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Re: PATCH: Add --alt-nops=short|long to x86/x86-64 assemblers

Hi H. J.

x86/x86-64 assemblers don't support -mtune/-march/-mcpu.

Ahh. How does the assembler know which instruction set variants are valid then ? (I am thinking of the all the different SSE, PowerNow, etc variants).

We need a switch to tell
assembler if the new nop instructions can be used at all. Secondly,
not all modern processors prefer "long" versions. We need another
switch to tell which kind of the new nop instructions should be used,
short or long.

In which case the default presumably ought to be the short version and the long version should only be enabled if explicitly requested via a command line switch.

Maybe I should add -march= and -mtune= to assembler.

It sounds like it would be a good idea, although if it is only to support this new feature then you may not want to go that far.

Cheers
  Nick

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