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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Redundant comparisons are not eliminated"
href="https://bugs.llvm.org/show_bug.cgi?id=34911">34911</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Redundant comparisons are not eliminated
</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>
<tr>
<th>OS</th>
<td>All
</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>
<tr>
<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jmuizelaar@mozilla.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>#include <stdlib.h>
int f(int x) {
if (x < 4)
exit(1);
if (x < 8)
exit(1);
if (x < 12)
exit(1);
if (x < 16)
exit(1);
return x + 5;
}
compiles to:
f(int): # @f(int)
pushq %rax
cmpl $3, %edi
jle .LBB0_5
cmpl $7, %edi
jle .LBB0_5
cmpl $11, %edi
jle .LBB0_5
cmpl $15, %edi
jle .LBB0_5
addl $5, %edi
movl %edi, %eax
popq %rcx
retq
.LBB0_5:
movl $1, %edi
callq exit
compared to gcc's
f(int):
cmpl $15, %edi
jle .L7
leal 5(%rdi), %eax
ret
.L7:
subq $8, %rsp
movl $1, %edi
call exit</pre>
</div>
</p>
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