non-conformant ELF symbol table on MIPS?

[Maciej W. Rozycki]

On Thu, 27 Jul 2023, Jan Beulich wrote:

> extending the gas elf/common3.s testcase (in the context of trying to fix
> PR gas/30688) to
> 
> 	.comm foobar,30,4
> 	.comm buf1, 5-1, 8
> 	.comm buf2, 4, 9-1
> 	.lcomm lbuf, 9-1
> 
> I notice a violation of the ELF spec on most (all?) MIPS targets I would
> routinely test for common code changes: "lbuf" is emitted last in the
> symbol table. The spec is quite clear: "In each symbol table, all
> symbols with STB_LOCAL binding precede the weak and global symbols." I
> guess I want/need to xfail that test for mips*-*-* for the time being,
> but it would be nice if you could shed some light on this behavior.

 Which specific MIPS target is it?

 There are two kinds of MIPS targets, ones that use the older IRIX symbol 
sorting rules and ones that use the newer "traditional" symbol sorting 
rules.  The IRIX symbol sorting rules mandate that section symbols precede 
all other symbols, see e.g. bfd/elf32-mips.c:mips_elf_sym_is_global.  
Mind that SGI was an early adopter of the ELF standard and things weren't 
as settled as they are nowadays, hence e.g. the odd solution for composed 
relocations with the n64 psABI (later n32 uses standard ELF gABI ones) and 
other peculiarities here and there.

 Determining whether a MIPS target uses the IRIX emulation is complex, see 
e.g. how binutils/testsuite/binutils-all/mips/mips.exp sets `irixemul'.  
If you provide me with test case details (input and output), then I may be 
able to give you further advice, but otherwise you may want to mark the 
test case with `notarget' or suchlike rather than `xfail', because that's 
not a bug with the backend that the symbol ordering varies.

  Maciej