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<base href="https://bugs.llvm.org/">
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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 mapping assembly-line at Og"
href="https://bugs.llvm.org/show_bug.cgi?id=51508">51508</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Wrong mapping assembly-line at Og
</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>artuso@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>Comment:
The increment of variable g_64 at line 6 is assigned to wrong assembly
instructions.
Steps to reproduce bug:
root@14f37d90482b:/home/stepping/output# clang -v
clang version 14.0.0 (<a href="https://github.com/llvm/llvm-project.git">https://github.com/llvm/llvm-project.git</a>
957334382cd12ec07b46c0ddfdcc220731f6d80f)
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
root@14f37d90482b:/home/stepping/output# lldb -v
lldb version 14.0.0 (<a href="https://github.com/llvm/llvm-project.git">https://github.com/llvm/llvm-project.git</a> revision
957334382cd12ec07b46c0ddfdcc220731f6d80f)
clang revision 957334382cd12ec07b46c0ddfdcc220731f6d80f
llvm revision 957334382cd12ec07b46c0ddfdcc220731f6d80f
root@9ac1f462aecb:/home/stepping/output# cat a.c
static char b = -1;
int g_64, c;
volatile int d;
char(a)(e, f) { return e - f; }
void func_42() {
++g_64;
c = 0;
for (; c != 3; c = a(c, 1))
d = 9 | b;
b = 0;
}
int main() { func_42(); }
root@9ac1f462aecb:/home/stepping/output# cat -n a.c
1 static char b = -1;
2 int g_64, c;
3 volatile int d;
4 char(a)(e, f) { return e - f; }
5 void func_42() {
6 ++g_64;
7 c = 0;
8 for (; c != 3; c = a(c, 1))
9 d = 9 | b;
10 b = 0;
11 }
12 int main() { func_42(); }
root@9ac1f462aecb:/home/stepping/output# clang -Og -g -Wno-everything -o opt
a.c
root@9ac1f462aecb:/home/stepping/output# lldb opt
(lldb) target create "opt"
Current executable set to '/home/stepping/output/opt' (x86_64).
(lldb) b 6
Breakpoint 1: 2 locations.
(lldb) r
Process 36 launched: '/home/stepping/output/opt' (x86_64)
Process 36 stopped
* thread #1, name = 'opt', stop reason = breakpoint 1.2
frame #0: 0x00000000004004f0 opt`main [inlined] func_42 at a.c:6:3
3 volatile int d;
4 char(a)(e, f) { return e - f; }
5 void func_42() {
-> 6 ++g_64;
7 c = 0;
8 for (; c != 3; c = a(c, 1))
9 d = 9 | b;
(lldb) di -l
opt`main:
-> 0x4004f0 <+0>: addl $0x1, 0x200b35(%rip) ; opt.PT_LOAD[1]..bss + 3
0x4004f7 <+7>: cmpb $0x0, 0x200b36(%rip) ; c + 3
0x4004fe <+14>: movl $0x9, %ecx
0x400503 <+19>: movl $0xffffffff, %eax ; imm = 0xFFFFFFFF
0x400508 <+24>: cmovnel %ecx, %eax
(lldb) si
Process 36 stopped
* thread #1, name = 'opt', stop reason = instruction step into
frame #0: 0x00000000004004f7 opt`main [inlined] func_42 at a.c:6:3
3 volatile int d;
4 char(a)(e, f) { return e - f; }
5 void func_42() {
-> 6 ++g_64;
7 c = 0;
8 for (; c != 3; c = a(c, 1))
9 d = 9 | b;
(lldb) di -l
opt`main:
0x4004f0 <+0>: addl $0x1, 0x200b35(%rip) ; opt.PT_LOAD[1]..bss + 3
-> 0x4004f7 <+7>: cmpb $0x0, 0x200b36(%rip) ; c + 3
0x4004fe <+14>: movl $0x9, %ecx
0x400503 <+19>: movl $0xffffffff, %eax ; imm = 0xFFFFFFFF
0x400508 <+24>: cmovnel %ecx, %eax
(lldb) si
Process 36 stopped
* thread #1, name = 'opt', stop reason = instruction step into
frame #0: 0x00000000004004fe opt`main [inlined] func_42 at a.c:6:3
3 volatile int d;
4 char(a)(e, f) { return e - f; }
5 void func_42() {
-> 6 ++g_64;
7 c = 0;
8 for (; c != 3; c = a(c, 1))
9 d = 9 | b;
(lldb) di -l
opt`main:
0x4004f0 <+0>: addl $0x1, 0x200b35(%rip) ; opt.PT_LOAD[1]..bss + 3
0x4004f7 <+7>: cmpb $0x0, 0x200b36(%rip) ; c + 3
-> 0x4004fe <+14>: movl $0x9, %ecx
0x400503 <+19>: movl $0xffffffff, %eax ; imm = 0xFFFFFFFF
0x400508 <+24>: cmovnel %ecx, %eax
(lldb) si
Process 36 stopped
* thread #1, name = 'opt', stop reason = instruction step into
frame #0: 0x0000000000400503 opt`main [inlined] func_42 at a.c:6:3
3 volatile int d;
4 char(a)(e, f) { return e - f; }
5 void func_42() {
-> 6 ++g_64;
7 c = 0;
8 for (; c != 3; c = a(c, 1))
9 d = 9 | b;
(lldb) di -l
opt`main:
0x4004f0 <+0>: addl $0x1, 0x200b35(%rip) ; opt.PT_LOAD[1]..bss + 3
0x4004f7 <+7>: cmpb $0x0, 0x200b36(%rip) ; c + 3
0x4004fe <+14>: movl $0x9, %ecx
-> 0x400503 <+19>: movl $0xffffffff, %eax ; imm = 0xFFFFFFFF
0x400508 <+24>: cmovnel %ecx, %eax
(lldb) si
Process 36 stopped
* thread #1, name = 'opt', stop reason = instruction step into
frame #0: 0x0000000000400508 opt`main [inlined] func_42 at a.c:6:3
3 volatile int d;
4 char(a)(e, f) { return e - f; }
5 void func_42() {
-> 6 ++g_64;
7 c = 0;
8 for (; c != 3; c = a(c, 1))
9 d = 9 | b;
(lldb) di -l
opt`main:
0x4004f0 <+0>: addl $0x1, 0x200b35(%rip) ; opt.PT_LOAD[1]..bss + 3
0x4004f7 <+7>: cmpb $0x0, 0x200b36(%rip) ; c + 3
0x4004fe <+14>: movl $0x9, %ecx
0x400503 <+19>: movl $0xffffffff, %eax ; imm = 0xFFFFFFFF
-> 0x400508 <+24>: cmovnel %ecx, %eax</pre>
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