Define several extra macros in bsd.sys.mk and sys/conf/kern.pre.mk, to

get rid of testing explicitly for clang (using ${CC:T:Mclang}) in
individual Makefiles.

Instead, use the following extra macros, for use with clang:
- NO_WERROR.clang       (disables -Werror)
- NO_WCAST_ALIGN.clang  (disables -Wcast-align)
- NO_WFORMAT.clang	(disables -Wformat and friends)
- CLANG_NO_IAS		(disables integrated assembler)
- CLANG_OPT_SMALL	(adds flags for extra small size optimizations)

As a side effect, this enables setting CC/CXX/CPP in src.conf instead of
make.conf!  For clang, use the following:

CC=clang
CXX=clang++
CPP=clang-cpp

MFC after:	2 weeks

3 files changed, 12 insertions, 10 deletions

diff --git a/sys/conf/Makefile.amd64 b/sys/conf/Makefile.amd64
index 5096829..33f146e 100644
--- a/sys/conf/Makefile.amd64
+++ b/sys/conf/Makefile.amd64
@@ -40,13 +40,12 @@ CFLAGS+=	-fno-omit-frame-pointer
 
 MKMODULESENV+= MACHINE=amd64
 
-.if ${CC:T:Mclang} == "clang"
 # XXX: clang integrated-as doesn't grok .codeNN directives yet
-ASM_CFLAGS+=	${.IMPSRC:T:Macpi_wakecode.S:C/^.+$/-no-integrated-as/}
-ASM_CFLAGS+=	${.IMPSRC:T:Mia32_sigtramp.S:C/^.+$/-no-integrated-as/}
-ASM_CFLAGS+=	${.IMPSRC:T:Mlinux32_locore.s:C/^.+$/-no-integrated-as/}
-ASM_CFLAGS+=	${.IMPSRC:T:Mmpboot.S:C/^.+$/-no-integrated-as/}
-.endif
+ASM_CFLAGS.acpi_wakecode.S=	${CLANG_NO_IAS}
+ASM_CFLAGS.ia32_sigtramp.S=	${CLANG_NO_IAS}
+ASM_CFLAGS.linux32_locore.s=	${CLANG_NO_IAS}
+ASM_CFLAGS.mpboot.S=		${CLANG_NO_IAS}
+ASM_CFLAGS+=			${ASM_CFLAGS.${.IMPSRC:T}}
 
 %BEFORE_DEPEND
 
diff --git a/sys/conf/Makefile.i386 b/sys/conf/Makefile.i386
index 5ea09d0..538ccbc 100644
--- a/sys/conf/Makefile.i386
+++ b/sys/conf/Makefile.i386
@@ -34,11 +34,10 @@ MACHINE=i386
 
 MKMODULESENV+=	MACHINE=${MACHINE}
 
-.if ${CC:T:Mclang} == "clang"
 # XXX: clang integrated-as doesn't grok .codeNN directives yet
-ASM_CFLAGS+=	${.IMPSRC:T:Macpi_wakecode.S:C/^.+$/-no-integrated-as/}
-ASM_CFLAGS+=	${.IMPSRC:T:Mmpboot.s:C/^.+$/-no-integrated-as/}
-.endif
+ASM_CFLAGS.acpi_wakecode.S=	${CLANG_NO_IAS}
+ASM_CFLAGS.mpboot.s=		${CLANG_NO_IAS}
+ASM_CFLAGS+=			${ASM_CFLAGS.${.IMPSRC:T}}
 
 %BEFORE_DEPEND
 
diff --git a/sys/conf/kern.pre.mk b/sys/conf/kern.pre.mk
index a209ddd..8edc1c9 100644
--- a/sys/conf/kern.pre.mk
+++ b/sys/conf/kern.pre.mk
@@ -101,6 +101,10 @@ WERROR?= -Werror
 # XXX LOCORE means "don't declare C stuff" not "for locore.s".
 ASM_CFLAGS= -x assembler-with-cpp -DLOCORE ${CFLAGS}
 
+.if ${CC:T:Mclang} == "clang"
+CLANG_NO_IAS= -no-integrated-as
+.endif
+
 .if defined(PROFLEVEL) && ${PROFLEVEL} >= 1
 CFLAGS+=	-DGPROF -falign-functions=16
 .if ${PROFLEVEL} >= 2