build: LLVM: Add Flang compiler support and enable OpenMP for Clang

Signed-off-by: Paul Osmialowski <pawel.osmialowski@arm.com>

Makefile.system

@@ -414,7 +414,6 @@ CCOMMON_OPT    += -fopenmp
 endif
 
 ifeq ($(C_COMPILER), CLANG)
-$(error OpenBLAS: Clang didn't support OpenMP yet.)
 CCOMMON_OPT    += -fopenmp
 endif
 
@@ -584,6 +583,23 @@ endif
 #  Fortran Compiler dependent settings
 #
 
+ifeq ($(F_COMPILER), FLANG)
+CCOMMON_OPT += -DF_INTERFACE_FLANG
+ifdef BINARY64
+ifdef INTERFACE64
+ifneq ($(INTERFACE64), 0)
+FCOMMON_OPT += -i8
+endif
+endif
+FCOMMON_OPT += -Wall
+else
+FCOMMON_OPT += -Wall
+endif
+ifeq ($(USE_OPENMP), 1)
+FCOMMON_OPT += -fopenmp
+endif
+endif
+
 ifeq ($(F_COMPILER), G77)
 CCOMMON_OPT += -DF_INTERFACE_G77
 FCOMMON_OPT += -Wall

cmake/fc.cmake

@@ -3,6 +3,21 @@
 ## Description: Ported from portion of OpenBLAS/Makefile.system
 ##              Sets Fortran related variables.
 
+if (${F_COMPILER} STREQUAL "FLANG")
+  set(CCOMMON_OPT "${CCOMMON_OPT} -DF_INTERFACE_FLANG")
+  if (BINARY64)
+    if (INTERFACE64)
+      set(FCOMMON_OPT "${FCOMMON_OPT} -i8")
+    endif ()
+    set(FCOMMON_OPT "${FCOMMON_OPT} -Wall")
+  else ()
+    set(FCOMMON_OPT "${FCOMMON_OPT} -Wall")
+  endif ()
+  if (USE_OPENMP)
+    set(FCOMMON_OPT "${FCOMMON_OPT} -fopenmp")
+  endif ()
+endif ()
+
 if (${F_COMPILER} STREQUAL "G77")
   set(CCOMMON_OPT "${CCOMMON_OPT} -DF_INTERFACE_G77")
   set(FCOMMON_OPT "${FCOMMON_OPT} -Wall")

common_arm64.h

@@ -39,7 +39,11 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #define INLINE inline
 
+#ifdef F_INTERFACE_FLANG
+#define RETURN_BY_STACK
+#else
 #define RETURN_BY_COMPLEX
+#endif
 
 #ifndef ASSEMBLER
 

f_check

@@ -33,6 +33,7 @@ if ($compiler eq "") {
               "ppuf77", "ppuf95", "ppuf90", "ppuxlf",
 	      "pathf90", "pathf95",
 	      "pgf95", "pgf90", "pgf77",
+	      "flang",
               "ifort");
 
 OUTER:
@@ -78,8 +79,13 @@ if ($compiler eq "") {
 		$vendor = GFORTRAN;
 		$openmp = "-fopenmp";
 	    } else {
-		$vendor = G77;
-		$openmp = "";
+		if ($compiler =~ /flang/) {
+		    $vendor = FLANG;
+		    $openmp = "-fopenmp";
+		} else {
+		    $vendor = G77;
+		    $openmp = "";
+		}
 	    }
 
 	}
@@ -197,6 +203,12 @@ if ($compiler eq "") {
 	    $openmp = "-mp";
 	}
 
+	if ($compiler =~ /flang/) {
+	    $vendor = FLANG;
+	    $bu     = "_";
+	    $openmp = "-fopenmp";
+	}
+
 	if ($vendor eq "") {
 	    $nofortran = 1;
 	    $compiler = "gfortran";
@@ -331,6 +343,10 @@ if ($vendor eq "INTEL"){
     $linker_a .= "-lgfortran"
 }
 
+if ($vendor eq "FLANG"){
+    $linker_a .= "-lflang"
+}
+
 open(MAKEFILE, ">> $makefile") || die "Can't append $makefile";
 open(CONFFILE, ">> $config"  ) || die "Can't append $config";