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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 - [InstCombine] Infinite loop by operating on same set of instructions in worklist"
href="https://bugs.llvm.org/show_bug.cgi?id=38915">38915</a>
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<th>Summary</th>
<td>[InstCombine] Infinite loop by operating on same set of instructions in worklist
</td>
</tr>
<tr>
<th>Product</th>
<td>tools
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>opt
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>anna@azul.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>This test goes into infinite loop when run with InstCombine on llvm ToT:
opt -instcombine test.ll <-- hangs with rerunning IC over the same set of
instructions in the worklist.
test.ll:
define void @baz(i32 %arg) {
bb:
switch i32 undef, label %bb4 [
i32 0, label %bb2
i32 1, label %bb3
i32 2, label %bb1
]
bb1: ; preds = %bb
ret void
bb2: ; preds = %bb
unreachable
bb3: ; preds = %bb
ret void
bb4: ; preds = %bb
%tmp = sub i32 0, %arg
%tmp5 = and i32 %tmp, 3
%tmp6 = sub i32 0, %tmp5
%tmp7 = sub i32 0, %tmp5
%tmp8 = sub i32 -2, %tmp5
%tmp9 = icmp sgt i32 %tmp6, -2147483647
%tmp10 = select i1 %tmp9, i32 %tmp6, i32 -2147483647
%tmp11 = mul i32 %tmp10, -1
%tmp12 = icmp sgt i32 %tmp7, -2147483647
%tmp13 = select i1 %tmp12, i32 %tmp7, i32 -2147483647
%tmp14 = mul i32 %tmp13, -1
%tmp15 = icmp sgt i32 %tmp11, %tmp14
%tmp16 = select i1 %tmp15, i32 %tmp11, i32 %tmp14
%tmp17 = sub i32 -1, %tmp16
%tmp18 = icmp sgt i32 %tmp17, %tmp8
%tmp19 = select i1 %tmp18, i32 %tmp17, i32 %tmp8
%tmp20 = sub i32 -1, %tmp19
%tmp21 = icmp sgt i32 %tmp20, 1
%tmp22 = select i1 %tmp21, i32 %tmp20, i32 1
%tmp23 = add i32 %tmp22, -1
%tmp24 = add i32 %tmp5, -1
%tmp25 = icmp sgt i32 %tmp24, %tmp23
br i1 %tmp25, label %bb26, label %bb27
bb26: ; preds = %bb4
unreachable
bb27: ; preds = %bb4
unreachable
}</pre>
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