OpenBLAS:改进OpenBLASConfig.cmake生成方式,解除cmake脚本的路径依赖

问题描述

当我们用OpenBLAS提供的Makefile进行编译，并用make install PREFIX=/you/install/path,安装到指定的路径时，你会发现，/you/install/path/lib/cmake/openblas/OpenBLASConfig.cmake文件中OpenBLAS_INCLUDE_DIRS和OpenBLAS_LIBRARIES的值都是绝对路径,如下：

/you/install/path/lib/cmake/openblas/OpenBLASConfig.cmake
(linux下生成动态库)

SET(OpenBLAS_VERSION "0.2.18")SET(OpenBLAS_INCLUDE_DIRS /home/hadoop/Desktop/caffe-static/release/OpenBLAS_linux_x86_64/include)SET(OpenBLAS_LIBRARIES /home/hadoop/Desktop/caffe-static/release/OpenBLAS_linux_x86_64/bin/libopenblas.so)

(linux下生成静态库)

SET(OpenBLAS_VERSION "0.2.18")SET(OpenBLAS_INCLUDE_DIRS /home/hadoop/Desktop/caffe-static/release/OpenBLAS_linux_x86_64/include)SET(OpenBLAS_LIBRARIES /home/hadoop/Desktop/caffe-static/release/OpenBLAS_linux_x86_64/lib/libopenblas.a)

(windows下生成动态库)

SET(OpenBLAS_VERSION "0.2.18")SET(OpenBLAS_INCLUDE_DIRS D:/caffe-static/release/OpenBLAS_windows_vc140_x86_mt/include)SET(OpenBLAS_LIBRARIES D:/caffe-static/release/OpenBLAS_windows_vc140_x86_mt/bin/libopenblas.dll)

关于windows下如何用MinGW编译OpenBLAS，参见我的另一篇博客《Windows下MSYS2中编译OpenBLAS过程记录》

如果你编译OpenBLAS只是在本机使用，那没啥问题，如果想把这个编译好的OpenBLAS 移到别的位置或提供给别人使用，并且也是用cmake编译项目。那么问题就来了，因为OpenBLASConfig.cmake中的路径依赖问题，导致cmake脚本中调用find_package( OpenBLAS NO_MODULE )返回的OpenBLAS_LIBRARIES和OpenBLAS_LIBRARIES的值都是错的!

而且你发现没有？上面Windows下生成的OpenBLASConfig.cmake中OpenBLAS_LIBRARIES的值居然是.dll的路径。而不是动态库导入库(import library)(.dll.a)的路径,也就是说OpenBLAS在生成OpenBLASConfig.cmake没有考虑到linux和windows的区别，只是按linux的方式将OpenBLAS_LIBRARIES置为静态库/动态库(.a,.so,dll)的路径。

如果你是用手工在Visual Studio中创建工程并设置工程参数，那么这都不是问题，对你没有任何影响，但如果你像我一样，用cmake进行工程编译，这是个很要命的问题，因为cmake根据这些错误的信息无法生成正确的Makefile,当然也不能正常编译。

原因分析

怎么办呢?指望OpenBLAS官方修改这个问题怕是来不及了,只能自己想办法解决。
于是我仔细研究了OpenBLAS的Makefile的体系。算是基本搞清楚了OpenBLAS源码下那一大堆Makefile.*的作用。最终找到了问题的关键点：
Makefile.install 这个文件是OpenBLAS的安装脚本，当执行 make install时其实就是执行这个脚本来执行安装工作的。

而在这其中生成OpenBLASConfig.cmake的代码就是如下几行(line 97-116 OpenBLAS 0.2.18)
(中文注释为本文作者所加)

