<html>
<head>
<base href="https://bugs.llvm.org/">
</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 - -polyhedral-info -polly-check-parallel analyzes non parallel loop as parallel."
href="https://bugs.llvm.org/show_bug.cgi?id=36388">36388</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>-polyhedral-info -polly-check-parallel analyzes non parallel loop as parallel.
</td>
</tr>
<tr>
<th>Product</th>
<td>Polly
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</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>Optimizer
</td>
</tr>
<tr>
<th>Assignee</th>
<td>polly-dev@googlegroups.com
</td>
</tr>
<tr>
<th>Reporter</th>
<td>takiuchi@oscartech.jp
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>The outer loop of the following program is analyzed as parallel by
-polyhedral-info -polly-check-parallel. But the outerloop has loop-carried
dependence and is analyzed as not parallel by -polly-parallel analysis.
float a[256],b[256];
float aa[256][256],bb[256][256],cc[256][256];
int main () {
for (int i = 1; i < 256;i++) {
a[i] = a[i-1]+b[i] ;
for (int j=0;j<256;j++ ) {
aa[i][j] = aa[i][j]+cc[i][j];
}
}
return 0;
}
clang -O1 -S -emit-llvm -o loop.s loop.c
opt -S -polly-canonicalize loop.s > loop.preopt.ll
opt -polly-parallel -polly-ast -polyhedral-info -polly-check-parallel -analyze
-q loop.preopt.ll -polly-process-unprofitable
Printing analysis 'Polly - Generate an AST from the SCoP (isl)' for region:
'for.body8 => for.cond.cleanup7' in function 'main':
Printing analysis 'Polly - Generate an AST from the SCoP (isl)' for region:
'for.body => for.cond.cleanup' in function 'main':
:: isl ast :: main :: %for.body---%for.cond.cleanup
if (1)
#pragma minimal dependence distance: 1
for (int c0 = 0; c0 <= 254; c0 += 1) {
Stmt0(c0);
#pragma simd
#pragma known-parallel
for (int c1 = 0; c1 <= 255; c1 += 1)
Stmt1(c0, c1);
}
else
{ /* original code */ }
Printing analysis 'Polly - Generate an AST from the SCoP (isl)' for region:
'entry => <Function Return>' in function 'main':
Printing analysis 'Polly - Interface to polyhedral analysis engine' for
function 'main':
for.body: Loop is parallel.
for.body8: Loop is parallel.</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>