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<div class="moz-cite-prefix">On 02/19/2016 04:47 AM, Norilo
Vesa-Petri via llvm-dev wrote:<br>
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<p class="MsoNormal"><span lang="FI">Dear LLVMers,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="FI"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="FI">I’m investigating the
response time of my JIT, and according to profiling,
optimization takes 85% of the compile time, while the rest
is being split evenly between the front-end and machine code
generation. Much of the optimizer time is spent in various
alias analysis passes. </span></p>
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Could you share more detailed profiling information? It's possible
you're tripping across a compile time bug or that seeing what
sections are hot would given insights into how to tweak your code to
avoid the problem. <br>
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<p class="MsoNormal"><span lang="FI"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="FI"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="FI">I’m happy with the
generated code quality and wouldn’t like to lower the
optimization level (O2).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="FI"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="FI">Would generating alias
metadata from the front-end help and speed up optimization?
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="FI"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="FI">If so, what kind of AA
would have the best return on investment in terms of compile
time? TBAA is not applicable to my language, but I could
provide C99 restrict and related semantics fairly easily.</span></p>
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In general, if you can give "easier" answers, that's always a good
thing. If you're using LLVM for inlining, you may find that
"noalias" attributes are quite useful for controlling compile time
(i.e. enable optimizations of callee before inlining). Without
knowing more about your source language and where you're currently
spending time, I can't really help more than that. <br>
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<p class="MsoNormal"><span lang="FI"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="FI"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="FI">Thanks!!<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Vesa Norilo<br>
Lecturer<br>
Centre for Music and Technology<br>
University of Arts Helsinki</p>
<p class="MsoNormal"><span
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Roman",serif"><o:p> </o:p></span></p>
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