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Date:      Mon, 18 Aug 2008 15:38:43 -0700
From:      John Silva <shonjir@gmail.com>
To:        freebsd-questions@freebsd.org
Subject:   Working ccache configuration for buildworld on amd64?
Message-ID:  <48A9F9F3.5030305@gmail.com>
References:  26ddd1750808150822r334f800bs73a1117bf310be11@mail.gmail.com

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>
> On Fri, 15 Aug 2008 11:22:01 -0400
> "Maxim Khitrov" <mkhitrov at gmail.com <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>>; wrote:
>
>
> >/ I think what's happening is that there is a collision in hash values
> />/ generated by ccache. That's the only thing I can think of, because
> />/ crt1.c is compiled twice; once from /usr/src/lib/csu/amd64/crt1.c, and
> />/ a second time from /usr/src/lib/csu/i386-elf/crt1.c. If LIB32 is
> />/ disabled in src.conf, only the first compilation takes place. If the
> />/ generated hash values are the same, by some chance, then the actual
> />/ problem is that the file is not compiled a second time when, in fact,
> />/ it should be. This is only a guess, however.
> /
> That collision isn't going to happen for several reasons, but it's
> missing the point I made earlier, that the build is failing on a cache
> miss.   If the kind of situation you're describing is happening, then it's
> happening earlier, and the observed error is just a side-effect.
>   
Nothing is wrong with ccache; it works just fine.

What's happening is that the build system is passing compiler options in 
the CC variable when invoking make for lib32, and the recommended 
make.conf config for ccache is blowing those away.

Here's how the lib32 build is invoked with ccache enabled:

cd /usr/src;  MAKEOBJDIRPREFIX=/usr/obj/lib32  
_SHLIBDIRPREFIX=/usr/obj/usr/src/lib32  MACHINE=i386  MACHINE_ARCH=i386  
INSTALL="sh /usr/src/tools/install.sh"  
PATH=/usr/obj/usr/src/tmp/legacy/usr/sbin:/usr/obj/usr/src/tmp/legacy/usr/bin:/usr/obj/usr/src/tmp/legacy/usr/games:/usr/obj/usr/src/tmp/usr/sbin:/usr/obj/usr/src/tmp/usr/bin:/usr/obj/usr/src/tmp/usr/games:/sbin:/bin:/usr/sbin:/usr/bin  
CC="/usr/local/libexec/ccache/world-cc -m32 -march=k8 -mfancy-math-387 
-DCOMPAT_32BIT  -iprefix /usr/obj/usr/src/lib32/usr/  
-L/usr/obj/usr/src/lib32/usr/lib32  -B/usr/obj/usr/src/lib32/usr/lib32"  
CXX="/usr/local/libexec/ccache/world-c++ -m32 -march=k8 -mfancy-math-387 
-DCOMPAT_32BIT  -iprefix /usr/obj/usr/src/lib32/usr/  
-L/usr/obj/usr/src/lib32/usr/lib32  -B/usr/obj/usr/src/lib32/usr/lib32"  
OBJC="cc -m32 -march=k8 -mfancy-math-387 -DCOMPAT_32BIT  -iprefix 
/usr/obj/usr/src/lib32/usr/  -L/usr/obj/usr/src/lib32/usr/lib32  
-B/usr/obj/usr/src/lib32/usr/lib32"  LD="ld -m elf_i386_fbsd -Y 
P,/usr/obj/usr/src/lib32/usr/lib32"  AS="as --32"  LIBDIR=/usr/lib32  
SHLIBDIR=/usr/lib32 make -DNO_CPU_CFLAGS -DCOMPAT_32BIT  -DWITHOUT_BIND 
-DWITHOUT_MAN -DWITHOUT_NLS -DWITHOUT_INFO  -DWITHOUT_HTML 
DESTDIR=/usr/obj/usr/src/lib32 -f Makefile.inc1 libraries
cd /usr/src;  make -f Makefile.inc1 _prereq_libs;  make -f Makefile.inc1 
_startup_libs;  make -f Makefile.inc1 _prebuild_libs;  make -f 
Makefile.inc1 _generic_libs;

Here's how the compiler gets called from the 2nd level make with the 
recommended settings:

/usr/local/libexec/ccache/world-cc -O2 -fno-strict-aliasing -pipe 
-I/usr/src/lib/libc/include -I/usr/src/lib/libc/../../include 
-I/usr/src/lib/libc/i386 -D__DBINTERFACE_PRIVATE 
-I/usr/src/lib/libc/../../contrib/gdtoa -DINET6 
-I/usr/obj/lib32/usr/src/lib/libc -I/usr/src/lib/libc/resolv 
-DPOSIX_MISTAKE -I/usr/src/lib/libc/locale -DBROKEN_DES -DPORTMAP 
-DDES_BUILTIN -I/usr/src/lib/libc/rpc -DYP -DNS_CACHING 
-DSYMBOL_VERSIONING -Wsystem-headers -Wall -Wno-format-y2k 
-Wno-uninitialized -Wno-pointer-sign -c

Here's what's supposed to be happening (without ccache):

cc -m32 -march=k8 -mfancy-math-387 -DCOMPAT_32BIT  -iprefix 
/usr/obj/usr/src/lib32/usr/  -L/usr/obj/usr/src/lib32/usr/lib32  
-B/usr/obj/usr/src/lib32/usr/lib32 -O2 -fno-strict-aliasing -pipe 
-I/usr/src/lib/libc/include -I/usr/src/lib/libc/../../include 
-I/usr/src/lib/libc/i386 -D__DBINTERFACE_PRIVATE 
-I/usr/src/lib/libc/../../contrib/gdtoa -DINET6 
-I/usr/obj/lib32/usr/src/lib/libc -I/usr/src/lib/libc/resolv 
-DPOSIX_MISTAKE -I/usr/src/lib/libc/locale -DBROKEN_DES -DPORTMAP 
-DDES_BUILTIN -I/usr/src/lib/libc/rpc -DYP -DNS_CACHING 
-DSYMBOL_VERSIONING -Wsystem-headers -Wall -Wno-format-y2k 
-Wno-uninitialized -Wno-pointer-sign -c 
/usr/src/lib/libc/i386/gen/_ctx_start.S

Notice the difference?

Try this instead:

# Special ccache for buildworld
.if exists(/usr/local/libexec/ccache/world-cc) && !defined(NOCCACHE) && \
        (!empty(.CURDIR:M/usr/src*) || !empty(.CURDIR:M/usr/obj*))
CC      := ${CC:C,^cc,/usr/local/libexec/ccache/world-cc,1}
CXX     := ${CXX:C,^c\+\+,/usr/local/libexec/ccache/world-c++,1}
.endif

Instead of hard-configuring CC/CXX, it selectively modifies it only on 
the first invocation of make.

Subsequent invocations are allowed to modify CC as needed using the 
original (modified) values as a seed.

-j





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