[Bug ld/27587] New: BFD (and gold) DWARF reader choke on DWARF5 as generated by LTO

[rguenth at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27587

            Bug ID: 27587
           Summary: BFD (and gold) DWARF reader choke on DWARF5 as
                    generated by LTO
           Product: binutils
           Version: 2.35.1
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: rguenth at gcc dot gnu.org
  Target Milestone: ---

When BFD ld or gold emit diagnostics they seem to try parse the DWARF in the
object files but they somehow choke if the objects are generated with -gdwarf-5
as opposed to -gdwarf-4 and contain references to abstract DIEs in other CUs
(residing in other object files).

Like so:

> ./xgcc -B. -gdwarf-5 -Werror -O2 t.i -flto -g 
> /usr/lib64/gcc/x86_64-suse-linux/7/../../../../x86_64-suse-linux/bin/ld: 
> /usr/lib64/gcc/x86_64-suse-linux/7/../../../../x86_64-suse-linux/bin/ld: 
> DWARF error: invalid abstract instance DIE ref
/tmp/cch4tY4L.ltrans0.ltrans.o: in function `main':
<artificial>:(.text.startup+0x1): undefined reference to `stack_size'
collect2: error: ld returned 1 exit status

where t.i is

char main_prompt[1];
int sprintf(char *, char *, ...);
void stack_size();
void main() { sprintf(main_prompt, "", stack_size); }

or simply invoking ld with the object files:

> ld -o a.out a-t.o.debug.temp.o ./a.ltrans0.ltrans.o        
ld: warning: cannot find entry symbol _start; defaulting to 00000000004000f0
ld: ld: DWARF error: invalid abstract instance DIE ref
./a.ltrans0.ltrans.o: in function `main':
<artificial>:(.text.startup+0x1): undefined reference to `stack_size'
ld: <artificial>:(.text.startup+0x12): undefined reference to `sprintf'

fixing the error by providing a stack_size definition in x.o:

> ld -o a.out a-t.o.debug.temp.o ./a.ltrans0.ltrans.o x.o -lc
ld: warning: cannot find entry symbol _start; defaulting to 00000000004002c0

and the issue is gone.

-- 
You are receiving this mail because:
You are on the CC list for the bug.