Making a better Makefile - makefile

so I learned what a Makefile was some time ago, created a template Makefile and all I do is copy and alter the same file for every program I'm doing. I changed it a few times, but it's still a very crude Makefile. How should I improve it? This is an example of my current version:
CC = g++
CFLAGS = -std=gnu++0x -m64 -O3 -Wall
IFLAGS = -I/usr/include/igraph
LFLAGS = -ligraph -lgsl -lgslcblas -lm
DFLAGS = -g -pg
# make all
all: run test
# make a fresh compilation from scratch
fresh: clean test
#makes the final executable binary
run: main.o foo1.o foo2.o
$(CC) $(CFLAGS) $(LFLAGS) $^ -o $#
#makes the test executable with debugging and profiling tags
test: test.o foo1.o foo2.o
$(CC) $(DFLAGS) $(CFLAGS) $(LFLAGS) $^ -o $#
#makes teste.o
teste.o: teste.cpp
$(CC) $(CFLAGS) $(IFLAGS) -c $^ -o $#
#makes main.o
main.o: main.cpp
$(CC) $(CFLAGS) $(IFLAGS) -c $^ -o $#
#file foo1
foo1.o: foo1.cpp
$(CC) $(CFLAGS) $(IFLAGS) -c $^ -o $#
#file foo2
foo2.o: foo2.cpp
$(CC) $(CFLAGS) $(IFLAGS) -c $^ -o $#
clean: clean-test clean-o clean-annoying
clean-test:
rm test-rfv
clean-o:
rm *.o -rfv
clean-annoying:
rm *~ -rfv
Just by visually comparing with other makefiles I saw around in the web, this seems to be not a very bright Makefile. I don't know how they work, but I can see there's significantly less boilerplate and more generic code in them.
Can this can be made better, safer, and easier to particularize for each project?

You don't want to name specific files in a makefile if you can get away with it, and 99% of the time you can. This page shows how to develop a very general makefile. The following is my own makefile, based on that page's info:
SHELL := bash
PROG := pathed.exe
OUTDIRS := bin/debug bin/rel obj/debug obj/rel
PROG_REL := bin/rel/$(PROG)
PROG_DEBUG := bin/debug/$(PROG)
SRCFILES := $(wildcard src/*.cpp)
OBJFILES_REL := $(patsubst src/%.cpp,obj/rel/%.o,$(SRCFILES))
OBJFILES_DEBUG := $(patsubst src/%.cpp,obj/debug/%.o,$(SRCFILES))
DEPFILES := $(patsubst src/%.cpp,obj/%.d,$(SRCFILES))
CFLAGS := -Iinc -Wall -Wextra -MMD -MP
DBFLAGS := -g
RELFLAGS :=
CC := g++
.PHONY: default all testmake debug release clean dirs
default: debug
all: dirs clean debug release
dirs:
#mkdir -p $(OUTDIRS)
debug: $(PROG_DEBUG)
release: $(PROG_REL)
testmake:
#echo OBJFILES_REL = $(OBJFILES_REL)
#echo OBJFILES_DEBUG = $(OBJFILES_DEBUG)
#echo SRCFILES = $(SRCFILES)
#echo DEPFILES = $(DEPFILES)
clean:
rm -f $(OBJFILES_REL) $(OBJFILES_DEBUG) $(DEPFILES) $(PROG)
$(PROG_REL): $(OBJFILES_REL)
$(CC) $(OBJFILES_REL) -o $(PROG_REL)
strip $(PROG_REL)
#echo "---- created release binary ----"
$(PROG_DEBUG): $(OBJFILES_DEBUG)
$(CC) $(OBJFILES_DEBUG) -o $(PROG_DEBUG)
#echo "---- created debug binary ----"
-include $(DEPFILES)
obj/rel/%.o: src/%.cpp
$(CC) $(RELFLAGS) $(CFLAGS) -MF $(patsubst obj/rel/%.o, obj/%.d,$#) -c $< -o $#
obj/debug/%.o: src/%.cpp
$(CC) $(DBFLAGS) $(CFLAGS) -MF $(patsubst obj/debug/%.o, obj/%.d,$#) -c $< -o $#

Do NOT use CC for the C++ compiler. The standard convention is that CC is the C compiler, CXX is the C++ compiler. CFLAGS are flags for the C compiler, CXXFLAGS are flags for the C++ compiler, and CPPFLAGS are flags for the pre-processor (eg, -I or -D flags). Use LDFLAGS for -L flags to the linker, and LDLIBS (or LOADLIBES) for -l flags.
Using the standard conventions is good not just because it makes things easier for others to understand, but also because it allows you to take advantage of implicit rules. If make needs to make a .o file from a .c file and you have not provided a rule, it will use a standard rule and honor the settings of CC, CFLAGS, and CPPFLAGS. If CC is a C++ compiler, things will probably not work.

