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<base href="http://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Performance regression caused by changes in machine sink"
href="http://llvm.org/bugs/show_bug.cgi?id=21115">21115</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Performance regression caused by changes in machine sink
</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>
<tr>
<th>OS</th>
<td>Linux
</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>Common Code Generator Code
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>avolkov.intel@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu, wujingyue@gmail.com, zinovy.nis@gmail.com
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=13108" name="attach_13108" title="Test">attachment 13108</a> <a href="attachment.cgi?id=13108&action=edit" title="Test">[details]</a></span>
Test
After changes in revision 216862 I see performance regression at least on x86
Silvermont on attached test case.
To reproduce compile it with:
llc -O2 -mcpu=slm test.ll
The reason of regression is machine sink doesn't move some add operations out
of loop:
Revision 216861:
addl %edx, %ebx
addl $1, %esi
addl %ebp, %ecx
cmpl $512, %ebx # imm = 0x200
jl .LBB0_5 <--- Back edge
# BB#6: # %for.cond4.for.end_crit_edge
# in Loop: Header=BB0_4 Depth=2
movl 20(%esp), %edx # 4-byte Reload
leal (%edx,%ecx), %edi <--- add moved out of loop
movl 16(%esp), %edx # 4-byte Reload
movl %edi, t_run_test.imagHi_1
leal (%edx,%ecx), %ebp <--- add moved out of loop
movl %esi, %edx
movl %eax, %esi
movl 12(%esp), %eax # 4-byte Reload
movl %ebp, t_run_test.realHi_1
addl %ecx, %eax <--- add moved out of loop
addl 8(%esp), %ecx # 4-byte Folded Reload <--- add moved out
of loop
movl %eax, t_run_test.imagLow_1
movl %esi, %eax
movl %edx, %esi
movl 4(%esp), %edx # 4-byte Reload
movl %ecx, t_run_test.realLow_1
Revision 21862:
cmpl $512, %ecx # imm = 0x200
leal (%eax,%ebx), %ebp <--- add inside loop
movl 24(%esp), %eax # 4-byte Reload
leal (%edx,%ebx), %edx <--- add inside loop
leal (%edi,%ebx), %edi <--- add inside loop
leal (%eax,%ebx), %eax <--- add inside loop
jl .LBB0_5 <--- Back edge
# BB#6: # %for.cond4.for.end_crit_edge
# in Loop: Header=BB0_4 Depth=2
movl %edi, t_run_test.realLow_1
movl %edx, t_run_test.imagLow_1
movl %eax, t_run_test.realHi_1
movl %ebp, t_run_test.imagHi_1</pre>
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