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<base href="https://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Registers swapped with -no-integrated-as"
href="https://llvm.org/bugs/show_bug.cgi?id=22995">22995</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Registers swapped with -no-integrated-as
</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>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>MC
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>russell_gallop@sn.scee.net
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Built from r232944.
Building this example using -no-integrated-as results in a small difference in
the generated code. The register operands of the instruction at 0xc are swapped
compared to direct object emission.
$ cat test.cpp
int a, b;
int fn1();
void fn2() {
if (a & fn1())
b = 0;
}
$ clang -c -O2 test.cpp -o direct.o && objdump -d direct.o
direct.o: file format elf64-x86-64
Disassembly of section .text:
0000000000000000 <_Z3fn2v>:
0: 53 push %rbx
1: 8b 1d 00 00 00 00 mov 0x0(%rip),%ebx # 7 <_Z3fn2v+0x7>
7: e8 00 00 00 00 callq c <_Z3fn2v+0xc>
c: 85 c3 test %eax,%ebx
e: 74 0a je 1a <_Z3fn2v+0x1a>
10: c7 05 00 00 00 00 00 movl $0x0,0x0(%rip) # 1a
<_Z3fn2v+0x1a>
17: 00 00 00
1a: 5b pop %rbx
1b: c3 retq
$ clang -c -O2 test.cpp -no-integrated-as -o no_int_as.o && objdump -d
no_int_as.o
no_int_as.o: file format elf64-x86-64
Disassembly of section .text:
0000000000000000 <_Z3fn2v>:
0: 53 push %rbx
1: 8b 1d 00 00 00 00 mov 0x0(%rip),%ebx # 7 <_Z3fn2v+0x7>
7: e8 00 00 00 00 callq c <_Z3fn2v+0xc>
c: 85 d8 test %ebx,%eax
e: 74 0a je 1a <_Z3fn2v+0x1a>
10: c7 05 00 00 00 00 00 movl $0x0,0x0(%rip) # 1a
<_Z3fn2v+0x1a>
17: 00 00 00
1a: 5b pop %rbx
1b: c3 retq</pre>
</div>
</p>
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