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<base href="https://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [X86][AVX] Broadcast loads don't respect dependencies"
href="https://llvm.org/bugs/show_bug.cgi?id=30596">30596</a>
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</tr>
<tr>
<th>Summary</th>
<td>[X86][AVX] Broadcast loads don't respect dependencies
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>3.9
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows NT
</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>
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<th>Component</th>
<td>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>llvm-dev@redking.me.uk
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>As detailed in <a href="https://reviews.llvm.org/D25039">https://reviews.llvm.org/D25039</a>:
declare void @gfunc(<4 x float>*)
declare void @llvm.lifetime.start(i64, i8*)
declare void @llvm.lifetime.end(i64, i8*)
define float @broadcast_lifetime() nounwind {
%1 = alloca <4 x float>, align 16
%2 = alloca <4 x float>, align 16
%3 = bitcast <4 x float>* %1 to i8*
%4 = bitcast <4 x float>* %2 to i8*
call void @llvm.lifetime.start(i64 16, i8* %3)
call void @gfunc(<4 x float>* %1)
%5 = load <4 x float>, <4 x float>* %1, align 16
call void @llvm.lifetime.end(i64 16, i8* %3)
call void @llvm.lifetime.start(i64 16, i8* %4)
call void @gfunc(<4 x float>* %2)
%6 = load <4 x float>, <4 x float>* %2, align 16
call void @llvm.lifetime.end(i64 16, i8* %4)
%7 = extractelement <4 x float> %5, i32 1
%8 = extractelement <4 x float> %6, i32 1
%9 = fsub float %8, %7
ret float %9
}
broadcast_lifetime:
subq $24, %rsp
movq %rsp, %rdi
callq gfunc
movq %rsp, %rdi
callq gfunc
vbroadcastss 4(%rsp), %xmm0 ## <-- 1st gfunc result
vbroadcastss 4(%rsp), %xmm1 ## <-- 2nd gfunc result
vsubss %xmm0, %xmm1, %xmm0
addq $24, %rsp
retq</pre>
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