mirror of
https://github.com/torvalds/linux
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09bd7c75e5
One of the most remarkable improvements in this cycle is, Kbuild is
now able to cache the result of shell commands. Some variables are
expensive to compute, for example, $(call cc-option,...) invokes the
compiler. It is not efficient to redo this computation every time,
even when we are not actually building anything. Kbuild creates a
hidden file ".cache.mk" that contains invoked shell commands and
their results. The speed-up should be noticeable.
Summary:
- Fix arch build issues (hexagon, sh)
- Clean up various Makefiles and scripts
- Fix wrong usage of {CFLAGS,LDFLAGS}_MODULE in arch Makefiles
- Cache variables that are expensive to compute
- Improve cc-ldopton and ld-option for Clang
- Optimize output directory creation
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Merge tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
"One of the most remarkable improvements in this cycle is, Kbuild is
now able to cache the result of shell commands. Some variables are
expensive to compute, for example, $(call cc-option,...) invokes the
compiler. It is not efficient to redo this computation every time,
even when we are not actually building anything. Kbuild creates a
hidden file ".cache.mk" that contains invoked shell commands and their
results. The speed-up should be noticeable.
Summary:
- Fix arch build issues (hexagon, sh)
- Clean up various Makefiles and scripts
- Fix wrong usage of {CFLAGS,LDFLAGS}_MODULE in arch Makefiles
- Cache variables that are expensive to compute
- Improve cc-ldopton and ld-option for Clang
- Optimize output directory creation"
* tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits)
kbuild: move coccicheck help from scripts/Makefile.help to top Makefile
sh: decompressor: add shipped files to .gitignore
frv: .gitignore: ignore vmlinux.lds
selinux: remove unnecessary assignment to subdir-
kbuild: specify FORCE in Makefile.headersinst as .PHONY target
kbuild: remove redundant mkdir from ./Kbuild
kbuild: optimize object directory creation for incremental build
kbuild: create object directories simpler and faster
kbuild: filter-out PHONY targets from "targets"
kbuild: remove redundant $(wildcard ...) for cmd_files calculation
kbuild: create directory for make cache only when necessary
sh: select KBUILD_DEFCONFIG depending on ARCH
kbuild: fix linker feature test macros when cross compiling with Clang
kbuild: shrink .cache.mk when it exceeds 1000 lines
kbuild: do not call cc-option before KBUILD_CFLAGS initialization
kbuild: Cache a few more calls to the compiler
kbuild: Add a cache for generated variables
kbuild: add forward declaration of default target to Makefile.asm-generic
kbuild: remove KBUILD_SUBDIR_ASFLAGS and KBUILD_SUBDIR_CCFLAGS
hexagon/kbuild: replace CFLAGS_MODULE with KBUILD_CFLAGS_MODULE
...
164 lines
6.2 KiB
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164 lines
6.2 KiB
Text
# SPDX-License-Identifier: GPL-2.0
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# ==========================================================================
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# Building binaries on the host system
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# Binaries are used during the compilation of the kernel, for example
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# to preprocess a data file.
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#
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# Both C and C++ are supported, but preferred language is C for such utilities.
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#
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# Sample syntax (see Documentation/kbuild/makefiles.txt for reference)
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# hostprogs-y := bin2hex
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# Will compile bin2hex.c and create an executable named bin2hex
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#
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# hostprogs-y := lxdialog
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# lxdialog-objs := checklist.o lxdialog.o
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# Will compile lxdialog.c and checklist.c, and then link the executable
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# lxdialog, based on checklist.o and lxdialog.o
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#
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# hostprogs-y := qconf
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# qconf-cxxobjs := qconf.o
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# qconf-objs := menu.o
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# Will compile qconf as a C++ program, and menu as a C program.
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# They are linked as C++ code to the executable qconf
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__hostprogs := $(sort $(hostprogs-y) $(hostprogs-m))
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host-cshlib := $(sort $(hostlibs-y) $(hostlibs-m))
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host-cxxshlib := $(sort $(hostcxxlibs-y) $(hostcxxlibs-m))
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# C code
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# Executables compiled from a single .c file
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host-csingle := $(foreach m,$(__hostprogs), \
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$(if $($(m)-objs)$($(m)-cxxobjs),,$(m)))
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# C executables linked based on several .o files
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host-cmulti := $(foreach m,$(__hostprogs),\
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$(if $($(m)-cxxobjs),,$(if $($(m)-objs),$(m))))
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# Object (.o) files compiled from .c files
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host-cobjs := $(sort $(foreach m,$(__hostprogs),$($(m)-objs)))
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# C++ code
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# C++ executables compiled from at least one .cc file
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# and zero or more .c files
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host-cxxmulti := $(foreach m,$(__hostprogs),$(if $($(m)-cxxobjs),$(m)))
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# C++ Object (.o) files compiled from .cc files
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host-cxxobjs := $(sort $(foreach m,$(host-cxxmulti),$($(m)-cxxobjs)))
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# Object (.o) files used by the shared libaries
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host-cshobjs := $(sort $(foreach m,$(host-cshlib),$($(m:.so=-objs))))
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host-cxxshobjs := $(sort $(foreach m,$(host-cxxshlib),$($(m:.so=-objs))))
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host-csingle := $(addprefix $(obj)/,$(host-csingle))
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host-cmulti := $(addprefix $(obj)/,$(host-cmulti))
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host-cobjs := $(addprefix $(obj)/,$(host-cobjs))
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host-cxxmulti := $(addprefix $(obj)/,$(host-cxxmulti))
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host-cxxobjs := $(addprefix $(obj)/,$(host-cxxobjs))
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host-cshlib := $(addprefix $(obj)/,$(host-cshlib))
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host-cxxshlib := $(addprefix $(obj)/,$(host-cxxshlib))
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host-cshobjs := $(addprefix $(obj)/,$(host-cshobjs))
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host-cxxshobjs := $(addprefix $(obj)/,$(host-cxxshobjs))
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#####
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# Handle options to gcc. Support building with separate output directory
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_hostc_flags = $(HOSTCFLAGS) $(HOST_EXTRACFLAGS) \
