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Re: Writing addend into instructions


Torbjorn Granlund writes:
 > Andrew Haley <aph@redhat.com> writes:
 > 
 >    > Hmm.  A toolchain that bases a relocation on such a value surely will
 >    > not work.  Consider a typical RISC sethi/oris/ldah type instruction.
 >    > If you put an addend that is smaller than a full address into its
 >    > (say) 16-bit field, and then let that take part of a relocation, you
 >    > lose carry.
 >   
 >   Certainly, but the relocation might be to somwhere known to be on the
 >   same page, in which case there needn't be any high part.  I'm not
 >   saying that it's common, but there might be uses for it.
 >   
 > You probably mean "needn't be any low part".

There needn't be any high part to carry into.

 > Could you please give me an example, preferably for ELF/PowerPC, where
 > something depends on that the addend is written into the relocation
 > field?

I know of none, but that doesn't help: surely if you want to remove a
feature you have to show that no-one uses it.

Andrew.


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