Avoid compiling BLAS/CBLAS files when disabled.

Details:
- Updated the top-level Makefile, build/config.mk.in template, and
  configure script so that object files corresponding to source files
  belonging to the BLAS compatibility layer are not compiled (or archived)
  when the compatibility layer is disabled. (Same for CBLAS.) Thanks
  to Devin Matthews for suggesting this optimization.
- Slight change to the way configure handles internal variables. Instead
  of converting (overwriting) some, such as enable_blas2blis and
  enable_cblas, from a "yes" or "no" to a "1" or "0" value, the latter are
  now stored in new variables that live alongside the originals (with the
  suffix "_01").  This is convenient since some values need to be
  sed-substituted into the config.mk.in template, which requires "yes" or
  "no", while some need to be written to the bli_config.h.in template,
  which requires "0" or "1".

Makefile

@@ -312,6 +312,19 @@ MK_BLIS_CONFIG_OBJS  += $(patsubst $(CONFIG_PATH)/%.c, $(BASE_OBJ_CONFIG_PATH)/%
 MK_ALL_BLIS_OBJS     := $(MK_BLIS_CONFIG_OBJS) \
                         $(MK_BLIS_FRAME_OBJS)
 
+# Optionally filter out the BLAS and CBLAS compatibility layer object files.
+# This is not actually necessary, since each affected file is guarded by C
+# preprocessor macros, but it but prevents "empty" object files from being
+# added into the library (and reduces compilation time).
+BASE_OBJ_BLAS_PATH   := $(BASE_OBJ_FRAME_PATH)/compat
+BASE_OBJ_CBLAS_PATH  := $(BASE_OBJ_FRAME_PATH)/compat/cblas
+ifeq ($(BLIS_ENABLE_CBLAS),no)
+MK_ALL_BLIS_OBJS     := $(filter-out $(BASE_OBJ_CBLAS_PATH)/%.o, $(MK_ALL_BLIS_OBJS) )
+endif
+ifeq ($(BLIS_ENABLE_BLAS2BLIS),no)
+MK_ALL_BLIS_OBJS     := $(filter-out $(BASE_OBJ_BLAS_PATH)/%.o,  $(MK_ALL_BLIS_OBJS) )
+endif
+
 
 
 #

build/config.mk.in

@@ -64,5 +64,9 @@ BLIS_ENABLE_VERBOSE_MAKE_OUTPUT := @enable_verbose@
 BLIS_ENABLE_STATIC_BUILD        := @enable_static@
 BLIS_ENABLE_DYNAMIC_BUILD       := @enable_dynamic@
 
+# The status of BLAS and CBLAS compatibility layers
+BLIS_ENABLE_BLAS2BLIS := @enable_blas2blis@
+BLIS_ENABLE_CBLAS     := @enable_cblas@
+
 # end of ifndef CONFIG_MK_INCLUDED conditional block
 endif

configure

@@ -486,16 +486,20 @@ main()
 	
 	
 	# Check the threading model flag.
-	enable_openmp=0
-	enable_pthreads=0
+	enable_openmp='no'
+	enable_openmp_01=0
+	enable_pthreads='no'
+	enable_pthreads_01=0
 	if [ "x${threading_model}" = "xauto" ]; then
 		echo "${script_name}: determining the threading model automatically."
 	elif [ "x${threading_model}" = "xomp" ]; then
 		echo "${script_name}: using OpenMP for threading."
-		enable_openmp=1
+		enable_openmp='yes'
+		enable_openmp_01=1
 	elif [ "x${threading_model}" = "xpthreads" ]; then
 		echo "${script_name}: using Pthreads for threading."
-		enable_pthreads=1
+		enable_pthreads='yes'
+		enable_pthreads_01=1
 	elif [ "x${threading_model}" = "xno" ]; then
 		echo "${script_name}: threading is disabled."
 	else
@@ -507,19 +511,19 @@ main()
 	# Convert 'yes' and 'no' flags to booleans.
 	if [ "x${enable_cblas}" = "xyes" ]; then
 	   echo "${script_name}: the CBLAS compatibility layer is enabled."
-	   enable_cblas=1
+	   enable_cblas_01=1
 	   # Force BLAS layer when CBLAS is enabled
-	   enable_blas='yes'
+	   enable_blas2blis='yes'
 	else
 	   echo "${script_name}: the CBLAS compatibility layer is disabled."
-	   enable_cblas=0
+	   enable_cblas_01=0
 	fi
 	if [ "x${enable_blas2blis}" = "xyes" ]; then
 	   echo "${script_name}: the BLAS compatibility layer is enabled."
-	   enable_blas2blis=1
+	   enable_blas2blis_01=1
 	else
 	   echo "${script_name}: the BLAS compatibility layer is disabled."
-	   enable_blas2blis=0
+	   enable_blas2blis_01=0
 	fi
 	
 	
@@ -561,6 +565,8 @@ main()
 		| sed "s/@enable_static@/${enable_static}/g" \
 		| sed "s/@enable_dynamic@/${enable_shared}/g" \
 		| sed "s/@threading_model@/${threading_model}/g" \
+		| sed "s/@enable_blas2blis@/${enable_blas2blis}/g" \
+		| sed "s/@enable_cblas@/${enable_cblas}/g" \
 		> "${config_mk_out_path}"
 		
 
@@ -568,12 +574,12 @@ main()
 	# to bli_config_h_out.
 	echo "${script_name}: creating ${bli_config_h_out_path} from ${bli_config_h_in_path}"
 	cat "${bli_config_h_in_path}" \
-		| sed "s/@enable_openmp@/${enable_openmp}/g" \
-		| sed "s/@enable_pthreads@/${enable_pthreads}/g" \
+		| sed "s/@enable_openmp@/${enable_openmp_01}/g" \
+		| sed "s/@enable_pthreads@/${enable_pthreads_01}/g" \
 		| sed "s/@int_type_size@/${int_type_size}/g" \
 		| sed "s/@blas2blis_int_type_size@/${blas2blis_int_type_size}/g" \
-		| sed "s/@enable_blas2blis@/${enable_blas2blis}/g" \
-		| sed "s/@enable_cblas@/${enable_cblas}/g" \
+		| sed "s/@enable_blas2blis@/${enable_blas2blis_01}/g" \
+		| sed "s/@enable_cblas@/${enable_cblas_01}/g" \
 		> "${bli_config_h_out_path}"