I thought we were doing good just using $target_cpu in our aclocal.m4
to detect x86_64... no idea how to check for specific instruction
sets.

-J

On Fri, Apr 4, 2008 at 10:36 PM, Roy Stogner <[EMAIL PROTECTED]> wrote:
>
>  We currently use icc -xP,
>
>  "Can generate SSE3, SSE2, and SSE instructions for Intel processors,
>  and it can optimize for  processors based on Intel(R) Core(TM)
>  microarchitecture and Intel NetBurst(R) microarchitecture, like
>  Intel(R) Core(TM) Duo processors, Pentium(R) 4 processors with SSE3,
>  and Intel(R) Xeon(R) pro- cessors with SSE3. This is the default on
>  Mac OS X systems using IA-32 architecture."
>
>  But what we apparently need on Opteron-based systems like Ranger is
>  icc -xW:
>
>  "Can generate SSE2 and SSE instructions, and it can optimize for
>  Intel(R) Pentium(R) 4 processors and Intel(R) Xeon(R) processors
>  with SSE2. This is the default on Linux systems using Intel(R) 64
>  architecture.  This option is  the same as specifying
>  -march=pentium4."
>
>  I could just switch the optimizations in our aclocal.m4 file to use
>  the more conservative -xW.  It's better for us to always work and
>  sometimes use suboptimal compiler flags than to sometimes work and
>  sometimes use broken compiler flags.
>
>  Alternatively, it would be nice if we could autodetect what we're
>  running on at configure time.  I don't suppose there's any
>  cross-platform way to do "grep sse3 /proc/cpuinfo"?
>
>  Finally, it looks like icc 10 has the option to generate multiple code
>  paths; we could use "-xW -axP" to use SSE3 where it's supported and
>  fall back to SSE2-only otherwise.  This sounds like a way to bload
>  library and executable size, though.
>
>  Any preferences?
>  ---
>  Roy
>
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