Hi Brent

>I would be willing to try debugging the problem on my Mac Mini after
>rebooting it into OSx,
>if this failure occurs with the default STACK_WIPE_SITES 0x2*** settings
>using gcc options
>that otherwise yield a stable unpatched ruby build,

Yes, it appears that these options cause patched ruby to crash with
either 0x2370 or 0x4370 set for stack_wipe_sites:

-O3 -fstrict-aliasing -fno-tree-pre

It seems that two of these options is not enough to cause the problem,
you need all three.

The crash looks like this (I get it when I run rake test to run my
rails app tests):
/usr/local/lib/ruby/site_ruby/1.8/rubygems/specification.rb:333: [BUG] Bus Error
ruby 1.8.7 (2009-1-11 MBARI 7/0x2370 on patchlevel 72) [i686-darwin9.6.0]
Abort trap

Yes, it's old gcc (gcc version 4.0.1 (Apple Inc. build 5465)), so it
may not be worth the effort to track down the issue.  On the other
hand, it might be interesting though.

Perhaps contact me directly if you wish to pursue this.

-Stephen