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Stage 2 project: new interference graph representation.
- From: Peter Bergner <bergner at vnet dot ibm dot com>
- To: "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Cc: Mark Mitchell <mark at codesourcery dot com>, Kenneth Zadeck <zadeck at naturalbridge dot com>, Seongbae Park (ëìë, ææ å) <seongbae dot park at gmail dot com>
- Date: Thu, 30 Aug 2007 23:37:00 -0500
- Subject: Stage 2 project: new interference graph representation.
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