Add newlib-nano as multilib

arm-software/embedded/CMakeLists.txt

@@ -170,7 +170,7 @@ set(LLVM_TOOLCHAIN_C_LIBRARY
     "Which C library to use."
 )
 set_property(CACHE LLVM_TOOLCHAIN_C_LIBRARY
-    PROPERTY STRINGS picolibc newlib llvmlibc)
+    PROPERTY STRINGS picolibc newlib newlib-nano llvmlibc)
 
 option(
     SHORT_BUILD_PATHS
@@ -286,7 +286,7 @@ include(ProcessorCount)
 if(LLVM_TOOLCHAIN_C_LIBRARY STREQUAL picolibc)
     include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/fetch_picolibc.cmake)
 endif()
-if(LLVM_TOOLCHAIN_C_LIBRARY STREQUAL newlib)
+if(LLVM_TOOLCHAIN_C_LIBRARY MATCHES "^newlib")
     include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/fetch_newlib.cmake)
 endif()
 
@@ -309,18 +309,18 @@ if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
 endif()
 ##################################################################################################
 
-if(LLVM_TOOLCHAIN_C_LIBRARY STREQUAL newlib)
+if(LLVM_TOOLCHAIN_C_LIBRARY MATCHES "^newlib")
     install(
         FILES
-        ${CMAKE_CURRENT_SOURCE_DIR}/newlib.cfg
+        ${CMAKE_CURRENT_SOURCE_DIR}/${LLVM_TOOLCHAIN_C_LIBRARY}.cfg
         DESTINATION bin
-        COMPONENT llvm-toolchain-newlib-configs
+        COMPONENT llvm-toolchain-${LLVM_TOOLCHAIN_C_LIBRARY}-configs
     )
     install(
         DIRECTORY
         ${CMAKE_CURRENT_SOURCE_DIR}/newlib-samples/
         DESTINATION samples
-        COMPONENT llvm-toolchain-newlib-configs
+        COMPONENT llvm-toolchain-${LLVM_TOOLCHAIN_C_LIBRARY}-configs
     )
 endif()
 
@@ -731,7 +731,7 @@ if(LLVM_TOOLCHAIN_C_LIBRARY STREQUAL picolibc)
         ${picolibc_SOURCE_DIR}/COPYING.picolibc         COPYING.picolibc
     )
 endif()
-if(LLVM_TOOLCHAIN_C_LIBRARY STREQUAL newlib)
+if(LLVM_TOOLCHAIN_C_LIBRARY MATCHES "^newlib")
     list(APPEND third_party_license_files
         ${newlib_SOURCE_DIR}/COPYING.NEWLIB             COPYING.NEWLIB
         ${newlib_SOURCE_DIR}/COPYING.LIBGLOSS           COPYING.LIBGLOSS

arm-software/embedded/README.md

@@ -7,7 +7,7 @@ bare-metal LLVM based toolchain targeting Arm based on:
 * libc++abi
 * libc++
 * compiler-rt
-* picolibc, or optionally newlib or LLVM's libc
+* picolibc, or optionally newlib(-nano) or LLVM's libc
 
 ## Goal
 
@@ -191,7 +191,7 @@ relying on the Arm GNU Toolchain.
 > *Note:* `picolibc` provides excellent
 > [support for Arm GNU Toolchain](https://github.com/picolibc/picolibc/blob/main/doc/using.md),
 > so projects that require using both Arm GNU Toolchain and Arm Toolchain for Embedded
-> can choose either `picolibc` or `newlib`.
+> can choose either `picolibc` or `newlib`/`newlib-nano`.
 
