On Thu, Oct 06, 2011 at 03:20:16PM -0300, Paulo César Pereira de Andrade wrote:
Em 6 de outubro de 2011 14:38, Jon Masters jcm@redhat.com escreveu:
On Tue, 2011-10-04 at 00:41 -0300, Paulo César Pereira de Andrade wrote:
For now I have been only considering gcc as compiler
I think, realistically, so have we. But I'm open to rethinking that.
The problem is that this compiler apparently only offers two options, softfp (not softfp calling convention) by generating code without fpu support, and hardfp that only supports float arguments on float registers. IMO, the hardfp abi is not something for a distribution, but for a "closed" (not necessarily closed source) image, where the exact hardware is known before hand, and from Linux pretty much only the kernel and a few packages are used.
Nope, not at all (as mentioned in my earlier message).
...
Hardfp abi adds a completely new set of incompatibility in the field, that should affect asm in different places, break pretty much any jit/ffi around, does not run armv5 or earlier binaries, and all to have what? Like 3% (with luck) increase in performance in fpu intensive applications, while almost everything else has no benefits. From my understanding, it was wrong from start, and most likely caused by comparing apples to oranges, err, software float vs hardware float, probably also the software float one not using armv6 instructions, not "softfp abi" vs "hardfp abi".
Konstantinos has benchmarks showing a lot more than "3%" improvements. I'll let him post links and explanations.
Cheers,