[LLVMdev] Constraints

[David Greene]

Can someone explain the Constraints system in X86*.td?

For example:

let Constraints = "$src1 = $dst"

This replaces isTwoAddress (according to svn logs), which I gather is how
two-address instructions used to be marked for X86.

Except isTwoAddress is still used in X86InstInfo.td.

So what gives?  What do these two properties actually do?

                                           -Dave