I fixed this. commit 3f0d4530a716b6db3c20b63825b56597e08b0d5e Author: Simon Peyton Jones Date: Fri Nov 22 10:12:55 2013 +0000 When removing unreachable code, remove unreachable info tables too This bug only shows up when you are using proc-point splitting. What was happening was: * We generate a proc-point for the stack check * And an info table * We eliminate the stack check because it's redundant * And the dangling info table caused a panic in CmmBuildInfoTables.bundle | -----Original Message----- | From: Simon Marlow [mailto:marlowsd@gmail.com] | Sent: 17 November 2013 09:57 | To: Simon Peyton-Jones; ghc-devs@haskell.org | Subject: Re: bundle panic | | On 16/11/13 00:16, Simon Peyton-Jones wrote: | > I've looked into this myself. I don't think it's actually anything | > wrong in gmp-wrappers. It's because CmmBuildInfoTables expects all | the | > info tables in the (CmmProc info_tbls lbl g) to be defined in the | graph g. | > | > But Jan's new optimisation to the stack overflow check (Note [Always | > false stack check] in CmmLayoutStack) ends up dropping a conditional | > branch, so a call to gc is eliminated, and hence a proc point is | > eliminated, and we end up with an unused thing in info_tbls, which | > confuses CmmBuildInfoTables | | > Sigh. I don't know why this only happens on Windows. I'm looking into | a fix | | Perhaps this is a problem that only shows up with proc points, which is | why you wouldn't see it on x86_64/Linux. Let me know if you get stuck | and I'll try to look into it. | | FYI eliminating always-false stack checks is not new, it was temporarily | broken by: | | commit 94125c97e49987e91fa54da6c86bc6d17417f5cf | Author: Jan Stolarek | Date: Wed Oct 16 09:45:56 2013 +0200 | | Generate (old + 0) instead of Sp in stack checks | | and then fixed up by: | | commit 1cf0c8ad321d1d358cbec46d35be02566faf2d00 | Author: Jan Stolarek | Date: Thu Oct 17 23:17:06 2013 +0200 | | Optimise stack checks that are always false | | Cheers, | Simon | | | > | > | > Simon | > | > *From:*Simon Peyton-Jones | > *Sent:* 15 November 2013 22:18 | > *To:* ghc-devs@haskell.org | > *Subject:* bundle panic | > | > Windows build is failing again in a new way. It was fine a couple of | > days ago. Does this ring any bells? | > | > ghc-stage1.exe: panic! (the 'impossible' happened) | > | > (GHC version 7.7.20131107 for i386-unknown-mingw32): | > | > bundle | > | > Simon | > | > "inplace/bin/ghc-stage1.exe" -static -H32m -O -Werror -Wall -H64m | > -O0 -package-name integer-gmp-0.5.1.0 -hide-all-packages -i | > -ilibraries/integer-gmp/. -ilibraries/integer-gmp/dist-install/build | > -ilibraries/integer-gmp/dist-install/build/autogen | > -Ilibraries/integer-gmp/dist-install/build | > -Ilibraries/integer-gmp/dist-install/build/autogen | > -Ilibraries/integer-gmp/. -optP-include | > -optPlibraries/integer-gmp/dist-install/build/autogen/cabal_macros.h | > -package ghc-prim-0.3.1.0 -Wall -package-name integer-gmp - | XHaskell2010 | > -dcore-lint -no-user-package-db -rtsopts | > -Ilibraries/integer-gmp/mkGmpDerivedConstants/dist -c | > libraries/integer-gmp/cbits/gmp-wrappers.cmm -o | > libraries/integer-gmp/dist-install/build/cbits/gmp-wrappers.o | > | > ghc-stage1.exe: panic! (the 'impossible' happened) | > | > (GHC version 7.7.20131107 for i386-unknown-mingw32): | > | > bundle | > | > c8 integer_cmm_importIntegerFromByteArrayzh [(c8, | > | > label: block{v | c8}_info | > | > rep:StackRep | [False, | > True, True, True]), | > | > (cg, | > | > label: block{v | cg}_info | > | > rep:StackRep | [False, | > True, True, True])] | > | > Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug | > | > HEAD (master)$ | > | > | > | > _______________________________________________ | > ghc-devs mailing list | > ghc-devs@haskell.org | > http://www.haskell.org/mailman/listinfo/ghc-devs | >