Marking ia64 psABI conformance (Re: PATCH: Support the .note.GNU-property section)

[Jim Wilson]

Wouldn't it be easier to just fix the IA-64 gcc port to be ABI compliant?

There are two issues here
1) We need to restore gp in epilogue in some cases where we currently do 
not.  This is a correctness issue.
2) We can optimize away gp save/restore around calls functions in the 
same load module.  This is an optimization.

The first one does not cause any ABI problems.  The second one does, and 
can only be implemented after the first one.

So a possible solution is to implement the first change now, wait a year 
or two, and then implement the second one.  After the second change, we 
can document that the next version of gcc is ABI incompatible with older 
linux releases.  There will be 3 or 4 version numbers between 
incompatible versions, so this shouldn't be a fatal problem.  We could 
even add an option to disable the optimization for people that need 
compatibility.  Of course, this requires long term planning which we 
aren't very good at.

Jim