[Bug target/33431] [SH4] performance regression between 3.4.6 and 4.x

["andrew dot stubbs at st dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #5 from andrew dot stubbs at st dot com  2007-09-17 10:30 -------
Subject: Re:   New: [SH4] performance regression between
 3.4.6 and 4.x

nbkolchin at gmail dot com wrote:
> Our target hardware has SH7750 processor running in little endian mode under
> RTEMS. Unfortunetaly there is no way to boot linux there.
> 
> After lurking inside backend sources, I found that m4 has several variants in
> GCC 4.x: m4-100, m4-200, etc. I've tried to compile this tests with m4-200
> switch, but it looks like m4-200 enforces big-endian.

The 7750 has direct mapped caches and so is not the best platform for 
benchmarking. A slight code perturbation can give a large change in 
performance. :(

The m4-200 option is NOT suitable for that target. The 7750 is a 100 
series core (not that that was a nomenclature that existed when it came 
out). As far as I know, anybody that has a 200 series or above has an 
official ST toolset to go with it (GCC of course).

Andrew


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33431