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Re: [PATCH] Target macro to redefine 'm' constraint letter

"Andreas Krebbel" <> writes:
> as discussed in the mail-thread starting with:
> it might be necessary to override the meaning of the 'm' constraint
> when adding new address formats to the GO_IF_LEGITIMATE_ADDRESS_P
> hook.
> The attached patch implements the suggestion from Richard Sandiford.
> A new target macro called TARGET_MEM_CONSTRAINT is introduced which
> allows to change the constraint letter used for the addresses matched
> by the legitimate address hook.  That way it is possible to extend the
> set of accepted addresses in the hook without changing the semantics of
> the 'm' constraint what would be fatal for inline assemblies using
> that constraint.
> Another solution might be to provide a more general mechanism letting
> back ends override all standard constraints.  The middle-end would
> just provide default implementations which might be replaced in a back
> end by using the standard constraint definition mechanism:
> Since I never got a response to that I've decided to go with Richards
> suggestion in order to have at least one supporter ;)


And yeah, the patch certainly looks good to me FWIW.  Hope it
gets approved.


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