Dec 30 patch causes large performance regression on ia64

[Richard Kenner]

    might cause a 20% performance drop when running the 147.vortex benchmark
    from SPEC95 on ia64-linux?

No, not at all.  It could have a negative affect on stack usage, but
shouldn't have an effect on execution speed other than a second-order
effect in that if stack slots aren't shared, the data cache hit rate
may go down, but that seems unlike to cause a 20% hit.