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Re: powerpc64le multilibs and multiarch dir

On Fri, Aug 23, 2013 at 01:45:14AM +0930, Alan Modra wrote:
> On Thu, Aug 22, 2013 at 10:06:48AM -0400, David Edelsohn wrote:
> > 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.
> That m64= is the newer syntax that specifies a mapping from a
> MUTLILIB_OPTIONS selection.  And, yes, without another tmake file this
> gives us exactly the same result as before.
> I needed to use the new syntax to specify the correct os dirs when
> adding cross-endian multilibs.

Without another tmake file it really is exactly the same as before.

old, after applying "make" string gunk
MULTILIB_OSDIRNAMES = ../lib64 ../lib

MULTILIB_OSDIRNAMES = m64=../lib64 m32=../lib

Either way, -m64 objects use ../lib64 and -m32 ../lib.

new with le multilib
MULTILIB_OPTIONS = m64/m32 mlittle
MULTILIB_OSDIRNAMES = m64=../lib64 m32=../lib m64.mlittle=../lib64le m32.mlittle=../lible

Trying to do the same with the old syntax isn't possible, because you
must specify 3 elements in MULTILIB_OSDIRNAMES to match the
combinations given in MULTILIB_OPTIONS, then the multilib machinery
mashes them together.  For instance

MULTILIB_OSDIRNAMES = ../lib64 ../lib le

results in
-m64 code to ../lib64
-m32 code to ../lib
-m64 -mlittle code to le
-m32 -mlittle code to ../lible

The reason you don't get ../lib64le for -m64 -mlittle is related to
-m64 being the default, -m64 is therefore omitted when compiling, and
just the "le" string used for the os multilib dir.

Alan Modra
Australia Development Lab, IBM

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