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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Condition that leads to __builtin_unreachable() is not propagated to other branches"
href="https://bugs.llvm.org/show_bug.cgi?id=37482">37482</a>
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<th>Summary</th>
<td>Condition that leads to __builtin_unreachable() is not propagated to other branches
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<th>Product</th>
<td>new-bugs
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Linux
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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>new bugs
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>sergei.a.izmailov@gmail.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<pre>Clang is unable to optimize the next code:
#include <stdexcept>
const double& safe_deref(double* a) {
if (a==nullptr) { // expansion of GSL Ensures macro with
GSL_UNENFORCED_ON_CONTRACT_VIOLATION
__builtin_unreachable();
}
if (a==nullptr) {
throw std::runtime_error("error");
}
return *a;
}
GCC optimize out both "if" statements, see <a href="https://godbolt.org/g/4hSgAA">https://godbolt.org/g/4hSgAA</a></pre>
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