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, 35 insertions, 15 deletions

diff --git a/share/mk/Makefile b/share/mk/Makefile
index 64c6549..5bab862 100644
--- a/share/mk/Makefile
+++ b/share/mk/Makefile
@@ -3,7 +3,8 @@
 
 FILES=	bsd.README
 FILES+=	bsd.arch.inc.mk
-FILES+=	bsd.compat.mk bsd.cpu.mk bsd.dep.mk bsd.doc.mk bsd.dtrace.mk
+FILES+=	bsd.compat.mk bsd.compiler.mk bsd.cpu.mk
+FILES+=	bsd.dep.mk bsd.doc.mk bsd.dtrace.mk
 FILES+=	bsd.endian.mk
 FILES+=	bsd.files.mk bsd.crunchgen.mk bsd.incs.mk bsd.info.mk bsd.init.mk
 FILES+=	bsd.kmod.mk
diff --git a/share/mk/bsd.compiler.mk b/share/mk/bsd.compiler.mk
new file mode 100644
index 0000000..cca3968
--- /dev/null
+++ b/share/mk/bsd.compiler.mk
@@ -0,0 +1,21 @@
+# $FreeBSD$
+
+.if !defined(COMPILER_TYPE)
+. if ${CC:T:Mgcc} == "gcc"
+COMPILER_TYPE:=	gcc  
+. elif ${CC:T:Mclang} == "clang"
+COMPILER_TYPE:=	clang
+. else
+_COMPILER_VERSION!=	${CC} --version
+.  if ${_COMPILER_VERSION:Mgcc} == "gcc"
+COMPILER_TYPE:=	gcc
+.  elif ${_COMPILER_VERSION:M\(GCC\)} == "(GCC)"
+COMPILER_TYPE:=	gcc
+.  elif ${_COMPILER_VERSION:Mclang} == "clang"
+COMPILER_TYPE:=	clang
+.  else
+.error Unable to determing compiler type for ${CC}
+.  endif
+.  undef _COMPILER_VERSION
+. endif
+.endif
diff --git a/share/mk/bsd.sys.mk b/share/mk/bsd.sys.mk
index 28c1a18..cc752a2 100644
--- a/share/mk/bsd.sys.mk
+++ b/share/mk/bsd.sys.mk
@@ -8,6 +8,8 @@
 
 # for GCC:   http://gcc.gnu.org/onlinedocs/gcc-4.2.1/gcc/Warning-Options.html
 
+.include <bsd.compiler.mk>
+
 # the default is gnu99 for now
 CSTD?=		gnu99
 
@@ -28,8 +30,8 @@ CFLAGS+=	-std=${CSTD}
 .if defined(WARNS)
 .if ${WARNS} >= 1
 CWARNFLAGS+=	-Wsystem-headers
-.if !defined(NO_WERROR) && ((${MK_CLANG_IS_CC} == "no" && \
-    ${CC:T:Mclang} != "clang") || !defined(NO_WERROR.clang))
+.if !defined(NO_WERROR) && (${COMPILER_TYPE} != "clang" \
+    || !defined(NO_WERROR.clang))
 CWARNFLAGS+=	-Werror
 .endif # !NO_WERROR && (!CLANG || !NO_WERROR.clang)
 .endif # WARNS >= 1
@@ -43,8 +45,8 @@ CWARNFLAGS+=	-W -Wno-unused-parameter -Wstrict-prototypes\
 .if ${WARNS} >= 4
 CWARNFLAGS+=	-Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wshadow\
 		-Wunused-parameter
-.if !defined(NO_WCAST_ALIGN) && ((${MK_CLANG_IS_CC} == "no" && \
-    ${CC:T:Mclang} != "clang") || !defined(NO_WCAST_ALIGN.clang))
+.if !defined(NO_WCAST_ALIGN) && (${COMPILER_TYPE} != "clang" \
+    || !defined(NO_WCAST_ALIGN.clang))
 CWARNFLAGS+=	-Wcast-align
 .endif # !NO_WCAST_ALIGN && (!CLANG || !NO_WCAST_ALIGN.clang)
 .endif # WARNS >= 4
@@ -61,8 +63,7 @@ CWARNFLAGS+=	-Wno-uninitialized
 CWARNFLAGS+=	-Wno-pointer-sign
 # Clang has more warnings enabled by default, and when using -Wall, so if WARNS
 # is set to low values, these have to be disabled explicitly.
-.if (${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang") && \
-    !defined(EARLY_BUILD)
+.if ${COMPILER_TYPE} == "clang" && !defined(EARLY_BUILD)
 .if ${WARNS} <= 6
 CWARNFLAGS+=	-Wno-empty-body -Wno-string-plus-int
 .endif # WARNS <= 6
@@ -89,20 +90,18 @@ WFORMAT=	1
 .if ${WFORMAT} > 0
 #CWARNFLAGS+=	-Wformat-nonliteral -Wformat-security -Wno-format-extra-args
 CWARNFLAGS+=	-Wformat=2 -Wno-format-extra-args
-.if (${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang") && \
-    !defined(EARLY_BUILD)
+.if ${COMPILER_TYPE} == "clang" && !defined(EARLY_BUILD)
 .if ${WARNS} <= 3
 CWARNFLAGS+=	-Wno-format-nonliteral
 .endif # WARNS <= 3
 .endif # CLANG
-.if !defined(NO_WERROR) && ((${MK_CLANG_IS_CC} == "no" && \
-    ${CC:T:Mclang} != "clang") || !defined(NO_WERROR.clang))
+.if !defined(NO_WERROR) && (${COMPILER_TYPE} != "clang" \
+    || !defined(NO_WERROR.clang))
 CWARNFLAGS+=	-Werror
 .endif # !NO_WERROR && (!CLANG || !NO_WERROR.clang)
 .endif # WFORMAT > 0
 .endif # WFORMAT
-.if defined(NO_WFORMAT) || ((${MK_CLANG_IS_CC} != "no" || \
-    ${CC:T:Mclang} == "clang") && defined(NO_WFORMAT.clang))
+.if defined(NO_WFORMAT) || (${COMPILER_TYPE} == "clang" && defined(NO_WFORMAT.clang))
 CWARNFLAGS+=	-Wno-format
 .endif # NO_WFORMAT || (CLANG && NO_WFORMAT.clang)
 .endif # !NO_WARNS
@@ -111,8 +110,7 @@ CWARNFLAGS+=	-Wno-format
 CWARNFLAGS+=	-Wno-unknown-pragmas
 .endif # IGNORE_PRAGMA
 
-.if (${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang") && \
-    !defined(EARLY_BUILD)
+.if ${COMPILER_TYPE} == "clang" && !defined(EARLY_BUILD)
 CLANG_NO_IAS=	 -no-integrated-as
 CLANG_OPT_SMALL= -mstack-alignment=8 -mllvm -inline-threshold=3\
 		 -mllvm -enable-load-pre=false -mllvm -simplifycfg-dup-ret