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<div class="moz-cite-prefix">On 3/6/2014 8:09 PM, Mark Seaborn
wrote:<br>
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<div class="gmail_extra">On 4 March 2014 15:17, Chandler Carruth
<span dir="ltr"><<a moz-do-not-send="true"
href="mailto:chandlerc@google.com" target="_blank">chandlerc@google.com</a>></span>
wrote:
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<div>Given that the bitcode is stable, I don't
understand why this is important.</div>
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<div>Is the bitcode format stable now? I heard talk that
LLVM is trying to do this now, but I don't remember seeing
an llvmdev thread stating that for sure. Was there a
thread about it that I missed? I just remember hearing
complaints last year that the format was still getting
changed. :-)</div>
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<br>
The addition of attribute groups is the last major change to IR that
I recall, and the final draft on it that I could find contains this
note:<br>
"As usual, LLVM 3.3 will be able to read and auto-upgrade previous
bitcode and `.ll' files." A naive search for stability brings up a
reply to the original LLVM IR is a compiler IR message, back in
2011, and subsequent references appear to follow back to the train.
Given that all recent references I recall (note: recall bias may be
present) to changing the bitcode format have brought up maintaining
the ability to read old files, I've made a working assumption that
the IR is going to be stable unless something drastic (like delete
an instruction) is done, and that such an occurrence is extremely
unlikely to happen. Metadata and intrinsics may be a different
story, though.<br>
<pre class="moz-signature" cols="72">--
Joshua Cranmer
Thunderbird and DXR developer
Source code archæologist</pre>
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