[RFC] external compiler support

Wed Feb 27 16:08:09 UTC 2013

Ooops, forgot to add one item..

On Feb 27, 2013, at 8:57 AM, Warner Losh wrote:

> 
> On Feb 26, 2013, at 5:35 PM, Brooks Davis wrote:
> 
>> Below (and at http://people.freebsd.org/~brooks/patches/xcc.diff) you
>> can find an initial patch with proposed commit for external compiler
>> support.  It relies on the existing cross binutils as I'm finding that
>> the two are fairly separable.  With this patch I've been able to build
>> from amd64 to arm, amd64, and i386 using clang from the lang/clang-devel
>> port.  I've also compiled the tree with a customized clang being
>> developed at the University of Cambridge.
> 
> Cool!
> 
>> The patch is untested with gcc.
> 
> I'd like to see it tested with gcc :)
> 
>> Does this seem like a reasonable approach?  I do plan to look at external
>> binutils support, but it's not on the critical path for our current work
>> so I've opted to avoid it for now.
> 
> The patches I posted a few months ago had that as well...
> 
>> As a bonus for those who don't need an external compiler, but do run
>> make buildworld frequently, the XCC, XCXX, and XCPP variables can be set
>> to the location of the installed base system compiler to avoid building
>> the compiler twice during buildworld.
> 
> I think this will work, but it is kludgy.  I had created a __X=<prefix-path> which was prepended to ${CC}, et al, in sys.mk. It was only defined when you set CROSS_COMPILER_PATH (or EXTERNAL_COMPILER_PATH, I forget) during the cross building stage. It also had the advantage of making external cross binutils available. Your patch could fairly easily use this interface instead of having to set 3 different variables, which will morph to 10 when you add binutil support.

I've also started looking into using clang --mumble to doing cross builds too, so I don't have to have 4 compilers configured and laying around for the different platforms I play with.  That isn't reflected in the port.

I also am having trouble finding my full patch, but a partial patch can be found at http://people.freebsd.org/~imp/simple-ext.diff. A patch that looks to be contaminated with other patches but that seems to have all the bits in it is in http://people.freebsd.org/~imp/ext_comp.diff. I've not tried to apply either of these patches, and they are about 9 months old at this point. Should be easy enough to merge forward by hand if patch just doesn't do it.

