Undefined reference to __atomic_store_8

[Gleb Popov]

On Sun, Aug 9, 2020 at 7:43 PM Konstantin Belousov <kostikbel at gmail.com>
wrote:

> I do not believe there were any change in the toolchain between p2 and p7,
> this is more likely indicates some fluctuation in the build.  The only
> change that could be even remotely declared as possibly related is
> EN-20:10.build r360473.
>

Right, I was using a wrong set of port's OPTIONS that hide the problem.

Indeed you need to look at the .o files that reference _8 symbol.  I would
> closely look at the compilation command used for them, for start.
>

After digging it a bit I found that the following command

cc -x c
/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/libraries/ghc-prim/cbits/atomic.c
-o /tmp/ghc_1.s -fno-PIC -Wimplicit -S \
-include
/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/includes/dist-install/build/ghcversion.h
-I/usr/local/include \
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/libraries/base/include \
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/libraries/base/dist-install/build/include
\
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/libraries/base/dist-install/build/dist-install/build/include
\
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/libraries/integer-gmp/include
\
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/libraries/integer-gmp/dist-install/build/include
\
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/libraries/integer-gmp/dist-install/build/dist-install/build/include
\
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/rts/dist/build
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/includes \
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/includes/dist-derivedconstants/header
\
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/includes/dist-install/build \
-march=i686 -U__i686

produce an assembly file with

calll   __atomic_load_8

instruction.

The value of -march flag seems to be ignored.

Interestingly, previous version of GHC calls C compiler in the following
way:

cc -U__i686 '-march=i686' -fno-stack-protector -DTABLES_NEXT_TO_CODE
'-march=i686' -x c
/wrkdirs/usr/ports/lang/ghc/work/ghc-8.10.1/libraries/ghc-prim/cbits/atomic.c
-o /tmp/ghc_1.s -Wimplicit -S \
-include
/wrkdirs/usr/ports/lang/ghc/work/ghc-8.6.5-boot/lib/ghc-8.6.5/include/ghcversion.h
\
-I/usr/local/include \
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.6.5-boot/lib/ghc-8.6.5/base-4.12.0.0/include
\
-I/wrkdirs/usr/ports/lang/ghc/work/ghc-8.6.5-boot/lib/ghc-8.6.5/include

And this command produces an assembly without calls to __atomic_load_8

Any ideas what makes it appear?