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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Bugs in handling of i1 vectors + memory"
href="https://llvm.org/bugs/show_bug.cgi?id=27600">27600</a>
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<th>Summary</th>
<td>Bugs in handling of i1 vectors + memory
</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>Linux
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Common Code Generator Code
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>fraser@codeplay.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>I've come across several problems in the treatment of i1 vectors in expansion
and DAG combining code.
They, so far, all concern the assumption that vector element types are of size
<span class="quote">> 1 byte.</span >
The first few are in the expansion of build/extract/insert vector when
expanding through the stack:
SDValue SelectionDAGLegalize::ExpandVectorBuildThroughStack(SDNode* Node) {
unsigned TypeByteSize = EltVT.getSizeInBits() / 8; -- Zero
for (unsigned i = 0, e = Node->getNumOperands(); i != e; ++i) {
unsigned Offset = TypeByteSize*i; // Always zero!
This means the offset from the stack is always 0, hence it'll load the wrong
element.
Same goes with ExpandExtractFromVectorThroughStack and
ExpandInsertToVectorThroughStack, from what I can see by reading the code.
Also buggy is DAGCombiner::ReplaceExtractVectorEltOfLoadWithNarrowedLoad. Same
problem - offsets of zero, combining to incorrect DAG result.
I haven't seen any more just yet, but I'll update this issue tracker if I find
more.</pre>
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