[LLVMdev] Register Alias Sets

[Chris Lattner]

On Fri, 6 Apr 2007, David Greene wrote:
> This makes it hard to do set comparisons.  RAX and EAX really have
> equivalent alias sets but one wouldn't know that from these definitions.

What do you mean by set comparisons?  Why do you need to know that two 
registers have the same alias set?

The idea of these alias sets is to efficiently respond to the query "do 
these two register alias".  Note that alias sets don't have many algebraic 
properties (like transitivity) that you might expect (e.g. AH aliases AX 
and AL aliases AX, but AH does not alias AL).

-Chris

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