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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Incorrect code generated for llvm.masked.store <2 x i1> with a variable mask"
href="https://llvm.org/bugs/show_bug.cgi?id=31305">31305</a>
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<th>Summary</th>
<td>Incorrect code generated for llvm.masked.store <2 x i1> with a variable mask
</td>
</tr>
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<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>
</tr>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: X86
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>zvi.rackover@intel.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>define void @unmasked(<2 x i1> %x, <2 x i1>* %ptr) nounwind {
store <2 x i1> %x, <2 x i1>* %ptr
ret void
}
define void @masked_const(<2 x i1> %x, <2 x i1>* %ptr) nounwind {
call void @llvm.masked.store.v2i1.p0v2i1(<2 x i1> %x, <2 x i1>* %ptr, i32 0,
<2 x i1> <i1 1, i1 1>)
ret void
}
For both functions above we generate:
llc -mcpu=skx
vpsllq $63, %xmm0, %xmm0
vptestmq %xmm0, %xmm0, %k0
kmovb %k0, (%rdi)
retq
But in the case of a variable mask:
define void @masked_var(<2 x i1> %x, <2 x i1>* %ptr) nounwind {
call void @llvm.masked.store.v2i1.p0v2i1(<2 x i1> %x, <2 x i1>* %ptr, i32 0,
<2 x i1> %x)
ret void
}
the generated code stores each vector element in a distinct byte:
vpsllq $63, %xmm0, %xmm0
vptestmq %xmm0, %xmm0, %k0
kshiftlw $15, %k0, %k1
kshiftrw $15, %k1, %k1
kmovw %k1, %eax
andl $1, %eax
testb %al, %al
je .LBB2_2
# BB#1: # %cond.store
kmovb %k1, (%rdi)
.LBB2_2: # %else
kshiftlw $14, %k0, %k0
kshiftrw $15, %k0, %k0
kmovw %k0, %eax
andl $1, %eax
testb %al, %al
je .LBB2_4
# BB#3: # %cond.store1
kmovb %k0, 1(%rdi)
.LBB2_4: # %else2
retq</pre>
</div>
</p>
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