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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Merge consecutive load insertions into a vector where possible"
href="https://bugs.llvm.org/show_bug.cgi?id=39473">39473</a>
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<th>Summary</th>
<td>Merge consecutive load insertions into a vector where possible
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<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>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Common Code Generator Code
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>llvm-dev@redking.me.uk
</td>
</tr>
<tr>
<th>CC</th>
<td>andrea.dibiagio@gmail.com, filcab@gmail.com, llvm-bugs@lists.llvm.org, spatel+llvm@rotateright.com
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<div>
<pre>#include <x86intrin.h>
__m128i load_00123456(const unsigned short *data) {
return _mm_setr_epi16(data[0], data[0], data[1], data[2], data[3], data[4],
data[5], data[6]);
}
-O3 -march=btver2
_Z13load_00123456PKt: # @_Z13load_00123456PKt
movzwl (%rdi), %eax
vmovd %eax, %xmm0
vpinsrw $1, %eax, %xmm0, %xmm0
vpinsrw $2, 2(%rdi), %xmm0, %xmm0
vpinsrw $3, 4(%rdi), %xmm0, %xmm0
vpinsrw $4, 6(%rdi), %xmm0, %xmm0
vpinsrw $5, 8(%rdi), %xmm0, %xmm0
vpinsrw $6, 10(%rdi), %xmm0, %xmm0
vpinsrw $7, 12(%rdi), %xmm0, %xmm0
retq
Many of the loads/insertions could be merged to something like:
_Z19load_00123456_mergePKt: # @_Z19load_00123456_mergePKt
movzwl (%rdi), %eax
vmovd %eax, %xmm0
vpshuflw $224, %xmm0, %xmm0 # xmm0 = xmm0[0,0,2,3,4,5,6,7]
vpshufd $0, %xmm0, %xmm0 # xmm0 = xmm0[0,0,0,0]
vpinsrd $1, 2(%rdi), %xmm0, %xmm0
vpinsrq $1, 6(%rdi), %xmm0, %xmm0
retq
<a href="https://godbolt.org/z/-HLpsE">https://godbolt.org/z/-HLpsE</a></pre>
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