Clang Compiling Against GCC On Ubuntu ARM Linux

[phoronix]

Phoronix: Clang Compiling Against GCC On Ubuntu ARM Linux

Here's an update on the LLVM/Clang vs. GCC compiler benchmarking on ARM hardware under Linux...

http://www.phoronix.com/vr.php?view=MTExNzg

[popper]

ROTFL
http://lists.cs.uiuc.edu/pipermail/l...ay/049690.html
"Evan Cheng apple.com Request for Help: Teach ARM target to auto-detect cpu / subtarget featuresThu May 10 22:11:23 CDT 2012

I believe one of the reason the benchmark numbers are totally bogus is that the compilation are done on ARM hosts.

Given the benchmarks are apparently compiled without -mcpu=cortex-a9, I suspect LLVM ended up generating code for "generic" ARMv4 cpu.

This article makes me sick in my stomach.
Thanks,Evan"

"Michael Larabel on June 11, 2012
The bench marking was still being done from a PandaBoard ES with Texas Instruments OMAP4460 dual-core ARM Cortex-A9 development board. Via the CFLAGS/CXXFLAGS, -march=armv7-a was passed to each compiler. "

On the other hand once you sort out your flags war and reach consensus it might be interesting to see this test run on a

Calxeda quad-core ARM Cortex-A9 processor optimized for using in Servers over 10Gigabit/s internal fabric on each card

sample box with 2 or more cards installed for 32 Cortex A9 cores/8 SOC and greater etc and you really should go and get the latest Linaro GCC etc too.

http://armdevices.net/2012/06/11/cal...owered-server/

http://<a href="http://www.youtube.c...5UCYJjpZoQ</a>

Hmm i cant seem to get in post video link working, odd.

[Michael]

On the other hand once you sort out your flags war

The flags used in this article were just normal, a compiler flag/tuning on ARM is forthcoming in a future multi-page article.

[chithanh]

armv7 is what e.g. Ubuntu will target in their upcoming ARM releases, so it seems very relevant how that performs. Compiling all software with hardware specific CFLAGS is typically only done by Gentoo or other source based distros.

[gururise]

armv7 is what e.g. Ubuntu will target in their upcoming ARM releases, so it seems very relevant how that performs. Compiling all software with hardware specific CFLAGS is typically only done by Gentoo or other source based distros.

Here are a few relavant flags I'd like to see tested:

1. Ubuntu Standard armv7 + hard-float
2. Android Standard armv7 + softfp (note: this is not soft-float, it's still using hardware fp, just the headers are compatible with soft-float).
3. Android Standard armv5 + soft-float

These three flags will cover most software written for Linux and Android.

[chithanh]

Possibly Ubuntu and other distros will use -march=armv7-a -mtune=cortex-a9 (same idea as -march=i486 -mtune=i686 for x86) so that would be another interesting data point.