toolchains: combine host variants

nashif · keith-packard · commit 6d52c9201ded · 2025-07-11T12:18:13.000-07:00
Combine toolchains provided by the host into one variant. This includes
both gcc and llvm installationt typically coming from the distribution
(on Linux).

Both gcc and llvm are now part of the 'host' variant, the default is the
gnu compiler, so setting

	ZEPHYR_TOOLCHAIN_VARIANT=host

Will select the gnu compiler. To select llvm or any other compuler
provided in this variant, use the follwoing format:

	ZEPHYR_TOOLCHAIN_VARIANT=&lt;variant&gt;/&lt;compiler&gt;

The following will select llvm:

	ZEPHYR_TOOLCHAIN_VARIANT=host/llvm

Although gnu is the default, it can also be selected using the above
syntax:

	ZEPHYR_TOOLCHAIN_VARIANT=host/gcc

This commit removes the llvm variant for now, it should be deperecated
in another commit to follow.

Signed-off-by: Anas Nashif &lt;anas.nashif@intel.com&gt;
diff --git a/Kconfig.zephyr b/Kconfig.zephyr
@@ -491,7 +491,7 @@ choice COMPILER_OPTIMIZATIONS
 	prompt "Optimization level"
 	default NO_OPTIMIZATIONS    if COVERAGE
 	default DEBUG_OPTIMIZATIONS if DEBUG
-	default SIZE_OPTIMIZATIONS_AGGRESSIVE if "$(ZEPHYR_TOOLCHAIN_VARIANT)" = "llvm"
+	default SIZE_OPTIMIZATIONS_AGGRESSIVE if "$(TOOLCHAIN_VARIANT_COMPILER)" = "llvm"
 	default SIZE_OPTIMIZATIONS
 	help
 	  Note that these flags shall only control the compiler
diff --git a/cmake/modules/FindHostTools.cmake b/cmake/modules/FindHostTools.cmake
@@ -73,7 +73,7 @@ endif()
 # Default to the host system's toolchain if we are targeting a host based target
 if((${BOARD_DIR} MATCHES "boards\/native") OR ("${ARCH}" STREQUAL "posix")
    OR ("${BOARD}" STREQUAL "unit_testing"))
-  if(NOT "${ZEPHYR_TOOLCHAIN_VARIANT}" STREQUAL "llvm")
+  if(NOT "${ZEPHYR_TOOLCHAIN_VARIANT}" STREQUAL "host/llvm")
     set(ZEPHYR_TOOLCHAIN_VARIANT "host")
   endif()
 endif()
@@ -102,6 +102,16 @@ endif()
 set(TOOLCHAIN_ROOT ${TOOLCHAIN_ROOT} CACHE STRING "Zephyr toolchain root" FORCE)
 assert(TOOLCHAIN_ROOT "Zephyr toolchain root path invalid: please set the TOOLCHAIN_ROOT-variable")
 
+
+# Check if ZEPHYR_TOOLCHAIN_VARIANT follows "<variant_name>/<compiler>" pattern
+if("${ZEPHYR_TOOLCHAIN_VARIANT}" MATCHES "^([^/]+)/([^/]+)$")
+  set(_variant "${CMAKE_MATCH_1}")
+  set(_compiler "${CMAKE_MATCH_2}")
+  set(ZEPHYR_TOOLCHAIN_VARIANT "${_variant}")
+  set(TOOLCHAIN_VARIANT_COMPILER "${_compiler}")
+  set(TOOLCHAIN_VARIANT_COMPILER ${_compiler} CACHE STRING "compiler used by the toolchain variant" FORCE)
+endif()
+
 # Set cached ZEPHYR_TOOLCHAIN_VARIANT.
 set(ZEPHYR_TOOLCHAIN_VARIANT ${ZEPHYR_TOOLCHAIN_VARIANT} CACHE STRING "Zephyr toolchain variant")
 