Related

How to let avr-gcc output *.o to separate folder in Makefile with `%.o: %.c`?

As showed in first screenshot, my ideal AVR project structure is that:
*.o, *.elf and *.hex files are in build folder.
PomoScheler.c and pinDefines.h as main files are in root folder, while other *.c and *.h are in src folder.
But *.o are always generated at the same folder as *.c like showed in second screenshot, no matter how.
(I attached my endeavors and whole Makefile below the screenshots)
Firstly, I tried build/ before $#, in vain. The terminal still the same.
# My first Makefile endeavor
%.o: %.c $(HEADERS)
$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o build/$#
# Terminal command generated by Makefile (Look at the end: *.o path still same as *.c)
avr-gcc -Os -g -std=gnu99 -Wall -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -ffunction-sections -fdata-sections -DF_CPU=1000000UL -DBAUD=9600UL -I. -I~/Developer/bin/avr8-gnu-toolchain-darwin_x86_64/avr/include -mmcu=atmega328p -c -o src/RotaryEncoder.o src/RotaryEncoder.c
Secondly, I tried to add mv $# build to explicitly move it to build folder. But nothing happened. Even echo are not displayed in Terminal.
# My second Makefile endeavor
%.o: %.c $(HEADERS)
$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o $#
mv $# build
echo ---------Hello---------
Thirdly, I delete $(HEADERS) and replace $< with $^ just to have a try. The mv is executed. But it cannot find *.o file this time even though I have VPATH = src:build in Makefile.
# My third Makefile endeavor
%.o: %.c
$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $^ -o $#
mv $# build
# Terminal error
Assembler messages:
Fatal error: can't create build/src/RotaryEncoder.o: No such file or directory
And my whole Makefile is here. Please help me out.
# My whole Makefile
MCU = atmega328p
F_CPU = 1000000UL
BAUD = 9600UL
LIBDIR = ~/Developer/bin/avr8-gnu-toolchain-darwin_x86_64/avr/include
PROGRAMMER_TYPE = usbtiny
PROGRAMMER_ARGS =
CC = avr-gcc
OBJCOPY = avr-objcopy
OBJDUMP = avr-objdump
AVRSIZE = avr-size
AVRDUDE = avrdude
##########------------------------------------------------------##########
VPATH = ./src:./build
TARGET = $(lastword $(subst /, ,$(CURDIR)))
SOURCES=$(wildcard *.c src/*.c $(LIBDIR)/*.c)
OBJECTS=$(SOURCES:.c=.o)
HEADERS=$(SOURCES:.c=.h)
CPPFLAGS = -DF_CPU=$(F_CPU) -DBAUD=$(BAUD) -I. -I$(LIBDIR)
CFLAGS = -Os -g -std=gnu99 -Wall
CFLAGS += -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums
CFLAGS += -ffunction-sections -fdata-sections
LDFLAGS = -Wl,-Map,build/$(TARGET).map
LDFLAGS += -Wl,--gc-sections
TARGET_ARCH = -mmcu=$(MCU)
%.o: %.c $(HEADERS)
$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o build/$#
$(TARGET).elf: $(OBJECTS)
$(CC) $(LDFLAGS) $(TARGET_ARCH) $^ $(LDLIBS) -o build/$#
%.hex: %.elf
$(OBJCOPY) -j .text -j .data -O ihex build/$< build/$#
all: $(TARGET).hex
size: $(TARGET).elf
$(AVRSIZE) -C --mcu=$(MCU) $(TARGET).elf
clean:
rm -f $(TARGET).elf $(TARGET).hex $(TARGET).obj \
$(TARGET).o $(TARGET).d $(TARGET).eep $(TARGET).lst \
$(TARGET).lss $(TARGET).sym $(TARGET).map $(TARGET)~ \
$(TARGET).eeprom
flash: $(TARGET).hex
$(AVRDUDE) -c $(PROGRAMMER_TYPE) -p $(MCU) $(PROGRAMMER_ARGS) -U flash:w:$<
This is clearly not right:
OBJECTS = $(SOURCES:.c=.o)
because the object files you want to create are not foo.o etc. which is what this will expand to; the object files are build/foo.o etc. So this has to be:
OBJECTS = $(patsubst %.c,build/%.o)
All of your attempts to trick make by telling it your recipe will build one target (foo.o) but actually building a totally different target (build/foo.o) are doomed to fail, regardless of whether you have the compiler do it directly, you use mv, or any other method.
If you just tell make what your recipe actually does, you will have a much simpler time of it:
build/%.o: %.c
mkdir -p $(#D)
$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $^ -o $#
Probably you have similar issues with the other rules that you want to put into other directories.
You can't do this by trying to hide it from make. Make has to know where the files actually are.
BTW, VPATH cannot help here. VPATH is for finding source files, it cannot be used for finding generated files. So you could use VPATH to find your .c files but not your .o files.

