[Git][ghc/ghc][wip/T26746] 10 commits: Don't re-use stack slots for growing registers

Simon Peyton Jones pushed to branch wip/T26746 at Glasgow Haskell Compiler / GHC Commits: 023c301c by sheaf at 2026-01-13T04:57:30-05:00 Don't re-use stack slots for growing registers This commit avoids re-using a stack slot for a register that has grown but already had a stack slot. For example, suppose we have stack slot assigments %v1 :: FF64 |-> StackSlot 0 %v2 :: FF64 |-> StackSlot 1 Later, we start using %v1 at a larger format (e.g. F64x2) and we need to spill it again. Then we **must not** use StackSlot 0, as a spill at format F64x2 would clobber the data in StackSlot 1. This can cause some fragmentation of the `StackMap`, but that's probably OK. Fixes #26668 - - - - - d0966e64 by fendor at 2026-01-13T04:58:11-05:00 Remove `traceId` from ghc-pkg executable - - - - - 20d7efec by Simon Peyton Jones at 2026-01-13T12:41:22-05:00 Make SpecContr rules fire a bit later See #26615 and Note [SpecConstr rule activation] - - - - - 8bc4eb8c by Andrew Lelechenko at 2026-01-13T12:42:03-05:00 Upgrade mtl submodule to 2.3.2 Fixes #26656 - - - - - c94aaacd by Cheng Shao at 2026-01-13T12:42:44-05:00 compiler: remove iserv and only use on-demand external interpreter This patch removes `iserv` from the tree completely. Hadrian would no longer build or distribute `iserv`, and the GHC driver would use the on-demand external interpreter by default when invoked with `-fexternal-interpreter`, without needing to specify `-pgmi ""`. This has multiple benefits: - It allows cleanup of a lot of legacy hacks in the hadrian codebase. - It paves the way for running cross ghc's iserv via cross emulator (#25523), fixing TH/ghci support for cross targets other than wasm/js. - - - - - c1fe0097 by Peter Trommler at 2026-01-14T03:54:49-05:00 PPC NCG: Fix shift right MO code The shift amount in shift right [arithmetic] MOs is machine word width. Therefore remove unnecessary zero- or sign-extending of shift amount. It looks harmless to extend the shift amount argument because the shift right instruction uses only the seven lowest bits (i. e. mod 128). But now we have a conversion operation from a smaller type to word width around a memory load at word width. The types are not matching up but there is no check done in CodeGen. The necessary conversion from word width down to the smaller width would be translated into a no-op on PowerPC anyway. So all seems harmless if it was not for a small optimisation in getRegister'. In getRegister' a load instruction with the smaller width of the conversion operation was generated. This loaded the most significant bits of the word in memory on a big-endian platform. These bits were zero and hence shift right was used with shift amount zero and not one as required in test Sized. Fixes #26519 - - - - - 2dafc65a by Cheng Shao at 2026-01-14T03:55:31-05:00 Tree-wide cleanup of cygwin logic GHC has not supported cygwin for quite a few years already, and will not resume support in the forseeable future. The only supported windows toolchain is clang64/clangarm64 of the msys2 project. This patch cleans up the unused cygwin logic in the tree. Co-authored-by: Codex - - - - - 66b96e2a by Teo Camarasu at 2026-01-14T03:56:13-05:00 Set default eventlog-flush-interval to 5s Resolves #26707 - - - - - d0254579 by Andrew Lelechenko at 2026-01-14T03:56:53-05:00 Document when -maxN RTS option was added - - - - - 4a01ec30 by Simon Peyton Jones at 2026-01-14T10:22:12+00:00 Improve newtype unwrapping Ticket #26746 