Currently, you need to manually run scripts/gen_compile_commands.py to create compile_commands.json. It parses all the .*.cmd files found under the specified directory. If you rebuild the kernel over again without 'make clean', .*.cmd files from older builds will create stale entries in compile_commands.json. This commit wires up the compile_commands.json rule to Makefile, and makes it parse only the .*.cmd files involved in the current build. Pass $(KBUILD_VMLINUX_OBJS), $(KBUILD_VMLINUX_LIBS), and modules.order to the script. The objects or archives linked to vmlinux are listed in $(KBUILD_VMLINUX_OBJS) or $(KBUILD_VMLINUX_LIBS). All the modules are listed in modules.order. You can create compile_commands.json from Make: $ make -j$(nproc) CC=clang compile_commands.json You can also build vmlinux, modules, and compile_commands.json all together in a single command: $ make -j$(nproc) CC=clang all compile_commands.json It works for M= builds as well. In this case, compile_commands.json is created in the top directory of the external module. This is convenient, but it has a drawback; the coverage of the compile_commands.json is reduced because only the objects linked to vmlinux or modules are handled. For example, the following C files are not included in the compile_commands.json: - Decompressor source files (arch/*/boot/) - VDSO source files - C files used to generate intermediates (e.g. kernel/bounds.c) - Standalone host programs I think it is fine for most developers because our main interest is the kernel-space code. If you want to cover all the compiled C files, please build the kernel, then run the script manually as you did before: $ make clean # if you want to remove stale .cmd files [optional] $ make -j$(nproc) CC=clang $ scripts/gen_compile_commands.py Here is a note for out-of-tree builds. 'make compile_commands.json' works with O= option, but please notice compile_commands.json is created in the object tree instead of the source tree. Some people may want to have compile_commands.json in the source tree because Clang Tools searches for it through all parent paths of the first input source file. However, you cannot do this for O= builds. Kbuild should never generate any build artifact in the source tree when O= is given because the source tree might be read-only. Any write attempt to the source tree is monitored and the violation may be reported. See the commit log of 8ef14c2c41d9. So, the only possible way is to create compile_commands.json in the object tree, then specify '-p <build-path>' when you use clang-check, clang-tidy, etc. Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> Acked-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> --- (no changes since v1) Makefile | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-) diff --git a/Makefile b/Makefile index 9cac6fde3479..65ed336a6de1 100644 --- a/Makefile +++ b/Makefile @@ -635,7 +635,7 @@ endif # in addition to whatever we do anyway. # Just "make" or "make all" shall build modules as well -ifneq ($(filter all modules nsdeps,$(MAKECMDGOALS)),) +ifneq ($(filter all modules nsdeps %compile_commands.json,$(MAKECMDGOALS)),) KBUILD_MODULES := 1 endif @@ -1464,7 +1464,8 @@ endif # CONFIG_MODULES # Directories & files removed with 'make clean' CLEAN_FILES += include/ksym vmlinux.symvers \ - modules.builtin modules.builtin.modinfo modules.nsdeps + modules.builtin modules.builtin.modinfo modules.nsdeps \ + compile_commands.json # Directories & files removed with 'make mrproper' MRPROPER_FILES += include/config include/generated \ @@ -1698,9 +1699,12 @@ KBUILD_MODULES := 1 build-dirs := $(KBUILD_EXTMOD) PHONY += modules -modules: descend +modules: $(MODORDER) $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost +$(MODORDER): descend + @: + PHONY += modules_install modules_install: _emodinst_ _emodinst_post @@ -1714,8 +1718,12 @@ PHONY += _emodinst_post _emodinst_post: _emodinst_ $(call cmd,depmod) +compile_commands.json: $(extmod-prefix)compile_commands.json +PHONY += compile_commands.json + clean-dirs := $(KBUILD_EXTMOD) -clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps +clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps \ + $(KBUILD_EXTMOD)/compile_commands.json PHONY += help help: @@ -1828,6 +1836,19 @@ nsdeps: export KBUILD_NSDEPS=1 nsdeps: modules $(Q)$(CONFIG_SHELL) $(srctree)/scripts/nsdeps +# Clang Tooling +# --------------------------------------------------------------------------- + +quiet_cmd_gen_compile_commands = GEN $@ + cmd_gen_compile_commands = $(PYTHON3) $< -a $(AR) -o $@ $(filter-out $<, $(real-prereqs)) + +$(extmod-prefix)compile_commands.json: scripts/gen_compile_commands.py \ + $(if $(KBUILD_EXTMOD),,$(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)) \ + $(if $(CONFIG_MODULES), $(MODORDER)) FORCE + $(call if_changed,gen_compile_commands) + +targets += $(extmod-prefix)compile_commands.json + # Scripts to check various things for consistency # --------------------------------------------------------------------------- -- 2.25.1
