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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - support runtime loop unroll with pointer type"
href="https://bugs.llvm.org/show_bug.cgi?id=51178">51178</a>
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<th>Summary</th>
<td>support runtime loop unroll with pointer type
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Loop Optimizer
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>jaykang10@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>The loop unroll pass does not support runtime loop unroll with pointer type.
Let's see a example.
declare i32 @foo(i8 *)
define void @test(i8* %s, i64 %a) {
entry:
%s.addr.a = getelementptr i8, i8* %s, i64 %a
br label %while.body.us
while.body.us:
%s.addr = phi i8* [ %incdec.ptr, %while.body.us ], [ %s, %entry ]
%incdec.ptr = getelementptr inbounds i8, i8* %s.addr, i64 1
%incdec.val = load i8, i8* %s.addr, align 1
%cmp1 = icmp eq i8 %incdec.val, 10
br i1 %cmp1, label %return.loopexit, label %while.body.us
return.loopexit:
ret void
}
As you can see, the iv's instruction is getelementptr and the pass fails to
runtime unroll the loop with the iv. You can reproduce it with below command.
opt -loop-unroll -unroll-runtime above_ir_code_file.ll -S -o -</pre>
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