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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - X86WinAllocaExpander::lower - Value stored to 'AmountReg' is never read"
href="https://bugs.llvm.org/show_bug.cgi?id=41786">41786</a>
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<th>Summary</th>
<td>X86WinAllocaExpander::lower - Value stored to 'AmountReg' is never read
</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
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<th>Status</th>
<td>NEW
</td>
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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: X86
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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>craig.topper@gmail.com, hans@chromium.org, hans@hanshq.net, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
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<pre>Ancient commit rL269828/rL269949
scan-build is complaining that the 'AmountReg' is written to but never read:
unsigned AmountReg = MI->getOperand(0).getReg();
MI->eraseFromParent();
// Delete the definition of AmountReg, possibly walking a chain of copies.
for (;;) {
if (!MRI->use_empty(AmountReg))
break;
MachineInstr *AmountDef = MRI->getUniqueVRegDef(AmountReg);
if (!AmountDef)
break;
if (AmountDef->isCopy() && AmountDef->getOperand(1).isReg())
AmountReg = AmountDef->getOperand(1).isReg();
AmountDef->eraseFromParent();
break;
}
I have no experience with this code, but the comment mentions walking the
copies, so should it be doing something like this?
if (AmountDef->isCopy() && AmountDef->getOperand(1).isReg()) {
AmountReg = AmountDef->getOperand(1).isReg();
continue;
}</pre>
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