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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Assertion `isa<Argument>(Val) && "Unknown live-in to the entry block"' failed"
href="https://bugs.llvm.org/show_bug.cgi?id=33364">33364</a>
</td>
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<th>Summary</th>
<td>Assertion `isa<Argument>(Val) && "Unknown live-in to the entry block"' failed
</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>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Global Analyses
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>warren_ristow@playstation.sony.com
</td>
</tr>
<tr>
<th>CC</th>
<td>anna@azul.com, llvm-bugs@lists.llvm.org
</td>
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<pre>Our internal testing hit a compile-time assertion failure with optimization
on trunk:
Using:
clang version 5.0.0 (trunk 304995)
Target: x86_64-unknown-linux-gnu
Thread model: posix
$ cat test.cpp
// ======================================================
typedef char char2 __attribute__((ext_vector_type(2)));
char2 a, b;
int c;
int foo() {
char2 d = {1};
char2 f = a;
for (int g = 0; g < c; ++g)
d = b;
char2 h = d <= 0;
char2 i = f & h;
return i[0] + i[1];
}
// ======================================================
$
It fails at -O1 or higher:
$ clang++ -c -O1 -c test.cpp
clang++: /home/warren/Upstream/llvm/lib/Analysis/LazyValueInfo.cpp:890: bool
{anonymous}::LazyValueInfoImpl::solveBlockValueNonLocal({anonymous}::LVILatticeVal&,
llvm::Value*, llvm::BasicBlock*): Assertion `isa<Argument>(Val) && "Unknown
live-in to the entry block"' failed.
...
$
We've bisected it to r298845
( <a href="http://llvm.org/viewvc/llvm-project?view=revision&revision=298845">http://llvm.org/viewvc/llvm-project?view=revision&revision=298845</a> ):
~~
[InstCombine] Avoid incorrect folding of select into phi nodes when incoming
element is a vector type
Summary:
We are incorrectly folding selects into phi nodes when the incoming value of a
phi node is a constant vector. This optimization is done in `FoldOpIntoPhi`
when the select condition is a phi node with constant incoming values.
Without the fix, we are miscompiling (i.e. incorrectly folding the select into
the phi node) when the vector contains non-zero elements.
This patch fixes the miscompile and we will correctly fold based on the
select vector operand (see added test cases).
Reviewers: majnemer, sanjoy, spatel
Subscribers: llvm-commits
Differential Revision: <a href="https://reviews.llvm.org/D31189">https://reviews.llvm.org/D31189</a>
~~</pre>
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