[LLVMdev] clang searching for many linux directories that do not exist on FreeBSD host

[Kurt Lidl]

Greetings -

I'm a user of clang (3.3), as it is the system compiler for my
installation of FreeBSD.  (In FreeBSD 10, it will be the default
compiler, but that's not my point.)  My system identifies itself
as:

FreeBSD 9.2-PRERELEASE #0: Tue Jul 16 13:00:08 EDT 2013 
lidl at nine0:/usr/obj/usr/src/sys/GENERIC

Recently, in preparation for the upcoming 9.2 release, they
imported the llvm 3.3 tree.  That works fine for me.

I did notice (while looking at an unrelated problem), that
clan looks around for a bunch of linux directories every time it
is started.  And those directories are never going to be found,
at least not on a FreeBSD system.

It was suggested that I take the issue here, rather than attempting
to fix it with a locally maintained FreeBSD patch.

I've included my trivial test program, and the ktrace output.
I trimmed output to be the legitimate accesses to shared libraries,
etc that clang must make - leaving most of the extraneous accesses.

It was easy to trace these patterns back to the file:
	tools/clang/lib/Driver/ToolChains.cpp

So my question is this:  Is there any easy modification to make that
will allow clang to skip doing all this work for no gain?  It seems
silly to me, when its being used as the system compiler, to have it
call stat() a little over two hundred times, each time
the compiler is started up.

(There's also a very Mac-looking /System/Library/... stat() at the
end too...)

Thanks for any help.

