查看C语言文件依赖关系(用-Wp,MD参数生成.d文件)

1、-wp,-MD参数介绍

(1)在编译c源文件时使用该参数，会生成对应C源文件的.d格式的文件，.d格式的文件内容是C源文件的依赖关系；
(2)C源文件的依赖关系就是源文件调用了哪些头文件，可以方便我们确认工程中的同名头文件到底是引用的哪一份；
(3)在大型项目中(比如内核)，有很多同名头文件，可能放在了不同平台、不同产品类型的目录下，本次编译到底引用的哪个路径下的头文件，并不能很直观的看出来，这时候就可以通过-wp,-MD参数生成.d文件来看文件依赖关系；

2、Makefile中使用示例

dep_file = .$@.d

#Makefe的规则
%.o : %.c
	$(CC) $(CFLAGS) -Wp,-MD,$(dep_file) -c -o $@ $<
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(1)将.c文件编译成.o文件，并且将.c文件的依赖关系写到$(dep_file)文件中；
(2)上面Makefile的规则达到的效果：比如编译main.c文件，会生成main.o文件和.main.o文件；
注意：.main.d文件是隐藏文件，需要ls -a才能看到；

3、示例代码

3.1、main.c

#include 
#include 

//我自己写的头文件

#include "config.h"
#include "fb.h"
#include "bmp.h"
#include "decode_jpg.h"
#include "decode_png.h"
#include "imageManager.h"
#include "touchScreen.h"

int main(int argc, char *argv[])
{
	······
}

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3.2、.main.d文件

main.o: main.c \
	
 //编译链提供的头文件

 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/stdc-predef.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/stdio.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/bits/libc-header-start.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/features.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/sys/cdefs.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/bits/wordsize.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/bits/long-double.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/gnu/stubs.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/gnu/stubs-soft.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/lib/gcc/arm-linux-gnueabi/6.3.0/include/stddef.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/bits/types.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/bits/typesizes.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/libio.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/_G_config.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/wchar.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/lib/gcc/arm-linux-gnueabi/6.3.0/include/stdarg.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/bits/stdio_lim.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/bits/sys_errlist.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/bits/stdio.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/string.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/xlocale.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/bits/string.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/bits/string2.h \
 /opt/hisi-linux/x86-arm/arm-himix200v002-linux/target/usr/include/stdlib.h \
 
 //我自己写的头文件的路径
 
 /home/aston/study_myself/picturePlayer/myPlayer/build/../include/common/config.h \
 /home/aston/study_myself/picturePlayer/myPlayer/build/../include/fb/fb.h \
 /home/aston/study_myself/picturePlayer/myPlayer/build/../include/decode/bmp/bmp.h \
 /home/aston/study_myself/picturePlayer/myPlayer/build/../include/decode/jpg/decode_jpg.h \
 /home/aston/study_myself/picturePlayer/myPlayer/build/../include/decode/png/decode_png.h \
 /home/aston/study_myself/picturePlayer/myPlayer/build/../include/imageManager/imageManager.h \
 /home/aston/study_myself/picturePlayer/myPlayer/build/../include/touchScreen/touchScreen.h

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