describes several relatively-minor shortcomings of newtype unwrapping. This MR addresses them, while also (arguably) simplifying the code a bit. See new Note [Solving newtype equalities: overview] and Note [Decomposing newtype equalities] and Note [Eager newtype decomposition] and Note [Even more eager newtype decomposition] - - - - - 82 changed files: - CODEOWNERS - cabal.project-reinstall - compiler/GHC/CmmToAsm/PPC/CodeGen.hs - compiler/GHC/CmmToAsm/Reg/Linear.hs - compiler/GHC/CmmToAsm/Reg/Linear/StackMap.hs - compiler/GHC/Core/FamInstEnv.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/Opt/WorkWrap.hs - compiler/GHC/Core/Rules.hs - compiler/GHC/Core/Unfold/Make.hs - compiler/GHC/Driver/MakeFile.hs - compiler/GHC/Runtime/Interpreter/Init.hs - compiler/GHC/Settings/IO.hs - compiler/GHC/SysTools/Terminal.hs - compiler/GHC/Tc/Instance/Family.hs - compiler/GHC/Tc/Solver/Equality.hs - compiler/GHC/Tc/Solver/Monad.hs - configure.ac - docs/users_guide/9.16.1-notes.rst - docs/users_guide/ghci.rst - docs/users_guide/packages.rst - docs/users_guide/phases.rst - docs/users_guide/using-concurrent.rst - docs/users_guide/win32-dlls.rst - driver/ghci/ghci.c - driver/utils/cwrapper.c - driver/utils/isMinTTY.c - hadrian/bindist/cwrappers/cwrapper.c - hadrian/doc/user-settings.md - hadrian/src/Packages.hs - hadrian/src/Rules/BinaryDist.hs - hadrian/src/Rules/CabalReinstall.hs - hadrian/src/Rules/Generate.hs - hadrian/src/Rules/Program.hs - hadrian/src/Rules/Test.hs - hadrian/src/Settings/Builders/Ghc.hs - hadrian/src/Settings/Default.hs - hadrian/src/Settings/Packages.hs - hadrian/src/Settings/Program.hs - libraries/base/tests/IO/T12010/cbits/initWinSock.c - libraries/ghc-internal/cbits/consUtils.c - libraries/ghc-internal/configure.ac - libraries/ghc-internal/src/GHC/Internal/ConsoleHandler.hsc - libraries/ghc-internal/src/GHC/Internal/IO/Handle.hs - libraries/mtl - m4/ghc_select_file_extensions.m4 - rts/RtsFlags.c - testsuite/driver/runtests.py - testsuite/driver/testglobals.py - testsuite/driver/testlib.py - testsuite/mk/test.mk - testsuite/tests/deriving/should_fail/T8984.stderr - testsuite/tests/deriving/should_fail/deriving-via-fail.stderr - testsuite/tests/deriving/should_fail/deriving-via-fail4.stderr - testsuite/tests/deriving/should_fail/deriving-via-fail5.stderr - − testsuite/tests/driver/T24731.hs - testsuite/tests/driver/all.T - testsuite/tests/rts/linker/rdynamic.hs - testsuite/tests/simplCore/should_compile/T14003.stderr - testsuite/tests/simplCore/should_compile/T19672.stderr - testsuite/tests/simplCore/should_compile/T21763.stderr - testsuite/tests/simplCore/should_compile/T21763a.stderr - + testsuite/tests/simplCore/should_compile/T26615.hs - + testsuite/tests/simplCore/should_compile/T26615.stderr - + testsuite/tests/simplCore/should_compile/T26615a.hs - testsuite/tests/simplCore/should_compile/T4908.stderr - testsuite/tests/simplCore/should_compile/all.T - testsuite/tests/simplCore/should_compile/spec-inline.stderr - + testsuite/tests/typecheck/should_compile/T26746.hs - testsuite/tests/typecheck/should_compile/all.T - testsuite/tests/typecheck/should_fail/T15801.stderr - testsuite/tests/typecheck/should_fail/T22924b.stderr - testsuite/tests/typecheck/should_fail/TcCoercibleFail.hs - testsuite/tests/typecheck/should_fail/TcCoercibleFail.stderr - testsuite/tests/typecheck/should_fail/all.T - utils/ghc-pkg/Main.hs - − utils/iserv/iserv.cabal.in - − utils/iserv/src/Main.hs The diff was not included because it is too large. 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