Warner

>> -- Brooks
>> 
>> -----
>> MFP4 222356, 222371, 222375, 222391, 222403, 222407, 222411
>> 
>> Add support for an external cross compiler.  The cross compiler is
>> specified by passing the XCC, XCXX, and XCPP variables (corresponding to
>> CC, CXX, and CPP) to buildworld/buildkernel.  The compiler must be clang
>> or be configured to target the appropriate architecture.
>> 
>> To speed build times, if XCC is an absolute path or
>> WITHOUT_CROSS_COMPILER is defined then no cross compiler will be built
>> during the cross-tools stage.
> 
> This change is likely good as-is.
> 
>> To facilitate the use of unmodified external compilers, a
>> WITHOUT_FORMAT_EXTENSIONS option is available to supress printf format
>> checking.
> 
> This one definitely is good as-is.
> 
>> As a short-term measure, supress a few new clang warnings during kernel
>> builds.
>> 
>> Sponsored by:	DARPA, AFRL
>> Reviewed by:	xxx
>> 
>> --- ../../freebsd/src/Makefile.inc1	2013-02-26 21:31:09.000000000 +0000
>> +++ ./Makefile.inc1	2013-02-26 21:10:50.000000000 +0000
>> @@ -280,16 +280,34 @@
>> .if ${MK_CDDL} == "no"
>> WMAKEENV+=	NO_CTF=1
>> .endif
>> -.if ${CC:T:Mgcc} == "gcc"
>> +XCC?=	${CC}
>> +XCXX?=	${CXX}
>> +XCPP?=	${CPP}
> 
> I don't like having three different variables to set. I don't think this will work with gcc, unless we've fixed all the instances in the tree where we called AS or LD directly.  The patches that I had would set ${CC}, etc based on a CROSS_COMPILER_PATH=xxx variable. I'd rather see us do that than have this hacky set 3 variables thing.
> 
>> +.if ${XCC:T:Mgcc} == "gcc"
>> WMAKE_COMPILER_TYPE=	gcc
>> -.elif ${CC:T:Mclang} == "clang"
>> +.elif ${XCC:T:Mclang} == "clang"
>> WMAKE_COMPILER_TYPE=	clang
>> .elif ${MK_CLANG_IS_CC} == "no"
>> WMAKE_COMPILER_TYPE=	gcc
>> .else
>> WMAKE_COMPILER_TYPE=	clang
>> .endif
> 
> Is there any way to set the WMAKE_COMPILER_TYPE with these patches? XCC might be something like mips-cavium-cc which won't trigger any of the above, unless you also have set WITHOUT_CLANG_IS_CC...
> 
>> -WMAKEENV+=	COMPILER_TYPE=${WMAKE_COMPILER_TYPE}
>> +.if ${XCC:M/*}
>> +XFLAGS=		--sysroot=${WORLDTMP} -B${WORLDTMP}/usr/bin
>> +.if ${TARGET_ARCH} != ${MACHINE_ARCH} && ${WMAKE_COMPILER_TYPE} == "clang"
>> +.if (${TARGET_ARCH} == "arm" || ${TARGET_ARCH} == "armv6") && \
>> +${MK_ARM_EABI} != "no"
>> +TARGET_ABI=	gnueabi
>> +.else
>> +TARGET_ABI=	unknown
>> +.endif
> 
> We need to fix the gnueabi issue with arm.  machine_arch should always be enough to be self-hosting, and while I fixed the armv6 issue, this has cropped up in its place :(.
> 
>> +TARGET_TRIPLE?=	${TARGET_ARCH:C/amd64/x86_64/}-${TARGET_ABI}-freebsd10.0
>> +XFLAGS+=	-target ${TARGET_TRIPLE}
>> +.endif
>> +.endif
>> +WMAKEENV+=	CC="${XCC} ${XFLAGS}" CXX="${XCXX} ${XFLAGS}" \
>> +		CPP="${XCPP} ${XFLAGS}" \
>> +		COMPILER_TYPE=${WMAKE_COMPILER_TYPE}
>> WMAKE=		${WMAKEENV} ${MAKE} ${WORLD_FLAGS} -f Makefile.inc1 DESTDIR=${WORLDTMP}
>> 
>> .if ${TARGET_ARCH} == "amd64" || ${TARGET_ARCH} == "powerpc64"
>> @@ -321,6 +339,7 @@
>> 
>> 
>> LIB32FLAGS=	-m32 ${LIB32CPUFLAGS} -DCOMPAT_32BIT \
>> +		--sysroot=${WORLDTMP} \
>> 		-isystem ${LIB32TMP}/usr/include/ \
>> 		-L${LIB32TMP}/usr/lib32 \
>> 		-B${LIB32TMP}/usr/lib32
>> @@ -336,8 +355,8 @@
>> 		SHLIBDIR=/usr/lib32 \
>> 		COMPILER_TYPE=${WMAKE_COMPILER_TYPE}
