****Re: ****Re: ****Re: ****What's up with 64 bit Linux

[Chris Gehlker]

On Nov 26, 2007, at 5:44 PM, Jon M. Hanson wrote:

> Chris Gehlker wrote:
>> In the Intel world, the data path isn't wider between i386 and
>> ix86-64. There are more registers, but compilers haven't really been
>> optimized to use them yet. But even when they are, one cache miss  
>> will
>> wipe out the gains from running hundreds of instructions with more
>> registers.
>>
> This isn't true at all. If you're running in x86-64 and something has
> been compiled as x86-64 you will absolutely use the additional
> registers. Compilers (at least GCC and Intel's compiler, I can't speak
> for Microsoft's) have supported x86-64 for quite a while now.

By "but compilers haven't really been optimized to use them yet" I  
didn't mean to imply that the compilers would ignore the registers. I  
meant that many of the  specific optimization strategies that   
compilers run are the same when generating 64-bit code. The benchmarks  
bear me out.

--
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