Re: fragile ABI and PPC64
Re: fragile ABI and PPC64
- Subject: Re: fragile ABI and PPC64
- From: Charles Srstka <email@hidden>
- Date: Mon, 20 Aug 2012 00:24:35 -0500
On Aug 20, 2012, at 12:14 AM, Dale Miller <email@hidden> wrote:
> On 8/12, John McCall wrote: 'In the so-called "fragile" ABI, which is what you get on PPC, PPC64, and i386...".
> PPC64's being included in this list surprised me, so I went to my docs (I'm on 10.5.8 until they pry my G5 from my dead,cold hands). All the mentions I can find of the fragile ABI explicitly describe it as inherent in a 32-bit environment, and the non-fragile environment being supported in the 64-bit environment, without any qualification as to PPC versus Intel.
> while I'm at it, I have noticed several times mention being made of "bugginess" in the PPC64 environment. I'm aware that converting a PPC application to 64-bit might not improve performance because of the increased size of pointers, etc, but this is really because the PPC (G5) does not provide additional registers (already has 32 GPR's) and uses registers for most parameter passing instead of having to put them in memory on the stack even in 32-bit mode. So can anyone let me know specific problems so I can avoid them? I have a personal use for a 64-bit application that I've been thinking of writing and I don't want to run it on my 10.6 Macbook.
>
> Dale Miller
Bitness has nothing to do with the modern ABI, really. The reason the modern ABI runs only on 64-bit on OS X is because 64-bit Intel was the latest and greatest architecture for OS X (and still is), and therefore was the architecture for which Apple decided to expend resources improving the ABI. It didn't hurt that there was next to no existing 64-bit OS X software at the time, so they didn't have to deal with any legacy software issues. On the iPhone, the modern ABI runs in 32-bit.
Charles
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