AC_NO_EXECUTABLES in libc/machine/sh

[Nick Clifton]

Hi Jeff,

> DJ Delorie wrote:
>> [snip]  However, in a local discussion, one of us also
>> noted that the objects in that directory don't seem to be correctly
>> overriding the generic C implementations of those functions, due to
>> new object naming conventions.  We're not sure what to do about that.

This was me.  It seems that nowadays the object files in the newlib 
sub-directories all have a "lib_a-" prefix.  So for example the source 
file newlib/libc/string/strlen.c compiles to lib_a-strlen.o.

The problem is that the object files built in the libc/machine/<target>/ 
directory are not being given this prefix.  So for example for the SH 
port the libc/machine/sh/strlen.S file is being compiled into strlen.o.

When the object files from the various sub-directories are extracted 
into the temporary directory as part of the process of building libc.a 
it used to be that the version from the machine/ sub-directory would 
have the same name as the version from the string/ sub-directory and 
(since it was extracted last) it would overwrite it.  Thus the machine 
specific version would be used by the application.

With the switch over to autoconf-2.59 and the appearance of this 
"lib_a-" prefix there are now two distinct filenames, and so both are 
copied into libc.a.  Since the "lib_a-" prefix is usually alphabetically 
prior to the un-prefixed name, the lib_a- version is usually the one 
picked up by an application that links with libc.a.  Thus applications 
do not get the versions that are optimized for their target 
architecture, and in some cases, the versions that are necessary for 
correct operation on their target architecture.

(Note this affects not just the SH port, but all ports that have machine 
specific versions of some libc functions, including the CRIS, CRX, 
H8300, HPPA, i386, i960, M68K, MIPS, MN10300, XSTORMY16 and Z8K).

Unfortunately I have not been able to work out why this "lib_a-" prefix 
has appeared, nor why it is not being applied to the files built in the 
machine sub-directory.  Any clues in this direction would be greatly 
appreciated.

Cheers
   Nick