-Kurt


lidl at nine0-309: cat hello.c
#include <stdlib.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
	printf("Hello world!\n");
	return 0;
}
lidl at nine0-310: ktrace -i clang -Wall hello.c
lidl at nine0-311: kdump | egrep -e NAMI -e /usr/lib | awk '{print $4}'
[...]
"/usr/lib64"
"/usr/lib"
"/usr/lib/gcc/x86_64-linux-gnu"
"/usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu"
"/usr/lib/x86_64-linux-gnu"
"/usr/lib/gcc/x86_64-unknown-linux-gnu"
"/usr/lib/x86_64-unknown-linux-gnu/gcc/x86_64-unknown-linux-gnu"
"/usr/lib/x86_64-unknown-linux-gnu"
"/usr/lib/gcc/x86_64-pc-linux-gnu"
"/usr/lib/x86_64-pc-linux-gnu/gcc/x86_64-pc-linux-gnu"
"/usr/lib/x86_64-pc-linux-gnu"
"/usr/lib/gcc/x86_64-redhat-linux6E"
"/usr/lib/x86_64-redhat-linux6E/gcc/x86_64-redhat-linux6E"
"/usr/lib/x86_64-redhat-linux6E"
"/usr/lib/gcc/x86_64-redhat-linux"
"/usr/lib/x86_64-redhat-linux/gcc/x86_64-redhat-linux"
"/usr/lib/x86_64-redhat-linux"
"/usr/lib/gcc/x86_64-suse-linux"
"/usr/lib/x86_64-suse-linux/gcc/x86_64-suse-linux"
"/usr/lib/x86_64-suse-linux"
"/usr/lib/gcc/x86_64-manbo-linux-gnu"
"/usr/lib/x86_64-manbo-linux-gnu/gcc/x86_64-manbo-linux-gnu"
"/usr/lib/x86_64-manbo-linux-gnu"
"/usr/lib/gcc/x86_64-linux-gnu"
"/usr/lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu"
"/usr/lib/x86_64-linux-gnu"
"/usr/lib/gcc/x86_64-slackware-linux"
"/usr/lib/x86_64-slackware-linux/gcc/x86_64-slackware-linux"
"/usr/lib/x86_64-slackware-linux"
"/usr/lib/gcc/x86_64-unknown-freebsd9.2"
"/usr/lib/x86_64-unknown-freebsd9.2/gcc/x86_64-unknown-freebsd9.2"
"/usr/lib/x86_64-unknown-freebsd9.2"
"/usr/lib32"
"/usr/lib32/gcc/i686-linux-gnu"
"/usr/lib32/i686-linux-gnu/gcc/i686-linux-gnu"
"/usr/lib32/i686-linux-gnu"
"/usr/lib32/gcc/i686-pc-linux-gnu"
"/usr/lib32/i686-pc-linux-gnu/gcc/i686-pc-linux-gnu"
"/usr/lib32/i686-pc-linux-gnu"
"/usr/lib32/gcc/i486-linux-gnu"
"/usr/lib32/i486-linux-gnu/gcc/i486-linux-gnu"
"/usr/lib32/i486-linux-gnu"
"/usr/lib32/gcc/i386-linux-gnu"
"/usr/lib32/i386-linux-gnu/gcc/i386-linux-gnu"
"/usr/lib32/i386-linux-gnu"
"/usr/lib32/gcc/i386-redhat-linux6E"
"/usr/lib32/i386-redhat-linux6E/gcc/i386-redhat-linux6E"
"/usr/lib32/i386-redhat-linux6E"
"/usr/lib32/gcc/i686-redhat-linux"
"/usr/lib32/i686-redhat-linux/gcc/i686-redhat-linux"
"/usr/lib32/i686-redhat-linux"
"/usr/lib32/gcc/i586-redhat-linux"
"/usr/lib32/i586-redhat-linux/gcc/i586-redhat-linux"
"/usr/lib32/i586-redhat-linux"
"/usr/lib32/gcc/i386-redhat-linux"
"/usr/lib32/i386-redhat-linux/gcc/i386-redhat-linux"
"/usr/lib32/i386-redhat-linux"
"/usr/lib32/gcc/i586-suse-linux"
"/usr/lib32/i586-suse-linux/gcc/i586-suse-linux"
"/usr/lib32/i586-suse-linux"
"/usr/lib32/gcc/i486-slackware-linux"
"/usr/lib32/i486-slackware-linux/gcc/i486-slackware-linux"
"/usr/lib32/i486-slackware-linux"
"/usr/lib32/gcc/i686-montavista-linux"
"/usr/lib32/i686-montavista-linux/gcc/i686-montavista-linux"
"/usr/lib32/i686-montavista-linux"
"/usr/lib32/gcc/i386-unknown-freebsd9.2"
"/usr/lib32/i386-unknown-freebsd9.2/gcc/i386-unknown-freebsd9.2"
"/usr/lib32/i386-unknown-freebsd9.2"
"/usr/lib"
"/usr/lib/gcc/i686-linux-gnu"
"/usr/lib/i686-linux-gnu/gcc/i686-linux-gnu"
