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Re: [Qemu-devel] [PATCH v2] configure: disable FORTIFY_SOURCE under clan
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v2] configure: disable FORTIFY_SOURCE under clang |
Date: |
Wed, 4 Nov 2015 14:53:38 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 |
On 03/11/2015 21:43, John Snow wrote:
> Some versions of clang may have difficulty compiling glibc headers when
> -D_FORTIFY_SOURCE is used. For example, Clang++ 3.5.0-9.fc22 cannot
> compile glibc's stdio headers when -D_FORTIFY_SOURCE=2 is used. This
> manifests currently as build failures with clang and any arm target.
>
> According to LLVM dev Richard Smith, clang does not target or support
> FORTIFY_SOURCE + glibc, and it should not be relied on.
> "It's still an unsupported combination, and while it might compile, some
> of the checks are unlikely to work because they require a frontend
> inliner to be useful"
>
> See: http://lists.llvm.org/pipermail/cfe-dev/2015-November/045846.html
>
> Conclusion: disable fortify-source if we appear to be using clang instead
> of testing for compile success or failure, which may be incidental or not
> indicative of proper support of the feature.
>
> Signed-off-by: John Snow <address@hidden>
> ---
> configure | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/configure b/configure
> index 7a1d08d..4d74fcc 100755
> --- a/configure
> +++ b/configure
> @@ -261,6 +261,7 @@ rdma=""
> gprof="no"
> debug_tcg="no"
> debug="no"
> +fortify_source=""
> strip_opt="yes"
> tcg_interpreter="no"
> bigendian="no"
> @@ -876,6 +877,7 @@ for opt do
> debug_tcg="yes"
> debug="yes"
> strip_opt="no"
> + fortify_source="no"
> ;;
> --enable-sparse) sparse="yes"
> ;;
> @@ -4435,6 +4437,19 @@ if ! compile_object "-Werror"; then
> ccache_cpp2=yes
> fi
>
> +#################################################
> +# clang does not support glibc + FORTIFY_SOURCE.
> +
> +if test "$fortify_source" != "no"; then
> + if echo | $cc -dM -E - | grep __clang__ > /dev/null 2>&1 ; then
> + fortify_source="no";
> + elif echo | $cxx -dM -E - | grep __clang__ > /dev/null 2>&1 ; then
> + fortify_source="no";
> + else
> + fortify_source="yes"
> + fi
> +fi
> +
> ##########################################
> # End of CC checks
> # After here, no more $cc or $ld runs
> @@ -4442,7 +4457,7 @@ fi
> if test "$gcov" = "yes" ; then
> CFLAGS="-fprofile-arcs -ftest-coverage -g $CFLAGS"
> LDFLAGS="-fprofile-arcs -ftest-coverage $LDFLAGS"
> -elif test "$debug" = "no" ; then
> +elif test "$fortify_source" = "yes" ; then
> CFLAGS="-O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $CFLAGS"
> fi
>
>
Queued, thanks!
Paolo