[RFC/PATCH] buildsys: cache build flags in vars

Khem Raj raj.khem at gmail.com
Mon Jan 16 18:00:47 UTC 2012


On Sat, Nov 26, 2011 at 9:22 PM, Mike Frysinger <vapier at gentoo.org> wrote:
> Running `make clean` atm takes like 20 seconds because every subdir
> re-evaluates all the toolchain flags.  Add some helpers to automate
> the process of setting up variables to cache the result of tests,
> as well as the checking of an already set flag.
>
> Now `make clean` takes like 2 seconds on my system.
>

this is causing some gripes. e.g. now -Wl,--hash-style=gnu is not being added to
linker flags which works all fine without this patch

> Signed-off-by: Mike Frysinger <vapier at gentoo.org>
> ---
>  Makerules             |    6 +-
>  Rules.mak             |  178 +++++++++++++++++++++++++++++++++----------------
>  ldso/ldso/Makefile.in |    4 +-
>  test/Rules.mak        |    3 +-
>  4 files changed, 128 insertions(+), 63 deletions(-)
>
> diff --git a/Makerules b/Makerules
> index 110ba39..6954b94 100644
> --- a/Makerules
> +++ b/Makerules
> @@ -308,7 +308,7 @@ define link.so
>        @$(disp_ld)
>        $(Q)$(CC) $(LDFLAGS-$(notdir $@)) $(LDFLAGS-y-$(@F)) \
>                -Wl,-soname=$(notdir $@).$(2) \
> -               $(NOSTDLIB_CFLAGS) -o $(dir $@)$(1) $(START_FILE-$(notdir $@)) \
> +               $(CFLAG_-nostdlib) -o $(dir $@)$(1) $(START_FILE-$(notdir $@)) \
>                -Wl,--whole-archive $(firstword $^) -Wl,--no-whole-archive \
>                $(LIBS-$(notdir $@)) $(LIBGCC) $(END_FILE-$(notdir $@))
>        $(Q)$(LN) -sf $(1) $@.$(2)
> @@ -333,7 +333,7 @@ LINK_FLAT_CRTS := $(top_builddir)lib/Scrt1.o $(top_builddir)lib/crti.o \
>  define link-flat.so
>        $(Q)$(RM) $(1) $@
>        @$(disp_ld)
> -       $(Q)$(CC) $(LDFLAGS-$(notdir $@)) $(NOSTDLIB_CFLAGS) -o $(1) \
> +       $(Q)$(CC) $(LDFLAGS-$(notdir $@)) $(CFLAG_-nostdlib) -o $(1) \
>                -Wl,-elf2flt -Wl,-shared-lib-id,$(2) $(top_builddir)lib/Scrt1.o \
>                $(top_builddir)/lib/crti.o -Wl,--whole-archive $(firstword $^) \
>                $(LIBGCC) -Wl,--no-whole-archive $(LIBS-$(notdir $@)) $(LIBGCC) \
> @@ -345,7 +345,7 @@ define linkm.so
>        $(do_strip)
>        @$(disp_ld)
>        $(Q)$(CC) $(LDFLAGS-$(notdir $@)) -Wl,-soname=$(notdir $@).$(2) \
> -               $(NOSTDLIB_CFLAGS) -o $(dir $@)$(1) $(START_FILE-$(notdir $@)) \
> +               $(CFLAG_-nostdlib) -o $(dir $@)$(1) $(START_FILE-$(notdir $@)) \
>                $^ \
>                $(LIBS-$(notdir $@)) $(LIBGCC) $(END_FILE-$(notdir $@))
>        $(Q)$(LN) -sf $(1) $@.$(2)
> diff --git a/Rules.mak b/Rules.mak
> index c419174..4dafa22 100644
> --- a/Rules.mak
> +++ b/Rules.mak
> @@ -173,6 +173,48 @@ check_ld=$(shell \
>        if $(LD) $(1) -o /dev/null -b binary /dev/null > /dev/null 2>&1; \
>        then echo "$(1)"; fi)
>
> +# Use variable indirection here so that we can have variable
> +# names with fun chars in them like equal signs
> +define check-tool-var
> +_v = $(2)_$(3)
> +ifndef $$(_v)
> +$$(_v) := $$(call $(1),$(subst %, ,$(3)))
> +export $$(_v)
> +endif
> +endef
> +
> +# Usage: check-gcc-var,<flag>
> +# Check the C compiler to see if it supports <flag>.
