[Issue 16067] New: Invalid source lines shown with disassembly with gdb and objdump

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16067

          Issue ID: 16067
           Summary: Invalid source lines shown with disassembly with gdb
                    and objdump
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: minor
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: christophe at meessen.net

Looking at disassembly with interleaved source code I detected a mismatch.
Trying with the following simple program app.d

  1    import std.stdio;
  2
  3    void main()
  4    {
  5        int a = 10;
  6
  7        a += 3;
  8
  9        ++a;
 10
 11        writefln("Value: %d", a);
 12
 13        writeln("Helloworld!");
 14
 15    }

I get this output with '$ objdump -d -S app' for the function _Dmain

000000000043aae8 <_Dmain>:
import std.stdio;

void main()
  43aae8:       55                      push   %rbp
  43aae9:       48 8b ec                mov    %rsp,%rbp
  43aaec:       48 83 ec 10             sub    $0x10,%rsp
{
        int a = 10;
  43aaf0:       c7 45 f8 0a 00 00 00    movl   $0xa,-0x8(%rbp)

    a += 3;
  43aaf7:       83 45 f8 03             addl   $0x3,-0x8(%rbp)

    ++a;
  43aafb:       ff 45 f8                incl   -0x8(%rbp)

    writefln("Value: %d", a);
  43aafe:       ba 60 e5 46 00          mov    $0x46e560,%edx
  43ab03:       be 09 00 00 00          mov    $0x9,%esi
{
        int a = 10;

    a += 3;

    ++a;
  43ab08:       8b 7d f8                mov    -0x8(%rbp),%edi
  43ab0b:       e8 18 00 00 00          callq  43ab28
<_D3std5stdio19__T8writeflnTAyaTiZ8writeflnFNfAyaiZv>

    writefln("Value: %d", a);

    writeln("Helloworld!");
  43ab10:       ba 6a e5 46 00          mov    $0x46e56a,%edx
  43ab15:       bf 0b 00 00 00          mov    $0xb,%edi
  43ab1a:       48 89 d6                mov    %rdx,%rsi
  43ab1d:       e8 e6 9b 00 00          callq  444708
<_D3std5stdio16__T7writelnTAyaZ7writelnFNfAyaZv>
  43ab22:       31 c0                   xor    %eax,%eax

}
  43ab24:       c9                      leaveq
  43ab25:       c3                      retq
  43ab26:       66 90                   xchg   %ax,%ax

000000000043ab28 <_D3std5stdio19__T8writeflnTAyaTiZ8writeflnFNfAyaiZv>:
}

Looking at the debug line table for the main function with the command '$
objdump --dwarf=decodedline app | less' I get this

./app.d:[++]
app.d                                      3            0x43aae8
app.d                                      5            0x43aaf0
app.d                                      7            0x43aaf7
app.d                                      9            0x43aafb
app.d                                     11            0x43aafe
app.d                                      9            0x43ab08
app.d                                     13            0x43ab10
app.d                                     15            0x43ab24

After closer inspection of the disassembly code it appears that the second line
with 9 should not be present. Removing it should provide a correct debug table. 

I didn't check the possible frequency of occurrence in a more complex program.

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