Use gcc "-fwhole-program" optimization.
Use "whole program" and "link time optimization" features of gcc. The whole-program optimization enables the compiler to evaluate the entire firmware for optimization instead of just one code file at a time. This leads to better overall optimizations.
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		| @@ -227,6 +227,22 @@ OPT = s | ||||
|  | ||||
| DEFINES ?= | ||||
|  | ||||
| # Program settings | ||||
| CC = $(AVR_TOOLS_PATH)avr-gcc | ||||
| CXX = $(AVR_TOOLS_PATH)avr-g++ | ||||
| OBJCOPY = $(AVR_TOOLS_PATH)avr-objcopy | ||||
| OBJDUMP = $(AVR_TOOLS_PATH)avr-objdump | ||||
| AR  = $(AVR_TOOLS_PATH)avr-ar | ||||
| SIZE = $(AVR_TOOLS_PATH)avr-size | ||||
| NM = $(AVR_TOOLS_PATH)avr-nm | ||||
| AVRDUDE = avrdude | ||||
| REMOVE = rm -f | ||||
| MV = mv -f | ||||
|  | ||||
| # Tool for testing compiler flags | ||||
| cc-option=$(shell if test -z "`$(1) $(2) -S -o /dev/null -xc /dev/null 2>&1`" \ | ||||
|     ; then echo "$(2)"; else echo "$(3)"; fi ;) | ||||
|  | ||||
| # Place -D or -U options here | ||||
| CDEFS = -DF_CPU=$(F_CPU) ${addprefix -D , $(DEFINES)} | ||||
| CXXDEFS = -DF_CPU=$(F_CPU) ${addprefix -D , $(DEFINES)} | ||||
| @@ -251,8 +267,10 @@ CTUNING += -DMOTHERBOARD=${HARDWARE_MOTHERBOARD} | ||||
| endif | ||||
| #CEXTRA = -Wa,-adhlns=$(<:.c=.lst) | ||||
|  | ||||
| CFLAGS = $(CDEBUG) $(CDEFS) $(CINCS) -O$(OPT) $(CWARN) $(CEXTRA) $(CTUNING) | ||||
| CXXFLAGS =         $(CDEFS) $(CINCS) -O$(OPT) -Wall    $(CEXTRA) $(CTUNING) | ||||
| CFLAGS := $(CDEBUG) $(CDEFS) $(CINCS) -O$(OPT) $(CWARN) $(CEXTRA) $(CTUNING) \ | ||||
|     $(call cc-option,$(CC),-flto -fwhole-program,) | ||||
| CXXFLAGS :=         $(CDEFS) $(CINCS) -O$(OPT) -Wall    $(CEXTRA) $(CTUNING) \ | ||||
|     $(call cc-option,$(CC),-flto -fwhole-program,) | ||||
| #ASFLAGS = -Wa,-adhlns=$(<:.S=.lst),-gstabs  | ||||
| LDFLAGS = -lm -Wl,--relax | ||||
|  | ||||
| @@ -264,18 +282,6 @@ AVRDUDE_FLAGS = -D -C $(ARDUINO_INSTALL_DIR)/hardware/tools/avrdude.conf \ | ||||
| 	-p $(MCU) -P $(AVRDUDE_PORT) -c $(AVRDUDE_PROGRAMMER) \ | ||||
| 	-b $(UPLOAD_RATE) | ||||
|  | ||||
| # Program settings | ||||
| CC = $(AVR_TOOLS_PATH)avr-gcc | ||||
| CXX = $(AVR_TOOLS_PATH)avr-g++ | ||||
| OBJCOPY = $(AVR_TOOLS_PATH)avr-objcopy | ||||
| OBJDUMP = $(AVR_TOOLS_PATH)avr-objdump | ||||
| AR  = $(AVR_TOOLS_PATH)avr-ar | ||||
| SIZE = $(AVR_TOOLS_PATH)avr-size | ||||
| NM = $(AVR_TOOLS_PATH)avr-nm | ||||
| AVRDUDE = avrdude | ||||
| REMOVE = rm -f | ||||
| MV = mv -f | ||||
|  | ||||
| # Define all object files. | ||||
| OBJ = ${patsubst %.c, $(BUILD_DIR)/%.o, ${SRC}} | ||||
| OBJ += ${patsubst %.cpp, $(BUILD_DIR)/%.o, ${CXXSRC}} | ||||
| @@ -372,9 +378,13 @@ extcoff: $(TARGET).elf | ||||
| 	$(NM) -n $< > $@ | ||||
|  | ||||
| 	# Link: create ELF output file from library. | ||||
| $(BUILD_DIR)/$(TARGET).elf: $(OBJ) Configuration.h | ||||
| $(BUILD_DIR)/$(TARGET).elf: $(BUILD_DIR)/$(TARGET).o | ||||
| 	$(Pecho) "  CXX   $@" | ||||
| 	$P $(CC) $(ALL_CXXFLAGS) -Wl,--gc-sections -o $@ -L. $(OBJ) $(LDFLAGS) | ||||
| 	$P $(CC) $(ALL_CXXFLAGS) -Wl,--gc-sections -o $@ -L. $^ $(LDFLAGS) | ||||
|  | ||||
| $(BUILD_DIR)/$(TARGET).o: $(OBJ) Configuration.h | ||||
| 	$(Pecho) "  CXX   $@" | ||||
| 	$P $(CC) $(ALL_CXXFLAGS) -nostdlib -Wl,-r -o $@ $(OBJ) | ||||
|  | ||||
| $(BUILD_DIR)/%.o: %.c Configuration.h Configuration_adv.h $(MAKEFILE) | ||||
| 	$(Pecho) "  CC    $<" | ||||
|   | ||||
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