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Re: [DOC PATCH] Rewrite docs for inline asm
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: dw <limegreensocks at yahoo dot com>
- Cc: Gerald Pfeifer <gerald at pfeifer dot com>, James Greenhalgh <James dot Greenhalgh at arm dot com>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Joseph Myers <joseph at codesourcery dot com>, Hans-Peter Nilsson <hp at bitrange dot com>, "aph at redhat dot com" <aph at redhat dot com>, Richard Sandiford <rdsandiford at googlemail dot com>, Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>
- Date: Tue, 29 Apr 2014 13:48:30 +0100
- Subject: Re: [DOC PATCH] Rewrite docs for inline asm
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On 29/04/14 11:47, dw wrote:
> While I'm waiting to hear back from Gerald about my responses to his
> other corrections, I have answered one question:
>
>> How does the user know what is dialect #0? Same for the others?
>>
>> When I originally wrote that section, I didn't know the answer (which
>> is why I left it vague). Now I think I do, but I'd like someone to
>> confirm. On my builds of gcc, the dialects are listed (in dialect
>> order) under "Known assembler dialects" in "gcc --target-help". Can I
>> rely on this enough to put it in the docs? Is there some better source?
>
> First of all, -masm is (currently) only supported on i386:
> http://gcc.gnu.org/onlinedocs/gcc/Option-Summary.html
>
> Second, i386 -masm only supports two options:
> http://gcc.gnu.org/onlinedocs/gcc/i386-and-x86-64-Options.html
>
> So, the inline asm docs could just say "att" and "intel." However,
> there's a difference between using "intel" and "att" as examples of how
> dialects work, and "hard coding" these names into this section as the
> list of available options. I'm not keen on putting machine-specific
> info like this into an otherwise machine-neutral section.
>
> Such being the case, I replaced the previously vague paragraph with:
>
> GCC may support multiple assembler dialects (such as "att" or "intel") for
It's generally wise to avoid 'may' in documentation; in this case I
think 'can' is acceptable.
Also, you should be clear at the time you introduce att and intel that
you are referring to the i386 compiler. Something like: "(for example,
GCC for i386 supports "att" and "intel" dialects)".
R.
> inline assembler. In builds that support this capability, the
> @option{-masm}
> option controls which dialect GCC uses as its default. The
> hardware-specific
> documentation for the @option{-masm} option contains the list of supported
> dialects, as well as the default dialect if the option is not specified.
> This
> information may be important to understand, since assembler code that works
> correctly when compiled using one dialect will likely fail if compiled
> using
> another.
>
> This keeps the machine-specific details with the already
> machine-specific compile options. While this option only applies to
> i386 currently, this text leaves the option open should some other
> platform make use of it in the future.
>
> Unless someone says otherwise, I'm calling this question resolved.
>
> dw
>