Question

我正在尝试让我的Makefile只编译已更改的源文件。在下面的Makefile中，如果源文件已更改，或者相应的.o对象文件不存在，我希望目标：%.o : ${SOURCE_DIR}/%.c和%.o : ${SOURCE_DIR}/%.s到仅编译。

不完全确定这里有什么问题，有人可以提供一些建议吗？

# Project name
# ---------------------------------------------------------------------------------------------------------------------

PROJECT_NAME = stm32f4_template

# Source configuration
# ---------------------------------------------------------------------------------------------------------------------

OUT_DIR = ./Build
SOURCE_DIR = ./Src

SOURCES  = main.c
SOURCES += startup.s

C_SOURCES  = $(filter %.c, $(SOURCES))
ASM_SOURCES +=  $(filter %.s, $(SOURCES))

OBJECTS  = $(C_SOURCES:.c=.o)
OBJECTS += $(ASM_SOURCES:.s=.o)

# Tools 
# ---------------------------------------------------------------------------------------------------------------------

CC = arm-none-eabi-gcc
LD = arm-none-eabi-ld -v
CP = arm-none-eabi-objcopy
OD = arm-none-eabi-objdump

# Compilation, linker and other tool flags
# ---------------------------------------------------------------------------------------------------------------------

CFLAGS  =  -I./ -c -fno-common -O0 -g -mcpu=cortex-m4 -mthumb
LFLAGS  = -nostartfiles -TLinker/memory.ld -TLinker/sections.ld
CPFLAGS = -Obinary
ODFLAGS = -S

# Target: all ---------------------------------------------------------------------------------------------------------
#
all: setup $(PROJECT_NAME).elf
    @echo "Done! $?"

# Target: setup -------------------------------------------------------------------------------------------------------
#
setup:
    @mkdir -p $(OUT_DIR)

# Target: $(PROJECT_NAME).elf 
# ---------------------------------------------------------------------------------------------------------------------

$(PROJECT_NAME).elf: $(OBJECTS)
    @echo "Linking $@"
    $(LD) $(LFLAGS) -o ${OUT_DIR}/main.elf $(OUT_DIR)/main.o
    @echo

# Target %.o (.c sources)
# ---------------------------------------------------------------------------------------------------------------------
%.o : ${SOURCE_DIR}/%.c # --> Execute only if source changed!!!
    @echo "Compiling $<"
    $(CC) $(CFLAGS) $< -o $(OUT_DIR)/$@
    @echo

# Target %.o (.s sources)
# ---------------------------------------------------------------------------------------------------------------------
%.o : ${SOURCE_DIR}/%.s # --> Execute only if source changed!!!
    @echo "Compiling $<"
    $(CC) $(CFLAGS) $< -o $(OUT_DIR)/$@
    @echo

# Target: clean
# --------------------------------------------------------------------------------------------------------------------- 
clean:
    @echo "Cleaning build output..."
    @rm -rf $(OUT_DIR)

Answer 1

这条规则：

%.o : ${SOURCE_DIR}/%.c # --> Execute only if source changed!!!
    @echo "Compiling $<"
    $(CC) $(CFLAGS) $< -o $(OUT_DIR)/$@

问题在于此规则的目标是main.o，因此Make使用它来构建main.o，因为另一个目标要求 main.o ，但这条规则实际构建的是Build/main.o。 Make继续运行此规则，因为它看到main.o不存在（并且elf文件的规则使用Build/main.o，Make使得重建不知不觉）。

我建议你改变它：

OBJECTS  = $(patsubst %.c, $(OUT_DIR)/%.o, $(C_SOURCES))

$(OUT_DIR)/%.o : ${SOURCE_DIR}/%.c # --> this should work
    @echo "Compiling $<"
    $(CC) $(CFLAGS) $< -o $@

其他％.o规则也是如此。

make make只重新编译未更改的源文件

1 个答案: