[LLVMdev] Clang/llvm performance tests on FreeBSD 10.0-CURRENT

Dimitry Andric dimitry at andric.com
Wed Sep 5 02:35:38 PDT 2012

On 2012-09-05 10:06, Duncan Sands wrote:
>> I recently performed a series of compiler performance tests on FreeBSD
>> 10.0-CURRENT, particularly comparing gcc 4.2.1 and gcc 4.7.1 against
>> clang 3.1 and clang 3.2.
> presumably you were compiling with optimization, but as you didn't mention
> what the compiler flags were it is hard to know.

Yes, I have been reminded of this by posters on the FreeBSD mailing
lists already. :)

In any case, for all three builds, the default optimization options were
used.  Basically:

1) For building the FreeBSD in-tree version of clang 3.2:

      -O2 -pipe -fno-strict-aliasing

    These are just the default FreeBSD optimization flags for building
    clang, which are probably used by the majority of users out there.
    This is the case that I was interested in particularly.  The
    -fno-strict-aliasing is not really my choice, but it was introduced
    in the past by Nathan Whitehorn, who apparently saw problems without
    it.  It will hopefully disappear in the future.

2) For building the FreeBSD in-tree version of gcc 4.2.1:

      -O2 -pipe

    These are the default FreeBSD optimization flags.

3) For building Boost 1.50.0:

      -ftemplate-depth-128 -O3 -finline-functions

    These are the Boost defaults for gcc-compatible compilers, from

I will add this information to the text file.

More information about the llvm-dev mailing list