[fpc-devel] [Dwarf AVR] DIE refers to abbreviation number which does not exist

[Florian Klämpfl]

Am 04.02.21 um 00:28 schrieb Dimitrios Chr. Ioannidis via fpc-devel:
> Hi,
> 
>   in Windows which cross tools / toolchain for avr should I use ? FPC's 
> avr-embedded-xxxx ( from 
> https://svn.freepascal.org/svn/fpcbuild/binaries/i386-win32 ) or 
> Microchip's AVR Toolchain for Windows ( 
> https://www.microchip.com/en-us/development-tools-tools-and-software/gcc-compilers-avr-and-arm 
> ) ?
> 
> AFAIK, the fpc's supplied avr cross ld, objdump, objcopy, etc version is 
> "GNU ld (GNU Binutils) 2.30" and Microchip's version is 
> "(AVR_8_bit_GNU_Toolchain_3.6.2_1778) 2.26.20160125" .
> 
> 
>   I'm asking because with FPC's avr-embedded-xxxx cross tools, I get the 
> following warning ( error ? ) but with Microchip's cross tools, the 
> warning ( error ? ) is gone.

Maybe our cross tools have a bug. I am using 2.36 on linux and it works 
here.

> 
> ( test program at the end )
> 
> "avr-embedded-objdump.exe: Warning: DIE at offset 0x119f refers to 
> abbreviation number 17 which does not exist"
> 
> and the output of avr-embedded-objdump.exe --dwarf 
> dwarf_DIE_ABBREV_Bug.elf is :
> 
> -------------------------------------------------------------
> 
> < a lot more before >
> 
>   <1><1025>: Abbrev Number: 7 (DW_TAG_base_type)
>      <1026>   DW_AT_name        : WORD
>      <102b>   DW_AT_encoding    : 7    (unsigned)
>      <102c>   DW_AT_byte_size   : 2
>   <1><102d>: Abbrev Number: 8 (DW_TAG_reference_type)
>      <102e>   DW_AT_type        : <0x101b>
>   <1><1032>: Abbrev Number: 0
>    Compilation Unit @ offset 0x1033:
>     Length:        0x1e4 (32-bit)
>     Version:       2
>     Abbrev Offset: 0x0

This is most likely wrong. Can you please compile the unit with -al send 
the .s file? If it is too big, send it to me in private.

>     Pointer Size:  4
>   <0><103e>: Abbrev Number: 1 (DW_TAG_compile_unit)
>      <103f>   DW_AT_name        : dwarf_DIE_ABBREV_Bug_used_unit.pas
>      <1062>   DW_AT_producer    : Free Pascal 3.3.1 2021/02/03
>      <107f>   DW_AT_comp_dir    : 
> G:/Programming/dimitris/Projects/fpc_avr_dwarf_bug/
>      <10b3>   DW_AT_language    : 9    (ANSI Pascal)
>      <10b4>   DW_AT_identifier_case: 3  (case_insensitive)
>      <10b5>   DW_AT_stmt_list   : 0x0
>      <10b9>   DW_AT_low_pc      : 0x0
>      <10bd>   DW_AT_high_pc     : 0x0
>   <1><10c1>: Abbrev Number: 2 (DW_TAG_variable)
>      <10c2>   DW_AT_name        : TMPARRAY
>      <10cb>   DW_AT_location    : 207 byte block: 10 0 0 3 54 4d 50 41 
> 52 52 41 59 0 4 2 e4 11 0 0 4 0 1 fb 11 0 0 0 5 c1 10 0 0 2 72 74 74 69 
> 64 65 66 24 52 54 54 49 5f 24 44 57 41 52 46 5f 44 49 45 5f 41 42 42 52 
> 45 56 5f 42 55 47 5f 55 53 45 44 5f 55 4e 49 54 5f 24 24 5f 54 4d 50 41 
> 52 52 41 59 0 2a 11 0 0 6 24 52 54 54 49 44 45 46 24 52 54 54 49 5f 24 
> 44 57 41 52 46 5f 44 49 45 5f 41 42 42 52 45 56 5f 42 55 47 5f 55 53 45 
> 44 5f 55 4e 49 54 5f 24 24 5f 54 4d 50 41 52 52 41 59 0 15 0 5 ec 10 0 0 
> 2 72 74 74 69 5f 6e 6f 72 6d 61 6c 5f 61 72 72 61 79 24 31 0 85 11 0 0 6 
> 24 52 54 54 49 5f 4e 4f 52 4d 41 4c 5f 41 52 52 41 59 24 31 0