https://sourceware.org/bugzilla/show_bug.cgi?id=29529
Bug ID: 29529
Summary: [objdump] -l flag can't parse -gdwarf-5 file name info
from clang
Product: binutils
Version: unspecified
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: binutils
Assignee: unassigned at sourceware dot org
Reporter: ndesaulniers at google dot com
Target Milestone: ---
Created attachment 14300
--> https://sourceware.org/bugzilla/attachment.cgi?id=14300&action=edit
clang++ -g -gdwarf-5 x.cpp
via: https://github.com/compiler-explorer/compiler-explorer/issues/3991
It looks like `objdump -dl a.out` isn't able to parse file info correctly from
DWARFv5 binaries generated by Clang.
I'm not sure if Clang is perhaps generating invalid debug info, but it seems
that llvm-objdump is able to parse output from either GCC or Clang.
```
$ cat x.cpp
int square(int num) {
return num * num;
}
int main () {
return square(3);
}
$ g++ -g -gdwarf-5 x.cpp
$ objdump -dl a.out | grep main\>: -A 13
0000000000001138 <main>:
main():
/tmp/x.cpp:5
1138: 55 push %rbp
1139: 48 89 e5 mov %rsp,%rbp
/tmp/x.cpp:6
113c: bf 03 00 00 00 mov $0x3,%edi
1141: e8 e3 ff ff ff call 1129 <_Z6squarei>
1146: 90 nop
/tmp/x.cpp:7
1147: 5d pop %rbp
1148: c3 ret
1149: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
$ llvm-objdump -dl a.out| grep main\>: -A 13
0000000000001138 <main>:
; main():
; /tmp/x.cpp:5
1138: 55 pushq %rbp
1139: 48 89 e5 movq %rsp, %rbp
; /tmp/x.cpp:6
113c: bf 03 00 00 00 movl $3, %edi
1141: e8 e3 ff ff ff callq 0x1129 <_Z6squarei>
1146: 90 nop
; /tmp/x.cpp:7
1147: 5d popq %rbp
1148: c3 retq
1149: 0f 1f 80 00 00 00 00 nopl (%rax)
$ clang++ -g -gdwarf-5 x.cpp
$ llvm-objdump -dl a.out| grep main\>: -A 13
0000000000001140 <main>:
; main():
; /tmp/x.cpp:5
1140: 55 pushq %rbp
1141: 48 89 e5 movq %rsp, %rbp
1144: 48 83 ec 10 subq $16, %rsp
1148: c7 45 fc 00 00 00 00 movl $0, -4(%rbp)
; /tmp/x.cpp:6
114f: bf 03 00 00 00 movl $3, %edi
1154: e8 d7 ff ff ff callq 0x1130 <_Z6squarei>
1159: 48 83 c4 10 addq $16, %rsp
115d: 5d popq %rbp
115e: c3 retq
115f: 90 nop
$ objdump -dl a.out | grep main\>: -A 13
0000000000001140 <main>:
main():
<unknown>:5
1140: 55 push %rbp
1141: 48 89 e5 mov %rsp,%rbp
1144: 48 83 ec 10 sub $0x10,%rsp
1148: c7 45 fc 00 00 00 00 movl $0x0,-0x4(%rbp)
<unknown>:6
114f: bf 03 00 00 00 mov $0x3,%edi
1154: e8 d7 ff ff ff call 1130 <_Z6squarei>
1159: 48 83 c4 10 add $0x10,%rsp
115d: 5d pop %rbp
115e: c3 ret
115f: 90 nop
```
See those `<unknown>` in the above.
```
$ clang --version
clang version 16.0.0 (g...@github.com:llvm/llvm-project.git
51a643230eadd67bf5ac18befc28d85ed4e83c81)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /android0/llvm-project/llvm/build/bin
$ g++ --version
g++ (Debian 11.3.0-5) 11.3.0
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ objdump --version
GNU objdump (GNU Binutils for Debian) 2.38.90.20220713
Copyright (C) 2022 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) any later version.
This program has absolutely no warranty.
$ llvm-objdump --version | head -n 2
LLVM (http://llvm.org/):
LLVM version 16.0.0git
```
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