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<base href="http://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 --- - DWARF debug info has overlapping, invalid line information"
href="http://llvm.org/bugs/show_bug.cgi?id=18790">18790</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>DWARF debug info has overlapping, invalid line information
</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>FreeBSD
</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>Common Code Generator Code
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>yuri@tsoft.com
</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>Created <span class=""><a href="attachment.cgi?id=12038" name="attach_12038" title="testcase">attachment 12038</a> <a href="attachment.cgi?id=12038&action=edit" title="testcase">[details]</a></span>
testcase
I am attaching the testcase which generates wrong debug line information in
elf.
Sources: h.bc and x.bc
Script to run (also included in the testcase):
llvm-link h.bc x.bc > all.bc
llc -filetype=obj all.bc
objdump -D all.o > all.asm
dwarfdump all.o > all.dwarf
Description:
ELF all.o in its .text segment has 2 areas with line information:
0x10-0x1a with the source file z/a.xxx (10 bytes)
0x40-0x41 with the source file z/b.xxx (1 byte)
all.dwarf shows this line information:
<pc> [row,col] NS BB ET PE EB IS= DI= uri: "filepath"
0x00000010 [ 651, 0] NS uri: "z/a.xxx"
0x00000010 [ 652, 5] NS PE
0x00000018 [ 654, 0] NS
0x00000041 [ 654, 0] NS ET
<pc> [row,col] NS BB ET PE EB IS= DI= uri: "filepath"
0x00000040 [ 2, 0] NS uri: "z/b.xxx"
0x00000040 [ 3, 0] NS PE
0x00000041 [ 3, 0] NS ET
The z/a.xxx section above ends at the wrong offset 0x41, and overlaps the
second section, which according to the DWARF info also ends at 0x41
As a result, 'addr2line -e all.o 0x40' command returns wrong line
'z/a.xxx:654', and it should return 'z/b.xxx:3'.
I also traced this in debugger in addr2line. If in debugger to set 'found=0'
after the line dwarf2.c:3660, it will find the correct line z/b.xxx:3 for
offset 0x40. The first cycle erroneously finds the line in z/a.xxx due to this
overlap.
rev.200186</pre>
</div>
</p>
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