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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Tune lsr for the wasm backend"
href="https://bugs.llvm.org/show_bug.cgi?id=39488">39488</a>
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<th>Summary</th>
<td>Tune lsr for the wasm backend
</td>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Backend: WebAssembly
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>alonzakai@gmail.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>We've noticed (e.g. [1]) that lsr is often unhelpful in the wasm backend and
leads to slower and larger code. sunfish suggests the pass may need to be tuned
for wasm.
Some data:
* The most extreme example is fannkuch, 5x slower in v8, 2x slower in sm, and
the crucial fannkuch_worker method is 45% larger, attaching.
* Many other minor examples too, primes-nocheck is 33% slower in v8 and 7%
slower in sm, and the main() function is 7% bigger with lsr, also attaching.
* This also affects real-world code, e.g. lua and box2d are 1% bigger.
[1] <a href="https://github.com/kripken/emscripten/pull/7386">https://github.com/kripken/emscripten/pull/7386</a></pre>
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