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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [InstCombine] Failure to fold sext(trunc(ashr(x,bw-1)) -> sext(ashr(x,bw-1)"
href="https://bugs.llvm.org/show_bug.cgi?id=49543">49543</a>
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<th>Summary</th>
<td>[InstCombine] Failure to fold sext(trunc(ashr(x,bw-1)) -> sext(ashr(x,bw-1)
</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>Windows NT
</td>
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<th>Status</th>
<td>NEW
</td>
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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>Scalar Optimizations
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>llvm-dev@redking.me.uk
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<th>CC</th>
<td>lebedev.ri@gmail.com, llvm-bugs@lists.llvm.org, nikita.ppv@gmail.com, spatel+llvm@rotateright.com
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<p>
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<pre>Alive2: <a href="https://alive2.llvm.org/ce/z/A3FMem">https://alive2.llvm.org/ce/z/A3FMem</a>
define i64 @src(i32 %a0) {
%a = ashr i32 %a0, 16 ; all valid 16 -> 31
%b = trunc i32 %a to i16
%c = sext i16 %b to i64
ret i64 %c
}
define i64 @tgt(i32 %a0) {
%a = ashr i32 %a0, 16
%c = sext i32 %a to i64
ret i64 %c
}
<a href="https://c.godbolt.org/z/zh7ffM">https://c.godbolt.org/z/zh7ffM</a></pre>
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