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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - missed opt: indeterminate value in lvalue expression does not optimize function call away"
href="https://bugs.llvm.org/show_bug.cgi?id=41112">41112</a>
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<th>Summary</th>
<td>missed opt: indeterminate value in lvalue expression does not optimize function call away
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<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
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Scalar Optimizations
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>gonzalobg88@gmail.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<p>
<div>
<pre>This code (<a href="https://gcc.godbolt.org/z/Zw-9jM">https://gcc.godbolt.org/z/Zw-9jM</a>):
extern int foo(int);
int bar() {
int a;
return foo(a);
}
int baz() {
int a;
return a;
}
compiles with -O3 to:
bar: # @bar
jmp foo # TAILCALL
baz: # @baz
retq
Here, `baz` is optimized away because an indeterminate value participates in an
lvalue-expression, which is undefined behavior.
However, an indeterminate value participates in an lvalue expression in `bar`,
yet the call to `foo` is not optimized away. I believe it should.</pre>
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