Quoting Martin Matuska <m...@freebsd.org> (from Thu, 10 Mar 2011
22:33:37 +0100):
Hi everyone,
we have performed a benchmark of the perl binary compiled with base gcc,
ports gcc and ports clang using the perlbench benchmark suite.
Our benchmark was performed solely on amd64 with 10 different processors
and we have tried different -march= flags to compare binary performance
of the same compiler with different flags.
Here is some statistics from the results:
- clang falls 10% behind the base gcc 4.2.1 (test average)
- gcc 4.5 from ports gives 5-10% better average performance than the
base gcc 4.2.1
Can you rule out gcc specific optimizations as a cause of this
difference for clang? As an example of what I mean: the configure
script of LAME will use additional optimization flags if it detects
gcc (even depending on the version of gcc). For clang (or other
compilers which have similar flags than gcc but are not identified as
gcc) there it will not use add those flags. Another possibility are
preprocessor checks for gcc-specific defines (in case clang does not
provide the same predefined defines, I do not know)?
Bye,
Alexander.
--
This MUST be a good party -- My RIB CAGE is being painfully pressed up
against someone's MARTINI!!
http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7
http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137
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