thanks for the memory work

[law@redhat.com]

In message <200311260003.49376.s.bosscher@student.tudelft.nl>, Steven Bosscher 
writes:
 >Here's one statistic that disappointed me somewhat.  I expected that we were 
 >creating millions of varrays for statement operands, but at least for 8361.ii
 > 
 >it's not so bad at all (numbers for -O2 -fno-tree-pre):
 >
 >             number of varrays
 > use_ops        326058
 > def_ops        327317
 >vuse_ops        204200
 >vdef_ops         88002
 >TOTAL           945577
 >
 >Assuming that only the "name" and "type" fields of the varray_head_tag struct
 > 
 >are redundant our purpose, there's less than 8 MB overhead from this.
Rather than focus on the waste within the varray, maybe the focus should
be on not creating the varray in the first place.

The overwhelming majority of statements produce a single output -- the
only reason def_ops is a varray is to handle those oddball cases like
asms which can have multiple outputs.

So an interesting question then becomes can we _cleanly_ avoid use of the
varray in the general case.   That would reduce the number of operand varrays
by 33%, which is probably more significant than trying to eliminate fields
within the varrays themselves.  That also has the advantage that there are
fewer nodes for the GC system to manage.


Jeff