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Re: First cut on outputing gimple for LTO using DWARF3. Discussion invited!!!!
- From: Mark Mitchell <mark at codesourcery dot com>
- To: mathieu lacage <Mathieu dot Lacage at sophia dot inria dot fr>
- Cc: Kenneth Zadeck <zadeck at naturalbridge dot com>, GCC <gcc at gcc dot gnu dot org>, "Berlin, Daniel" <dberlin at dberlin dot org>, "Hubicha, Jan" <jh at suse dot cz>, "Novillo, Diego" <dnovillo at redhat dot com>, Ian Lance Taylor <ian at airs dot com>, "Edelsohn, David" <dje at watson dot ibm dot com>
- Date: Thu, 31 Aug 2006 16:00:25 -0700
- Subject: Re: First cut on outputing gimple for LTO using DWARF3. Discussion invited!!!!
- References: <44F2F642.firstname.lastname@example.org> <44F606CD.email@example.com> <1157019802.2574.25.camel@mathieu>
mathieu lacage wrote:
I have spent a considerable amount of time looking at the abbrev tables
output by gcc are not totally random: their entries are sorted by their
abbrev code. That is, the abbrev code of entry i+1 is higher than that
of entry i.
That's an interesting observation. Essentially, you've shown that by
storing lg(n) information, you can cut the cost to find an entry in an
abbreviation table of size n to a constant. Since, for LTO, we
certainly can depend on the .o file being produced by GCC, we could
depend on this behavior, even though it's not mandated by the DWARF
I think this is probably moot, since I believe that Kenny feels DWARF is
not suitable for reasons other than the abbreviation table issue, but
this is a clever technique.
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