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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW " title="NEW --- - mem2reg generates incorrect code" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_bugs_show-5Fbug.cgi-3Fid-3D24179&d=AwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=pF93YEPyB-J_PERP4DUZOJDzFVX5ZQ57vQk33wu0vio&m=XPzlwbTS7OxbJW7OPU2OTbwr-aMQ0L9G-R0Yn3o17y4&s=jUfvizqctiXJji2-iMjKID2wGaQU5eEUFXVDd9ExuMc&e=">24179</a>
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<th>Summary</th>
<td>mem2reg generates incorrect code
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</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>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>sanjoy@playingwithpointers.com
</td>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Running -mem2reg on
declare i1 @use(i32)
define void @f() {
entry:
%t = alloca i32
br label %loop
loop:
%v = load i32, i32* %t
%c = call i1 @use(i32 %v)
store i32 46, i32* %t
store i32 42, i32* %t
br i1 %c, label %loop, label %exit
exit:
ret void
}
gives
declare i1 @use(i32)
define void @f() {
entry:
br label %loop
loop: ; preds = %loop, %entry
%c = tail call i1 @use(i32 undef)
br i1 %c, label %loop, label %exit
exit: ; preds = %loop
ret void
}
when %c should be undef only on the first iteration and 42 for all subsequent
iterations.</pre>
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