[Bug testsuite/106680] Test gcc.target/powerpc/bswap64-4.c fails on 32-bit BE

["linkw at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106680

--- Comment #11 from Kewen Lin <linkw at gcc dot gnu.org> ---
(In reply to Sebastian Huber from comment #8)
> Yes, it seems that -mcpu=e6500 -mno-powerpc64 yields the right code for the
> attached test case (with or without the -m32).

The default is -m32 I guess? :)

> 
> I am now a bit confused what the purpose of the -m32 and -m64 options is.

For -m32/-m64, the manual says:

Generate code for 32-bit or 64-bit environments of Darwin and SVR4 targets
(including GNU/Linux). The 32-bit environment sets int, long and pointer to 32
bits and generates code that runs on any PowerPC variant. The 64-bit
environment sets int to 32 bits and long and pointer to 64 bits, and generates
code for PowerPC64, as for -mpowerpc64.

But it's possible to interact with option powerpc64, like cpu e6500 which by
default supports powerpc64 and if applied OS is able to support the necessary
context switches, we want -mpowerpc64 kept and it's able to generate more
efficient code (leveraging insns guarded with powerpc64 flag).