> +# Export the variable CFLAG_<flag> if it does.
> +define check-gcc-var
> +$(call check-tool-var,check_gcc,CFLAG,$(1))
> +endef
> +# Usage: check-as-var,<flag>
> +# Check the assembler to see if it supports <flag>.  Export the
> +# variable ASFLAG_<flag> if it does (for invoking the assembler),
> +# as well CFLAG_-Wa<flag> (for invoking the compiler driver).
> +define check-as-var
> +$(call check-tool-var,check_as,ASFLAG,$(1))
> +export CFLAG_-Wa$(1) = $(if $$(ASFLAG_$(1)),-Wa$(comma)$$(ASFLAG_$(1)))
> +endef
> +# Usage: check-ld-var,<flag>
> +# Check the linker to see if it supports <flag>.  Export the
> +# variable LDFLAG_<flag> if it does (for invoking the linker),
> +# as well CFLAG_-Wl<flag> (for invoking the compiler driver).
> +define check-ld-var
> +$(call check-tool-var,check_ld,LDFLAG,$(1))
> +export CFLAG_-Wl$(1) = $(if $$(LDFLAG_$(1)),-Wl$(comma)$$(LDFLAG_$(1)))
> +endef
> +# Usage: cache-output-var,<variable>,<shell command>
> +# Execute <shell command> and cache the output in <variable>.
> +define cache-output-var
> +ifndef $(1)
> +$(1) := $$(shell $(2))
> +export $(1)
> +endif
> +endef
> +
> +
>  ARFLAGS:=cr
>
>
> @@ -180,24 +222,37 @@ ARFLAGS:=cr
>
>  OPTIMIZATION:=
>  # Use '-Os' optimization if available, else use -O2, allow Config to override
> -OPTIMIZATION+=$(call check_gcc,-Os,-O2)
> +$(eval $(call check-gcc-var,-Os))
> +ifneq ($(CFLAG_-Os),)
> +OPTIMIZATION += $(CFLAG_-Os)
> +else
> +$(eval $(call check-gcc-var,-O2))
> +OPTIMIZATION += $(CFLAG_-O2)
> +endif
>  # Use the gcc 3.4 -funit-at-a-time optimization when available
> -OPTIMIZATION+=$(call check_gcc,-funit-at-a-time,)
> +$(eval $(call check-gcc-var,-funit-at-a-time))
> +OPTIMIZATION += $(CFLAG_-funit-at-a-time)
>  # shrinks code by about 0.1%
> -OPTIMIZATION+=$(call check_gcc,-fmerge-all-constants)
> -OPTIMIZATION+=$(call check_gcc,-fstrict-aliasing)
> +$(eval $(call check-gcc-var,-fmerge-all-constants))
> +$(eval $(call check-gcc-var,-fstrict-aliasing))
> +OPTIMIZATION += $(CFLAG_-fmerge-all-constants) $(CFLAG_-fstrict-aliasing)
>
> -GCC_MAJOR_VER?=$(shell $(CC) -dumpversion | cut -d . -f 1)
> -#GCC_MINOR_VER?=$(shell $(CC) -dumpversion | cut -d . -f 2)
> +$(eval $(call cache-output-var,GCC_VER,$(CC) -dumpversion))
> +GCC_VER := $(subst ., ,$(GCC_VER))
> +GCC_MAJOR_VER ?= $(word 1,$(GCC_VER))
> +#GCC_MINOR_VER ?= $(word 2,$(GCC_VER))
>
>  ifeq ($(GCC_MAJOR_VER),4)
>  # shrinks code, results are from 4.0.2
>  # 0.36%
> -OPTIMIZATION+=$(call check_gcc,-fno-tree-loop-optimize,)
> +$(eval $(call check-gcc-var,-fno-tree-loop-optimize))
> +OPTIMIZATION += $(CFLAG_-fno-tree-loop-optimize)
>  # 0.34%
> -OPTIMIZATION+=$(call check_gcc,-fno-tree-dominator-opts,)
> +$(eval $(call check-gcc-var,-fno-tree-dominator-opts))
> +OPTIMIZATION += $(CFLAG_-fno-tree-dominator-opts)
>  # 0.1%
> -OPTIMIZATION+=$(call check_gcc,-fno-strength-reduce,)
> +$(eval $(call check-gcc-var,-fno-strength-reduce))
> +OPTIMIZATION += $(CFLAG_-fno-strength-reduce)
>  endif
>
>
> @@ -208,7 +263,8 @@ endif
>  # sign extension of 'char' type for 10 hours straight. Not fun.
