<html>
<head>
<base href="http://llvm.org/bugs/" />
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [AVX512] bitcast and compare of compile-time i1 vector not optimized well"
href="http://llvm.org/bugs/show_bug.cgi?id=20678">20678</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[AVX512] bitcast and compare of compile-time i1 vector not optimized well
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>matt@pharr.org
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=12906" name="attach_12906" title="test case">attachment 12906</a> <a href="attachment.cgi?id=12906&action=edit" title="test case">[details]</a></span>
test case
The attached test program has the following at its start:
br i1 icmp ne (i16 bitcast (<16 x i1> <i1 true, i1 true, i1 true, i1 true, i1
true, i1 true, i1 true, i1 true, i1 false, i1 false, i1 false, i1 false, i1
false, i1 false, i1 false, i1 false> to i16), i16 0), label %safe_if_run_true,
label %safe_if_after_true
It seems that LLVM isn't determining that this is a compile-time constant test,
since the following code is generated for the function. (In addition to the
unnecessary movw/testw/je at the start, not also that there is a redundant movw
after the je.)
_add___UM_vyfvyf: ## @add___UM_vyfvyf
## BB#0: ## %allocas
movw $255, %ax
testw %ax, %ax
je LBB1_2
## BB#1: ## %safe_if_run_true
movw $255, %ax
kmovw %eax, %k1
vmovups %zmm1, _array(%rip) {%k1}
LBB1_2: ## %safe_if_after_true
vaddps %zmm1, %zmm0, %zmm0
retq</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>