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I have no objection to the patch, but I am curious to know why you
see a speedup here. I'd really expect a combination of inlining and
register allocation tricks* to cut the cost of the argument passing
to near zero. If it isn't, that seems like something we should fix
in the compiler. (I'm assuming you're compiling with a recent Clang
here?)<br>
<br>
* In many of these cases, the argument register doesn't need to be
preserved over the inner call because a) it's not a callee saved
register and b) it's not used after the return. <br>
<br>
Have you looked at the resulting assembly to see where the time is
spent?<br>
<br>
Philip<br>
<br>
<br>
<div class="moz-cite-prefix">On 01/14/2016 03:46 PM, Matthias Braun
via llvm-commits wrote:<br>
</div>
<blockquote
cite="mid:differential-rev-PHID-DREV-gymxjoux2thtko3sowsc-req@reviews.llvm.org"
type="cite">
<pre wrap="">MatzeB created this revision.
MatzeB added reviewers: hfinkel, majnemer, sanjoy.
MatzeB added a subscriber: llvm-commits.
MatzeB set the repository for this revision to rL LLVM.
After r251146 computeKnownBits() is called multiple times for every instruction in the program, which resulted in a 3% compiletime regression. This patch tries to get some of that compiletime back by optimizing the function:
Put DataLayout reference into the Query structure.
It looks nicer and improves the compiletime of a typical
clang -O3 -emit-llvm run by ~0.6% for me.
Repository:
rL LLVM
<a class="moz-txt-link-freetext" href="http://reviews.llvm.org/D16205">http://reviews.llvm.org/D16205</a>
Files:
lib/Analysis/ValueTracking.cpp
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