[PATCH] config: Fix host -rdynamic detection for build != host != target

[PATCH] config: Fix host -rdynamic detection for build != host != target

[Joseph Myers]

The GCC_ENABLE_PLUGINS configure logic for detecting whether -rdynamic
is necessary and supported uses an appropriate objdump for $host
binaries (running on $build) in cases where $host is $build or
$target.

However, it is missing such logic in the case where $host is neither
$build nor $target, resulting in the compilers not being linked with
-rdynamic and plugins not being usable with such a compiler.  In fact
$ac_cv_prog_OBJDUMP, as used when $build = $host, is always an objdump
for $host binaries that runs on $build; that is, it's appropriate to
use in this case as well.

Tested in such a configuration that it does result in cc1 being linked
with -rdynamic as expected.  Also bootstrapped with no regressions for
x86_64-pc-linux-gnu.

config/
	* gcc-plugin.m4 (GCC_ENABLE_PLUGINS): Use
	export_sym_check="$ac_cv_prog_OBJDUMP -T" also when host is not
	build or target.

gcc/
	* configure: Regenerate.

libcc1/
	* configure: Regenerate.

diff --git a/config/gcc-plugin.m4 b/config/gcc-plugin.m4
index c731a6fab38..c30cfdd8fad 100644
--- a/config/gcc-plugin.m4
+++ b/config/gcc-plugin.m4
@@ -49,7 +49,7 @@ AC_DEFUN([GCC_ENABLE_PLUGINS],
        elif test x$host = x$target; then
 	 export_sym_check="$gcc_cv_objdump -T"
        else
-	 export_sym_check=
+	 export_sym_check="$ac_cv_prog_OBJDUMP -T"
        fi
      ;;
    esac
diff --git a/gcc/configure b/gcc/configure
index ea1ad6606a6..db5812d4a63 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -31975,7 +31975,7 @@ fi
        elif test x$host = x$target; then
 	 export_sym_check="$gcc_cv_objdump -T"
        else
-	 export_sym_check=
+	 export_sym_check="$ac_cv_prog_OBJDUMP -T"
        fi
      ;;
    esac
diff --git a/libcc1/configure b/libcc1/configure
index 1a63a0e4e1a..2a914a0bfc8 100755
--- a/libcc1/configure
+++ b/libcc1/configure
@@ -15120,7 +15120,7 @@ fi
        elif test x$host = x$target; then
 	 export_sym_check="$gcc_cv_objdump -T"
        else
-	 export_sym_check=
+	 export_sym_check="$ac_cv_prog_OBJDUMP -T"
        fi
      ;;
    esac

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: [PATCH] config: Fix host -rdynamic detection for build != host != target

[Richard Biener]

On Thu, Aug 10, 2023 at 11:31 PM Joseph Myers <joseph@codesourcery.com> wrote:
>
> The GCC_ENABLE_PLUGINS configure logic for detecting whether -rdynamic
> is necessary and supported uses an appropriate objdump for $host
> binaries (running on $build) in cases where $host is $build or
> $target.
>
> However, it is missing such logic in the case where $host is neither
> $build nor $target, resulting in the compilers not being linked with
> -rdynamic and plugins not being usable with such a compiler.  In fact
> $ac_cv_prog_OBJDUMP, as used when $build = $host, is always an objdump
> for $host binaries that runs on $build; that is, it's appropriate to
> use in this case as well.
>
> Tested in such a configuration that it does result in cc1 being linked
> with -rdynamic as expected.  Also bootstrapped with no regressions for
> x86_64-pc-linux-gnu.

OK.

> config/
>         * gcc-plugin.m4 (GCC_ENABLE_PLUGINS): Use
>         export_sym_check="$ac_cv_prog_OBJDUMP -T" also when host is not
>         build or target.
>
> gcc/
>         * configure: Regenerate.
>
> libcc1/
>         * configure: Regenerate.
>
> diff --git a/config/gcc-plugin.m4 b/config/gcc-plugin.m4
> index c731a6fab38..c30cfdd8fad 100644
> --- a/config/gcc-plugin.m4
> +++ b/config/gcc-plugin.m4
> @@ -49,7 +49,7 @@ AC_DEFUN([GCC_ENABLE_PLUGINS],
>         elif test x$host = x$target; then
>          export_sym_check="$gcc_cv_objdump -T"
>         else
> -        export_sym_check=
> +        export_sym_check="$ac_cv_prog_OBJDUMP -T"
>         fi
>       ;;
>     esac
> diff --git a/gcc/configure b/gcc/configure
> index ea1ad6606a6..db5812d4a63 100755
> --- a/gcc/configure
> +++ b/gcc/configure
> @@ -31975,7 +31975,7 @@ fi
>         elif test x$host = x$target; then
>          export_sym_check="$gcc_cv_objdump -T"
>         else
> -        export_sym_check=
> +        export_sym_check="$ac_cv_prog_OBJDUMP -T"
>         fi
>       ;;
>     esac
> diff --git a/libcc1/configure b/libcc1/configure
> index 1a63a0e4e1a..2a914a0bfc8 100755
> --- a/libcc1/configure
> +++ b/libcc1/configure
> @@ -15120,7 +15120,7 @@ fi
>         elif test x$host = x$target; then
>          export_sym_check="$gcc_cv_objdump -T"
>         else
> -        export_sym_check=
> +        export_sym_check="$ac_cv_prog_OBJDUMP -T"
>         fi
>       ;;
>     esac
>
> --
> Joseph S. Myers
> joseph@codesourcery.com