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Re: [PATCH] Pass -mtune and -march options to assembler.

Mark Mitchell <> writes:
> Valdimir Volynsky wrote:
>> 2009-06-04  Vladimir Volynsky  <>
>>     PR target/40171
>>     * config/i386/linux64.h (ASM_SPEC): Pass -mtune to the GNU assembler.
>>     * config/i386/mingw-w64.h (ASM_SPEC): Likewise.
>>     * config/i386/sol2-10.h (ASM_SPEC): Likewise.
>>     * config/i386/x86-64.h (ASM_SPEC): Likewise.
> Sorry to keep going around on this -- but why not put directives in the
> .s file?  You're already conditionalizing on HAVE_GNU_AS, so you know
> you're using the GNU assembler.

My usual answer to this is that we want gcc to be consistent when
used as a driver interface.  So both of the following commands:

    gcc -mtune=foo blah.c
    gcc -mtune=foo blah.S

should produce code that is tuned for architecture "foo".  We don't
require users to hard-code the tune target in C files (in the form
of pragmas, etc.) so it would be inconsistent to require them to
hard-code the tune target in asm code.  (The role of the tuning target
is exactly the same in both: optimise for the given processor within
the limits imposed by the current architecture.)

A quick grep suggests that the only other gas ports to support -mtune
are MIPS and IA64.  MIPS passes -mtune options down, so cross-platform
consistency is another argument in favour of the patch.  (IA64 doesn't
pass it down, but I can't find a comment explaining why, or any indication
that this is deliberate.)


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