#Generating OpenBLASConfig.cmake    @echo Generating $(OPENBLAS_CMAKE_CONFIG) in $(DESTDIR)$(OPENBLAS_CMAKE_DIR)    # 对应OpenBLASConfig.cmake中line 1    @echo "SET(OpenBLAS_VERSION \"${VERSION}\")" > $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)        # 对应OpenBLASConfig.cmake中line 2    @echo "SET(OpenBLAS_INCLUDE_DIRS ${OPENBLAS_INCLUDE_DIR})" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)ifndef NO_SHARED#ifeq logical or# 判断操作系统将OpenBLAS_LIBRARIES置为动态库文件路径ifeq ($(OSNAME), $(filter $(OSNAME),Linux FreeBSD NetBSD))    # 对应OpenBLASConfig.cmake中line 3    @echo "SET(OpenBLAS_LIBRARIES ${OPENBLAS_LIBRARY_DIR}/$(LIBPREFIX).so)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)endififeq ($(OSNAME), $(filter $(OSNAME),WINNT CYGWIN_NT))    # 对应OpenBLASConfig.cmake中line 3    # 这里 LIBDLLNAME   = $(LIBPREFIX).dll 参见 Makefile.system    @echo "SET(OpenBLAS_LIBRARIES ${OPENBLAS_BINARY_DIR}/$(LIBDLLNAME))" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)endififeq ($(OSNAME), Darwin)    # 对应OpenBLASConfig.cmake中line 3    @echo "SET(OpenBLAS_LIBRARIES ${OPENBLAS_LIBRARY_DIR}/$(LIBPREFIX).dylib)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)endifelse# 将OpenBLAS_LIBRARIES置为静态库文件路径#only static    # 对应OpenBLASConfig.cmake中line 3    @echo "SET(OpenBLAS_LIBRARIES ${OPENBLAS_LIBRARY_DIR}/$(LIBPREFIX).$(LIBSUFFIX))" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)endif

OPENBLAS_INCLUDE_DIR,OPENBLAS_LIBRARY_DIR,OPENBLAS_BINARY_DIR在Makefile.install文件开头定义 (line 8-10 OpenBLAS 0.2.18)

上面的三行@echo的代码清晰的对应着OpenBLASConfig.cmake中的三行代码，由此我们理解为什么OpenBLASConfig.cmake中的路径都是绝对路径，而且windows下OpenBLAS_LIBRARIES的值是.dll文件的路径了。

