Introduce a new make variable COMPILER_TYPE that specifies what

type of compiler is being used (currently clang or gcc).  COMPILER_TYPE
is set in the new bsd.compiler.mk file based on the value of the CC
variable or, should it prove informative, by running ${CC} --version
and examining the output.

To avoid negative performance impacts in the default case and correct
value for COMPILER_TYPE type is determined and passed in the environment
of submake instances while building world.

Replace adhoc attempts at determining the compiler type by examining
CC or MK_CLANG_IS_CC with checks of COMPILER_TYPE.  This eliminates
bootstrapping complications when first setting WITH_CLANG_IS_CC.

Sponsored by:	DARPA, AFRL
Reviewed by:	Yamaya Takashi <yamayan@kbh.biglobe.ne.jp>, imp, linimon
		(with some modifications post review)
MFC after:	2 weeks

3 files changed, 9 insertions, 7 deletions

diff --git a/sys/conf/kern.mk b/sys/conf/kern.mk
index 5e031b3..e42b753 100644
--- a/sys/conf/kern.mk
+++ b/sys/conf/kern.mk
@@ -15,7 +15,7 @@ CWARNFLAGS?=	-Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
 # Disable a few warnings for clang, since there are several places in the
 # kernel where fixing them is more trouble than it is worth, or where there is
 # a false positive.
-.if ${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang"
+.if ${COMPILER_TYPE} == "clang"
 NO_WCONSTANT_CONVERSION=	-Wno-constant-conversion
 NO_WARRAY_BOUNDS=		-Wno-array-bounds
 NO_WSHIFT_COUNT_NEGATIVE=	-Wno-shift-count-negative
@@ -52,7 +52,7 @@ CWARNEXTRA?=	-Wno-error-tautological-compare -Wno-error-empty-body \
 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 #
 .if ${MACHINE_CPUARCH} == "i386"
-.if ${MK_CLANG_IS_CC} == "no" && ${CC:T:Mclang} != "clang"
+.if ${COMPILER_TYPE} != "clang"
 CFLAGS+=	-mno-align-long-strings -mpreferred-stack-boundary=2
 .else
 CFLAGS+=	-mno-aes -mno-avx
@@ -100,7 +100,7 @@ INLINE_LIMIT?=	15000
 # (-mfpmath= is not supported)
 #
 .if ${MACHINE_CPUARCH} == "amd64"
-.if ${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang"
+.if ${COMPILER_TYPE} == "clang"
 CFLAGS+=	-mno-aes -mno-avx
 .endif
 CFLAGS+=	-mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
diff --git a/sys/conf/kern.pre.mk b/sys/conf/kern.pre.mk
index b491c75..fbf686a 100644
--- a/sys/conf/kern.pre.mk
+++ b/sys/conf/kern.pre.mk
@@ -4,6 +4,7 @@
 # of the definitions that need to be before %BEFORE_DEPEND.
 
 .include <bsd.own.mk>
+.include <bsd.compiler.mk>
 
 # backwards compat option for older systems.
 MACHINE_CPUARCH?=${MACHINE_ARCH:C/mips(n32|64)?(el)?/mips/:C/arm(v6)?(eb)?/arm/:C/powerpc64/powerpc/}
@@ -35,7 +36,7 @@ _MINUS_O=	-O2
 .endif
 .endif
 .if ${MACHINE_CPUARCH} == "amd64"
-.if ${MK_CLANG_IS_CC} == "no" && ${CC:T:Mclang} != "clang"
+.if ${COMPILER_TYPE} != "clang"
 COPTFLAGS?=-O2 -frename-registers -pipe
 .else
 COPTFLAGS?=-O2 -pipe
@@ -85,7 +86,7 @@ INCLUDES+= -I$S/dev/cxgb -I$S/dev/cxgbe
 
 CFLAGS=	${COPTFLAGS} ${C_DIALECT} ${DEBUG} ${CWARNFLAGS}
 CFLAGS+= ${INCLUDES} -D_KERNEL -DHAVE_KERNEL_OPTION_HEADERS -include opt_global.h
-.if ${MK_CLANG_IS_CC} == "no" && ${CC:T:Mclang} != "clang"
+.if ${COMPILER_TYPE} != "clang"
 CFLAGS+= -fno-common -finline-limit=${INLINE_LIMIT}
 .if ${MACHINE_CPUARCH} != "mips"
 CFLAGS+= --param inline-unit-growth=100
@@ -102,7 +103,7 @@ WERROR?= -Werror
 # XXX LOCORE means "don't declare C stuff" not "for locore.s".
 ASM_CFLAGS= -x assembler-with-cpp -DLOCORE ${CFLAGS}
 
-.if ${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang"
+.if ${COMPILER_TYPE} == "clang"
 CLANG_NO_IAS= -no-integrated-as
 .endif
 
diff --git a/sys/conf/kmod.mk b/sys/conf/kmod.mk
index 772e5cd..86955e9 100644
--- a/sys/conf/kmod.mk
+++ b/sys/conf/kmod.mk
@@ -73,6 +73,7 @@ OBJCOPY?=	objcopy
 .endif
 
 .include <bsd.init.mk>
+.include <bsd.compiler.mk>
 
 .SUFFIXES: .out .o .c .cc .cxx .C .y .l .s .S
 
@@ -108,7 +109,7 @@ CFLAGS+=	-I. -I@
 # for example.
 CFLAGS+=	-I@/contrib/altq
 
-.if ${MK_CLANG_IS_CC} == "no" && ${CC:T:Mclang} != "clang"
+.if ${COMPILER_TYPE} != "clang"
 CFLAGS+=	-finline-limit=${INLINE_LIMIT}
 CFLAGS+= --param inline-unit-growth=100
 CFLAGS+= --param large-function-growth=1000