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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 --- - Invalid optimization with -fPIC"
href="http://llvm.org/bugs/show_bug.cgi?id=19405">19405</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Invalid optimization with -fPIC
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>3.3
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</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>Interprocedural Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>hubicka@ucw.cz
</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>#include "stdio.h"
int
b(void)
{
return 1;
}
int a(int (*b)(void))
{
return b();
}
m()
{
int i;
for (i=0; i<1000000;i++)
i+=a(b);
printf ("%i\n",i);
c();
}
With -O2 -fPIC is compiled as (on Linux):
m: # @m
.cfi_startproc
# BB#0:
pushq %rax
.Ltmp3:
.cfi_def_cfa_offset 16
leaq .L.str(%rip), %rdi
movl $1000000, %esi # imm = 0xF4240
xorb %al, %al
callq printf@PLT
xorb %al, %al
popq %rdx
jmp c@PLT # TAILCALL
.Ltmp4:
This is not valid, since ELF interpositionallows you to replace a by different
function returning different value.</pre>
</div>
</p>
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