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<div class="moz-cite-prefix">On 01/07/2015 11:52 AM, Matt Arsenault
wrote:<br>
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<div class="">On Jan 7, 2015, at 2:25 PM, Owen Anderson <<a
moz-do-not-send="true" href="mailto:resistor@mac.com"
class="">resistor@mac.com</a>> wrote:</div>
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<div class="">I'm not aware of any such restriction, and I
know of several LLVM based systems that use address
space 1 for something other than that.<br class="">
<br class="">
-Owen</div>
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<div>Yes, this would be a problem for us. We use 1 for a normal
address space where 0 is invalid. However, we also have a
problem where some other address spaces do want 0 to be a
valid address, which just sort of don’t work correctly now.</div>
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If you have an example with a null in a non-0 address space being
mishandled, please file a bug. We'll fix them as we find them. <br>
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<div>-Matt</div>
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On Jan 7, 2015, at 1:18 PM, Philip Reames <<a
moz-do-not-send="true"
href="mailto:listmail@philipreames.com" class="">listmail@philipreames.com</a>>
wrote:<br class="">
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On the review for <a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="http://reviews.llvm.org/D6808">http://reviews.llvm.org/D6808</a>,
<a moz-do-not-send="true"
href="http://reviews.llvm.org/p/majnemer/" class="
phui-handle phui-link-person">majnemer</a> commented
that:<br class="">
<span class="transaction-comment"
data-sigil="transaction-comment" data-meta="14_7">"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."<br class="">
<br class="">
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?<br class="">
<br class="">
The only address spaces with special meanings I know
of are:<br class="">
- 0 (the normal address space, null is not
dereferencable)<br class="">
- 256 - TLS, GS relative addressing<br class="">
- 257 - FS relative addressing<br class="">
<br class="">
Philip<br class="">
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