Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl

[Jonas Maebe <jonas-devlists at watlock dot be>]

Jan Beulich wrote on Fri, 01 Jul 2016:

> Nor do we support (prior to this patch) the respective movsb and
> movsw. Adding support for them (and then consistently, i.e.
> including movsl) is the purpose of this patch.

I think that is a really bad idea. movsb, movsw and movsl are existing  
mnemonics for completely different opcodes (as in "rep movsb"). It  
also seems to be against the spirit of AT&T syntax, which normally  
requires you to explicitly specify all operand sizes fully with the  
mnemonic in all cases, even if the assembler could in theory deduce  
them from the operands.

If partial "movz"-mnemonics were accepted before, then that seems to  
be a bug that should be fixed, rather than extending this behaviour to  
"movs".


Jonas