 ## Building from source
 

arm-software/embedded/arm-multilib/CMakeLists.txt

@@ -23,7 +23,7 @@ set(llvmproject_src_dir ${TOOLCHAIN_SOURCE_DIR}/../..)
 set(MULTILIB_JSON "" CACHE STRING "JSON file to load library definitions from.")
 set(ENABLE_VARIANTS "all" CACHE STRING "Semicolon separated list of variants to build, or \"all\". Must match entries in the json.")
 set(C_LIBRARY "picolibc" CACHE STRING "Which C library to use.")
-set_property(CACHE C_LIBRARY PROPERTY STRINGS picolibc newlib llvmlibc)
+set_property(CACHE C_LIBRARY PROPERTY STRINGS picolibc newlib newlib-nano llvmlibc)
 set(PROJECT_PREFIX "${CMAKE_BINARY_DIR}/lib-builds" CACHE STRING "Directory to build subprojects in.")
 option(
     NUMERICAL_BUILD_NAMES
@@ -95,7 +95,7 @@ include(ExternalProject)
 if(C_LIBRARY STREQUAL picolibc)
     include(${TOOLCHAIN_SOURCE_DIR}/cmake/fetch_picolibc.cmake)
     list(APPEND passthrough_dirs "-DFETCHCONTENT_SOURCE_DIR_PICOLIBC=${FETCHCONTENT_SOURCE_DIR_PICOLIBC}")
-elseif(C_LIBRARY STREQUAL newlib)
+elseif(C_LIBRARY MATCHES "^newlib")
     include(${TOOLCHAIN_SOURCE_DIR}/cmake/fetch_newlib.cmake)
     list(APPEND passthrough_dirs "-DFETCHCONTENT_SOURCE_DIR_NEWLIB=${FETCHCONTENT_SOURCE_DIR_NEWLIB}")
 endif()

arm-software/embedded/arm-runtimes/CMakeLists.txt

@@ -21,7 +21,7 @@ set(llvmproject_src_dir ${TOOLCHAIN_SOURCE_DIR}/../..)
 # CMake arguments are loaded from the JSON file depending on which C
 # library is used, so this must be set before the JSON is processed.
 set(C_LIBRARY "picolibc" CACHE STRING "Which C library to use.")
-set_property(CACHE C_LIBRARY PROPERTY STRINGS picolibc newlib llvmlibc)
+set_property(CACHE C_LIBRARY PROPERTY STRINGS picolibc newlib newlib-nano llvmlibc)
 
 set(VARIANT_JSON "" CACHE STRING "JSON file to load args from.")
 if(VARIANT_JSON)
@@ -37,7 +37,12 @@ if(VARIANT_JSON)
         set(${json_param}_def ${json_val})
     endforeach()
     # Load arguments specific to the chosen library, overwriting any existing values.
-    string(JSON json_args GET ${variant_json_read} "args" ${C_LIBRARY})
+    if(C_LIBRARY MATCHES "^newlib")
+        # Treat newlib variants as newlib for library compatibility
+        string(JSON json_args GET ${variant_json_read} "args" "newlib")
+    else()
+        string(JSON json_args GET ${variant_json_read} "args" ${C_LIBRARY})
+    endif()
     string(JSON json_args_len LENGTH ${json_args})
     math(EXPR json_args_len_dec "${json_args_len} - 1")
     foreach(json_idx RANGE ${json_args_len_dec})
@@ -85,7 +90,7 @@ set(PICOLIBC_BUILD_TYPE ${PICOLIBC_BUILD_TYPE_def} CACHE STRING "Picolibc config
 set_property(CACHE PICOLIBC_BUILD_TYPE PROPERTY STRINGS minsize release)
 
 set(ENABLE_CXX_LIBS ${ENABLE_CXX_LIBS_def} CACHE BOOL "Build CXX libs")
-set(ENABLE_LIBC_TESTS ${ENABLE_LIBC_TESTS_def} CACHE BOOL "Enable libc tests (picolibc, newlib or llvm-libc).")
+set(ENABLE_LIBC_TESTS ${ENABLE_LIBC_TESTS_def} CACHE BOOL "Enable libc tests (picolibc, newlib, newlib-nano or llvm-libc).")
 set(ENABLE_COMPILER_RT_TESTS ${ENABLE_COMPILER_RT_TESTS_def} CACHE BOOL "Enable compiler-rt tests.")
 set(ENABLE_LIBCXX_TESTS ${ENABLE_LIBCXX_TESTS_def} CACHE BOOL "Enable libcxx tests.")
 set(LLVM_BINARY_DIR "" CACHE PATH "Path to LLVM toolchain root to build libraries with")
@@ -459,11 +464,44 @@ endif()
 # newlib
 ###############################################################################
 
-if(C_LIBRARY STREQUAL newlib)
+if(C_LIBRARY MATCHES "^newlib")
     if(ENABLE_LIBC_TESTS)
         message(FATAL_ERROR "Tests cannot yet be enabled using newlib libc.")
     endif()
 
