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<p><tt>Dear Sir/Madam</tt></p>
<p><tt><br>
</tt></p>
<p><tt>Our company</tt><tt>, 4Js software, has developed an SQL data
base software that runs under different operating systems:
Windows, Linux, Mac OS X. This software compiles each SQL
statement into a C program that is compiled "on the fly" and
executed by our JIT, Just In Time compiler.</tt></p>
<p><tt>We wanted to port it to Apple's iOS, and spent a lot of time
retargetting the JIT for supporting the ARM 64 CPU, but to our
surprise, when everything was ready, we learned that Apple iOS
forbids software to generate dynamically an executable.</tt></p>
<p><tt>After several months of reflections we think we can get
around this problem by using a C interpreter. Instead of
compiling it to machine code, we would pass the generated C
program to a C interpreter that would interpret the C program.</tt></p>
<p><tt>After looking at several interpreters, we think that the llvm
based CLING interpreter could do the job. To test these ideas,
we have recompiled the llvm/Clang system in a small linux/ARM64
based machine. Our preliminary tests seem to work and cling is
able to load the generated program.<br>
</tt></p>
<p><tt>There are several possible problems that we see.</tt></p>
<p><tt><br>
</tt></p>
<p><tt>The first and most obvious one is the incredible size of the
CLING interpreter (200MB stripped). Our whole data base is 80MB
stripped. We are targetting an Apple iPad, boosted with 1TO
SSD/6GB RAM. What would be the minimum requirements for CLING in
terms of RAM size?</tt></p>
<p><tt>The second question is that we have still concerns over the
overall approach. Do you see any problems with this
architecture? Can it work on principle?</tt></p>
<p><tt>The third question concerns the feasibility of our JIT
generating byte codes for the LLVM interpreter, boosting
performance and reducing RAM footprint. Would that be a better
solution than using the CLING interpreter? Is that possible
within Apple's iOS?</tt></p>
<p><tt>And yet another question is the need to modify the CLING
interpreter so that it receives its input from a character
buffer instead of a file, and other small tweaks. Is that
possible?</tt></p>
<p><tt>Are there any copyright issues? Are we allowed to embed the
llvm software into our system? Of course we would publish any
modifications done to the source code.<br>
</tt></p>
<p><tt>We thank you in advance for any answers to the questions
above.</tt></p>
<p><tt><br>
</tt></p>
<p><tt>Yours sincerely</tt></p>
<p><tt><br>
</tt></p>
<p><tt>Jacob Navia</tt></p>
<p><tt>iOS Project Manager</tt></p>
<p><tt>4Js Software. <a class="moz-txt-link-freetext" href="https://4js.com">https://4js.com</a></tt><tt><br>
</tt><tt><span class="w8qArf" style="font-weight: bolder;
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Quai Gallieni, 92150 Suresnes</span></tt></p>
<p><tt><span class="LrzXr" style="caret-color: rgb(34, 34, 34);
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