Request for reviews (M): 6957939: Reduce registers usage by DecodeN/EncodeP

[Tom Rodriguez]

It might be nice to use this with Conv's as well.  Maybe we should have a new Node flag to tag nodes that have this copy like behaviour.  Can we avoid doing a whole second pass over the instruction to record the bias, maybe by tagging LRGs as copy LRGs and overwriting non-copy LRGs in record_bias?

tom

On Jun 3, 2010, at 2:33 PM, Vladimir Kozlov wrote:

> http://cr.openjdk.java.net/~kvn/6957939/webrev
> 
> Fixed 6957939: Reduce registers usage by DecodeN/EncodeP
> 
> DecodeN/EncodeP usually produce result in the different
> from input register because types difference (32bit narrow
> oop vs 64bit oop).
> 
> Try to reuse input regiser for result if DecodeN/EncodeP is
> the only user by recording bias for input and ouput lrgs.
> It is done after copy bias for spill copies was recorded
> so they will get priority since only one copy bias could
> be recorded.
> 
> Tested with CTW, GCBasher with +VerifyOops.