From: Tommi Rantala <tt.rantala@gmail.com>
To: davej@codemonkey.org.uk
Cc: trinity@vger.kernel.org, Tommi Rantala <tt.rantala@gmail.com>
Subject: [PATCH 3/5] Makefile: improve build time with immediate variables
Date: Sun, 5 Feb 2017 17:53:50 +0200 [thread overview]
Message-ID: <20170205155352.13191-3-tt.rantala@gmail.com> (raw)
In-Reply-To: <20170205155352.13191-1-tt.rantala@gmail.com>
It looks like "CFLAGS += $(shell ..." is a bad idea, as make will repeat the
shell expansion again and again during the build.
Use immediate variables where we can to avoid the issue.
make -j4 before this patch:
real 0m10.774s
user 0m24.541s
sys 0m10.676s
make -j4 with this patch:
real 0m8.173s
user 0m20.817s
sys 0m7.632s
---
Makefile | 74 +++++++++++++++++++++++++++++++++-------------------------------
1 file changed, 38 insertions(+), 36 deletions(-)
diff --git a/Makefile b/Makefile
index 8088608..8a061b1 100644
--- a/Makefile
+++ b/Makefile
@@ -18,13 +18,15 @@ LD := $(CROSS_COMPILE)$(LD)
CFLAGS += -Wall -Wextra -g -O2 -I. -Iinclude/ -Wimplicit -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -D__linux__
-CFLAGS += $(shell if $(CC) -std=gnu11 -S -o /dev/null -xc /dev/null >/dev/null 2>&1; then echo "-std=gnu11"; else echo "-std=gnu99"; fi)
+CCSTD := $(shell if $(CC) -std=gnu11 -S -o /dev/null -xc /dev/null >/dev/null 2>&1; then echo "-std=gnu11"; else echo "-std=gnu99"; fi)
+CFLAGS += $(CCSTD)
# Only enabled during development, and on gcc 4.9+
ifeq ($(DEVEL), 1)
CPP_MAJOR := $(shell $(CPP) -dumpversion 2>&1 | cut -d'.' -f1)
CPP_MINOR := $(shell $(CPP) -dumpversion 2>&1 | cut -d'.' -f2)
-CFLAGS += $(shell if [ $(CPP_MAJOR) -eq 5 -a $(CPP_MINOR) -ge 1 ] ; then echo "-Werror"; else echo ""; fi)
+WERROR := $(shell if [ $(CPP_MAJOR) -eq 5 -a $(CPP_MINOR) -ge 1 ] ; then echo "-Werror"; else echo ""; fi)
+CFLAGS += $(WERROR)
endif
ifneq ($(SYSROOT),)
@@ -75,40 +77,40 @@ test:
@if [ ! -f config.h ]; then echo "^[[1;31mRun configure.sh first.^[[0m" ; exit; fi
-MACHINE = $(shell $(CC) -dumpmachine)
-SYSCALLS_ARCH = $(shell case "$(MACHINE)" in \
- (sh*) echo syscalls/sh/*.c ;; \
- (ia64*) echo syscalls/ia64/*.c ;; \
- (ppc*|powerpc*) echo syscalls/ppc/*.c ;; \
- (sparc*) echo syscalls/sparc/*.c ;; \
- (x86_64*) echo syscalls/x86/*.c \
- syscalls/x86/i386/*.c \
- syscalls/x86/x86_64/*.c;; \
- (i?86*) echo syscalls/x86/*.c \
- syscalls/x86/i386/*.c;; \
- esac)
-
-HEADERS = $(patsubst %.h,%.h,$(wildcard *.h)) $(patsubst %.h,%.h,$(wildcard syscalls/*.h)) $(patsubst %.h,%.h,$(wildcard ioctls/*.h))
-
-SRCS = $(wildcard *.c) \
- $(wildcard childops/*.c) \
- $(wildcard fds/*.c) \
