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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - cmp+store is not optimized to an unconditional store"
href="https://bugs.llvm.org/show_bug.cgi?id=38450">38450</a>
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<th>Summary</th>
<td>cmp+store is not optimized to an unconditional store
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<th>Product</th>
<td>new-bugs
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<th>Version</th>
<td>trunk
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<th>Hardware</th>
<td>PC
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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>new bugs
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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>chandlerc@gmail.com, hfinkel@anl.gov, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
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<p>
<div>
<pre>See <a href="https://godbolt.org/g/5W5q2K">https://godbolt.org/g/5W5q2K</a> , the following LLVM-IR:
define void @foo(i32* noalias nocapture dereferenceable(4) %x) {
start:
%0 = load i32, i32* %x, align 4
%1 = icmp eq i32 %0, 0
br i1 %1, label %bb2, label %bb1
bb1:
store i32 0, i32* %x, align 4
br label %bb2
bb2:
ret void
}
does not optimize to anything better with opt -O3. Using llc, it generates the
following x86_64 assembly code (<a href="https://godbolt.org/g/RX81Sn">https://godbolt.org/g/RX81Sn</a>):
cmpl $0, (%rdi)
je .LBB0_2
movl $0, (%rdi)
.LBB0_2:
retq
I would expect this to just generate "movl $0, (%rdi); retq".</pre>
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