>  CPU_CFLAGS-y := -funsigned-char -fno-builtin
>
> -CPU_CFLAGS-y += $(call check_gcc,-fno-asm,)
> +$(eval $(call check-gcc-var,-fno-asm))
> +CPU_CFLAGS-y += $(CFLAG_-fno-asm)
>
>  LDADD_LIBFLOAT=
>  ifeq ($(UCLIBC_HAS_SOFT_FLOAT),y)
> @@ -231,7 +287,8 @@ ifeq ($(TARGET_ARCH),arm)
>  endif
>  endif
>
> -CPU_CFLAGS-y += $(call check_gcc,-std=gnu99,)
> +$(eval $(call check-gcc-var,-std=gnu99))
> +CPU_CFLAGS-y += $(CFLAG_-std=gnu99)
>
>  CPU_CFLAGS-$(UCLIBC_FORMAT_SHARED_FLAT) += -mid-shared-library
>  CPU_CFLAGS-$(UCLIBC_FORMAT_FLAT_SEP_DATA) += -msep-data
> @@ -247,7 +304,8 @@ PIEFLAG_NAME:=-fPIE
>
>  # Some nice CPU specific optimizations
>  ifeq ($(TARGET_ARCH),i386)
> -       OPTIMIZATION+=$(call check_gcc,-fomit-frame-pointer,)
> +$(eval $(call check-gcc-var,-fomit-frame-pointer))
> +       OPTIMIZATION += $(CFLAG_-fomit-frame-pointer)
>
>  ifeq ($(CONFIG_386)$(CONFIG_486)$(CONFIG_586)$(CONFIG_586MMX),y)
>        # Non-SSE capable processor.
> @@ -257,7 +315,8 @@ ifeq ($(CONFIG_386)$(CONFIG_486)$(CONFIG_586)$(CONFIG_586MMX),y)
>        # -m32 is needed if host is 64-bit
>        OPTIMIZATION+=$(call check_gcc,-m32 -mpreferred-stack-boundary=2,)
>  else
> -       OPTIMIZATION+=$(call check_gcc,-mpreferred-stack-boundary=4,)
> +$(eval $(call check-gcc-var,-mpreferred-stack-boundary=4))
> +       OPTIMIZATION += $(CFLAG_-mpreferred-stack-boundary=4)
>  endif
>
>        # Choice of alignment (please document why!)
> @@ -296,13 +355,10 @@ endif
>        # It specifies 4 byte align for .text even if not told to do so:
>        # Idx Name          Size      VMA       LMA       File off  Algn
>        #   0 .text         xxxxxxxx  00000000  00000000  xxxxxxxx  2**2 <===!
