEnv.hs - compiler/GHC/Tc/Types/Origin.hs - compiler/GHC/Tc/Types/TH.hs - compiler/GHC/Tc/Utils/Monad.hs - compiler/GHC/Tc/Utils/Unify.hs - ghc/GHCi/UI.hs - hadrian/src/Settings/Packages.hs - hie.yaml - libraries/base/changelog.md - libraries/base/src/Control/Applicative.hs - libraries/base/src/Control/Monad.hs - libraries/base/src/Data/Array/Byte.hs - libraries/base/src/Data/Fixed.hs - + libraries/ghc-boot-th/GHC/Boot/TH/Monad.hs - libraries/ghc-boot-th/ghc-boot-th.cabal.in - libraries/ghc-internal/ghc-internal.cabal.in - libraries/ghc-internal/src/GHC/Internal/Base.hs - libraries/ghc-internal/src/GHC/Internal/Control/Monad.hs - libraries/ghc-internal/src/GHC/Internal/Data/Data.hs - libraries/ghc-internal/src/GHC/Internal/List.hs - libraries/ghc-internal/src/GHC/Internal/TH/Lib.hs - libraries/ghc-internal/src/GHC/Internal/TH/Lift.hs - + libraries/ghc-internal/src/GHC/Internal/TH/Monad.hs - libraries/ghc-internal/src/GHC/Internal/TH/Quote.hs - libraries/ghc-internal/src/GHC/Internal/TH/Syntax.hs - libraries/ghci/GHCi/Message.hs - libraries/ghci/GHCi/Run.hs - libraries/ghci/GHCi/TH.hs - libraries/template-haskell/Language/Haskell/TH/Quote.hs - libraries/template-haskell/Language/Haskell/TH/Syntax.hs - 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testsuite/tests/rep-poly/RepPolyDoBind.stderr - testsuite/tests/rep-poly/RepPolyDoBody1.stderr - testsuite/tests/rep-poly/RepPolyDoBody2.stderr - testsuite/tests/rep-poly/RepPolyRecordUpdate.stderr - testsuite/tests/splice-imports/SI29.stderr - testsuite/tests/th/T11452.stderr - testsuite/tests/th/T15321.stderr - testsuite/tests/th/T7276.stderr - testsuite/tests/th/TH_NestedSplicesFail3.stderr - testsuite/tests/th/TH_NestedSplicesFail4.stderr - testsuite/tests/typecheck/should_compile/T14590.stderr - + testsuite/tests/typecheck/should_compile/T25996.hs - testsuite/tests/typecheck/should_compile/valid_hole_fits.stderr - testsuite/tests/typecheck/should_fail/DoExpansion1.stderr - testsuite/tests/typecheck/should_fail/DoExpansion2.stderr - testsuite/tests/typecheck/should_fail/T10971d.stderr - testsuite/tests/typecheck/should_fail/T13311.stderr - testsuite/tests/typecheck/should_fail/T24064.stderr - + testsuite/tests/typecheck/should_fail/T25970.hs - + testsuite/tests/typecheck/should_fail/T25996.hs - testsuite/tests/typecheck/should_fail/T3323.stderr - testsuite/tests/typecheck/should_fail/T3613.stderr - testsuite/tests/typecheck/should_fail/T7851.stderr - testsuite/tests/typecheck/should_fail/T8603.stderr - testsuite/tests/typecheck/should_fail/T9612.stderr - testsuite/tests/typecheck/should_fail/tcfail102.stderr - testsuite/tests/typecheck/should_fail/tcfail128.stderr - testsuite/tests/typecheck/should_fail/tcfail168.stderr - testsuite/tests/warnings/should_fail/CaretDiagnostics1.stderr The diff was not included because it is too large. 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