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@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)$
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