linker behaviour for sections having flags SHF_MERGE/SHF_STRINGS

[Alan Modra]

On Fri, Nov 09, 2012 at 09:14:30AM -0800, shankarke@gmail.com wrote:
> $gold merge_test.o
> $ readelf -p 2 a.out
> 
> String dump of section '.rodata':
>   [     0]  abc
>   [     4]  c
> 
> Question :-
> Why is the difference ?

Possibly a gold bug.

> merge_test.s
> --------------
>         .section .rodata.str,"aM","progbits",3
> .LC0:
>         .asciz  "abc"
> .LC1:
>         .asciz  "abc"
> .LC2:
>         .asciz  "cde"
> .LC3:
>         .asciz  "cde"

Your testcase is broken.  With an entsize of 3, the elements are
abc,\0ab,c\0c,de\0,cde,\0

>         .section .rodata.str,"aMS","progbits",2
> .LC0:
>         .asciz  "ab"
> .LC1:
>         .asciz  "ab"

Similarly here.  The zero terminator should be entsize bytes wide.

> $gold merge_test.o
> gold: warning: merge_test.o: last entry in mergeable string section
> '.rodata.str' not null terminated
> 
> $ld merge_test.o
> (no error)

And this is a ld bug.  It should complain too.  Nitpick on the gold
message: strings aren't null terminated, they are NUL terminated.

-- 
Alan Modra
Australia Development Lab, IBM