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https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
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c2bd08ba20
In Makefiles, $(error ), $(warning ), and $(info ) expand to the empty string, as explained in the GNU Make manual [1]: "The result of the expansion of this function is the empty string." Therefore, they are no-op except for logging purposes. $(shell ...) expands to the output of the command. It expands to the empty string when the command does not print anything to stdout. Hence, $(shell mkdir ...) is no-op except for creating the directory. Remove meaningless assignments. [1]: https://www.gnu.org/software/make/manual/make.html#Make-Control-Functions Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com> Reviewed-by: Ian Rogers <irogers@google.com> Link: https://lore.kernel.org/r/20240221134201.2656908-1-masahiroy@kernel.org Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-perf-users@vger.kernel.org
192 lines
6.1 KiB
Makefile
192 lines
6.1 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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ifneq ($(O),)
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ifeq ($(origin O), command line)
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$(if $(shell cd $(PWD); test -d $(O) || echo $(O)),$(error O=$(O) does not exist),)
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ABSOLUTE_O := $(shell cd $(PWD); cd $(O) ; pwd)
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OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/)
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COMMAND_O := O=$(ABSOLUTE_O)
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ifeq ($(objtree),)
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objtree := $(O)
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endif
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endif
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endif
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# check that the output directory actually exists
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ifneq ($(OUTPUT),)
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OUTDIR := $(shell cd $(OUTPUT) && pwd)
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$(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
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endif
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#
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# Include saner warnings here, which can catch bugs:
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#
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EXTRA_WARNINGS := -Wbad-function-cast
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EXTRA_WARNINGS += -Wdeclaration-after-statement
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EXTRA_WARNINGS += -Wformat-security
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EXTRA_WARNINGS += -Wformat-y2k
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EXTRA_WARNINGS += -Winit-self
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EXTRA_WARNINGS += -Wmissing-declarations
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EXTRA_WARNINGS += -Wmissing-prototypes
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EXTRA_WARNINGS += -Wnested-externs
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EXTRA_WARNINGS += -Wno-system-headers
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EXTRA_WARNINGS += -Wold-style-definition
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EXTRA_WARNINGS += -Wpacked
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EXTRA_WARNINGS += -Wredundant-decls
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EXTRA_WARNINGS += -Wstrict-prototypes
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EXTRA_WARNINGS += -Wswitch-default
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EXTRA_WARNINGS += -Wswitch-enum
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EXTRA_WARNINGS += -Wundef
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EXTRA_WARNINGS += -Wwrite-strings
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EXTRA_WARNINGS += -Wformat
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EXTRA_WARNINGS += -Wno-type-limits
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# Makefiles suck: This macro sets a default value of $(2) for the
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# variable named by $(1), unless the variable has been set by
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# environment or command line. This is necessary for CC and AR
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# because make sets default values, so the simpler ?= approach
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# won't work as expected.
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define allow-override
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$(if $(or $(findstring environment,$(origin $(1))),\
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$(findstring command line,$(origin $(1)))),,\
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$(eval $(1) = $(2)))
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endef
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ifneq ($(LLVM),)
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ifneq ($(filter %/,$(LLVM)),)
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LLVM_PREFIX := $(LLVM)
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else ifneq ($(filter -%,$(LLVM)),)
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LLVM_SUFFIX := $(LLVM)
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endif
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$(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
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$(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
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$(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
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$(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX))
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$(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
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else
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# Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
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$(call allow-override,CC,$(CROSS_COMPILE)gcc)
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$(call allow-override,AR,$(CROSS_COMPILE)ar)
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$(call allow-override,LD,$(CROSS_COMPILE)ld)
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$(call allow-override,CXX,$(CROSS_COMPILE)g++)
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$(call allow-override,STRIP,$(CROSS_COMPILE)strip)
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endif
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CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
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ifneq ($(LLVM),)
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HOSTAR ?= $(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)
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HOSTCC ?= $(LLVM_PREFIX)clang$(LLVM_SUFFIX)
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HOSTLD ?= $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)
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else
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HOSTAR ?= ar
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HOSTCC ?= gcc
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HOSTLD ?= ld
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endif
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# Some tools require Clang, LLC and/or LLVM utils
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CLANG ?= clang
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LLC ?= llc
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LLVM_CONFIG ?= llvm-config
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LLVM_OBJCOPY ?= llvm-objcopy
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LLVM_STRIP ?= llvm-strip
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ifeq ($(CC_NO_CLANG), 1)
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EXTRA_WARNINGS += -Wstrict-aliasing=3
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else ifneq ($(CROSS_COMPILE),)
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# Allow userspace to override CLANG_CROSS_FLAGS to specify their own
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# sysroots and flags or to avoid the GCC call in pure Clang builds.
