This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [patch] ree.c: don't abuse GTY
On Fri, Dec 7, 2012 at 11:34 AM, Jakub Jelinek wrote:
> On Fri, Dec 07, 2012 at 11:25:38AM +0100, Steven Bosscher wrote:
>> Perhaps somewhere during the development of ree.c struct ext_cand was
>> GGC-allocated, in which case TODO_ggc_collect would make sense, to
>> collect the ext_cands (there can be many of them). But since ext_cands
>> are not GGC-allocated, the only garbage "produced" by ree.c is when it
>> removes redundant extensions (via delete_insn). This is typically only
>> a very small percentage of the instructions, so there isn't a lot of
>> garbage produced.
>
> That isn't the only garbage produced, it also updates the PATTERNs of
> various instructions with something different. Have you done any
> measurement on what kind of percentage of the instructions is modified,
> or is "very small percentage" just a guess?
I almost never guess, and try to measure the impact of my patches.
In this case, I couldn't even get the garbage collector to trigger
without bringing the collection threshold down by a factor 10 or so.
Ciao!
Steven