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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [amdgpu] rL343329: [InstCombine] don't propagate wider shufflevector arguments to predecessors cause regression in storing char3 vectors"
href="https://bugs.llvm.org/show_bug.cgi?id=39132">39132</a>
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<th>Summary</th>
<td>[amdgpu] rL343329: [InstCombine] don't propagate wider shufflevector arguments to predecessors cause regression in storing char3 vectors
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: AMDGPU
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>jan.vesely@rutgers.edu
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
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<pre>Created <span class=""><a href="attachment.cgi?id=20942" name="attach_20942" title="piglit test that fails">attachment 20942</a> <a href="attachment.cgi?id=20942&action=edit" title="piglit test that fails">[details]</a></span>
piglit test that fails
this change introduces failures when loading/storing char3 vectors in
OpenCL (amdgcn backend):
llc: /home/orome/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:4159:
llvm::SDValue llvm::SelectionDAG::getNode(unsigned int, const
llvm::SDLoc&, llvm::EVT, llvm::SDValue, llvm::SDNodeFlags): Assertion
`VT.getSizeInBits() == Operand.getValueSizeInBits() && "Cannot BITCAST
between types of different sizes!"' failed.
Stack dump:
0. Program arguments: /home/orome/.local/bin/llc -march=amdgcn
1. Running pass 'CallGraph Pass Manager' on module '<stdin>'.
2. Running pass 'AMDGPU DAG->DAG Pattern Instruction Selection'
on function '@vload3_constant'
the patch changes how char3 vector is constructed. instead of starting
with <4xi8> (edited):
%3 = insertelement <4 x i8> undef, i8 %2, i32 0
%5 = insertelement <4 x i8> %3, i8 %4, i32 1
%7 = insertelement <4 x i8> %5, i8 %6, i32 2
store <4 x i8> %7, <4 x i8> addrspace(1)* %storetmp, align 4, !tbaa !11
it creates <3 x i8>, which is then shuffled into another <3 x i8>, which is
then bitcast to <4 x i8>:
%vecinit.i = insertelement <3 x i8> undef, i8 %2, i32 0
%vecinit1.i = insertelement <3 x i8> %vecinit.i, i8 %3, i32 1
%vecinit4.i = insertelement <3 x i8> %vecinit1.i, i8 %4, i32 2
%extractVec = shufflevector <3 x i8> %vecinit4.i, <3 x i8> undef, <4 x i32>
<i32 0, i32 1, i32 2, i32 undef>
%storetmp = bitcast <3 x i8> addrspace(1)* %out to <4 x i8> addrspace(1)*
^^^ I originally claimed that this one fails, but it's a pointer cast so it
really shouldn't
store <4 x i8> %extractVec, <4 x i8> addrspace(1)* %storetmp, align 4, !tbaa
!11
the attached .cl file will need libclc</pre>
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