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ifeq ($(CLANG_CROSS_FLAGS),)
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CLANG_CROSS_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%))
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GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc 2>/dev/null))
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ifneq ($(GCC_TOOLCHAIN_DIR),)
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CLANG_CROSS_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
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CLANG_CROSS_FLAGS += --sysroot=$(shell $(CROSS_COMPILE)gcc -print-sysroot)
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CLANG_CROSS_FLAGS += --gcc-toolchain=$(realpath $(GCC_TOOLCHAIN_DIR)/..)
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endif # GCC_TOOLCHAIN_DIR
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endif # CLANG_CROSS_FLAGS
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CFLAGS += $(CLANG_CROSS_FLAGS)
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AFLAGS += $(CLANG_CROSS_FLAGS)
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else
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CLANG_CROSS_FLAGS :=
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endif # CROSS_COMPILE
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# Hack to avoid type-punned warnings on old systems such as RHEL5:
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# We should be changing CFLAGS and checking gcc version, but this
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# will do for now and keep the above -Wstrict-aliasing=3 in place
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# in newer systems.
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# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h
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#
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# See https://lore.kernel.org/lkml/9a8748490611281710g78402fbeh8ff7fcc162dbcbca@mail.gmail.com/
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# and https://gcc.gnu.org/gcc-4.8/changes.html,
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# that takes into account Linus's comments (search for Wshadow) for the reasoning about
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# -Wshadow not being interesting before gcc 4.8.
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ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3
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EXTRA_WARNINGS += -fno-strict-aliasing
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EXTRA_WARNINGS += -Wno-shadow
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else
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EXTRA_WARNINGS += -Wshadow
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endif
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ifneq ($(findstring $(MAKEFLAGS), w),w)
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PRINT_DIR = --no-print-directory
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else
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NO_SUBDIR = :
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endif
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# If the user is running make -s (silent mode), suppress echoing of commands
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# make-4.0 (and later) keep single letter options in the 1st word of MAKEFLAGS.
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ifeq ($(filter 3.%,$(MAKE_VERSION)),)
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short-opts := $(firstword -$(MAKEFLAGS))
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else
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short-opts := $(filter-out --%,$(MAKEFLAGS))
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endif
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ifneq ($(findstring s,$(short-opts)),)
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silent=1
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endif
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#
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# Define a callable command for descending to a new directory
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#
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# Call by doing: $(call descend,directory[,target])
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#
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descend = \
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+mkdir -p $(OUTPUT)$(1) && \
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$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
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QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir
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QUIET_SUBDIR1 =
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ifneq ($(silent),1)
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ifneq ($(V),1)
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QUIET_CC = @echo ' CC '$@;
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QUIET_CC_FPIC = @echo ' CC FPIC '$@;
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QUIET_CLANG = @echo ' CLANG '$@;
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QUIET_AR = @echo ' AR '$@;
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QUIET_LINK = @echo ' LINK '$@;
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QUIET_MKDIR = @echo ' MKDIR '$@;
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QUIET_GEN = @echo ' GEN '$@;
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QUIET_SUBDIR0 = +@subdir=
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QUIET_SUBDIR1 = ;$(NO_SUBDIR) \
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echo ' SUBDIR '$$subdir; \
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$(MAKE) $(PRINT_DIR) -C $$subdir
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QUIET_FLEX = @echo ' FLEX '$@;
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QUIET_BISON = @echo ' BISON '$@;
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QUIET_GENSKEL = @echo ' GENSKEL '$@;
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descend = \
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+@echo ' DESCEND '$(1); \
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mkdir -p $(OUTPUT)$(1) && \
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$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
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QUIET_CLEAN = @printf ' CLEAN %s\n' $1;
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QUIET_INSTALL = @printf ' INSTALL %s\n' $1;
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QUIET_UNINST = @printf ' UNINST %s\n' $1;
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endif
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endif
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pound := \#
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