- $(wildcard ioctls/*.c) \
- $(wildcard mm/*.c) \
- $(wildcard net/*.c) \
- $(wildcard rand/*.c) \
- $(wildcard syscalls/*.c) \
- $(SYSCALLS_ARCH)
-
-OBJS = $(sort $(patsubst %.c,%.o,$(wildcard *.c))) \
- $(sort $(patsubst %.c,%.o,$(wildcard childops/*.c))) \
- $(sort $(patsubst %.c,%.o,$(wildcard fds/*.c))) \
- $(sort $(patsubst %.c,%.o,$(wildcard ioctls/*.c))) \
- $(sort $(patsubst %.c,%.o,$(wildcard mm/*.c))) \
- $(sort $(patsubst %.c,%.o,$(wildcard net/*.c))) \
- $(sort $(patsubst %.c,%.o,$(wildcard rand/*.c))) \
- $(sort $(patsubst %.c,%.o,$(wildcard syscalls/*.c))) \
- $(sort $(patsubst %.c,%.o,$(SYSCALLS_ARCH)))
+MACHINE := $(shell $(CC) -dumpmachine)
+SYSCALLS_ARCH := $(shell case "$(MACHINE)" in \
+ (sh*) echo syscalls/sh/*.c ;; \
+ (ia64*) echo syscalls/ia64/*.c ;; \
+ (ppc*|powerpc*) echo syscalls/ppc/*.c ;; \
+ (sparc*) echo syscalls/sparc/*.c ;; \
+ (x86_64*) echo syscalls/x86/*.c \
+ syscalls/x86/i386/*.c \
+ syscalls/x86/x86_64/*.c;; \
+ (i?86*) echo syscalls/x86/*.c \
+ syscalls/x86/i386/*.c;; \
+ esac)
+
+HEADERS := $(patsubst %.h,%.h,$(wildcard *.h)) $(patsubst %.h,%.h,$(wildcard syscalls/*.h)) $(patsubst %.h,%.h,$(wildcard ioctls/*.h))
+
+SRCS := $(wildcard *.c) \
+ $(wildcard childops/*.c) \
+ $(wildcard fds/*.c) \
+ $(wildcard ioctls/*.c) \
+ $(wildcard mm/*.c) \
+ $(wildcard net/*.c) \
+ $(wildcard rand/*.c) \
+ $(wildcard syscalls/*.c) \
+ $(SYSCALLS_ARCH)
+
+OBJS := $(sort $(patsubst %.c,%.o,$(wildcard *.c))) \
+ $(sort $(patsubst %.c,%.o,$(wildcard childops/*.c))) \
+ $(sort $(patsubst %.c,%.o,$(wildcard fds/*.c))) \
+ $(sort $(patsubst %.c,%.o,$(wildcard ioctls/*.c))) \
+ $(sort $(patsubst %.c,%.o,$(wildcard mm/*.c))) \
+ $(sort $(patsubst %.c,%.o,$(wildcard net/*.c))) \
+ $(sort $(patsubst %.c,%.o,$(wildcard rand/*.c))) \
+ $(sort $(patsubst %.c,%.o,$(wildcard syscalls/*.c))) \
+ $(sort $(patsubst %.c,%.o,$(SYSCALLS_ARCH)))
DEPDIR= .deps
--
2.9.3
next prev parent reply other threads:[~2017-02-05 15:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-05 15:53 [PATCH 1/5] Makefile: use grep -c to avoid wc -l Tommi Rantala
2017-02-05 15:53 ` [PATCH 2/5] Makefile: use findstring to check if we are building in development mode Tommi Rantala
2017-02-05 15:53 ` Tommi Rantala [this message]
2017-02-05 15:53 ` [PATCH 4/5] Makefile: -Werror also for gcc 6.x Tommi Rantala
2017-02-05 15:53 ` [PATCH 5/5] btrfs/ioctl.h is not really needed Tommi Rantala
2017-02-07 10:05 ` [PATCH 1/5] Makefile: use grep -c to avoid wc -l Michael Ellerman
2017-02-07 14:14 ` Dave Jones
2017-02-08 3:52 ` Michael Ellerman
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