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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - libunwind: Evaluating DWARF operation DW_OP_pick is broken"
href="https://bugs.llvm.org/show_bug.cgi?id=43872">43872</a>
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<th>Summary</th>
<td>libunwind: Evaluating DWARF operation DW_OP_pick is broken
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<th>Product</th>
<td>libc++abi
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<th>Version</th>
<td>9.0
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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
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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>All Bugs
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>ilya.burylov@intel.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
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<p>
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<pre>The problem is in libunwind: src/DwarfInstructions.hpp
DwarfInstructions<A, R>::evaluateExpression()
...
uint32_t reg;
...
case DW_OP_pick:
// pick from
reg = addressSpace.get8(p);
p += 1;
value = sp[-reg];
*(++sp) = value;
DW_OP_pick instructs to push an stack entry on the stack with the specified
index (0 through 255, inclusive)
Since reg is unsigned, -reg does not do, what it was supposed to do.</pre>
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