How to compile source objects into another directory and then build an executable?

Good day. I am in a directory, where is Makefile and folders src and bin. How can I compile object files into bin folder and then build an executable file?
I read some instructions and added $(BIN) before %.o, but it didn't helped, object files appear in folder with makefile. Where is the problem?
CC = arm-linux-gnueabihf-gcc
CXX = arm-linux-gnueabihf-g++
CPPFLAGS = -I .
CFLAGS =-g -std=gnu99 -O1 -Wall
CXXFLAGS = -g -std=gnu++11 -O1 -Wall
LDFLAGS = -lrt -lpthread
SRCDIR = src
BIN = bin
SOURCES = $(wildcard $(SRCDIR)/*.cpp) $(wildcard $(SRCDIR)/*.c)*
...
OBJECTS += $(filter %.o,$(SOURCES:%.c=%.o))
OBJECTS += $(filter %.o,$(SOURCES:%.cpp=%.o))
#$(warning OBJECTS=$(OBJECTS))
ifeq ($(filter %.cpp,$(SOURCES)),)
LINKER = $(CC)
LDFLAGS += $(CFLAGS) $(CPPFLAGS)
else
LINKER = $(CXX)
LDFLAGS += $(CXXFLAGS) $(CPPFLAGS)
endif
$(BIN)/%.o:%.c
$(CC) $(CFLAGS) -c $<
$(BIN)/%.o:%.cpp
$(CXX) $(CXXFLAGS) -c $<
all: $(TARGET_EXE)
$(TARGET_EXE): $(OBJECTS)
$(LINKER) $(LDFLAGS) -L. $^ -o $#
.PHONY : dep all run copy-executable debug
dep: depend
depend: $(SOURCES) *.h
echo '# autogenerat`enter code here`ed dependencies' > depend
ifneq ($(filter %.c,$(SOURCES)),)
$(CC) $(CFLAGS) $(CPPFLAGS) -w -E -M $(filter %.c,$(SOURCES)) \
>> depend
endif
ifneq ($(filter %.cpp,$(SOURCES)),)
$(CXX) $(CXXFLAGS) $(CPPFLAGS) -w -E -M $(filter %.cpp,$(SOURCES)) \
>> depend
endif
clean:
rm -f *.o *.a $(OBJECTS) $(TARGET_EXE) connect.gdb depend
...
It's not clear to me how this makefile can works as well as it does, given that you haven't told it where to find the source files (unless you do so in one of the elided sections).
In these rules:
$(BIN)/%.o:%.c
$(CC) $(CFLAGS) -c $<
$(BIN)/%.o:%.cpp
$(CXX) $(CXXFLAGS) -c $<
you tell the compiler to build object files, but you don't specify where to build them, and the default is to build them in the working directory. You can override that with the -o option:
$(BIN)/%.o:%.c
$(CC) $(CFLAGS) -c $< -o $#
$(BIN)/%.o:%.cpp
$(CXX) $(CXXFLAGS) -c $< -o $#
Once you have the object files where you want them (bin/), you must ensure that the linking rule:
$(TARGET_EXE):$(OBJECTS)
$(LINKER) $(LDFLAGS) -L. $^ -o $#
can find them. The best way to do that is to ensure that OBJECTS contains the correct paths to the object files. I'm not sure how to advise you to do that, since from the look of your makefile that variable might not contain what you think it does.
EDIT:
Let's take this in stages.
Suppose we have on source file, src/foo.c. What we want is:
src/foo.c -> bin/foo.o
bin/foo.o -> foo
This requires two rules, which we can write like this:
$(BIN)/%.o: src/%.c
$(CC) $(CFLAGS) -c $< -o $#
$(TARGET_EXE): bin/foo.o
$(LINKER) $(LDFLAGS) -L. $^ -o $#
We actually have many source files, some of which are C++ files. So we must have a rule for them:
$(BIN)/%.o: src/%.cpp
$(CXX) $(CXXFLAGS) -c $< -o $#
and construct a longer list of objects:
OBJECTS := bin/foo.o bin/bar.o bin/baz.o bin/quartz.o...
$(TARGET_EXE): $(OBJECTS)
$(LINKER) $(LDFLAGS) -L. $^ -o $#
(Mixing C and C++ seems unhealthy to me, but never mind.)
And how do we construct that list of objects? We must start with the list of sources which wildcard can produce:
SRC := src
C_SOURCES := $(wildcard $(SRC/*.c)
# this is src/foo.c src/bar.c
SRC := src
CPP_SOURCES := $(wildcard $(SRC/*.cpp)
# this is src/baz.cpp src/quartz.cpp
and then convert them to the object file names we actually want:
BIN := bin
OBJECTS := $(patsubst $(SRC)/%.cpp,$(BIN)/%.o, $(CPP_SOURCES))
OBJECTS += $(patsubst $(SRC)/%.c,$(BIN)/%.o, $(C_SOURCES))
# this is bin/foo.o bin/bar.o bin/baz.o bin/quartz.o
That should give you the effect you want, and if you understand it you will understan why your old makefile did not.

