Re: configure erroneously detects eh_frame misoptimization

[Andrew Pinski <pinskia at gmail dot com>]

On Tue, Sep 19, 2017 at 4:42 PM, Steven Taschuk <steven@amotlpaa.org> wrote:
> The behaviour of echo for arguments containing the two-character
> substring `\0` varies among implementations: in coreutils echo,
> and in the builtins of ash, bash, busybox sh, csh, and fish, the two
> characters `\0` are emitted literally; the builtins of tcsh and zsh
> emit a null character and continue rendering the rest of the string;
> dash's builtin terminates the string early.
>
> Ubuntu since 6.10 uses dash as /bin/sh, so on such systems,
> configure misdiagnoses the assembler as unable to optimize eh_frame
> sections correctly, yielding ultimately an unnecessary use of
> `--traditional-format` in the driver's invocation of the assembler.


configure is autogenerated so you should be modifying configure.ac and
regenerate configure.
I think overall this patch is correct approach to fix this bug.  You
should provide a changelog and have the patch against the trunk of GCC
rather than doing it against a release (especially a release is from a
no longer a supported branch).

Please https://gcc.gnu.org/contribute.html for some more information
on the all of the requirements when it comes to submitting a patch.  I
provided some of the requirements above.  Note since this is a small
enough patch, the legal requirement is waved but if you are thinking
about contributing in the future, you should think about getting a
copyright assigned signed if you don't already have one.

Thanks,
Andrew

Thanks,
Andrew

>
> diff -ru gcc-4.2.1-orig/gcc/configure gcc-4.2.1/gcc/configure
> --- gcc-4.2.1-orig/gcc/configure        2007-01-01 22:44:31.000000000 -0500
> +++ gcc-4.2.1/gcc/configure     2017-09-19 06:50:48.546060400 -0400
> @@ -14076,7 +14076,8 @@
>  .LSCIE1:
>         .4byte  0x0
>         .byte   0x1
> -       .ascii "z\0"
> +       .ascii "z"
> +       .byte   0x0
>         .byte   0x1
>         .byte   0x78
>         .byte   0x1a