> -       CPU_CFLAGS-y  += $(call check_gcc,-ffunction-sections -fdata-sections,)
> -ifneq ($(call check_ld,--sort-common),)
> -       CPU_LDFLAGS-y += -Wl,--sort-common
> -endif
> -ifneq ($(call check_ld,--sort-section alignment),)
> -       CPU_LDFLAGS-y += -Wl,--sort-section,alignment
> -endif
> +       CPU_CFLAGS-y  += $(CFLAG_-ffunction-sections) $(CFLAG_-fdata-sections)
> +       CPU_LDFLAGS-y += $(CFLAG_-Wl--sort-common)
> +$(eval $(call check-ld-var,--sort-section%alignment))
> +       CPU_LDFLAGS-y += $(CFLAG_-Wl--sort-section%alignment)
>
>        CPU_LDFLAGS-y+=-m32
>        CPU_CFLAGS-y+=-m32
> @@ -366,7 +422,8 @@ ifeq ($(TARGET_ARCH),nios)
>  endif
>
>  ifeq ($(TARGET_ARCH),sh)
> -       OPTIMIZATION+= $(call check_gcc,-mprefergot,)
> +$(eval $(call check-gcc-var,-mprefergot))
> +       OPTIMIZATION += $(CFLAG_-mprefergot)
>        CPU_CFLAGS-$(ARCH_LITTLE_ENDIAN)+=-ml
>        CPU_CFLAGS-$(ARCH_BIG_ENDIAN)+=-mb
>        CPU_CFLAGS-$(CONFIG_SH2)+=-m2
> @@ -476,17 +533,16 @@ ifeq ($(TARGET_ARCH),c6x)
>        CPU_LDFLAGS-y += $(CPU_CFLAGS)
>  endif
>
> -# Keep the check_gcc from being needlessly executed
> -ifndef PIEFLAG
> -export PIEFLAG:=$(call check_gcc,$(PIEFLAG_NAME),$(PICFLAG))
> +$(eval $(call check-gcc-var,$(PIEFLAG_NAME)))
> +PIEFLAG := $(CFLAG_$(PIEFLAG_NAME))
> +ifeq ($(PIEFLAG),)
> +PIEFLAG := $(PICFLAG)
>  endif
>  # We need to keep track of both the CC PIE flag (above) as
>  # well as the LD PIE flag (below) because we can't rely on
>  # gcc passing -pie if we used -fPIE. We need to directly use -pie
>  # instead of -Wl,-pie as gcc picks up the wrong startfile/endfile
> -ifndef LDPIEFLAG
> -export LDPIEFLAG:=$(shell $(LD) --help 2>/dev/null | grep -q -- -pie && echo "-pie")
> -endif
> +$(eval $(call cache-output-var,LDPIEFLAG,$(LD) --help 2>/dev/null | grep -q -- -pie && echo "-pie"))
>
>  # Check for --as-needed support in linker
>  ifndef LD_FLAG_ASNEEDED
> @@ -525,13 +581,9 @@ endif
>  endif
>
>  # Add a bunch of extra pedantic annoyingly strict checks
> -XWARNINGS=$(call qstrip,$(WARNINGS))
> -XWARNINGS+=$(foreach w,\
> -       -Wstrict-prototypes \
> -       -Wstrict-aliasing \
> -       , $(call check_gcc,$(w),))
> +WARNING_FLAGS = -Wstrict-prototypes -Wstrict-aliasing
>  ifeq ($(EXTRA_WARNINGS),y)
> -XWARNINGS+=$(foreach w,\
> +WARNING_FLAGS += \
>        -Wformat=2 \
>        -Wmissing-noreturn \
>        -Wmissing-format-attribute \
> @@ -542,23 +594,32 @@ XWARNINGS+=$(foreach w,\
>        -Wold-style-declaration \
>        -Wold-style-definition \
>        -Wshadow \
> -       -Wundef \
> -       , $(call check_gcc,$(w),))
> +       -Wundef
>  # Works only w/ gcc-3.4 and up, can't be checked for gcc-3.x w/ check_gcc()
> -#XWARNINGS+=-Wdeclaration-after-statement
> +WARNING_FLAGS-4 += -Wdeclaration-after-statement
>  endif
> +WARNING_FLAGS += $(WARNING_FLAGS-$(GCC_MAJOR_VER))
> +$(foreach w,$(WARNING_FLAGS),$(eval $(call check-gcc-var,$(w))))
> +XWARNINGS = $(call qstrip,$(WARNINGS)) $(foreach w,$(WARNING_FLAGS),$(CFLAG_$(w)))
> +
>  CPU_CFLAGS=$(call qstrip,$(CPU_CFLAGS-y))
>
> -SSP_DISABLE_FLAGS ?= $(call check_gcc,-fno-stack-protector,)
> +# Save the tested flag in a single variable and force it to be
> +# evaluated just once.  Then use that computed value.
