Hi Ilias! On Wed, 2023-09-20 at 14:54 +0300, Ilias Tsitsimpis wrote: > Thanks for working on this, comments inline.
Thanks for the useful hints! > On Wed, Sep 20, 2023 at 12:15PM, John Paul Adrian Glaubitz wrote: > > I have been bisecting this issue but in order to be successful, I need a > > simple > > reproducer which isn't trivial since I cannot just reuse the build > > directory of > > an unsuccessful build due to the changing Haskell libraries for different > > GHC > > versions. > > > > Ideally, we should have a single command line with GHC which will trigger > > the > > segmentation fault. > > Are you bisecting the segfault issue? If yes, then a simple reproducer > would be to try and compile haskell-random. > > Since you already have cabal-install on your system, you can do > something like: > > $ cabal install --with-ghc=/usr/bin/ghc --with-ghc-pkg=/usr/bin/ghc-pkg > random-1.2.1.1 > > (replace ghc and ghc-pkg with the ones you have built). Thanks, this is the exact reproducer I need. I can reproduce the crash using this command line inside a 32-bit PowerPC chroot on perotto with ghc 9.0.2. > > To bisect, I have done the following: > > > > # git bisect start > > # git bisect good ghc-8.10.7-release > > # git bisect bad ghc-9.2.7-release > > Since this issue is also present in ghc-9.0.2, maybe we can start from > there. Yes, that's what I am trying now as well. > > # git submodule update --init > > # ./boot ; python3 boot > > # echo "SRC_HC_OPTS += -lffi -latomic -optl-pthread" >> mk/build.mk && \ > > echo "Stage1Only := YES" >> mk/build.mk && \ > > echo 'utils/genprimopcode_CONFIGURE_OPTS += "-f-build-tool-depends"' \ > > >> mk/build.mk && echo 'compiler_CONFIGURE_OPTS += > > "-f-build-tool-depends"' \ > > >> mk/build.mk && echo 'utils/hpc_CONFIGURE_OPTS += > > "-f-build-tool-depends"' \ > > >> mk/build.mk && echo "HADDOCK_DOCS := NO" >> mk/build.mk \ > > && echo "BUILD_SPHINX_HTML := NO" >> mk/build.mk && echo > > "BUILD_SPHINX_PDF := NO" \ > > >> mk/build.mk > > # ./configure && make -j32 > > > > For newer versions, the build has to be performed with Hadrian, so the last > > step > > would be: > > > > # ./hadrian/build -j > > Keep in mind that hadrian doesn't take into account 'mk/build.mk'. You > will have to configure hadrian in the same way, see also > https://www.haskell.org/ghc/blog/20220805-make-to-hadrian.html. Thanks, good to know! > Let me summarize the current state to make sure we are not missing > anything: > > 1. GHC 9.0.2 with the native code generator is currently broken on > powerpc and segfaults while building (at least) haskell-random and > GHC-9.4.6. Strangely enough, we can compile GHC 9.0.2 itself. > > 2. An unregisterised GHC 9.0.2 is *also* broken on powerpc, producing > code that overflows integers. We are also seeing unregisterised GHC > 9.4.6 on i386 being broken, since the tests for haskell-quickcheck fail > (see > https://buildd.debian.org/status/package.php?p=haskell-quickcheck&suite=sid). > The plan for i386 is to registerise GHC and use the LLVM backend by > default (to avoid the baseline violation). I see. > 3. We cannot cross-compile GHC 9.4 and newer any more (we are discussing > this here as well https://gitlab.haskell.org/ghc/ghc/-/issues/23975). This can be trivially fixed with the help of this patch: > https://gitlab.haskell.org/ghc/ghc/-/commit/9cb385098f2dfd647c13ca509d71786c56277cff > Given the above, I can think of the following: > > 1. Fix the native code generator in GHC 9.0.2 > 2. Fix unregisterised GHCs on 32-bit architectures FWIW, I am seeing the overflow on 32-bit PowerPC only. I don't see it on m68k, for example. > 3. Try and use the LLVM backend in GHC 9.0.2 on powerpc, and see if this > produces valid code and allows us to compile GHC 9.4.6. Ah, that's actually a possible approach to take. FWIW, I have not been able to build GHC from git on 32-bit PowerPC even for 8.10.7. I assume, I will need to add some of Debian's patches on top of vanilla GHC in order to get the build to succeed. Trying to build GHC 9.0.2 fails for example with: > http://paste.debian.net/hidden/31954e9a/ > For the record, I have started working on migrating GHC in Debian to use > the new Hadrian build system, you can find the latest code here > https://salsa.debian.org/haskell-team/DHG_packages/-/tree/hadrian. I am > at a really good state right now where I can build GHC, and doing a lot > of tests to verify I haven't missed anything. If you are working on GHC > right now as well, I would appreciate if you can take a look, and/or > start using this branch for all your tests, so we catch any errors > early. I want to get the build issue on 32-bit PowerPC sorted out first. Adrian -- .''`. John Paul Adrian Glaubitz : :' : Debian Developer `. `' Physicist `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
