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<body><span class="vcard"><a class="email" href="mailto:spatel+llvm@rotateright.com" title="Sanjay Patel <spatel+llvm@rotateright.com>"> <span class="fn">Sanjay Patel</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Poor codegen for targets with no native shifts"
href="https://bugs.llvm.org/show_bug.cgi?id=43542">bug 43542</a>
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<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>FIXED
</td>
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<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
</td>
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<td style="text-align:right;">Fixed By Commit(s)</td>
<td>
</td>
<td>r373666
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Poor codegen for targets with no native shifts"
href="https://bugs.llvm.org/show_bug.cgi?id=43542#c11">Comment # 11</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Poor codegen for targets with no native shifts"
href="https://bugs.llvm.org/show_bug.cgi?id=43542">bug 43542</a>
from <span class="vcard"><a class="email" href="mailto:spatel+llvm@rotateright.com" title="Sanjay Patel <spatel+llvm@rotateright.com>"> <span class="fn">Sanjay Patel</span></a>
</span></b>
<pre>(In reply to Joan Lluch from <a href="show_bug.cgi?id=43542#c10">comment #10</a>)
<span class="quote">> On the other hand, some issues are difficult to explain because they never
> show on the trunk targets due to a different combination of features. It's
> also understandable that it's hard to get approval of changes that will not
> bring any real improvement (or fixes to bugs that don't show on the existing
> backends, in spite that they may be actual bugs in the LLVM code).</span >
Yes, I agree - it's going to take more effort to make changes without a known
test/improvement. Feel free to raise that on llvm-dev.
Hopefully, this report has provided a recipe for fixing the simplest cases.
As I mentioned before, changing instcombine canonicalization is generally a
higher degree of difficulty.
For CodeGenPrepare patches, if you can show the problem in IR alone (use "opt
-codegenprepare"), that is preferred to creating an explicit test for a
specific target's asm, and it might make your job easier.
<a href="https://reviews.llvm.org/rL373666">https://reviews.llvm.org/rL373666</a></pre>
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