[tree-ssa][ GC, Virtual operands, and GCing between passes

[law@redhat.com]

In message <1071016677.17667.2918.camel@p4>, Andrew MacLeod writes:
 >
 >I have array of pointers to trees.
 >
 >so 
 >
 >tree **defs;
Really pointers to pointers to trees.


 >I don't want what defs points to to be marked, since they are marked
 >otherwise, I just need the defs vector itself collected:
Is that really the reason why you're going through these contortions?  Does
it really buy us any measurable improvement?

I wouldn't expect a huge overhead to check the mark on an object that we
marked via some other chain of pointers.  But hey, maybe I'm wrong :-)

jeff