Solicit more code for donation to the test suite: the more extensive the
testsuite, the smaller the risk of breaking things in the future! We can
keep code private on request.
Bug hunting/squishing
Find bugs and write more test cases! Test cases are especially very
welcome, because it allows us to concentrate on fixing bugs instead of
isolating them. Going through the bugzilla database at
http://gcc.gnu.org/bugzilla/ to reduce testcases posted there and
add more information (for example, for which version does the testcase
work, for which versions does it fail?) is also very helpful.