+    if(C_LIBRARY STREQUAL newlib-nano)
+        # Taken from https://gitlab.arm.com/tooling/gnu-devtools-for-arm/-/blob/main/build-baremetal-toolchain.sh#L582
+        set(newlib_flags
+            --disable-newlib-supplied-syscalls
+            --disable-nls
+            --enable-lite-exit
+            --disable-multilib
+            --enable-newlib-retargetable-locking
+            --enable-newlib-nano-malloc
+            --disable-newlib-unbuf-stream-opt
+            --enable-newlib-reent-small
+            --disable-newlib-fseek-optimization
+            --enable-newlib-nano-formatted-io
+            --disable-newlib-fvwrite-in-streamio
+            --disable-newlib-wide-orient
+            --enable-lite-exit
+            --enable-newlib-global-atexit)
+        set(newlib_optim_flags
+            "-g -Oz")
+    else()
+        set(newlib_flags
+            --enable-newlib-io-long-long
+            --enable-newlib-register-fini
+            --disable-newlib-supplied-syscalls
+            --enable-newlib-io-c99-formats
+            --disable-nls
+            --enable-lite-exit
+            --disable-multilib
+            --enable-newlib-retargetable-locking)
+        set(newlib_optim_flags
+            "-g -O2")
+    endif()
+
     include(${TOOLCHAIN_SOURCE_DIR}/cmake/fetch_newlib.cmake)
     set(build_env
         "CC_FOR_TARGET=${LLVM_BINARY_DIR}/bin/clang -target ${target_triple} -ffreestanding"
@@ -474,8 +512,8 @@ if(C_LIBRARY STREQUAL newlib)
         "RANLIB_FOR_TARGET=${LLVM_BINARY_DIR}/bin/llvm-ranlib"
         "READELF_FOR_TARGET=${LLVM_BINARY_DIR}/bin/llvm-readelf"
         "STRIP_FOR_TARGET=${LLVM_BINARY_DIR}/bin/llvm-strip"
-        "CFLAGS_FOR_TARGET=${flags} -Wno-error=implicit-function-declaration -D__USES_INITFINI__ -U_HAVE_INIT_FINI --sysroot ${TEMP_LIB_DIR}"
-        "CCASFLAGS=${flags} -Wno-error=implicit-function-declaration -D__USES_INITFINI__ -U_HAVE_INIT_FINI --sysroot ${TEMP_LIB_DIR}"
+        "CFLAGS_FOR_TARGET=${flags} ${newlib_optim_flags} ${lib_compile_flags} -Wno-error=implicit-function-declaration -D__USES_INITFINI__ -U_HAVE_INIT_FINI"
+        "CCASFLAGS=${flags} ${newlib_optim_flags} ${lib_compile_flags} -Wno-error=implicit-function-declaration -D__USES_INITFINI__ -U_HAVE_INIT_FINI"
     )
 
     include(ProcessorCount)
@@ -486,7 +524,7 @@ if(C_LIBRARY STREQUAL newlib)
     endif()
 
     ExternalProject_Add(
-        newlib
+        ${C_LIBRARY}
         STAMP_DIR ${PROJECT_PREFIX}/newlib/${VARIANT_BUILD_ID}/stamp
         BINARY_DIR ${PROJECT_PREFIX}/newlib/${VARIANT_BUILD_ID}/build
         DOWNLOAD_DIR ${PROJECT_PREFIX}/newlib/${VARIANT_BUILD_ID}/dl
@@ -499,14 +537,7 @@ if(C_LIBRARY STREQUAL newlib)
             --target=${target_triple}
             --prefix "${TEMP_LIB_DIR}"
             --exec_prefix <BINARY_DIR>/tmpinstall
-            --enable-newlib-io-long-long
-            --enable-newlib-register-fini
-            --disable-newlib-supplied-syscalls
-            --enable-newlib-io-c99-formats
-            --disable-nls
-            --enable-lite-exit
-            --disable-multilib
-            --enable-newlib-retargetable-locking
+            ${newlib_flags}
         BUILD_COMMAND
             ${CMAKE_COMMAND} -E env ${build_env}
             make ${make_flags}
@@ -690,7 +721,7 @@ if(ENABLE_CXX_LIBS)
                 -DLLVM_LIT_ARGS=${cxxlibs_lit_args}
             )
         endif()
-    elseif(C_LIBRARY STREQUAL newlib)
+    elseif(C_LIBRARY MATCHES "^newlib")
         set(cxxlibs_extra_cmake_options
             -DLIBCXXABI_ENABLE_THREADS=OFF
             -DLIBCXX_ENABLE_MONOTONIC_CLOCK=OFF
@@ -703,6 +734,9 @@ if(ENABLE_CXX_LIBS)
             -DLIBCXX_ENABLE_EXCEPTIONS=${ENABLE_EXCEPTIONS}
             -DLIBCXX_ENABLE_RTTI=${ENABLE_RTTI}
         )
+        if(C_LIBRARY STREQUAL newlib-nano)
+            set(lib_compile_flags "${lib_compile_flags} -g -Oz")
+        endif()
     endif()
 