"/usr/lib/i686-linux-gnu"
"/usr/lib/gcc/i686-pc-linux-gnu"
"/usr/lib/i686-pc-linux-gnu/gcc/i686-pc-linux-gnu"
"/usr/lib/i686-pc-linux-gnu"
"/usr/lib/gcc/i486-linux-gnu"
"/usr/lib/i486-linux-gnu/gcc/i486-linux-gnu"
"/usr/lib/i486-linux-gnu"
"/usr/lib/gcc/i386-linux-gnu"
"/usr/lib/i386-linux-gnu/gcc/i386-linux-gnu"
"/usr/lib/i386-linux-gnu"
"/usr/lib/gcc/i386-redhat-linux6E"
"/usr/lib/i386-redhat-linux6E/gcc/i386-redhat-linux6E"
"/usr/lib/i386-redhat-linux6E"
"/usr/lib/gcc/i686-redhat-linux"
"/usr/lib/i686-redhat-linux/gcc/i686-redhat-linux"
"/usr/lib/i686-redhat-linux"
"/usr/lib/gcc/i586-redhat-linux"
"/usr/lib/i586-redhat-linux/gcc/i586-redhat-linux"
"/usr/lib/i586-redhat-linux"
"/usr/lib/gcc/i386-redhat-linux"
"/usr/lib/i386-redhat-linux/gcc/i386-redhat-linux"
"/usr/lib/i386-redhat-linux"
"/usr/lib/gcc/i586-suse-linux"
"/usr/lib/i586-suse-linux/gcc/i586-suse-linux"
"/usr/lib/i586-suse-linux"
"/usr/lib/gcc/i486-slackware-linux"
"/usr/lib/i486-slackware-linux/gcc/i486-slackware-linux"
"/usr/lib/i486-slackware-linux"
"/usr/lib/gcc/i686-montavista-linux"
"/usr/lib/i686-montavista-linux/gcc/i686-montavista-linux"
"/usr/lib/i686-montavista-linux"
"/usr/lib/gcc/i386-unknown-freebsd9.2"
"/usr/lib/i386-unknown-freebsd9.2/gcc/i386-unknown-freebsd9.2"
"/usr/lib/i386-unknown-freebsd9.2"
"/usr/bin/.."
"/usr/bin/../lib64"
"/usr/bin/../lib"
"/usr/bin/../lib/gcc/x86_64-linux-gnu"
"/usr/bin/../lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu"
"/usr/bin/../lib/x86_64-linux-gnu"
"/usr/bin/../lib/gcc/x86_64-unknown-linux-gnu"
"/usr/bin/../lib/x86_64-unknown-linux-gnu/gcc/x86_64-unknown-linux-gnu"
"/usr/bin/../lib/x86_64-unknown-linux-gnu"
"/usr/bin/../lib/gcc/x86_64-pc-linux-gnu"
"/usr/bin/../lib/x86_64-pc-linux-gnu/gcc/x86_64-pc-linux-gnu"
"/usr/bin/../lib/x86_64-pc-linux-gnu"
"/usr/bin/../lib/gcc/x86_64-redhat-linux6E"
"/usr/bin/../lib/x86_64-redhat-linux6E/gcc/x86_64-redhat-linux6E"
"/usr/bin/../lib/x86_64-redhat-linux6E"
"/usr/bin/../lib/gcc/x86_64-redhat-linux"
"/usr/bin/../lib/x86_64-redhat-linux/gcc/x86_64-redhat-linux"
"/usr/bin/../lib/x86_64-redhat-linux"
"/usr/bin/../lib/gcc/x86_64-suse-linux"
"/usr/bin/../lib/x86_64-suse-linux/gcc/x86_64-suse-linux"
"/usr/bin/../lib/x86_64-suse-linux"
"/usr/bin/../lib/gcc/x86_64-manbo-linux-gnu"
"/usr/bin/../lib/x86_64-manbo-linux-gnu/gcc/x86_64-manbo-linux-gnu"
"/usr/bin/../lib/x86_64-manbo-linux-gnu"
"/usr/bin/../lib/gcc/x86_64-linux-gnu"
"/usr/bin/../lib/x86_64-linux-gnu/gcc/x86_64-linux-gnu"
"/usr/bin/../lib/x86_64-linux-gnu"
"/usr/bin/../lib/gcc/x86_64-slackware-linux"
"/usr/bin/../lib/x86_64-slackware-linux/gcc/x86_64-slackware-linux"
"/usr/bin/../lib/x86_64-slackware-linux"
"/usr/bin/../lib/gcc/x86_64-unknown-freebsd9.2"
"/usr/bin/../lib/x86_64-unknown-freebsd9.2/gcc/x86_64-unknown-freebsd9.2"
"/usr/bin/../lib/x86_64-unknown-freebsd9.2"
"/usr/bin/../lib32"
"/usr/bin/../lib32/gcc/i686-linux-gnu"
"/usr/bin/../lib32/i686-linux-gnu/gcc/i686-linux-gnu"
"/usr/bin/../lib32/i686-linux-gnu"
"/usr/bin/../lib32/gcc/i686-pc-linux-gnu"
"/usr/bin/../lib32/i686-pc-linux-gnu/gcc/i686-pc-linux-gnu"
"/usr/bin/../lib32/i686-pc-linux-gnu"
