Question

我尝试使用函数的输出初始化全局变量。它与gnu-gcc一样正常工作，但是当使用avr-gcc编译时，变量初始化为0.我希望变量由函数初始化，因为在实际场景中它是一个引用（MyClass& myclass = MyClass::getInstance()。

以下是代码：

extern "C"
{
    #include "led.h"
}

int getInteger() 
{
    return 10;
}

int my_int = getInteger();

int main (void)
{
    LED_On(LED2);

    //my_int = getInteger();    //* This line really sets my_int = 10;

    if(my_int == 10)
    {
        LED_On(LED1);
    }

    while(1){
        __asm__ ("nop");            
    }

    return 0;
}

这是我的Makefile：

PROJ_NAME=TEST

# Include paths for project folder
SRCS_INC += -I. -I./preprocessor

# Sources files for project folder (*.c and *.cpp)
SRCS += main.cpp exception_noNMI.S startup_uc3.S trampoline_uc3.S intc.c led.c

AS = avr32-gcc
ASFLAGS = -x assembler-with-cpp -c -mpart=uc3c1512c -mrelax 
ASFLAGS += ${SRCS_INC}

CC = avr32-gcc 
CFLAGS += -mpart=uc3c1512c
CFLAGS += ${SRCS_INC}

CXX = avr32-g++

LINKER = avr32-g++
OBJCOPY = avr32-objcopy

LDFLAGS  = -nostartfiles -mpart=uc3c1512c
LDFLAGS += ${SRCS_INC}

OBJS += $(addsuffix .o, $(basename $(SRCS)))

# Main rule
all: $(PROJ_NAME).elf

# Linking
${PROJ_NAME}.elf: ${OBJS}
    @echo Linking...
    @$(CXX) $(LDFLAGS) $^ -o $@  
    @$(OBJCOPY) -O ihex ${OBJCOPYFLAGS} $(PROJ_NAME).elf $(PROJ_NAME).hex
    @$(OBJCOPY) -O binary $(PROJ_NAME).elf $(PROJ_NAME).bin

# Assembly files in source folder
%.o: ./%.S
    @mkdir -p $(dir $@)
    @$(AS) $(ASFLAGS) -c $< -o $@

# C files in source folder
%.o: ./%.c
    @mkdir -p $(dir $@)
    @$(CC) -c $< -o $@ $(CFLAGS)

# CPP files in SRC folder
%.o: ./%.cpp
    @mkdir -p $(dir $@)
    @$(CXX) -c $< -o $@ $(CFLAGS)

.PHONY: clean
clean:
    @rm -f $(OBJS) $(PROJ_NAME).elf $(PROJ_NAME).hex $(PROJ_NAME).bin

我还尝试使用__attribute(constructor创建一个init函数，如this answer中所述。仍然不是原谅。

Answer 1

据我所知，您没有启用优化。因此，编译器实际上可能在启动期间调用getInteger。现在，您将使用未显示的内容替换默认启动。也许您只需要确保在启动期间完成此操作？此外，您可以尝试启用优化并查看呼叫是否已解决。

avr-gcc：未使用函数输出

1 个答案: