Previously, we would set -fno-strict-aliasing only when
--enable-checking was given to configure but not
--enable-checking=all. The intent seems to have been to
only warn about strict aliasing violations when --enable-checking=all
is in use, but that there was no need to disable the strict-aliasing
diagnostics when -Werror was not enabled.
Unfortunately, -fno-strict-aliasing affects not only the diagnostics
emitted by the compiler, but also the code generation! So we were
leaving the normal (no --enable-checking) case with the compiler
assuming C's strict aliasing rules. The OpenAFS codebase has
historically not been strict-aliasing safe (for example,
commit
15e8678661ec49f5eac3954defad84c06b3e0164 refers to a
runtime crash using a certain compiler version, which is diagnosed
as the compiler using the C strict aliasing rules to make
optimizations that exposed the invalid program code.
To avoid futher surprises due to new compiler optimizations
that utilize the C strict aliasing rules, always disable
strict aliasing except when --enable-checking=all is used.
Change-Id: Ib5d3bbd7c88686bd9a878b6b2c5e7c2b4eeccc04
Reviewed-on: https://gerrit.openafs.org/11988
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
fi
CFLAGS_NOERROR=
-CFLAGS_NOSTRICT=
+CFLAGS_NOSTRICT=-fno-strict-aliasing
CFLAGS_NOUNUSED=
CFLAGS_NOOLDSTYLE=
XCFLAGS_NOCHECKING="$XCFLAGS"
XCFLAGS="${XCFLAGS} -Wall -Wstrict-prototypes -Wold-style-definition -Werror -fdiagnostics-show-option -Wpointer-arith"
if test "x$enable_checking" != "xall"; then
CFLAGS_NOERROR="-Wno-error"
- CFLAGS_NOSTRICT="-fno-strict-aliasing"
CFLAGS_NOUNUSED="-Wno-unused"
CFLAGS_NOOLDSTYLE="-Wno-old-style-definition"
AC_DEFINE(IGNORE_SOME_GCC_WARNINGS, 1, [define to disable some gcc warnings in warnings-as-errors mode])
+ else
+ CFLAGS_NOSTRICT=
fi
fi
else