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<base href="https://bugs.llvm.org/">
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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 - LLDB show a wrong value for function argument"
href="https://bugs.llvm.org/show_bug.cgi?id=46181">46181</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>LLDB show a wrong value for function argument
</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>Linux
</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>DebugInfo
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>massarelli@diag.uniroma1.it
</td>
</tr>
<tr>
<th>CC</th>
<td>jdevlieghere@apple.com, keith.walker@arm.com, llvm-bugs@lists.llvm.org, paul_robinson@playstation.sony.com
</td>
</tr></table>
<p>
<div>
<pre>Argument p_8 in func_7 is shown to have a wrong value.
dwarf-dump information seems correct.
$ cat -n a.c
1 typedef long int64_t;
2 int a, b, c;
3 static int func_7(int64_t p_8) {
4 p_8 &&b;
5 return a;
6 }
7 int main() {
8 int d = func_7(0xED9A924C00011151);
9 c = d;
10 }
$ cat a.c
typedef long int64_t;
int a, b, c;
static int func_7(int64_t p_8) {
p_8 &&b;
return a;
}
int main() {
int d = func_7(0xED9A924C00011151);
c = d;
}
$ clang -v
clang version 11.0.0 (<a href="https://github.com/llvm/llvm-project.git">https://github.com/llvm/llvm-project.git</a>
d4ef654673a921878ba5aedb9725b2ac32681f01)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Candidate multilib: .;@m64
Selected multilib: .;@m64
$ lldb -v
lldb version 11.0.0
clang revision d4ef654673a921878ba5aedb9725b2ac32681f01
llvm revision d4ef654673a921878ba5aedb9725b2ac32681f01
$ gdb -v
GNU gdb (Ubuntu 8.1-0ubuntu3.2) 8.1.0.20180409-git
$ clang -Og -g -o opt a.c
$ llvm-dwarf-dump opt
...
0x0000007a: DW_TAG_formal_parameter
DW_AT_const_value (-1325586285191949999)
DW_AT_name ("p_8")
DW_AT_decl_file ("a.c")
DW_AT_decl_line (3)
DW_AT_type (0x0000008c "int64_t")
...
$ lldb opt
(lldb) target create "opt"
Current executable set to 'opt' (x86_64).
(lldb) b main
Breakpoint 1: where = opt`main + 1 at a.c:8:11, address = 0x0000000000400481
(lldb) r
Process 460 launched: 'opt' (x86_64)
Process 460 stopped
* thread #1, name = 'opt', stop reason = breakpoint 1.1
frame #0: 0x0000000000400481 opt`main at a.c:8:11
5 return a;
6 }
7 int main() {
-> 8 int d = func_7(0xED9A924C00011151);
9 c = d;
10 }
(lldb) s
Process 460 stopped
* thread #1, name = 'opt', stop reason = step in
frame #0: 0x0000000000400490 opt`func_7(p_8=-2147413679) at a.c:5:10
2 int a, b, c;
3 static int func_7(int64_t p_8) {
4 p_8 &&b;
-> 5 return a;
6 }
7 int main() {
8 int d = func_7(0xED9A924C00011151);
(lldb) s
Process 460 stopped
* thread #1, name = 'opt', stop reason = step in
frame #0: 0x0000000000400486 opt`main at a.c:9:5
6 }
7 int main() {
8 int d = func_7(0xED9A924C00011151);
-> 9 c = d;
10 }
(lldb) s
Process 460 stopped
* thread #1, name = 'opt', stop reason = step in
frame #0: 0x000000000040048c opt`main at a.c:10:1
7 int main() {
8 int d = func_7(0xED9A924C00011151);
9 c = d;
-> 10 }
$ gdb opt
(gdb) b main
Breakpoint 1 at 0x400481: file a.c, line 8.
(gdb) r
Starting program: opt
Breakpoint 1, main () at a.c:8
8 int d = func_7(0xED9A924C00011151);
(gdb) s
func_7 (p_8=-1325586285191949999) at a.c:5
5 return a;
(gdb)</pre>
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