> +$(eval $(call check-gcc-var,-fno-stack-protector))
> +SSP_DISABLE_FLAGS ?= $(CFLAG_-fno-stack-protector)
>  ifeq ($(UCLIBC_BUILD_SSP),y)
> -SSP_CFLAGS := $(call check_gcc,-fno-stack-protector-all,)
> -SSP_CFLAGS += $(call check_gcc,-fstack-protector,)
> -SSP_ALL_CFLAGS ?= $(call check_gcc,-fstack-protector-all,)
> +$(eval $(call check-gcc-var,-fno-stack-protector-all))
> +$(eval $(call check-gcc-var,-fstack-protector))
> +$(eval $(call check-gcc-var,-fstack-protector-all))
> +SSP_CFLAGS := $(CFLAG_-fno-stack-protector-all)
> +SSP_CFLAGS += $(CFLAG_-fstack-protector)
> +SSP_ALL_CFLAGS ?= $(CFLAG_-fstack-protector-all)
>  else
>  SSP_CFLAGS := $(SSP_DISABLE_FLAGS)
>  endif
>
> -NOSTDLIB_CFLAGS:=$(call check_gcc,-nostdlib,)
> +$(eval $(call check-gcc-var,-nostdlib))
>
>  # Collect all CFLAGS components
>  CFLAGS := -include $(top_srcdir)include/libc-symbols.h \
> @@ -572,13 +633,17 @@ ifneq ($(HAVE_SHARED),y)
>  CFLAGS += -DSTATIC
>  endif
>
> -LDFLAG_WARN_ONCE:=$(if $(call check_ld,--warn-once),-Wl$(comma)--warn-once)
> -LDFLAG_SORT_COMMON:=$(if $(call check_ld,--sort-common),-Wl$(comma)--sort-common)
> -LDFLAG_DISCARD_ALL:=$(if $(call check_ld,--discard-all),-Wl$(comma)--discard-all)
> +$(eval $(call check-ld-var,--warn-once))
> +$(eval $(call check-ld-var,--sort-common))
> +$(eval $(call check-ld-var,--discard-all))
>  LDFLAGS_NOSTRIP:=$(CPU_LDFLAGS-y) -shared \
> -       -Wl,--warn-common $(LDFLAG_WARN_ONCE) -Wl,-z,combreloc
> +       -Wl,--warn-common $(CFLAG_-Wl--warn-once) -Wl,-z,combreloc
>  # binutils-2.16.1 warns about ignored sections, 2.16.91.0.3 and newer are ok
> -#LDFLAGS_NOSTRIP+=$(call check_ld,--gc-sections)
> +#$(eval $(call check-ld-var,--gc-sections))
> +#LDFLAGS_NOSTRIP += $(LDFLAG_--gc-sections)
> +
> +$(eval $(call check-gcc-var,-fdata-sections))
> +$(eval $(call check-gcc-var,-ffunction-sections))
>
>  ifeq ($(UCLIBC_BUILD_RELRO),y)
>  LDFLAGS_NOSTRIP+=-Wl,-z,relro
> @@ -590,13 +655,13 @@ endif
>
>  ifeq ($(LDSO_GNU_HASH_SUPPORT),y)
>  # Be sure that binutils support it
> -LDFLAGS_GNUHASH:=$(call check_ld,--hash-style=gnu)
> -ifeq ($(LDFLAGS_GNUHASH),)
> +$(eval $(call check-ld-var,--hash-style=gnu))
> +ifeq ($(LDFLAG_--hash-style=gnu),)
>  ifneq ($(filter-out $(clean_targets) install_headers headers-y,$(MAKECMDGOALS)),)
>  $(error Your binutils do not support --hash-style option, while you want to use it)
>  endif
>  else
> -LDFLAGS_NOSTRIP += -Wl,$(LDFLAGS_GNUHASH)
> +LDFLAGS_NOSTRIP += $(CFLAG_-Wl--hash-style=gnu)
>  endif
>  endif
>
> @@ -624,7 +689,8 @@ ifeq ($(DOMULTI),y)
>  ifeq ($(GCC_MAJOR_VER),3)
>  DOMULTI:=n
>  else
> -CFLAGS+=$(call check_gcc,--combine,)