diff --git a/cmake/modules/kconfig.cmake b/cmake/modules/kconfig.cmake
@@ -168,6 +168,7 @@ set(COMMON_KCONFIG_ENV_SETTINGS
   KCONFIG_BINARY_DIR=${KCONFIG_BINARY_DIR}
   APPLICATION_SOURCE_DIR=${APPLICATION_SOURCE_DIR}
   ZEPHYR_TOOLCHAIN_VARIANT=${ZEPHYR_TOOLCHAIN_VARIANT}
+  TOOLCHAIN_VARIANT_COMPILER=${TOOLCHAIN_VARIANT_COMPILER}
   TOOLCHAIN_KCONFIG_DIR=${TOOLCHAIN_KCONFIG_DIR}
   TOOLCHAIN_HAS_NEWLIB=${_local_TOOLCHAIN_HAS_NEWLIB}
   TOOLCHAIN_HAS_PICOLIBC=${_local_TOOLCHAIN_HAS_PICOLIBC}
diff --git a/cmake/toolchain/host/generic.cmake b/cmake/toolchain/host/generic.cmake
@@ -1,10 +1,19 @@
 # SPDX-License-Identifier: Apache-2.0
 
-set(COMPILER host-gcc)
-set(LINKER ld)
-set(BINTOOLS host-gnu)
+if(TOOLCHAIN_VARIANT_COMPILER STREQUAL "gnu" OR
+    NOT DEFINED TOOLCHAIN_VARIANT_COMPILER)
 
-set(TOOLCHAIN_HAS_NEWLIB OFF CACHE BOOL "True if toolchain supports newlib")
-set(TOOLCHAIN_HAS_GLIBCXX ON CACHE BOOL "True if toolchain supports libstdc++")
+  if (NOT DEFINED TOOLCHAIN_VARIANT_COMPILER)
+    set(TOOLCHAIN_VARIANT_COMPILER "gnu" CACHE STRING "compiler used by the toolchain variant" FORCE)
+  endif()
 
-message(STATUS "Found toolchain: host (gcc/ld)")
+  include(${ZEPHYR_BASE}/cmake/toolchain/host/gnu/generic.cmake)
+
+  set(TOOLCHAIN_KCONFIG_DIR ${ZEPHYR_BASE}/cmake/toolchain/host/gnu)
+  set(TOOLCHAIN_HAS_NEWLIB OFF CACHE BOOL "True if toolchain supports newlib")
+  set(TOOLCHAIN_HAS_GLIBCXX ON CACHE BOOL "True if toolchain supports libstdc++")
+elseif(TOOLCHAIN_VARIANT_COMPILER STREQUAL "llvm")
+
+  include(${ZEPHYR_BASE}/cmake/toolchain/host/llvm/generic.cmake)
+  set(TOOLCHAIN_KCONFIG_DIR ${ZEPHYR_BASE}/cmake/toolchain/host/llvm)
+endif()
diff --git a/cmake/toolchain/host/gnu/Kconfig b/cmake/toolchain/host/gnu/Kconfig
@@ -1,4 +1,4 @@
-# Copyright (c) 2024 Basalte bv
+# Copyright The Zephyr Project Contributors
 # SPDX-License-Identifier: Apache-2.0
 
 config TOOLCHAIN_HOST_SUPPORTS_GNU_EXTENSIONS
diff --git a/cmake/toolchain/host/gnu/generic.cmake b/cmake/toolchain/host/gnu/generic.cmake
@@ -0,0 +1,9 @@
+
+set(TOOLCHAIN_VARIANT_COMPILER gcc CACHE STRING "Variant compiler being used")
+set(COMPILER host-gcc)
+set(LINKER ld)
+set(BINTOOLS host-gnu)
+
+set(TOOLCHAIN_HAS_NEWLIB OFF CACHE BOOL "True if toolchain supports newlib")
+
+message(STATUS "Found toolchain: host (gcc/ld)")
diff --git a/cmake/toolchain/host/gnu/target.cmake b/cmake/toolchain/host/gnu/target.cmake
@@ -0,0 +1 @@
+# SPDX-License-Identifier: Apache-2.0
diff --git a/cmake/toolchain/host/llvm/Kconfig b/cmake/toolchain/host/llvm/Kconfig
@@ -1,9 +1,9 @@
-# Copyright (c) 2023 Intel Corporation
+# Copyright The Zephyr Project Contributors
+# Copyright (c) 2024 Basalte bv
 # SPDX-License-Identifier: Apache-2.0
-
+#
 choice LLVM_LINKER
 	prompt "LLVM Linker"
-	depends on "${ZEPHYR_TOOLCHAIN_VARIANT}" = "llvm"
 	default LLVM_USE_LD
 
