bundle panic

[Simon Peyton-Jones]

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

Simon



From: Simon Peyton-Jones
Sent: 15 November 2013 22:18
To: ghc-devs at 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



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