> +$(eval $(call check-gcc-var,--combine))
> +CFLAGS += $(CFLAG_--combine)
>  endif
>  else
>  DOMULTI:=n
> @@ -696,7 +762,7 @@ CFLAGS += -I$(top_srcdir)libc/sysdeps/linux/common
>  CFLAGS += -I$(KERNEL_HEADERS)
>
>  #CFLAGS += -iwithprefix include-fixed -iwithprefix include
> -CC_IPREFIX := $(shell $(CC) --print-file-name=include)
> +$(eval $(call cache-output-var,CC_IPREFIX,$(CC) --print-file-name=include))
>  CC_INC := -isystem $(dir $(CC_IPREFIX))include-fixed -isystem $(CC_IPREFIX)
>  CFLAGS += $(CC_INC)
>
> @@ -709,17 +775,13 @@ CFLAGS+=-D__UCLIBC_UNDERSCORES__
>  endif
>
>  # Keep the check_as from being needlessly executed
> -ifndef ASFLAGS_NOEXEC
>  ifeq ($(UCLIBC_BUILD_NOEXECSTACK),y)
> -export ASFLAGS_NOEXEC := $(call check_as,--noexecstack)
> -else
> -export ASFLAGS_NOEXEC :=
> -endif
> +$(eval $(call check-as-var,--noexecstack))
>  endif
> -ASFLAGS = $(ASFLAGS_NOEXEC)
> +ASFLAGS = $(ASFLAG_--noexecstack)
>
>  LIBGCC_CFLAGS ?= $(CFLAGS) $(CPU_CFLAGS-y)
> -LIBGCC:=$(shell $(CC) $(LIBGCC_CFLAGS) -print-libgcc-file-name)
> +$(eval $(call cache-output-var,LIBGCC,$(CC) $(LIBGCC_CFLAGS) -print-libgcc-file-name))
>  LIBGCC_DIR:=$(dir $(LIBGCC))
>
>  # moved from libpthread/linuxthreads
> diff --git a/ldso/ldso/Makefile.in b/ldso/ldso/Makefile.in
> index ad8edbb..eb1570a 100644
> --- a/ldso/ldso/Makefile.in
> +++ b/ldso/ldso/Makefile.in
> @@ -36,7 +36,9 @@ LDFLAGS-$(UCLIBC_LDSO_NAME).so := $(LDFLAGS)
>  else
>  LDFLAGS-$(UCLIBC_LDSO_NAME).so := $(LDFLAGS_NOSTRIP) -Wl,-z,defs
>  endif
> -LDFLAGS-$(UCLIBC_LDSO_NAME).so += -Wl,-e,_start -Wl,-z,now -Wl,-Bsymbolic -Wl,--export-dynamic $(LDFLAG_SORT_COMMON) -Wl,--discard-locals $(LDFLAG_DISCARD_ALL) -Wl,--no-undefined
> +LDFLAGS-$(UCLIBC_LDSO_NAME).so += -Wl,-e,_start -Wl,-z,now -Wl,-Bsymbolic \
> +       -Wl,--export-dynamic $(CFLAG_-Wl--sort-common) -Wl,--discard-locals \
> +       $(CFLAG_-Wl--discard-all) -Wl,--no-undefined
>
>  ldso_FULL_NAME := $(UCLIBC_LDSO_NAME)-$(VERSION).so
>
> diff --git a/test/Rules.mak b/test/Rules.mak
> index 2131a7b..4b4345e 100644
> --- a/test/Rules.mak
> +++ b/test/Rules.mak
> @@ -57,7 +57,8 @@ endif
>  endif
>
>  XCOMMON_CFLAGS := -I$(top_builddir)test -D_GNU_SOURCE
> -XWARNINGS      += $(call check_gcc,-Wstrict-prototypes,)
> +CFLAG_-Wstrict-prototypes ?= $(call check_gcc,-Wstrict-prototypes,)
> +XWARNINGS      += $(CFLAG_-Wstrict-prototypes)
>  CFLAGS         := -nostdinc -I$(top_builddir)$(LOCAL_INSTALL_PATH)/usr/include
>  CFLAGS         += $(XCOMMON_CFLAGS) $(KERNEL_INCLUDES) $(CC_INC)
>  CFLAGS         += $(OPTIMIZATION) $(CPU_CFLAGS) $(XWARNINGS)
> --
> 1.7.6.1
>
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