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Re: Hot and Cold Partitioning (Was: GCC 4.1 Projects)
- From: Mark Mitchell <mark at codesourcery dot com>
- To: Caroline Tice <ctice at apple dot com>
- Cc: Joern RENNECKE <joern dot rennecke at st dot com>, gcc at gcc dot gnu dot org, Dale Johannesen <dalej at apple dot com>
- Date: Tue, 01 Mar 2005 11:24:54 -0800
- Subject: Re: Hot and Cold Partitioning (Was: GCC 4.1 Projects)
- Organization: CodeSourcery, LLC
- References: <421F64CA.6010008@st.com> <F34354DA-8758-11D9-8055-000393D76DAA@apple.com> <422311F7.8080800@st.com> <D7AC6C82-89B2-11D9-8055-000393D76DAA@apple.com> <422360AA.1020200@st.com> <CF80FCB8-89B7-11D9-8055-000393D76DAA@apple.com> <42237A6D.6030209@st.com> <af0ccfbb348ed970378ab2ac3c9b6b12@apple.com>
Caroline Tice wrote:
There might be some validity in the idea of modifying this optimization,
in the future, to consider
the size of a basic block in addition to it's "hot-ness", when deciding
which partition to put it into.
I expect this would not be that difficult to implement, and would
probably address your concerns.
However, at the moment, I would first like to get the "correctness"
fixes for the hot/cold partitioning
optimization into FSF mainline.
I agree. The optimization is already checked in; as I understand it,
all you are trying to do is make it work better on more systems, such as
those with DWARF. I think that Joern's objections can be dealt with
after you get those fixes in place; I would imagine that you would just
mark small basic blocks directly reachable from hot blocks as "hot",
whether or not profiling data actually suggested them to be hot.
--
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
(916) 791-8304