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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - wasm32: Opcodes for some SIMD float operations disagree with current spec"
href="https://bugs.llvm.org/show_bug.cgi?id=39272">39272</a>
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<th>Summary</th>
<td>wasm32: Opcodes for some SIMD float operations disagree with current spec
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<th>Product</th>
<td>libraries
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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>Windows NT
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
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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>alex@crichton.co
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, tlively@google.com
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<p>
<div>
<pre>In testing the wasm32 SIMD support of LLVM, I ran across a few opcodes that
looked like they weren't currently matching the spec online. It looks like the
issue is that after the SIMD leading opcode (0xfd) it's expected that the SIMD
operation is encoded as a leb128 integer, but currently LLVM is just emitting
an extra byte.
For example f64x2.abs -
<a href="https://github.com/llvm-mirror/llvm/blob/d069d45aa888c5b8a44521d4cade32767c09b35e/test/MC/WebAssembly/simd-encodings.s#L382-L383">https://github.com/llvm-mirror/llvm/blob/d069d45aa888c5b8a44521d4cade32767c09b35e/test/MC/WebAssembly/simd-encodings.s#L382-L383</a>
- is encoded as 0xfd,0x80, but I think that should be 0xfd,0x80,0x01 with
leb128 encoding.
I haven't currently got a super minimal test case for this, but I can
definitely make one if necessary!</pre>
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