Re: [PATCH] MIPS: use arch_32/64 instead of default_mips_arch

[Xi Ruoyao <xry111@xry111.site>]

On Fri, 2023-02-03 at 14:08 +0000, Richard Sandiford via Gcc-patches
wrote:
> > Do you mean that the "wrong" format is quite interesting?
> > Yes, While this format is never used at all.
> 
> My point was that there is nothing wrong in principle with creating
> an o32 executable that has a 64-bit rather than a 32-bit ISA (since
> the
> 64-bit ISAs are pure extensions of 32-bit ISAs).  Doing that is even
> useful in some cases.  For example, MIPS4+O32 is a useful combination,
> even though MIPS4 is a 64-bit ISA.  Same for Octeon3+O32, etc.
> 
> So is the linker behaviour really correct?  Doesn't it mean that
> Octeon3 O32 binaries are link-incompatible with MIPS32 o32 binaries?

On gcc230:

xry111@gcc230:~$ cat a.c
int a() { return 42; }
xry111@gcc230:~$ cat b.c
extern int a(void);
int main() { return a() ^ 42; }
xry111@gcc230:~$ cc a.c -mabi=32 -march=mips32r2 -c
xry111@gcc230:~$ cc b.c -mabi=32 -march=mips64r2 -c
xry111@gcc230:~$ cc a.o b.o
xry111@gcc230:~$ ./a.out && echo ok
ok
xry111@gcc230:~$ 
xry111@gcc230:~$ ld -version
GNU ld (GNU Binutils for Debian) 2.31.1
Copyright (C) 2018 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) a later version.
This program has absolutely no warranty.

So I'd consider the issue a GNU ld regression if it suddenly stops to
behave like this.
-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University