1# SPDX-License-Identifier: GPL-2.0
  2ifneq ($(O),)
  3ifeq ($(origin O), command line)
  4	dummy := $(if $(shell cd $(PWD); test -d $(O) || echo $(O)),$(error O=$(O) does not exist),)
  5	ABSOLUTE_O := $(shell cd $(PWD); cd $(O) ; pwd)
  6	OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/)
  7	COMMAND_O := O=$(ABSOLUTE_O)
  8ifeq ($(objtree),)
  9	objtree := $(O)
 10endif
 11endif
 12endif
 13
 14# check that the output directory actually exists
 15ifneq ($(OUTPUT),)
 16OUTDIR := $(shell cd $(OUTPUT) && pwd)
 17$(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
 18endif
 19
 20#
 21# Include saner warnings here, which can catch bugs:
 22#
 23EXTRA_WARNINGS := -Wbad-function-cast
 24EXTRA_WARNINGS += -Wdeclaration-after-statement
 25EXTRA_WARNINGS += -Wformat-security
 26EXTRA_WARNINGS += -Wformat-y2k
 27EXTRA_WARNINGS += -Winit-self
 28EXTRA_WARNINGS += -Wmissing-declarations
 29EXTRA_WARNINGS += -Wmissing-prototypes
 30EXTRA_WARNINGS += -Wnested-externs
 31EXTRA_WARNINGS += -Wno-system-headers
 32EXTRA_WARNINGS += -Wold-style-definition
 33EXTRA_WARNINGS += -Wpacked
 34EXTRA_WARNINGS += -Wredundant-decls
 35EXTRA_WARNINGS += -Wstrict-prototypes
 36EXTRA_WARNINGS += -Wswitch-default
 37EXTRA_WARNINGS += -Wswitch-enum
 38EXTRA_WARNINGS += -Wundef
 39EXTRA_WARNINGS += -Wwrite-strings
 40EXTRA_WARNINGS += -Wformat
 41EXTRA_WARNINGS += -Wno-type-limits
 42
 43# Makefiles suck: This macro sets a default value of $(2) for the
 44# variable named by $(1), unless the variable has been set by
 45# environment or command line. This is necessary for CC and AR
 46# because make sets default values, so the simpler ?= approach
 47# won't work as expected.
 48define allow-override
 49  $(if $(or $(findstring environment,$(origin $(1))),\
 50            $(findstring command line,$(origin $(1)))),,\
 51    $(eval $(1) = $(2)))
 52endef
 53
 54ifneq ($(LLVM),)
 55$(call allow-override,CC,clang)
 56$(call allow-override,AR,llvm-ar)
 57$(call allow-override,LD,ld.lld)
 58$(call allow-override,CXX,clang++)
 59$(call allow-override,STRIP,llvm-strip)
 60else
 61# Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
 62$(call allow-override,CC,$(CROSS_COMPILE)gcc)
 63$(call allow-override,AR,$(CROSS_COMPILE)ar)
 64$(call allow-override,LD,$(CROSS_COMPILE)ld)
 65$(call allow-override,CXX,$(CROSS_COMPILE)g++)
 66$(call allow-override,STRIP,$(CROSS_COMPILE)strip)
 67endif
 68
 69CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
 70
 71ifneq ($(LLVM),)
 72HOSTAR  ?= llvm-ar
 73HOSTCC  ?= clang
 74HOSTLD  ?= ld.lld
 75else
 76HOSTAR  ?= ar
 77HOSTCC  ?= gcc
 78HOSTLD  ?= ld
 79endif
 80
 81# Some tools require Clang, LLC and/or LLVM utils
 82CLANG		?= clang
 83LLC		?= llc
 84LLVM_CONFIG	?= llvm-config
 85LLVM_OBJCOPY	?= llvm-objcopy
 86LLVM_STRIP	?= llvm-strip
 87
 88ifeq ($(CC_NO_CLANG), 1)
 89EXTRA_WARNINGS += -Wstrict-aliasing=3
 90endif
 91
 92# Hack to avoid type-punned warnings on old systems such as RHEL5:
 93# We should be changing CFLAGS and checking gcc version, but this
 94# will do for now and keep the above -Wstrict-aliasing=3 in place
 95# in newer systems.
 96# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h
 97#
 98# See https://lore.kernel.org/lkml/9a8748490611281710g78402fbeh8ff7fcc162dbcbca@mail.gmail.com/
 99# and https://gcc.gnu.org/gcc-4.8/changes.html,
100# that takes into account Linus's comments (search for Wshadow) for the reasoning about
101# -Wshadow not being interesting before gcc 4.8.
102
103ifneq ($(filter 3.%,$(MAKE_VERSION)),)  # make-3
104EXTRA_WARNINGS += -fno-strict-aliasing
105EXTRA_WARNINGS += -Wno-shadow
106else
107EXTRA_WARNINGS += -Wshadow
108endif
109
110ifneq ($(findstring $(MAKEFLAGS), w),w)
111PRINT_DIR = --no-print-directory
112else
113NO_SUBDIR = :
114endif
115
116ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
117  silent=1
118endif
119
120#
121# Define a callable command for descending to a new directory
122#
123# Call by doing: $(call descend,directory[,target])
124#
125descend = \
126	+mkdir -p $(OUTPUT)$(1) && \
127	$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
128
129QUIET_SUBDIR0  = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir
130QUIET_SUBDIR1  =
131
132ifneq ($(silent),1)
133  ifneq ($(V),1)
134	QUIET_CC       = @echo '  CC      '$@;
135	QUIET_CC_FPIC  = @echo '  CC FPIC '$@;
136	QUIET_CLANG    = @echo '  CLANG   '$@;
137	QUIET_AR       = @echo '  AR      '$@;
138	QUIET_LINK     = @echo '  LINK    '$@;
139	QUIET_MKDIR    = @echo '  MKDIR   '$@;
140	QUIET_GEN      = @echo '  GEN     '$@;
141	QUIET_SUBDIR0  = +@subdir=
142	QUIET_SUBDIR1  = ;$(NO_SUBDIR) \
143			  echo '  SUBDIR  '$$subdir; \
144			 $(MAKE) $(PRINT_DIR) -C $$subdir
145	QUIET_FLEX     = @echo '  FLEX    '$@;
146	QUIET_BISON    = @echo '  BISON   '$@;
147	QUIET_GENSKEL  = @echo '  GENSKEL '$@;
148
149	descend = \
150		+@echo	       '  DESCEND '$(1); \
151		mkdir -p $(OUTPUT)$(1) && \
152		$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
153
154	QUIET_CLEAN    = @printf '  CLEAN   %s\n' $1;
155	QUIET_INSTALL  = @printf '  INSTALL %s\n' $1;
156	QUIET_UNINST   = @printf '  UNINST  %s\n' $1;
157  endif
158endif
159
160pound := \#