Defer evaluation of automatic variables in recipes

I have the following makefile:
CC ?= gcc
LD := gcc
CFLAGS := -Wall -Wextra -Werror -Wfatal-errors
LDFLAGS :=
LIBRARIES := m c
INCLUDEDIRS := .
LIBS = $(addprefix -l,$(LIBRARIES))
INCLUDES = $(addprefix -I,$(INCLUDEDIRS))
SRC := $(wildcard *.c)
TARGET = $(TARGETDIR)/test
OBJDIR = $(TARGETDIR)/obj/
OBJ = $(addprefix $(OBJDIR),$(SRC:%.c=%.c.o))
.SUFFIXES:
.SUFFIXES: .c.o
.PHONY: all debug i7avx i7avx-debug
all: TARGETDIR := generic
all: CFLAGS += -O3
all: LDFLAGS += -s
all: $(TARGET)
debug: CFLAGS += -Og
debug: TARGETDIR := generic/dbg
debug: $(TARGET)
$(OBJDIR):
#mkdir -p $(OBJDIR)
$(OBJ): | $(OBJDIR)
$(OBJDIR)%.c.o : %.c
$(CC) $(CFLAGS) $(INCLUDES) -c $< -o $#
$(TARGET) : $(OBJ)
$(LD) $(LDFLAGS) -o $# $^ $(LIBS)
The special thing here is that the output directory depends on the target.
Currently, only all and debug is defined, but the idea is to support a whole slew of architectures, and to define an outputdir per target.
Problem: this does not work. If I run this, I get:
cc -Wall -Wextra -Werror -Wfatal-errors -O3 -I. -c main.c -o /obj/main.c.o
Assembler messages:
Fatal error: can't create /obj/main.c.o: No such file or directory
make: *** [Makefile:37: /obj/main.c.o] Error 1
Which implies that the TARGETDIR variable was expanded too late.
If I replace the automatic variables with real variables, it does work:
$(OBJ): | $(OBJDIR)
$(OBJDIR)%.c.o : %.c
$(CC) $(CFLAGS) $(INCLUDES) -c $(SRC) -o $(OBJ)
$(TARGET) : $(OBJ)
$(LD) $(LDFLAGS) -o $(TARGET) $(OBJ) $(LIBS)
running this:
cc -Wall -Wextra -Werror -Wfatal-errors -O3 -I. -c main.c -o generic/obj/main.c.o
gcc -s -o generic/test generic/obj/main.c.o -lm -lc
Sooo, how can I make the autmatic variables expand after the TARGETDIR was defined?
Make does handle wildcards very deftly, or this would be a much easier problem.
As it is, I think the best solution is to use recursive Make. Just change this:
all: $(TARGET)
debug: $(TARGET)
to this:
all debug:
$(MAKE) $(TARGET) TARGETDIR=$(TARGETDIR) CFLAGS+='$(CFLAGS)' LDFLAGS=$(LDFLAGS)
First, the reason why it does not work :
You're using target-specific variables, but those are only available in the context of a target recipe (I'm quoting the manual here), not during the rules evaluation :
Make will first read your Makefile, evaluate your $(OBJDIR) and $(TARGET) rules (at this point $(TARGETDIR)is not yet defined) then, it will try to update all, and at this point set $(TARGETDIR) to the target-specific value for all (which explains why you're second example work, but it should rebuild every time).
I may have some hints to achieving what you're trying to do (I'm actually planning on doing a similar thing soon) :
you could use the eval function to generate one rule for each build/archi, like this:
#define TARGET_RULE
$(TARGET) : $(OBJ)
$$(RECIPE)
#endif
$(foreach TARGETDIR, $(BUILD_LIST), $(eval $(TARGET_RULE))
($$ is needed for the recipe to avoid it being expanded during the rule evaluation)
You should also be able to define only the rule or rules for the target you are currently building (not sure if that would make a signifiant perf difference).