     ExternalProject_Add(

arm-software/embedded/cmake/generate_version_txt.cmake

@@ -18,8 +18,14 @@ if(NOT ${armtoolchain_COMMIT} MATCHES "^[a-f0-9]+$")
 endif()
 
 if(NOT (LLVM_TOOLCHAIN_C_LIBRARY STREQUAL llvmlibc)) # libc in a separate repo?
+    if(LLVM_TOOLCHAIN_C_LIBRARY MATCHES "^newlib")
+        set(base_library newlib)
+    else()
+        set(base_library $(LLVM_TOOLCHAIN_C_LIBRARY))
+    endif()
+
     execute_process(
-        COMMAND git -C ${${LLVM_TOOLCHAIN_C_LIBRARY}_SOURCE_DIR} rev-parse HEAD
+        COMMAND git -C ${${base_library}_SOURCE_DIR} rev-parse HEAD
         OUTPUT_VARIABLE ${LLVM_TOOLCHAIN_C_LIBRARY}_COMMIT
         OUTPUT_STRIP_TRAILING_WHITESPACE 
         COMMAND_ERROR_IS_FATAL ANY

arm-software/embedded/docs/migrating.md

@@ -37,7 +37,7 @@ Armv8-M or later architecture, including the
 |Binutils​|`objdump`, `readelf`, ...|`llvm-objdump`, `llvm-readelf`, ...|
 |Compiler runtime library​|`libgcc​`|`compiler-rt`​|
 |Unwinder​|`libgcc`​|`libunwind`​|
-|C standard library​|`newlib`, `newlib-nano`|`picolibc`|​
+|C standard library​|`newlib`, `newlib-nano`|`picolibc` (or `newlib`/`newlib-nano` as overlay)|​
 |C++ ABI library​|`libsupc++.a`|`libc++abi`​|​
 |C++ standard library​|`libstdc++​`|`libc++`​|
 
@@ -90,7 +90,7 @@ however uses different command line options to control selection of semihosting.
 |--------|-----------|------------|
 |No semihosting|`--specs=nosys.specs`|
 |Semihosting|`--specs=rdimon.specs`|`-nostartfiles -lcrt0-semihost -lsemihost`|
-|Newlib-nano|`--specs=nano.specs`|Not available: `picolibc` is an equivalent of `newlib-nano`.
+|Newlib-nano|`--specs=nano.specs`|`--config=newlib-nano.cfg` (with [`newlib-nano` overlay](./newlib.md) installed)|
 
 ## Linker
 

arm-software/embedded/docs/newlib.md

@@ -46,4 +46,10 @@ overlay package.
 
 Note that the `-DLLVM_TOOLCHAIN_LIBRARY_OVERLAY_INSTALL=on` option
 only generates the `newlib` package, but does not install it as part
-of the `install` CMake target.
+of the `install` CMake target.
+
+## About `newlib-nano`
+`newlib-nano` is provided as a separate package, and is meant to be equal
+to using GCC with `--specs=nano.specs`. In order to use the nano version
+of newlib, where the documentation in this file refers to `newlib`, replace
+it with `newlib-nano`.

arm-software/embedded/newlib-nano.cfg

@@ -0,0 +1 @@
+--sysroot <CFGDIR>/../lib/clang-runtimes/newlib-nano