wmake: added rules for linuxArm64Gcc to compile on aarch64 (Arm-based) processors.

No code change was required to compile OpenFOAM on Arm using the Gcc compiler.

etc/config.csh/settings

@@ -2,7 +2,7 @@
 # =========                 |
 # \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
 #  \\    /   O peration     | Website:  https://openfoam.org
-#   \\  /    A nd           | Copyright (C) 2011-2019 OpenFOAM Foundation
+#   \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
 #    \\/     M anipulation  |
 #------------------------------------------------------------------------------
 # License
@@ -81,6 +81,16 @@ case Linux:
         endsw
         breaksw
 
+    case aarch64:
+        setenv WM_ARCH linuxArm64
+        setenv WM_COMPILER_LIB_ARCH 64
+        setenv WM_CC 'gcc'
+        setenv WM_CXX 'g++'
+        setenv WM_CFLAGS '-fPIC'
+        setenv WM_CXXFLAGS '-fPIC -std=c++0x'
+        setenv WM_LDFLAGS ''
+        ;;
+
     case ppc64:
         setenv WM_ARCH linuxPPC64
         setenv WM_COMPILER_LIB_ARCH 64

etc/config.sh/settings

@@ -2,7 +2,7 @@
 # =========                 |
 # \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
 #  \\    /   O peration     | Website:  https://openfoam.org
-#   \\  /    A nd           | Copyright (C) 2011-2018 OpenFOAM Foundation
+#   \\  /    A nd           | Copyright (C) 2011-2020 OpenFOAM Foundation
 #    \\/     M anipulation  |
 #------------------------------------------------------------------------------
 # License
@@ -74,6 +74,16 @@ Linux)
         esac
         ;;
 
+    aarch64)
+        WM_ARCH=linuxArm64
+        export WM_COMPILER_LIB_ARCH=64
+        export WM_CC='gcc'
+        export WM_CXX='g++'
+        export WM_CFLAGS='-fPIC'
+        export WM_CXXFLAGS='-fPIC -std=c++0x'
+        export WM_LDFLAGS=
+        ;;
+
     armv7l)
         WM_ARCH=linuxARM7
         export WM_ARCH_OPTION=32

wmake/rules/linuxArm64Gcc/c

@@ -0,0 +1,16 @@
+SUFFIXES += .c
+
+cWARN        = -Wall
+
+cc          = gcc
+
+include $(DEFAULT_RULES)/c$(WM_COMPILE_OPTION)
+
+cFLAGS      = $(GFLAGS) $(cWARN) $(cOPT) $(cDBUG) $(LIB_HEADER_DIRS) -fPIC
+
+ctoo        = $(WM_SCHEDULER) $(cc) $(cFLAGS) -c $< -o $@
+
+LINK_LIBS   = $(cDBUG)
+
+LINKLIBSO   = $(cc) -fuse-ld=bfd -shared
+LINKEXE     = $(cc) -fuse-ld=bfd -Xlinker --add-needed -Xlinker -z -Xlinker nodefs

wmake/rules/linuxArm64Gcc/c++

@@ -0,0 +1,25 @@
+SUFFIXES += .C
+
+c++WARN     = -Wall -Wextra -Wold-style-cast -Wnon-virtual-dtor -Wno-unused-parameter \
+              -Wno-invalid-offsetof -Wno-attributes
+
+# Suppress some warnings for flex++ and CGAL
+c++LESSWARN = -Wno-old-style-cast -Wno-unused-local-typedefs -Wno-array-bounds
+
+CC          = g++ -std=c++11
+
+include $(DEFAULT_RULES)/c++$(WM_COMPILE_OPTION)
+
+ptFLAGS     = -DNoRepository -ftemplate-depth-100
+
+c++FLAGS    = $(GFLAGS) $(c++WARN) $(c++OPT) $(c++DBUG) $(ptFLAGS) $(LIB_HEADER_DIRS) -fPIC
+
+Ctoo        = $(WM_SCHEDULER) $(CC) $(c++FLAGS) -c $< -o $@
+cxxtoo      = $(Ctoo)
+cctoo       = $(Ctoo)
+cpptoo      = $(Ctoo)
+
+LINK_LIBS   = $(c++DBUG)
+
+LINKLIBSO   = $(CC) $(c++FLAGS) -fuse-ld=bfd -shared -Xlinker --add-needed -Xlinker --no-as-needed
+LINKEXE     = $(CC) $(c++FLAGS) -fuse-ld=bfd -Xlinker --add-needed -Xlinker --no-as-needed

wmake/rules/linuxArm64Gcc/c++Debug

@@ -0,0 +1,2 @@
+c++DBUG    = -ggdb3 -DFULLDEBUG
+c++OPT      = -O0 -fdefault-inline

wmake/rules/linuxArm64Gcc/c++Opt

@@ -0,0 +1,4 @@
+c++DBUG     =
+c++OPT      = -O3 -mcpu=native
+
+ROUNDING_MATH = -frounding-math

wmake/rules/linuxArm64Gcc/c++Prof

@@ -0,0 +1,2 @@
+c++DBUG    = -pg
+c++OPT     = -O2

wmake/rules/linuxArm64Gcc/cDebug

@@ -0,0 +1,2 @@
+cDBUG       = -ggdb -DFULLDEBUG
+cOPT        = -O1 -fdefault-inline -finline-functions

wmake/rules/linuxArm64Gcc/cOpt

@@ -0,0 +1,2 @@
+cDBUG       =
+cOPT        = -O3

wmake/rules/linuxArm64Gcc/cProf

@@ -0,0 +1,2 @@
+cDBUG       = -pg
+cOPT        = -O2

wmake/rules/linuxArm64Gcc/general

@@ -0,0 +1,8 @@
+CPP        = cpp -traditional-cpp $(GFLAGS)
+
+PROJECT_LIBS = -l$(WM_PROJECT) -ldl
+
+include $(GENERAL_RULES)/standard
+
+include $(DEFAULT_RULES)/c
+include $(DEFAULT_RULES)/c++