I want to experiment with GCC whole program optimizations. To do so I have to pass all C-files at once to the compiler frontend. However, I use makefiles to automate my build process, and I'm not an expert when it comes to makefile magic.
How should I modify the makefile if I want to compile (maybe even link) using just one call to GCC?
For reference - my makefile looks like this:
LIBS = -lkernel32 -luser32 -lgdi32 -lopengl32
CFLAGS = -Wall
OBJ = 64bitmath.o \
monotone.o \
node_sort.o \
planesweep.o \
triangulate.o \
prim_combine.o \
welding.o \
test.o \
main.o
%.o : %.c
gcc -c $(CFLAGS) $< -o $@
test: $(OBJ)
gcc -o $@ $^ $(CFLAGS) $(LIBS)
SRCS=$(wildcard *.c)
OBJS=$(SRCS:.c=.o)
all: $(OBJS)
You need to take out your suffix rule (%.o: %.c) in favour of a big-bang rule. Something like this:
LIBS = -lkernel32 -luser32 -lgdi32 -lopengl32
CFLAGS = -Wall
OBJ = 64bitmath.o \
monotone.o \
node_sort.o \
planesweep.o \
triangulate.o \
prim_combine.o \
welding.o \
test.o \
main.o
SRCS = $(OBJ:%.o=%.c)
test: $(SRCS)
gcc -o $@ $(CFLAGS) $(LIBS) $(SRCS)
If you're going to experiment with GCC's whole-program optimization, make sure that you add the appropriate flag to CFLAGS, above.
On reading through the docs for those flags, I see notes about link-time optimization as well; you should investigate those too.
Source: Stackoverflow.com