RFR (L): 7173584: Implement arraycopy as a macro node

[Vladimir Kozlov]

Sorry, somehow I missed this.

Roland Westrelin wrote:
> Here is a new one for this (ignore the comments below the file names. They are broken):
> 
> http://cr.openjdk.java.net/~roland/7173584/webrev.01/
> 
> The 2 changes are:
> 
> - the fix for 7174363 is merged
> - I hit an assert once during testing:
> assert(proj->_con == predicate_proj->_con, "must match");
> loopPredicate.cpp line 825
> One of the predicates added for an array copy is mistaken for a range check predicate but with the IfTrue/IfFalse projections swapped so I tried to change the code so that proj->_con != predicate_proj->_con is supported.

I am not comfortable with this predicate change. The check come from 
generate_limit_guard() :

  if (a.length u< offset+copy_length) uncommon_trap; else arraycopy;

which is reversed by igvn to

  if (offset+copy_length u< a.length) arraycopy; else uncommon_trap;

So it should not be IfFalse projection. Can you explain the case which you hit?

Also instead of duplicating gen_subtype_check() in macroArrayCopy.cpp can you 
modify the original one to work for you (by passing additional flag)?

Thanks,
Vlaidmir

> 
> Roland.