 config LLVM_USE_LD
diff --git a/cmake/toolchain/host/llvm/clang_compiler_rt.cfg b/cmake/toolchain/host/llvm/clang_compiler_rt.cfg
diff --git a/cmake/toolchain/host/llvm/clang_libgcc.cfg b/cmake/toolchain/host/llvm/clang_libgcc.cfg
diff --git a/cmake/toolchain/host/llvm/generic.cmake b/cmake/toolchain/host/llvm/generic.cmake
@@ -1,11 +1,7 @@
-# SPDX-License-Identifier: Apache-2.0
-
-# Purpose of the generic.cmake is to define a generic C compiler which can be
-# used for devicetree pre-processing and other pre-processing tasks which must
-# be performed before the target can be determined.
 
 # Todo: deprecate CLANG_ROOT_DIR
 set_ifndef(LLVM_TOOLCHAIN_PATH "$ENV{CLANG_ROOT_DIR}")
+set(TOOLCHAIN_VARIANT_COMPILER llvm CACHE STRING "Variant compiler being used")
 zephyr_get(LLVM_TOOLCHAIN_PATH)
 
 if(LLVM_TOOLCHAIN_PATH)
diff --git a/cmake/toolchain/host/llvm/target.cmake b/cmake/toolchain/host/llvm/target.cmake
@@ -55,5 +55,7 @@ elseif(CONFIG_COMPILER_RT_RTLIB)
   set(runtime_lib "compiler_rt")
 endif()
 
-list(APPEND TOOLCHAIN_C_FLAGS --config=${ZEPHYR_BASE}/cmake/toolchain/llvm/clang_${runtime_lib}.cfg)
-list(APPEND TOOLCHAIN_LD_FLAGS --config=${ZEPHYR_BASE}/cmake/toolchain/llvm/clang_${runtime_lib}.cfg)
+list(APPEND TOOLCHAIN_C_FLAGS --config
+  ${ZEPHYR_BASE}/cmake/toolchain/host/llvm/clang_${runtime_lib}.cfg)
+list(APPEND TOOLCHAIN_LD_FLAGS --config
+  ${ZEPHYR_BASE}/cmake/toolchain/host/llvm/clang_${runtime_lib}.cfg)
diff --git a/cmake/toolchain/host/target.cmake b/cmake/toolchain/host/target.cmake
@@ -1,3 +1,10 @@
 # SPDX-License-Identifier: Apache-2.0
 
