Re: XCode 2.4 and 32/64-bit universal binaries
Re: XCode 2.4 and 32/64-bit universal binaries
- Subject: Re: XCode 2.4 and 32/64-bit universal binaries
- From: Herbie Robinson <email@hidden>
- Date: Sat, 19 Aug 2006 16:53:58 -0400
At 4:52 PM +0300 8/17/06, Artemiy Pavlov wrote:
Floating-point registers are the same size despite of CPU is 32-bit
or 64-bit.
Even ancient 8087 FPU had 80-bit floating-point registers, although
8086 was a 16-bit CPU
Yes, my mistake, apologies.
It is integer calculation which could benefit from 32-bit to 64-bit
transition.
64 bit integer calculation is available in both environments, too.
The fundamental difference is the address space: Pointers are 64
bits in a 64 bit environment (unless Apple has a different definition
of 64 bit environment than the rest of the world).
Okay, so, what about a 32-bit app on a 64 bit CPU vs. the same app
compiled for that target 64-bit CPU? Will the latter work faster or
no?
The experience with RISC machines (that I am aware of) is that 64 bit
applications often run a little slower because the cache footprint
becomes larger and there are more cache misses. If your code is
written in a highly transportable fashion (i.e., all of your integers
are declared using the types in stdint.h or the Apple equivalents),
the hit should be minimal. With the Intel architecture, the 64 bit
mode has twice as many hardware registers and is reported to run
faster. I don't think anybody is talking about more than 10%
differences, BTW. The main reason you want to think about doing a 64
bit application is if you need the address space (which seems
unlikely for audio applications).
--
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