[LLVMdev] Is address space 1 reserved?

[Pete Cooper]

> On Jan 7, 2015, at 11:32 AM, Philip Reames <listmail at philipreames.com> wrote:
> 
> 
> On 01/07/2015 11:28 AM, Pete Cooper wrote:
>> 
>>> On Jan 7, 2015, at 11:18 AM, Philip Reames <listmail at philipreames.com <mailto:listmail at philipreames.com>> wrote:
>>> 
>>> On the review for http://reviews.llvm.org/D6808 <http://reviews.llvm.org/D6808>, majnemer <http://reviews.llvm.org/p/majnemer/> commented that:
>>> "Address space 1 has a special meaning in LLVM, it's identical to address space 0 except for the fact that "null" may be dereferenced. You might want to consider a different address space."
>>> 
>>> This is the first I've heard of this and I can't find any documentation about it being reserved, either in general, or specifically for x86.  Can anyone clarify?
>> First i’ve heard of it...
>>> 
>>> The only address spaces with special meanings I know of are:
>>> - 0 (the normal address space, null is not dereferencable)
>>> - 256 - TLS, GS relative addressing
>>> - 257 - FS relative addressing
>> I didn’t even know 256/257 had special meanings.  I thought they were only used by x86.  It would be good to clarify them too just incase other targets ever wanted to use them.
> Sorry, let me clarify.  To my knowledge, 256/257 are only reserved on x86.  
Ah cool.  Thanks.

Pete
>> 
>> Thanks,
>> Pete
>>> 
>>> Philip
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>> 
> 

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