powerpc64le multilibs and multiarch dir

[David Edelsohn]

On Wed, Aug 21, 2013 at 11:57 PM, Alan Modra <amodra@gmail.com> wrote:

> Index: gcc/config/rs6000/t-linux64
> ===================================================================
> --- gcc/config/rs6000/t-linux64 (revision 201834)
> +++ gcc/config/rs6000/t-linux64 (working copy)
> @@ -25,8 +25,8 @@
>  # it doesn't tell anything about the 32bit libraries on those systems.  Set
>  # MULTILIB_OSDIRNAMES according to what is found on the target.
>
> -MULTILIB_OPTIONS        = m64/m32
> -MULTILIB_DIRNAMES       = 64 32
> -MULTILIB_EXTRA_OPTS     = fPIC
> -MULTILIB_OSDIRNAMES    = ../lib64$(call if_multiarch,:powerpc64-linux-gnu)
> -MULTILIB_OSDIRNAMES    += $(if $(wildcard $(shell echo $(SYSTEM_HEADER_DIR))/../../usr/lib32),../lib32,../lib)$(call if_multiarch,:powerpc-linux-gnu)
> +MULTILIB_OPTIONS    := m64/m32
> +MULTILIB_DIRNAMES   := 64 32
> +MULTILIB_EXTRA_OPTS :=
> +MULTILIB_OSDIRNAMES := m64=../lib64$(call if_multiarch,:powerpc64-linux-gnu)
> +MULTILIB_OSDIRNAMES += m32=$(if $(wildcard $(shell echo $(SYSTEM_HEADER_DIR))/../../usr/lib32),../lib32,../lib)$(call if_multiarch,:powerpc-linux-gnu)

What is the purpose of the change to MULTILIB_OSDIRNAMES? Why the
addition of m64= and m32=? A secondary tmake file is not always set to
post-process those macros, AFAICT.

Thanks, David