Re: [Xen-devel] [PATCH v2 1/2] tools/foreign: Avoid using alignment directives when not appropriate

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Mar 09, 2016 at 07:03:15PM +0000, Andrew Cooper wrote:
> The foreign header generation blindly replaces 'uint64_t' with '__align8__
> uint64_t', to get correct alignment when built as 32bit.  This is correct in
> most circumstances, but Clang objects to two specific uses.
> 
>  * Inside a sizeof() expression
>  * As part of a typecast
> 
> An example error looks like:
> 
> /local/xen.git/tools/libxc/../../tools/include/xen/foreign/x86_64.h:204:44:
> error: 'aligned' attribute ignored when parsing type 
> [-Werror,-Wignored-attributes]
>     __align8__ uint64_t evtchn_mask[sizeof(__align8__ uint64_t) * 8];
>                                            ^~~~~~~~~~
> /local/xen.git/tools/libxc/../../tools/include/xen/foreign/x86_64.h:13:36:
> note: expanded from macro '__align8__'
>                                    ^~~~~~~~~~~
> 
> This sedary is sufficient to fix all the bad examples without touching any of
> the legitimate uses, and is more simple than teaching mkheader.py how to parse
> C.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>

> ---
> CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> 
> v2: Use .tmp file.  Make sedary able to deal with int64_t
> ---
>  tools/include/xen-foreign/Makefile | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/include/xen-foreign/Makefile 
> b/tools/include/xen-foreign/Makefile
> index 80a446a..bb09c93 100644
> --- a/tools/include/xen-foreign/Makefile
> +++ b/tools/include/xen-foreign/Makefile
> @@ -34,7 +34,10 @@ x86_32.h: mkheader.py structs.py 
> $(ROOT)/arch-x86/xen-x86_32.h $(ROOT)/arch-x86/
>       $(PYTHON) $< $* $@ $(filter %.h,$^)
>  
>  x86_64.h: mkheader.py structs.py $(ROOT)/arch-x86/xen-x86_64.h 
> $(ROOT)/arch-x86/xen.h $(ROOT)/xen.h
> -     $(PYTHON) $< $* $@ $(filter %.h,$^)
> +     $(PYTHON) $< $* $@.tmp $(filter %.h,$^)
> +     #Avoid mixing an alignment directive with a uint64_t cast or sizeof 
> expression
> +     sed 's/(__align8__ \(u\?int64_t\))/(\1)/g' -i $@.tmp
> +     $(call move-if-changed,$@.tmp,$@)
>  
>  checker.c: mkchecker.py structs.py
>       $(PYTHON) $< $@ $(architectures)
> -- 
> 2.1.4
> 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel