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Re: Native compilation article
- From: Jeff Sturm <jsturm at one-point dot com>
- To: Tom Tromey <tromey at redhat dot com>
- Cc: Anthony Green <green at redhat dot com>, shudo at computer dot org, java at gcc dot gnu dot org
- Date: Thu, 31 Jan 2002 16:46:17 -0500 (EST)
- Subject: Re: Native compilation article
On 28 Jan 2002, Tom Tromey wrote:
> Runs with `long' were uniformly much slower than `int'.
Interesting...
> 16364 int -O2 -funroll-all-loops
...
> 48362 long -O2
The huge (factor of 3) difference appears to be caused by register
spillage. Perhaps the experiemental regalloc would help. From a quick
look at the assembly it wasn't obvious to me how it would improve (though
I'm certainly no expert on x86).
But the same test with primes.java on IBM's JDK shows it runs _faster_
with long's than int's. What optimization could they possibly be using?
Jeff