>> LIB32WMAKEFLAGS+=	\
>> -		CC="${CC} ${LIB32FLAGS}" \
>> -		CXX="${CXX} ${LIB32FLAGS}" \
>> +		CC="${XCC} ${LIB32FLAGS}" \
>> +		CXX="${XCXX} ${LIB32FLAGS}" \
>> 		DESTDIR=${LIB32TMP} \
>> 		-DCOMPAT_32BIT \
>> 		-DLIBRARIES_ONLY \
>> @@ -1288,6 +1307,9 @@
>> _binutils=	gnu/usr.bin/binutils
>> .endif
>> 
>> +# If an full path to an external cross compiler is given, don't build
>> +# a cross compiler.
>> +.if ${XCC:M/*} == "" && ${MK_CROSS_COMPILER} != "no"
>> .if ${MK_CLANG} != "no" && (${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang")
>> _clang=		usr.bin/clang
>> _clang_libs=	lib/clang
>> @@ -1296,6 +1318,7 @@
>> .if ${MK_GCC} != "no" && (${MK_CLANG_IS_CC} == "no" || ${TARGET} == "pc98")
>> _cc=		gnu/usr.bin/cc
>> .endif
>> +.endif
>> 
>> cross-tools:
>> .for _tool in \
>> --- ../../freebsd/src/share/mk/bsd.own.mk	2013-02-15 18:49:13.000000000 +0000
>> +++ share/mk/bsd.own.mk	2013-02-26 21:10:50.000000000 +0000
>> @@ -262,6 +262,7 @@
>>    CAPSICUM \
>>    CDDL \
>>    CPP \
>> +    CROSS_COMPILER \
>>    CRYPT \
>>    CTM \
>>    CVS \
>> @@ -271,6 +272,7 @@
>>    ED_CRYPTO \
>>    EXAMPLES \
>>    FLOPPY \
>> +    FORMAT_EXTENSIONS \
>>    FORTH \
>>    FP_LIBC \
>>    FREEBSD_UPDATE \
>> --- ../../freebsd/src/sys/conf/kern.mk	2012-11-11 22:15:16.000000000 +0000
>> +++ sys/conf/kern.mk	2013-02-26 20:35:48.000000000 +0000
>> @@ -5,7 +5,7 @@
>> #
>> CWARNFLAGS?=	-Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
>> 		-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual \
>> -		-Wundef -Wno-pointer-sign -fformat-extensions \
>> +		-Wundef -Wno-pointer-sign ${FORMAT_EXTENTIONS} \
>> 		-Wmissing-include-dirs -fdiagnostics-show-option \
>> 		${CWARNEXTRA}
>> #
>> @@ -29,7 +29,18 @@
>> # enough to error out the whole kernel build.  Display them anyway, so there is
>> # some incentive to fix them eventually.
>> CWARNEXTRA?=	-Wno-error-tautological-compare -Wno-error-empty-body \
>> -		-Wno-error-parentheses-equality
>> +		-Wno-error-parentheses-equality \
>> +		-Wno-sizeof-pointer-memaccess \
>> +		-Wno-unused-command-line-argument \
>> +		${NO_WFORMAT}
>> +.endif
>> +
>> +# External compilers may not support our format extensions.  Allow them
>> +# to be disabled.  WARNING: format checking is disabled in this case.
>> +.if ${MK_FORMAT_EXTENSIONS} == "no"
>> +NO_WFORMAT=		-Wno-format
>> +.else
>> +FORMAT_EXTENTIONS=	-fformat-extensions
>> .endif
>> 
>> #
>> diff -uN ../../freebsd/src/tools/build/options/WITHOUT_CROSS_COMPILER tools/build/options/WITHOUT_CROSS_COMPILER
>> --- ../../freebsd/src/tools/build/options/WITHOUT_CROSS_COMPILER	1970-01-01 00:00:00.000000000 +0000
>> +++ tools/build/options/WITHOUT_CROSS_COMPILER	2013-02-26 21:10:50.000000000 +0000
>> @@ -0,0 +1,3 @@
>> +.\" $FreeBSD$
>> +Set to not build a cross compiler in the cross-tools stage of
>> +buildworld, buildkernel, etc.
>> diff -uN ../../freebsd/src/tools/build/options/WITHOUT_FORMAT_EXTENSIONS tools/build/options/WITHOUT_FORMAT_EXTENSIONS
>> --- ../../freebsd/src/tools/build/options/WITHOUT_FORMAT_EXTENSIONS	1970-01-01 00:00:00.000000000 +0000
>> +++ tools/build/options/WITHOUT_FORMAT_EXTENSIONS	2013-02-26 20:35:48.000000000 +0000
>> @@ -0,0 +1,5 @@
>> +.\" $FreeBSD$
>> +Set to not enable
>> +.Fl fformat-extensions
>> +when compiling the kernel.
>> +Also disables all format checking.
> 