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Re: [GCC 3.x] Performance testing for QA
- From: Dale Johannesen <dalej at apple dot com>
- To: dewar at gnat dot com (Robert Dewar)
- Cc: Dale Johannesen <dalej at apple dot com>, tjw at omnigroup dot com, Peter dot Sasi at t-systems dot co dot hu, aj at suse dot de, gcc at gcc dot gnu dot org
- Date: Tue, 3 Sep 2002 10:32:44 -0700
- Subject: Re: [GCC 3.x] Performance testing for QA
On Monday, September 2, 2002, at 03:49 PM, Robert Dewar wrote:
<< I only reason I think its nice to have the compiler bootstrap as
part
of the benchmark is to make sure that the compiler is fast. Instead, I
think it would be more interesting to see how fast the compiler could
build all the other benchmarks -- not how fast it could build itself :)
I disagree, gcc is a very interesting benchmark because of its locality
patterns. It precisely is NOT a collection of tight loops, and unlike
some of the other tests in SPEC, it is very hard to tune a compiler
to do artifically well on the gcc benchmark.
Since the benchmark gcc is never fed any erroneous source while running
the benchmark, none of the error-handling stuff is ever executed. With
profile-based optimization it's possible to move a lot of that stuff so
it never gets paged in; that's a significant win. The same conditions
don't apply when running gcc normally, so this is fairly artificial.