Cheng Shao pushed to branch wip/bytecode-serialize-3 at Glasgow Haskell Compiler / GHC Commits: 18036d52 by Simon Peyton Jones at 2025-08-11T11:31:20-04:00 Take more care in zonkEqTypes on AppTy/AppTy This patch fixes #26256. See Note [zonkEqTypes and the PKTI] in GHC.Tc.Solver.Equality - - - - - c8d76a29 by Zubin Duggal at 2025-08-11T11:32:02-04:00 ci: upgrade bootstrap compiler on windows to 9.10.1 - - - - - 442a31bf by Rodrigo Mesquita at 2025-08-12T08:32:40+00:00 cleanup: Move dehydrateCgBreakInfo to Stg2Bc This no longer has anything to do with Core. - - - - - 0143961b by Rodrigo Mesquita at 2025-08-12T08:32:40+00:00 rts/Disassembler: Fix spacing of BRK_FUN - - - - - 79c53983 by Rodrigo Mesquita at 2025-08-12T08:32:40+00:00 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. - - - - - 879b29d2 by Rodrigo Mesquita at 2025-08-12T08:32:40+00:00 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). - - - - - 0704a9d7 by Rodrigo Mesquita at 2025-08-12T08:32:40+00:00 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 = <<case g x of <--- end up here, whole case highlighted 1 -> ... 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 <<putStrLn "hello2.1">> <--- 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 <<putStrLn "hello3">> <--- straight to the next line putStrLn "hello4" Finishes #26042 - - - - - df83b0f5 by Rodrigo Mesquita at 2025-08-12T08:32:40+00:00 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 - - - - - ad864ef9 by Cheng Shao at 2025-08-12T11:40:13+00:00 compiler: implement and test bytecode serialization logic - - - - - 48 changed files: - .gitlab/generate-ci/gen_ci.hs - .gitlab/jobs.yaml - compiler/GHC/Builtin/PrimOps.hs - compiler/GHC/ByteCode/Asm.hs - compiler/GHC/ByteCode/Breakpoints.hs - compiler/GHC/ByteCode/Instr.hs - + compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/ByteCode/Types.hs - compiler/GHC/CoreToIface.hs - compiler/GHC/Data/FlatBag.hs - compiler/GHC/Data/SmallArray.hs - compiler/GHC/Driver/Main.hs - compiler/GHC/HsToCore/Breakpoints.hs - compiler/GHC/Linker/Loader.hs - compiler/GHC/Runtime/Debugger/Breakpoints.hs - compiler/GHC/Runtime/Eval.hs - compiler/GHC/StgToByteCode.hs - compiler/GHC/Tc/Solver/Equality.hs - compiler/GHC/Types/SptEntry.hs - compiler/GHC/Types/Tickish.hs - compiler/GHC/Utils/Binary.hs - compiler/ghc.cabal.in - ghc/GHCi/UI.hs - libraries/ghci/GHCi/Run.hs - rts/Disassembler.c - rts/Interpreter.c - rts/Profiling.c - rts/include/rts/Bytecodes.h - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - testsuite/tests/ghci.debugger/scripts/T26042b.script - testsuite/tests/ghci.debugger/scripts/T26042b.stdout - testsuite/tests/ghci.debugger/scripts/T26042c.script - testsuite/tests/ghci.debugger/scripts/T26042c.stdout - + testsuite/tests/ghci.debugger/scripts/T26042d2.hs - + testsuite/tests/ghci.debugger/scripts/T26042d2.script - + testsuite/tests/ghci.debugger/scripts/T26042d2.stdout - testsuite/tests/ghci.debugger/scripts/T26042e.stdout - testsuite/tests/ghci.debugger/scripts/T26042f.script - testsuite/tests/ghci.debugger/scripts/T26042f1.stdout - testsuite/tests/ghci.debugger/scripts/T26042f2.stdout - testsuite/tests/ghci.debugger/scripts/T26042g.stdout - testsuite/tests/ghci.debugger/scripts/all.T - + testsuite/tests/partial-sigs/should_compile/T26256.hs - + testsuite/tests/partial-sigs/should_compile/T26256.stderr - testsuite/tests/partial-sigs/should_compile/all.T - + testsuite/tests/typecheck/should_compile/T26256a.hs - testsuite/tests/typecheck/should_compile/all.T The diff was not included because it is too large. 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