#15338: ghc-pkg misbehaves after possible miscompilation on m68k and sh4 -------------------------------------+------------------------------------- Reporter: glaubitz | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 Resolution: | Keywords: Operating System: Linux | Architecture: m68k Type of failure: Incorrect result | Test Case: at runtime | Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4959 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Sergei Trofimovich <slyfox@…>): In [changeset:"8ec48990fee9e245bb2fe40dc6f65b61b8612157/ghc" 8ec48990/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="8ec48990fee9e245bb2fe40dc6f65b61b8612157" driver: skip -Bsymbolic on unregisterised targets (Trac #15338) Trac #15338 is yet another example where -Bsymbolic breaks semantics of a C program: global variable duplication happens and unsafePerformIO creates two stdout copies. When -Bsymbolic is not used both C compiler and linker agree on how global variables are handled. In case of sh4 it consists on a few assertions: 1. global variable is exported from shared library 2. code is referred to this variable via GOT-like mechanism to allow interposition 3. global variable is present .bss section on an executable (as an R_*_COPY relocation: symbol contents is copied at executable startup time) 4. and symbol in executable interposes symbol in shared library. This way both code in shared library and code in executable refer to a copy of global variable in .bss section of an executable. Unfortunately -Bsymbolic option breaks assumption [2.] and generates direct references to the symbol. This causes mismatch between values seen from executable and values seen from shared library code. This change disables '-Bsymbolic' for unregisterised targets. Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org> Test Plan: test 'ghc-pkg --version | cat' to emit data Reviewers: simonmar, bgamari, jrtc27 Reviewed By: jrtc27 Subscribers: rwbarton, thomie, carter GHC Trac Issues: #15338 Differential Revision: https://phabricator.haskell.org/D4959 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15338#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler