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<body><span class="vcard"><a class="email" href="mailto:sanjay3.0.0.0@gmail.com" title="Sanjay <sanjay3.0.0.0@gmail.com>"> <span class="fn">Sanjay</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - loop increment/compare/branch should be removed for vectorized and unrolled code"
href="http://llvm.org/bugs/show_bug.cgi?id=17803">bug 17803</a>
<br>
<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
</td>
</tr>
<tr>
<td style="text-align:right;">CC</td>
<td>
</td>
<td>sanjay3.0.0.0@gmail.com
</td>
</tr>
<tr>
<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>FIXED
</td>
</tr></table>
<p>
<div>
<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - loop increment/compare/branch should be removed for vectorized and unrolled code"
href="http://llvm.org/bugs/show_bug.cgi?id=17803#c3">Comment # 3</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - loop increment/compare/branch should be removed for vectorized and unrolled code"
href="http://llvm.org/bugs/show_bug.cgi?id=17803">bug 17803</a>
from <span class="vcard"><a class="email" href="mailto:sanjay3.0.0.0@gmail.com" title="Sanjay <sanjay3.0.0.0@gmail.com>"> <span class="fn">Sanjay</span></a>
</span></b>
<pre>This looks ideal with clang 3.5 (r205798):
bin$ ./clang -v
clang version 3.5.0 (trunk 205798) (llvm/trunk 205792)
Target: x86_64-apple-darwin13.1.0
Thread model: posix
bin$ ./clang xor.c -O3 -fomit-frame-pointer -o - -S -march=core-avx2
...
## BB#0: ## %entry
vmovaps LCPI0_0(%rip), %ymm0
vxorps (%rdi), %ymm0, %ymm1
vxorps 32(%rdi), %ymm0, %ymm2
vxorps 64(%rdi), %ymm0, %ymm3
vxorps 96(%rdi), %ymm0, %ymm0
vmovups %ymm1, (%rdi)
vmovups %ymm2, 32(%rdi)
vmovups %ymm3, 64(%rdi)
vmovups %ymm0, 96(%rdi)
vzeroupper
retq
With a plain 'avx' target rather than 'avx2', we go through all kinds of
gymnastics to avoid unaligned 32-bit load or store, but the leftover loop
problem is still fixed:
$ ./clang xor.c -O3 -fomit-frame-pointer -o - -S -march=corei7-avx
...
## BB#0: ## %entry
vmovups (%rdi), %xmm0
vmovups 32(%rdi), %xmm1
vmovups 64(%rdi), %xmm2
vmovups 96(%rdi), %xmm3
vinsertf128 $1, 16(%rdi), %ymm0, %ymm0
vinsertf128 $1, 48(%rdi), %ymm1, %ymm1
vinsertf128 $1, 80(%rdi), %ymm2, %ymm2
vinsertf128 $1, 112(%rdi), %ymm3, %ymm3
vmovaps LCPI0_0(%rip), %ymm4
vxorps %ymm4, %ymm0, %ymm0
vxorps %ymm4, %ymm1, %ymm1
vxorps %ymm4, %ymm2, %ymm2
vxorps %ymm4, %ymm3, %ymm3
vextractf128 $1, %ymm0, %xmm4
vmovups %xmm4, 16(%rdi)
vmovups %xmm0, (%rdi)
vextractf128 $1, %ymm1, %xmm0
vmovups %xmm0, 48(%rdi)
vmovups %xmm1, 32(%rdi)
vextractf128 $1, %ymm2, %xmm0
vmovups %xmm0, 80(%rdi)
vmovups %xmm2, 64(%rdi)
vextractf128 $1, %ymm3, %xmm0
vmovups %xmm0, 112(%rdi)
vmovups %xmm3, 96(%rdi)
vzeroupper
retq</pre>
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