-# This file intentionally left blank.
+if(TOOLCHAIN_VARIANT_COMPILER STREQUAL "gnu" OR
+   TOOLCHAIN_VARIANT_COMPILER STREQUAL "default")
+ include(${ZEPHYR_BASE}/cmake/toolchain/host/gnu/target.cmake)
+elseif (TOOLCHAIN_VARIANT_COMPILER STREQUAL "llvm")
+  include(${ZEPHYR_BASE}/cmake/toolchain/host/llvm/target.cmake)
+else()
+  message(FATAL_ERROR "Unsupported TOOLCHAIN_VARIANT_COMPILER: ${TOOLCHAIN_VARIANT_COMPILER}")
+endif()
diff --git a/cmake/verify-toolchain.cmake b/cmake/verify-toolchain.cmake
@@ -32,10 +32,12 @@ find_package(HostTools)
 if("${FORMAT}" STREQUAL "json")
   set(json "{\"ZEPHYR_TOOLCHAIN_VARIANT\" : \"${ZEPHYR_TOOLCHAIN_VARIANT}\", ")
   string(APPEND json "\"SDK_VERSION\": \"${SDK_VERSION}\", ")
+  string(APPEND json "\"TOOLCHAIN_VARIANT_COMPILER\": \"${TOOLCHAIN_VARIANT_COMPILER}\", ")
   string(APPEND json "\"ZEPHYR_SDK_INSTALL_DIR\" : \"${ZEPHYR_SDK_INSTALL_DIR}\"}")
   _message("${json}")
 else()
   message(STATUS "ZEPHYR_TOOLCHAIN_VARIANT: ${ZEPHYR_TOOLCHAIN_VARIANT}")
+  message(STATUS "TOOLCHAIN_VARIANT_COMPILER: ${TOOLCHAIN_VARIANT_COMPILER}")
   if(DEFINED SDK_VERSION)
     message(STATUS "SDK_VERSION: ${SDK_VERSION}")
   endif()
diff --git a/lib/cpp/Kconfig b/lib/cpp/Kconfig
@@ -95,8 +95,8 @@ config FULL_LIBCPP_SUPPORTED
 choice LIBCPP_IMPLEMENTATION
 	prompt "C++ Standard Library Implementation"
 	default EXTERNAL_LIBCPP if REQUIRES_FULL_LIBCPP && NATIVE_BUILD
-	default LIBCXX_LIBCPP if REQUIRES_FULL_LIBCPP && "$(TOOLCHAIN_HAS_LIBCXX)" = "y"
-	default GLIBCXX_LIBCPP if REQUIRES_FULL_LIBCPP && "$(TOOLCHAIN_HAS_GLIBCXX)" = "y"
+	default LIBCXX_LIBCPP if REQUIRES_FULL_LIBCPP && "$(TOOLCHAIN_HAS_LIBCXX)" = "y" && "$(TOOLCHAIN_VARIANT_COMPILER)" = "llvm"
+	default GLIBCXX_LIBCPP if REQUIRES_FULL_LIBCPP
 	default MINIMAL_LIBCPP
 
 config MINIMAL_LIBCPP
@@ -124,6 +124,7 @@ config LIBCXX_LIBCPP
 	depends on "$(TOOLCHAIN_HAS_LIBCXX)" = "y"
 	depends on !NATIVE_APPLICATION
 	depends on NEWLIB_LIBC || PICOLIBC
+	depends on "$(TOOLCHAIN_VARIANT_COMPILER)" = "llvm"
 	select FULL_LIBCPP_SUPPORTED
 	help
 	  Build with LLVM C++ Standard Library (libc++) provided by LLVM
diff --git a/lib/runtime/Kconfig b/lib/runtime/Kconfig
@@ -4,7 +4,7 @@
 config COMPILER_RT_SUPPORTED
 	bool
 	default y
-	depends on "${ZEPHYR_TOOLCHAIN_VARIANT}" = "llvm"
+	depends on "${TOOLCHAIN_VARIANT_COMPILER}" = "llvm"
 	help
 	  Selected when the compiler supports compiler-rt runtime library.
 
diff --git a/subsys/testsuite/Kconfig b/subsys/testsuite/Kconfig
@@ -56,7 +56,7 @@ config COVERAGE_NATIVE_GCOV
 config COVERAGE_NATIVE_SOURCE
 	bool "Host compiler source based code coverage"
 	depends on NATIVE_BUILD
-	depends on "${ZEPHYR_TOOLCHAIN_VARIANT}" = "llvm"
+	depends on "${TOOLCHAIN_VARIANT_COMPILER}" = "llvm"
 	help
 	  Build natively with the compiler source based coverage options.
 	  Today this is only supported with LLVM

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-# Copyright (c) 2024 Basalte bv`
	`1`	`+# Copyright The Zephyr Project Contributors`
`2`	`2`	`# SPDX-License-Identifier: Apache-2.0`
`3`	`3`
`4`	`4`	`config TOOLCHAIN_HOST_SUPPORTS_GNU_EXTENSIONS`