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$(HOSTCFLAGS_$(basetarget).o)
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_hostcxx_flags = $(HOSTCXXFLAGS) $(HOST_EXTRACXXFLAGS) \
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$(HOSTCXXFLAGS_$(basetarget).o)
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ifeq ($(KBUILD_SRC),)
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__hostc_flags = $(_hostc_flags)
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__hostcxx_flags = $(_hostcxx_flags)
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else
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__hostc_flags = -I$(obj) $(call flags,_hostc_flags)
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__hostcxx_flags = -I$(obj) $(call flags,_hostcxx_flags)
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endif
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hostc_flags = -Wp,-MD,$(depfile) $(__hostc_flags)
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hostcxx_flags = -Wp,-MD,$(depfile) $(__hostcxx_flags)
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#####
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# Compile programs on the host
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# Create executable from a single .c file
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# host-csingle -> Executable
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quiet_cmd_host-csingle = HOSTCC $@
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cmd_host-csingle = $(HOSTCC) $(hostc_flags) -o $@ $< \
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$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
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$(host-csingle): $(obj)/%: $(src)/%.c FORCE
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$(call if_changed_dep,host-csingle)
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# Link an executable based on list of .o files, all plain c
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# host-cmulti -> executable
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quiet_cmd_host-cmulti = HOSTLD $@
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cmd_host-cmulti = $(HOSTCC) $(HOSTLDFLAGS) -o $@ \
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$(addprefix $(obj)/,$($(@F)-objs)) \
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$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
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$(host-cmulti): FORCE
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$(call if_changed,host-cmulti)
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$(call multi_depend, $(host-cmulti), , -objs)
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# Create .o file from a single .c file
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# host-cobjs -> .o
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quiet_cmd_host-cobjs = HOSTCC $@
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cmd_host-cobjs = $(HOSTCC) $(hostc_flags) -c -o $@ $<
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$(host-cobjs): $(obj)/%.o: $(src)/%.c FORCE
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$(call if_changed_dep,host-cobjs)
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# Link an executable based on list of .o files, a mixture of .c and .cc
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# host-cxxmulti -> executable
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quiet_cmd_host-cxxmulti = HOSTLD $@
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cmd_host-cxxmulti = $(HOSTCXX) $(HOSTLDFLAGS) -o $@ \
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$(foreach o,objs cxxobjs,\
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$(addprefix $(obj)/,$($(@F)-$(o)))) \
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$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
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$(host-cxxmulti): FORCE
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$(call if_changed,host-cxxmulti)
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$(call multi_depend, $(host-cxxmulti), , -objs -cxxobjs)
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# Create .o file from a single .cc (C++) file
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quiet_cmd_host-cxxobjs = HOSTCXX $@
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cmd_host-cxxobjs = $(HOSTCXX) $(hostcxx_flags) -c -o $@ $<
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$(host-cxxobjs): $(obj)/%.o: $(src)/%.cc FORCE
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$(call if_changed_dep,host-cxxobjs)
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# Compile .c file, create position independent .o file
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# host-cshobjs -> .o
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quiet_cmd_host-cshobjs = HOSTCC -fPIC $@
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cmd_host-cshobjs = $(HOSTCC) $(hostc_flags) -fPIC -c -o $@ $<
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$(host-cshobjs): $(obj)/%.o: $(src)/%.c FORCE
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$(call if_changed_dep,host-cshobjs)
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# Compile .c file, create position independent .o file
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# Note that plugin capable gcc versions can be either C or C++ based
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# therefore plugin source files have to be compilable in both C and C++ mode.
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# This is why a C++ compiler is invoked on a .c file.
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# host-cxxshobjs -> .o
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quiet_cmd_host-cxxshobjs = HOSTCXX -fPIC $@
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cmd_host-cxxshobjs = $(HOSTCXX) $(hostcxx_flags) -fPIC -c -o $@ $<
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$(host-cxxshobjs): $(obj)/%.o: $(src)/%.c FORCE
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$(call if_changed_dep,host-cxxshobjs)
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# Link a shared library, based on position independent .o files
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# *.o -> .so shared library (host-cshlib)
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quiet_cmd_host-cshlib = HOSTLLD -shared $@
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cmd_host-cshlib = $(HOSTCC) $(HOSTLDFLAGS) -shared -o $@ \
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$(addprefix $(obj)/,$($(@F:.so=-objs))) \
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$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
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$(host-cshlib): FORCE
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$(call if_changed,host-cshlib)
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$(call multi_depend, $(host-cshlib), .so, -objs)
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# Link a shared library, based on position independent .o files
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# *.o -> .so shared library (host-cxxshlib)
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quiet_cmd_host-cxxshlib = HOSTLLD -shared $@
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cmd_host-cxxshlib = $(HOSTCXX) $(HOSTLDFLAGS) -shared -o $@ \
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$(addprefix $(obj)/,$($(@F:.so=-objs))) \
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$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
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$(host-cxxshlib): FORCE
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$(call if_changed,host-cxxshlib)
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$(call multi_depend, $(host-cxxshlib), .so, -objs)
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targets += $(host-csingle) $(host-cmulti) $(host-cobjs)\
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$(host-cxxmulti) $(host-cxxobjs) $(host-cshlib) $(host-cshobjs) $(host-cxxshlib) $(host-cxxshobjs)
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