[fpc-devel] Incorrect debug info for ESP32, linker error?

[Florian Klämpfl]

Am 04.12.2021 um 14:04 schrieb Christo Crause via fpc-devel:
> When compiling a simple test for esp32 (xtensa-freertos), the incorrect values for DW_AT_low_PC and DW_AT_high_PC are 
> generated.  From my inspection of the generated assembler I cannot see anything wrong, but the values supplied by the 
> linker are wrong.  Any ideas on how to fix this?
> 
> This can be seen below, where there is no overlap between the unit's low/high PC and main's low/high PC:
> 
>   <0><b>: Abbrev Number: 1 (DW_TAG_compile_unit)
>      <c>   DW_AT_name        : test.pp
>      <14>   DW_AT_producer    : Free Pascal 3.3.1 2021/11/27
>      <31>   DW_AT_comp_dir    : /home/christo/fpc/xtensa/examples/test/
>      <59>   DW_AT_language    : 9 (ANSI Pascal)
>      <5a>   DW_AT_identifier_case: 3 (case_insensitive)
>      <5b>   DW_AT_stmt_list   : 0x0
>      <5f>   DW_AT_low_pc      : 0x400e49e4
>      <63>   DW_AT_high_pc     : 0x400e49e4
>   <1><67>: Abbrev Number: 2 (DW_TAG_subprogram)
>      <68>   DW_AT_name        : $main
>      <6e>   DW_AT_prototyped  : 1
>      <6f>   DW_AT_external    : 1
>      <70>   DW_AT_low_pc      : 0x400d0a70
>      <74>   DW_AT_high_pc     : 0x400d0ab3
> 
>  From the compiler generated assembly it appears that the labels for these values are correctly placed
> (DEBUGSTART_$P$TEST placed at start of code):
> 
> .globl DEBUGSTART_$P$TEST
> DEBUGSTART_$P$TEST:
> # End asmlist al_begin
> # Begin asmlist al_procedures
> 
> .section .text.n_main,"ax"
> .balign 4
> .globl main
> main:
> .globl PASCALMAIN
> PASCALMAIN:
> .Lc2:
> #   Start of abi_windowed entry localsize=0
> 
> Below the label is used in the debug info section:
> 
> .section .debug_info
> .Ldebug_info0:
> .long .Ledebug_info0-.Lf2
> .Lf2:
> .short 3
> .long .Ldebug_abbrev0
> .byte 4
> .uleb128 1
> .ascii "test.pp\000"
> .ascii "Free Pascal 3.3.1 2021/11/27\000"
> .ascii "/home/christo/fpc/xtensa/examples/test/\000"
> .byte 9
> .byte 3
> .long .Ldebug_line0
> .long DEBUGSTART_$P$TEST
> .long DEBUGEND_$P$TEST

How does the debug info section look like for a gcc generated program?