[commit: ghc] master: Re-add more primops for atomic ops on byte arrays (4ee4ab0)

[Páli Gábor János]

Hello Johan,

2014-06-30 22:13 GMT+02:00  <git at git.haskell.org>:
> commit 4ee4ab01c1d97845aecb7707ad2f9a80933e7a49
> Author: Johan Tibell <johan.tibell at gmail.com>
> Date:   Fri Jun 27 13:48:24 2014 +0200
>
>     Re-add more primops for atomic ops on byte arrays

It seems this change breaks the build on FreeBSD/i386 [1]:

"inplace/bin/ghc-stage1" -o
utils/dll-split/dist-install/build/tmp/dll-split -hisuf dyn_hi -osuf
dyn_o -hcsuf dyn_hc -fPIC -dynamic  -H32m -O    -hide-all-packages -i
-iutils/dll-split/. -iutils/dll-split/dist-install/build
-iutils/dll-split/dist-install/build/autogen
-Iutils/dll-split/dist-install/build
-Iutils/dll-split/dist-install/build/autogen     -optP-include
-optPutils/dll-split/dist-install/build/autogen/cabal_macros.h
-package base-4.7.1.0 -package containers-0.5.5.1 -package
filepath-1.3.0.2 -XHaskell2010  -no-user-package-db -rtsopts
-odir utils/dll-split/dist-install/build -hidir
utils/dll-split/dist-install/build -stubdir
utils/dll-split/dist-install/build
-optl-L'/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/filepath/dist-install/build'
-optl-L'/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/containers/dist-install/build'
-optl-L'/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/deepseq/dist-install/build'
-optl-L'/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/array/dist-install/build'
-optl-L'/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/base/dist-install/build'
-optl-L'/usr/local/lib'
-optl-L'/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/integer-gmp/dist-install/build'
-optl-L'/usr/local/lib'
-optl-L'/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/ghc-prim/dist-install/build'
-optl-L'/usr/home/ghc-builder/work/builder/tempbuild/build/rts/dist/build'
-optl-liconv -optl-lcharset -optl-lgmp -optl-lm -optl-lrt
-optl-lpthread -fPIC -dynamic  -H32m -O    -hide-all-packages -i
-iutils/dll-split/. -iutils/dll-split/dist-install/build
-iutils/dll-split/dist-install/build/autogen
-Iutils/dll-split/dist-install/build
-Iutils/dll-split/dist-install/build/autogen     -optP-include
-optPutils/dll-split/dist-install/build/autogen/cabal_macros.h
-package base-4.7.1.0 -package containers-0.5.5.1 -package
filepath-1.3.0.2 -XHaskell2010  -no-user-package-db -rtsopts
-fno-use-rpaths -optl-Wl,-rpath -optl-Wl,'$ORIGIN/../filepath-1.3.0.2'
-optl-Wl,-rpath -optl-Wl,'$ORIGIN/../containers-0.5.5.1'
-optl-Wl,-rpath -optl-Wl,'$ORIGIN/../deepseq-1.3.0.2' -optl-Wl,-rpath
-optl-Wl,'$ORIGIN/../array-0.5.0.0' -optl-Wl,-rpath
-optl-Wl,'$ORIGIN/../base-4.7.1.0' -optl-Wl,-rpath
-optl-Wl,'$ORIGIN/../integer-gmp-0.5.1.0' -optl-Wl,-rpath
-optl-Wl,'$ORIGIN/../ghc-prim-0.3.1.0' -optl-Wl,-rpath
-optl-Wl,'$ORIGIN/../rts-1.0' -optl-Wl,-zorigin
utils/dll-split/dist-install/build/Main.dyn_o
/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/ghc-prim/dist-install/build/libHSghc-prim-0.3.1.0-ghc7.9.20140703.so:
undefined reference to `__sync_fetch_and_xor_8'
/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/ghc-prim/dist-install/build/libHSghc-prim-0.3.1.0-ghc7.9.20140703.so:
undefined reference to `__sync_fetch_and_and_8'
/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/ghc-prim/dist-install/build/libHSghc-prim-0.3.1.0-ghc7.9.20140703.so:
undefined reference to `__sync_fetch_and_nand_8'
/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/ghc-prim/dist-install/build/libHSghc-prim-0.3.1.0-ghc7.9.20140703.so:
undefined reference to `__sync_val_compare_and_swap_8'
/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/ghc-prim/dist-install/build/libHSghc-prim-0.3.1.0-ghc7.9.20140703.so:
undefined reference to `__sync_fetch_and_sub_8'
/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/ghc-prim/dist-install/build/libHSghc-prim-0.3.1.0-ghc7.9.20140703.so:
undefined reference to `__sync_fetch_and_add_8'
/usr/home/ghc-builder/work/builder/tempbuild/build/libraries/ghc-prim/dist-install/build/libHSghc-prim-0.3.1.0-ghc7.9.20140703.so:
undefined reference to `__sync_fetch_and_or_8'
collect2: error: ld returned 1 exit status

This probably due to the strict defaults of the FreeBSD of GCC, where
march=i386 is assumed, which does not support the required CMPXCHG8B
instruction.  One would need at least an i586 to get that.  It is not
observed on GNU/Linux as it allegedly defaults to i586 code
generation.

The trivial patch below makes this explicit so now it could build:

--- ghc-prim.cabal.orig 2014-07-03 03:06:16.000000000 +0200
+++ ghc-prim.cabal      2014-07-03 20:27:49.709087595 +0200
@@ -62,3 +62,6 @@
     -- We need to set the package name to ghc-prim (without a version number)
     -- as it's magic.
     ghc-options: -package-name ghc-prim
+    -- Due to CMPXCHG8B, we have to ask for Pentium code generation.
+    cc-options: -march=i586
+

However, my fellow developer, Konstantin Belousov pointed out that
using CMPXCHG8B would officially require checking for the
corresponding CPUID bit set, because that is what truly indicates the
presence of that instruction.


[1] http://haskell.inf.elte.hu/builders/freebsd-i386-head/304/10.html