How to write a makefile for llvm IR

If I have 3 files, function.h, function.c and my_program.c which calls a method in function.h all in the same directory, what would be the best way to write a makefile so that I end up with a my_program.bc that would actually run when I type in lli my_program.bc? (I need to run a user defined pass that would insert stuff into the functions - should I run the pass on function.bc and test.bc, or should I link before running the pass?)
I've tried llvm-link function.bc my_program.bc with no luck. I feel I'm either missing something simple or going about the whole thing wrong.
Current terrible none-working makefile:
.PHONY: all clean
CC = clang
CFLAGS = -std=gnu99 -D_POSIX_C_SOURCE=200809L -g -Wall
IRFLAGS = -O3 -emit-llvm
TARGET = test
DEPS = functions.h
all: $(TARGET)
bc: test2
%.o: %.c $(DEPS)
$(CC) -c -o $# $< $(CFLAGS)
%.bc: %.c $(DEPS)
$(CC) $(IRFLAGS) -c -o $# $<
test2: test.bc functions.bc
llvm-link -o test2.bc $< functions.bc
test: test.o functions.o
$(CC) $(CFLAGS) -o $# $^
clean:
$(RM) $(TARGET) *.o *.bc
Why not just write a normal Makefile to produce the desired executable,
then use wllvm?
Shameless plug for wllvm:
https://github.com/SRI-CSL/whole-program-llvm
I do not use lli, so I would be interested to hear about how it resolved
any reliance on stdlibc that your program may have.

gcc cannot specify -o with -c or -S with Multiple files

Whenever I am trying to build something like this in my Makefile -
gcc -o main.o -IStarterWare_Files -c main.c StarterWare_Files/test.h StarterWare_Files/add.h
It throws me error that gcc: cannot specify -o with -c or -S with multiple files. Basically I want my makefile to build the target again if I change for example some macro in one of my header files. My current Makefile is -
EXE = nextgenrsm
CC = gcc
LIBS = StarterWare_Files/
CPPFLAGS = _IStarterWare_Files/
MAIN_OBS = $(patsubst %.c,%.o,$(wildcard *.c))
LIB_OBS = $(patsubst %.c,%.o,$(wildcard StarterWare_Files/*.c))
all: $(EXE)
$(EXE): $(MAIN_OBS) $(LIB_OBS)
$(CC) -o $# $(LDFLAGS) $(MAIN_OBS) $(LIB_OBS) $(LDLIBS)
%.o: %.c
$(CC) -o $# -MD -MP $(CPPFLAGS) $(CFLAGS) -c $^
ALL_DEPS = $(patsubst %.o,%.d,$(MAIN_OBS), $(LIB_OBS))
-include $(ALL_DEPS)
clean:
rm -f $(LIB_OBS) $(EXE) $(MAIN_OBS) $(ALL_DEPS)
.PHONY: all clean
I can't figure out what changes to make to build my executable again if one of the header files is modified. I don't want to do make clean and make again.
The way the automake system handles this is to not use %.o: %.c but instead list the C file and all of the headers in the C file.
So for example:
main.o: main.c StarterWare_Files/test.h StarterWare_Files/add.h
$(CC) -o $# -MD -MP $(CPPFLAGS) $(CFLAGS) -c $^
See makedepends for a tool that will read C files and figure out the make dependencies.

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