As a somewhat related follow on to Kenny's new interference graph builder patch (which is still waiting for a full review):
http://gcc.gnu.org/ml/gcc-patches/2007-08/msg01729.html I'd like to squeeze in a new representation of the interference graph that in some cases can save a significant amount of memory. The actual amount of memory savings can vary, depending on the function we're compiling, but in the worst case, we save just over half the space (n * (n - 1)) / 2 versus n * n. In some cases, we can save a lot more. For example, using the test case attached to: http://gcc.gnu.org/PR33237 the old interference graph uses just over 20 Mbytes of space, while the new representation uses only 806 Kbytes. There's also the possibility we can save even more space in the future. I should have a patch ready to post tomorrow for people to look at. Peter