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<base href="http://llvm.org/bugs/" />
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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 --- - wrong code by LTO on x86_64-linux-gnu in 64-bit mode"
href="http://llvm.org/bugs/show_bug.cgi?id=19072">19072</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>wrong code by LTO on x86_64-linux-gnu in 64-bit mode
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</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>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>su@cs.ucdavis.edu
</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>The current clang trunk miscompiles the following code when using LTO on
x86_64-linux-gnu in 64-bit mode (but not 32-bit mode).
$ clang-trunk -v
clang version 3.5.0 (trunk 203119)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8.1
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.1
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
$
$ clang-trunk -O0 fn1.c fn2.c fn3.c main.c
$ a.out
0
$ clang-trunk -flto -O0 -c fn1.c
$ clang-trunk -flto -O1 -c fn2.c
$ clang-trunk -flto -O0 -c fn3.c
$ clang-trunk -flto -O0 -c main.c
$ clang-trunk -flto -O1 fn1.o fn2.o fn3.o main.o
$ a.out
1293820360
$
$
$ cat fn1.c
extern int d;
void
fn1 (int p)
{
if (!p)
d = 0;
}
$ cat fn2.c
extern void fn1 (int);
extern short b;
void
fn2 (void)
{
for (b = 1; b; b++)
fn1 (b);
}
$ cat fn3.c
extern void fn2 (void);
extern volatile int c;
extern int d;
void
fn3 (void)
{
fn2 ();
int e = 0, t;
if (d)
{
t = e || e ? 0 : e;
c;
}
}
$ cat main.c
extern int printf (const char *, ...);
extern void fn3 (void);
int a[6];
short b;
volatile int c;
int d = 1;
int
main ()
{
a[1] = 0;
fn3 ();
printf ("%d\n", a[a[0]]);
return 0;
}</pre>
</div>
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