"/usr/bin/../lib32/gcc/i486-linux-gnu"
"/usr/bin/../lib32/i486-linux-gnu/gcc/i486-linux-gnu"
"/usr/bin/../lib32/i486-linux-gnu"
"/usr/bin/../lib32/gcc/i386-linux-gnu"
"/usr/bin/../lib32/i386-linux-gnu/gcc/i386-linux-gnu"
"/usr/bin/../lib32/i386-linux-gnu"
"/usr/bin/../lib32/gcc/i386-redhat-linux6E"
"/usr/bin/../lib32/i386-redhat-linux6E/gcc/i386-redhat-linux6E"
"/usr/bin/../lib32/i386-redhat-linux6E"
"/usr/bin/../lib32/gcc/i686-redhat-linux"
"/usr/bin/../lib32/i686-redhat-linux/gcc/i686-redhat-linux"
"/usr/bin/../lib32/i686-redhat-linux"
"/usr/bin/../lib32/gcc/i586-redhat-linux"
"/usr/bin/../lib32/i586-redhat-linux/gcc/i586-redhat-linux"
"/usr/bin/../lib32/i586-redhat-linux"
"/usr/bin/../lib32/gcc/i386-redhat-linux"
"/usr/bin/../lib32/i386-redhat-linux/gcc/i386-redhat-linux"
"/usr/bin/../lib32/i386-redhat-linux"
"/usr/bin/../lib32/gcc/i586-suse-linux"
"/usr/bin/../lib32/i586-suse-linux/gcc/i586-suse-linux"
"/usr/bin/../lib32/i586-suse-linux"
"/usr/bin/../lib32/gcc/i486-slackware-linux"
"/usr/bin/../lib32/i486-slackware-linux/gcc/i486-slackware-linux"
"/usr/bin/../lib32/i486-slackware-linux"
"/usr/bin/../lib32/gcc/i686-montavista-linux"
"/usr/bin/../lib32/i686-montavista-linux/gcc/i686-montavista-linux"
"/usr/bin/../lib32/i686-montavista-linux"
"/usr/bin/../lib32/gcc/i386-unknown-freebsd9.2"
"/usr/bin/../lib32/i386-unknown-freebsd9.2/gcc/i386-unknown-freebsd9.2"
"/usr/bin/../lib32/i386-unknown-freebsd9.2"
"/usr/bin/../lib"
"/usr/bin/../lib/gcc/i686-linux-gnu"
"/usr/bin/../lib/i686-linux-gnu/gcc/i686-linux-gnu"
"/usr/bin/../lib/i686-linux-gnu"
"/usr/bin/../lib/gcc/i686-pc-linux-gnu"
"/usr/bin/../lib/i686-pc-linux-gnu/gcc/i686-pc-linux-gnu"
"/usr/bin/../lib/i686-pc-linux-gnu"
"/usr/bin/../lib/gcc/i486-linux-gnu"
"/usr/bin/../lib/i486-linux-gnu/gcc/i486-linux-gnu"
"/usr/bin/../lib/i486-linux-gnu"
"/usr/bin/../lib/gcc/i386-linux-gnu"
"/usr/bin/../lib/i386-linux-gnu/gcc/i386-linux-gnu"
"/usr/bin/../lib/i386-linux-gnu"
"/usr/bin/../lib/gcc/i386-redhat-linux6E"
"/usr/bin/../lib/i386-redhat-linux6E/gcc/i386-redhat-linux6E"
"/usr/bin/../lib/i386-redhat-linux6E"
"/usr/bin/../lib/gcc/i686-redhat-linux"
"/usr/bin/../lib/i686-redhat-linux/gcc/i686-redhat-linux"
"/usr/bin/../lib/i686-redhat-linux"
"/usr/bin/../lib/gcc/i586-redhat-linux"
"/usr/bin/../lib/i586-redhat-linux/gcc/i586-redhat-linux"
"/usr/bin/../lib/i586-redhat-linux"
"/usr/bin/../lib/gcc/i386-redhat-linux"
"/usr/bin/../lib/i386-redhat-linux/gcc/i386-redhat-linux"
"/usr/bin/../lib/i386-redhat-linux"
"/usr/bin/../lib/gcc/i586-suse-linux"
"/usr/bin/../lib/i586-suse-linux/gcc/i586-suse-linux"
"/usr/bin/../lib/i586-suse-linux"
"/usr/bin/../lib/gcc/i486-slackware-linux"
"/usr/bin/../lib/i486-slackware-linux/gcc/i486-slackware-linux"
"/usr/bin/../lib/i486-slackware-linux"
"/usr/bin/../lib/gcc/i686-montavista-linux"
"/usr/bin/../lib/i686-montavista-linux/gcc/i686-montavista-linux"
"/usr/bin/../lib/i686-montavista-linux"
"/usr/bin/../lib/gcc/i386-unknown-freebsd9.2"
"/usr/bin/../lib/i386-unknown-freebsd9.2/gcc/i386-unknown-freebsd9.2"
"/usr/bin/../lib/i386-unknown-freebsd9.2"
[...]
"/System/Library/CoreServices/SystemVersion.plist"
[...]