[Issue 20253] New: bad debug line info for function without epilog

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20253

          Issue ID: 20253
           Summary: bad debug line info for function without epilog
           Product: D
           Version: D2
          Hardware: All
                OS: Windows
            Status: NEW
          Keywords: symdeb
          Severity: major
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: r.sagitario at gmx.de

This module:

string foo(string s1, string s2)
{
    throw new Exception("x");
}

built with "dmd -g -m64 test.c" generates an object file with invalid debug
line info:

***** SECTION #C

*** LINES

  0000:00000000-00000086, flags = 0000, fileid = 00000000

      2 00000000      4 00000013

  fileid = 00000008

   2607 00000060

  fileid = 00000000

      5 00000086

 <<<< WARNING >>>> 1 line/addr pairs are out of bounds!

*** SYMBOLS

(000064) S_UDT:             0x1004, string

(000073) S_GPROC32: [0000:00000000], Cb: 00000086, Type:             0x1006,
dbginf.foo
         Parent: 00000000, End: 00000000, Next: 00000000
         Debug start: 00000013, Debug end: 00000086

(0000A5)  S_REGREL32: rbp+00000010, Type:             0x1007, s2
(0000B6)  S_REGREL32: rbp+00000018, Type:             0x1007, s1
(0000C7)  S_ENDARG

(0000CB) S_END

The line info beyond the end of the function can overlap with code of the
following function, causing it not to be shown in the debugger.

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