This is the mail archive of the
cgen@sourceware.org
mailing list for the CGEN project.
Re: [patch][rfa] Don't Generate Code to Support Unused Write Stacks
- From: Dave Brolley <brolley at redhat dot com>
- To: "Frank Ch. Eigler" <fche at redhat dot com>
- Cc: cgen at sources dot redhat dot com, sid at sources dot redhat dot com
- Date: Thu, 13 Jul 2006 14:43:20 -0400
- Subject: Re: [patch][rfa] Don't Generate Code to Support Unused Write Stacks
- References: <44B564FE.1030002@redhat.com> <y0mmzbequl5.fsf@ton.toronto.redhat.com>
Frank Ch. Eigler wrote:
brolley wrote:
[...]
When generating write stacks and the supporting code in order to
suppor the (delay ...) rtl construct for SID, cgen currently generates
a write stack for all registers and memory modes regardless of whether
they are used or not. [...]
For the internal port for which performance was an issue, this yielded
an improvement of 17%. [...]
Sounds good. I'm surprised though that your change should cause such
a noticeable improvement. It may be that the sid-side code to handle
the write queue testing/iteration is rather deficient. (Try adding
some UNLIKELY markers to the CPU::writeback() function's while()
conditions.)
I think that the difference was 39 vs 2 write stacks to manage for this
port.
Dave