[llvm-bugs] [Bug 51308] New: invalid symbol redefinition when -O2 enabled

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51308

            Bug ID: 51308
           Summary: invalid symbol redefinition when -O2 enabled
           Product: clang
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: C
          Assignee: unassignedclangbugs at nondot.org
          Reporter: zhan3299 at purdue.edu
                CC: blitzrakete at gmail.com, dgregor at apple.com,
                    erik.pilkington at gmail.com, llvm-bugs at lists.llvm.org,
                    richard-llvm at metafoo.co.uk

Following code can be successfully compiled by O0 optimization on, but not O2.

Example code:
---
#include <stdio.h>

int func() {
    int filter;
    asm volatile(
        "  leaq _filter(%%rip), %%rax\n"
        "  jmp _out\n"
        "_filter:\n"
        ".ascii \"\\040\"\n"
        "_out:"
        : "=rax"(filter)
        :
        :);
    return filter;
}
int main() {
    printf("%#x", func());
    return 0;
}
---

Error message:
---
<source>:8:10: error: symbol '_filter' is already defined
        "_filter:\n"
         ^
<inline asm>:3:1: note: instantiated into assembly here
_filter:
^
<source>:10:10: error: symbol '_out' is already defined
        "_out:"
         ^
<inline asm>:5:1: note: instantiated into assembly here
_out:
^
2 errors generated.
ASM generation compiler returned: 1
<source>:8:10: error: symbol '_filter' is already defined
        "_filter:\n"
         ^
<inline asm>:3:1: note: instantiated into assembly here
_filter:
^
<source>:10:10: error: symbol '_out' is already defined
        "_out:"
         ^
<inline asm>:5:1: note: instantiated into assembly here
_out:
^
2 errors generated.
Execution build compiler returned: 1
---

It affects 11.0, 12.0, and trunk.

Trunk O0: https://godbolt.org/z/7afYjhGzc
Trunk O2: https://godbolt.org/z/6K71Tde6s

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