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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Instcombine tries to create invalid IR"
href="https://llvm.org/bugs/show_bug.cgi?id=27236">27236</a>
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<th>Summary</th>
<td>Instcombine tries to create invalid IR
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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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>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Scalar Optimizations
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>anton@korobeynikov.info
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</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16174" name="attach_16174" title="Testcase">attachment 16174</a> <a href="attachment.cgi?id=16174&action=edit" title="Testcase">[details]</a></span>
Testcase
Consider the attached IR.
opt -instcombine -debug yields:
IC: Replacing %.sroa.4.0 = select i1 %4, float %3, float 0.000000e+00
with %2 = select i1 %1, i32 1, i32 %0
Assertion failed: (New->getType() == getType() && "replaceAllUses of value with
new value of different type!"), function replaceAllUsesWith, file
/Users/asl/Projects/llvm/2commit/llvm/lib/IR/Value.cpp, line 375.
Which is certainly incorrect. I believe the problem was exposed by the recent
changes in min/max optimizations and min(min) / max(max) folding.
The "big hammer" fix is to have something like this:
Index: lib/Transforms/InstCombine/InstCombineSelect.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineSelect.cpp (revision 265487)
+++ lib/Transforms/InstCombine/InstCombineSelect.cpp (working copy)
@@ -642,6 +642,9 @@
Value *A, Value *B,
Instruction &Outer,
SelectPatternFlavor SPF2, Value *C) {
+ if (Outer.getType() != Inner->getType())
+ return nullptr;
+
if (C == A || C == B) {
// MAX(MAX(A, B), B) -> MAX(A, B)
// MIN(MIN(a, b), a) -> MIN(a, b)
However, I believe we need to make sure we never call stuff this way</pre>
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