Re: [PATCH] x86: reject architecture settings that are invalid to be set from the command line

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Jun 10, 2010 at 7:25 AM, Jan Beulich <JBeulich@novell.com> wrote:
>>>> On 10.06.10 at 16:19, "H.J. Lu" <hjl.tools@gmail.com> wrote:
>> On Thu, Jun 10, 2010 at 12:05 AM, Jan Beulich <JBeulich@novell.com> wrote:
>>>>>> On 09.06.10 at 18:02, "H.J. Lu" <hjl.tools@gmail.com> wrote:
>>>> On Wed, Jun 9, 2010 at 8:36 AM, Jan Beulich <JBeulich@novell.com> wrote:
>>>>> So far, options like -march=i8086 were accepted despite the assembler
>>>>> subsequently choking on other consistency checks, leading to reasonably
>>>>> cryptic error messages. This patch makes it so that impossible
>>>>> architecure settings are neither accepted nor displayed (i.e. it is now
>>>>> made sure that those settings can only be used via directives).
>>>>>
>>>>> gas/
>>>>> 2010-06-09 ?Jan Beulich ?<jbeulich@novell.com>
>>>>>
>>>>> ? ? ? ?* config/tc-i386.c (md_parse_option): Ignore impossible processor
>>>>> ? ? ? ?types.
>>>>> ? ? ? ?(show_arch): New parameter 'check'.
>>>>> ? ? ? ?(md_show_usage): Adjust calls to show_arch().
>>>>>
>>>>> --- 2010-06-09/gas/config/tc-i386.c ? ? 2010-06-09 17:04:12.000000000 +0200
>>>>> +++ 2010-06-09/gas/config/tc-i386.c ? ? 2010-06-09 17:24:59.000000000 +0200
>>>>> @@ -8166,6 +8166,11 @@ md_parse_option (int c, char *arg)
>>>>> ? ? ? ? ? ? ?if (strcmp (arch, cpu_arch [j].name) == 0)
>>>>> ? ? ? ? ? ? ? ?{
>>>>> ? ? ? ? ? ? ? ? ?/* Processor. ?*/
>>>>> + ? ? ? ? ? ? ? ? if (! (strcmp (default_arch, "i386")
>>>>> + ? ? ? ? ? ? ? ? ? ? ? ?? cpu_arch[j].flags.bitfield.cpulm
>>>>> + ? ? ? ? ? ? ? ? ? ? ? ?: cpu_arch[j].flags.bitfield.cpui386))
>>>>> + ? ? ? ? ? ? ? ? ? continue;
>>>>> +
>>>>> ? ? ? ? ? ? ? ? ?cpu_arch_name = cpu_arch[j].name;
>>>>> ? ? ? ? ? ? ? ? ?cpu_sub_arch_name = NULL;
>>>>> ? ? ? ? ? ? ? ? ?cpu_arch_flags = cpu_arch[j].flags;
>>>>> @@ -8297,7 +8302,7 @@ md_parse_option (int c, char *arg)
>>>>> ?"
>>>> ? ? ?"
>>>>>
>>>>> ?static void
>>>>> -show_arch (FILE *stream, int ext)
>>>>> +show_arch (FILE *stream, int ext, int check)
>>>>> ?{
>>>>> ? static char message[] = MESSAGE_TEMPLATE;
>>>>> ? char *start = message + 27;
>>>>> @@ -8334,6 +8339,13 @@ show_arch (FILE *stream, int ext)
>>>>> ? ? ? ? ?/* It is an processor. ?Skip if we show only extension. ?*/
>>>>> ? ? ? ? ?continue;
>>>>> ? ? ? ?}
>>>>> + ? ? ?else if (check && ! (strcmp (default_arch, "i386")
>>>>> + ? ? ? ? ? ? ? ? ? ? ? ? ?? cpu_arch[j].flags.bitfield.cpulm
>>>>> + ? ? ? ? ? ? ? ? ? ? ? ? ?: cpu_arch[j].flags.bitfield.cpui386))
>>>>> + ? ? ? {
>>>>> + ? ? ? ? /* It is an impossible processor - skip. ?*/
>>>>> + ? ? ? ? continue;
>>>>> + ? ? ? }
>>>>>
>>>>>
>>>>
>>>> Do we need to check cpu_arch[j].flags.bitfield.cpulm? Can we
>>>> just check cpu_arch[j].flags.bitfield.cpui386 like
>>>>
>>>> if (check && !cpu_arch[j].flags.bitfield.cpui386)
>>>> ? continue?
>>>>
>>>
>>> I'm of the opinion that when the assembler is in 64-bit mode it
>>> should reject those architectures that aren't 64-bit capable,
>>> otherwise specifying e.g. -march=i386 has the same ugly effect
>>> as has passing -march=i8086 in 32-bit mode. And if we reject
>>> them, we should also not display them as available.
>>>
>>
>> On Linux/x86-64, your patch gave me
>>
>> ../as-new --help
>>
>> ? --32/--64 ? ? ? ? ? ? ? generate 32bit/64bit code
>> ? --divide ? ? ? ? ? ? ? ?ignored
>> ? -march=CPU[,+EXTENSION...]
>> ? ? ? ? ? ? ? ? ? ? ? ? ? generate code for CPU and EXTENSION, CPU is one
>> of:
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ?generic64, nocona, core2, corei7, l1om, opteron,
>> k8,
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ?amdfam10, bdver1
>>
>> I don't see how it can be correct since "--32 -march=i386" works fine.
>>
>
> Just try ../as-new --32 --help - it'll show the 32-bit possibilities
> as well.

It doesn't look right to me.


-- 
H.J.