armclang: support for armclang compiler and armlink linker

This is the initial support for the armclang compiler together with the
armlink linker.

Introduced in this commit:
- armclang compiler support
- armlink linker support
- armlink scatter file generator for scatter loading
- dual pass linker script generation

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

cmake/compiler/armclang/target.cmake

@@ -0,0 +1,79 @@
+# find the compilers for C, CPP, assembly
+find_program(CMAKE_C_COMPILER ${CROSS_COMPILE}armclang PATH ${TOOLCHAIN_HOME} NO_DEFAULT_PATH)
+find_program(CMAKE_CXX_COMPILER ${CROSS_COMPILE}armclang PATH ${TOOLCHAIN_HOME} NO_DEFAULT_PATH)
+find_program(CMAKE_ASM_COMPILER ${CROSS_COMPILE}armclang PATH ${TOOLCHAIN_HOME} NO_DEFAULT_PATH)
+
+# The CMAKE_REQUIRED_FLAGS variable is used by check_c_compiler_flag()
+# (and other commands which end up calling check_c_source_compiles())
+# to add additional compiler flags used during checking. These flags
+# are unused during "real" builds of Zephyr source files linked into
+# the final executable.
+#
+include(${ZEPHYR_BASE}/cmake/gcc-m-cpu.cmake)
+set(CMAKE_SYSTEM_PROCESSOR ${GCC_M_CPU})
+
+list(APPEND TOOLCHAIN_C_FLAGS
+  -fshort-enums
+  )
+
+if(CONFIG_ARM64)
+  list(APPEND TOOLCHAIN_C_FLAGS   -mcpu=${GCC_M_CPU})
+
+  list(APPEND TOOLCHAIN_C_FLAGS   -mabi=lp64)
+  list(APPEND TOOLCHAIN_LD_FLAGS  -mabi=lp64)
+else()
+  list(APPEND TOOLCHAIN_C_FLAGS   -mcpu=${GCC_M_CPU})
+
+  if(CONFIG_COMPILER_ISA_THUMB2)
+    list(APPEND TOOLCHAIN_C_FLAGS   -mthumb)
+  endif()
+
+  list(APPEND TOOLCHAIN_C_FLAGS -mabi=aapcs)
+
+  # Defines a mapping from GCC_M_CPU to FPU
+
+  if(CONFIG_CPU_HAS_FPU_DOUBLE_PRECISION)
+    set(PRECISION_TOKEN)
+  else()
+    set(PRECISION_TOKEN sp-)
+  endif()
+
+  set(FPU_FOR_cortex-m4      fpv4-${PRECISION_TOKEN}d16)
+  set(FPU_FOR_cortex-m7      fpv5-${PRECISION_TOKEN}d16)
+  set(FPU_FOR_cortex-m33     fpv5-${PRECISION_TOKEN}d16)
+
+  if(CONFIG_FPU)
+    list(APPEND TOOLCHAIN_C_FLAGS   -mfpu=${FPU_FOR_${GCC_M_CPU}})
+    if    (CONFIG_FP_SOFTABI)
+      list(APPEND TOOLCHAIN_C_FLAGS   -mfloat-abi=softfp)
+    elseif(CONFIG_FP_HARDABI)
+      list(APPEND TOOLCHAIN_C_FLAGS   -mfloat-abi=hard)
+    endif()
+  endif()
+endif()
+
+foreach(file_name include/stddef.h)
+  execute_process(
+    COMMAND ${CMAKE_C_COMPILER} --print-file-name=${file_name}
+    OUTPUT_VARIABLE _OUTPUT
+    )
+  get_filename_component(_OUTPUT "${_OUTPUT}" DIRECTORY)
+  string(REGEX REPLACE "\n" "" _OUTPUT ${_OUTPUT})
+
+  list(APPEND NOSTDINC ${_OUTPUT})
+endforeach()
+
+foreach(isystem_include_dir ${NOSTDINC})
+  list(APPEND isystem_include_flags -isystem ${isystem_include_dir})
+endforeach()
+
+set(CMAKE_REQUIRED_FLAGS -nostartfiles -nostdlib ${isystem_include_flags})
+string(REPLACE ";" " " CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
+
+# Load toolchain_cc-family macros
+
+macro(toolchain_cc_nostdinc)
+  if(NOT "${ARCH}" STREQUAL "posix")
+    zephyr_compile_options( -nostdinc)
+  endif()
+endmacro()