Conditional execute within Makefile - makefile

Question

I would like to check if a file exists in a Makefile and run a recipe if it doesn't exist and stop after creating it else continue working with the file that exists and execute more recipes. I think this is best illustrated with an example in my Makefile:
GEN_C_FILES: GEN_C_FLS
$(shell cat $(DESIGN_TOP).c.tmp c_template.c.tmp > $(DESIGN_TOP).c )
$(DESIGN_TOP).c:
$(MAKE) GEN_C_FILES
#(echo $(DESIGN_TOP).c created and modify it to suit the design before running COMPILE)
exit 1
COMPILE: $(DESIGN_TOP).c
#(echo bsub -I compile_script-batch $(DESIGN_TOP).c -log $(DESIGN_TOP).log)
#(bsub -I compile_script -batch $(DESIGN_TOP).c -log $(DESIGN_TOP).log)
I can accomplish what I want but the exit produces an error message. I want it to exit if the recipe of $(DESIGN_TOP).c is executed but if the recipe is not executed the file exist and so it need not be generated and the rest of COMPILE target should complete by running the compile on bsub. Is there a better way to accomplish this without generating the error on exit?. Thanks

Answer 1

You can't make it work as you want when running make COMPILE. The only way to get make to stop in the middle of a build process and not proceed any further is to fail. But, instead you can change what make wants to build in the first place, like this:
GOAL = $(if $(wildcard $(DESIGN_TOP).c),COMPILE,$(DESIGN_TOP).c)
all: $(GOAL)
$(DESIGN_TOP).c:
cat $(DESIGN_TOP).c.tmp c_template.c.tmp > $#
#echo $# created and modify it to suit the design
COMPILE: $(DESIGN_TOP).c
bsub -I compile_script -batch $< -log $(DESIGN_TOP).log
Now if you run make or make all and the source file does not exist, the prerequisite of all will be the source file and nothing else, so it will be built then make will stop.
If the source file does exist, then the prerequisite of all will be COMPILE and it will be built.