解决方法

原因搞清楚就好办了，要解决问题，只要修改上面这段代码，改进生成OpenBLASConfig.cmake的逻辑就可以了。

以下是上面代码(Makefile.install)修改后的版本：

#Generating OpenBLASConfig.cmake# modified by guyadong for windows build    @echo Generating $(OPENBLAS_CMAKE_CONFIG) in $(DESTDIR)$(OPENBLAS_CMAKE_DIR)       @echo "SET(OpenBLAS_VERSION \"${VERSION}\")" > $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)        @echo "# modified by guyadong,use relative path instead of absolute path" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)        @echo "# Compute the installation prefix relative to this file." >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)     @echo "get_filename_component(_IMPORT_PREFIX \"\$${CMAKE_CURRENT_LIST_FILE}\" PATH)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "get_filename_component(_IMPORT_PREFIX \"\$${_IMPORT_PREFIX}\" PATH)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)        @echo "get_filename_component(_IMPORT_PREFIX \"\$${_IMPORT_PREFIX}\" PATH)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)       @echo "get_filename_component(_IMPORT_PREFIX \"\$${_IMPORT_PREFIX}\" PATH)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)      @echo "if(_IMPORT_PREFIX STREQUAL \"/\")" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo " set(_IMPORT_PREFIX \"\")" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "endif()" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "SET(OpenBLAS_INCLUDE_DIRS \$${_IMPORT_PREFIX}/include)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)ifndef NO_SHARED#ifeq logical orifeq ($(OSNAME), $(filter $(OSNAME),Linux FreeBSD NetBSD))    @echo "SET(OpenBLAS_LIBRARIES \$${_IMPORT_PREFIX}/lib/$(LIBPREFIX).so)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)endififeq ($(OSNAME), $(filter $(OSNAME),WINNT CYGWIN_NT))# windows下编译时生成条件判断语句    @echo "# use dynamic import library if MSVC" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)        @echo "if(MSVC)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo " SET(OpenBLAS_LIBRARIES \$${_IMPORT_PREFIX}/lib/$(LIBDLLNAME).a)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "else(MSVC)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo " SET(OpenBLAS_LIBRARIES \$${_IMPORT_PREFIX}/bin/$(LIBDLLNAME))" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "endif(MSVC)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "SET(OPENBLAS_IS_DYNAMIC true)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)endififeq ($(OSNAME), Darwin)    @echo "SET(OpenBLAS_LIBRARIES \$${_IMPORT_PREFIX}/lib/$(LIBPREFIX).dylib)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)endifelse#only static    @echo "SET(OpenBLAS_LIBRARIES \$${_IMPORT_PREFIX}/lib/$(LIBPREFIX).$(LIBSUFFIX))" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)# windows下编译时生成条件判断语句ifeq ($(OSNAME), $(filter $(OSNAME),WINNT CYGWIN_NT))        @echo "if(MSVC)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo " message(STATUS \"OpenBLAS_LIBRARIES(static library):\$${OpenBLAS_LIBRARIES}\" )" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo " message(FATAL_ERROR \"With Visual Studio, only dynamic linking is supported,please reinstall OpenBLAS without NO_STATIC=1\" )" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "endif(MSVC)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "SET(OPENBLAS_IS_DYNAMIC false)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)endif   endififeq ($(OSNAME), $(filter $(OSNAME),WINNT CYGWIN_NT))        @echo "# if OpenBlas_USE_STATIC is true,force to use static library with MinGW" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "if(OPENBLAS_IS_DYNAMIC)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo " if(EXISTS \"\$${_IMPORT_PREFIX}/lib/$(LIBPREFIX).$(LIBSUFFIX)\" AND OpenBlas_USE_STATIC AND NOT MSVC)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "     MESSAGE(STATUS \"use OpenBlas static library\")" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "     SET(OpenBLAS_LIBRARIES \$${_IMPORT_PREFIX}/lib/$(LIBPREFIX).$(LIBSUFFIX))" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo " endif()" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "endif(OPENBLAS_IS_DYNAMIC)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)    @echo "unset(OPENBLAS_IS_DYNAMIC)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)endif    @echo "unset(_IMPORT_PREFIX)" >> $(DESTDIR)$(OPENBLAS_CMAKE_DIR)/$(OPENBLAS_CMAKE_CONFIG)

经过上面的修改，再重新执行make install PREFIX=/you/install/path,生成的OpenBLASConfig.cmake(中文注释为本文作者所加)
(linux下生成静态态库)

# modified by guyadong,use relative path instead of absolute path# Compute the installation prefix relative to this file.# 三次调用 get_filename_component 计算 OpenBLAS安装路径# _IMPORT_PREFIX为OpenBLAS安装路径get_filename_component(_IMPORT_PREFIX "${CMAKE_CURRENT_LIST_DIR}" PATH)get_filename_component(_IMPORT_PREFIX "${_IMPORT_PREFIX}" PATH)get_filename_component(_IMPORT_PREFIX "${_IMPORT_PREFIX}" PATH)if(_IMPORT_PREFIX STREQUAL "/")    set(_IMPORT_PREFIX "")endif()SET(OpenBLAS_INCLUDE_DIRS ${_IMPORT_PREFIX}/include)SET(OpenBLAS_LIBRARIES ${_IMPORT_PREFIX}/lib/libopenblas.a)unset(_IMPORT_PREFIX)

(windows下生成动态库)

# modified by guyadong,use relative path instead of absolute path# Compute the installation prefix relative to this file.# 三次调用 get_filename_component 计算 OpenBLAS安装路径# _IMPORT_PREFIX为OpenBLAS安装路径get_filename_component(_IMPORT_PREFIX "${CMAKE_CURRENT_LIST_DIR}" PATH)get_filename_component(_IMPORT_PREFIX "${_IMPORT_PREFIX}" PATH)get_filename_component(_IMPORT_PREFIX "${_IMPORT_PREFIX}" PATH)if(_IMPORT_PREFIX STREQUAL "/")    set(_IMPORT_PREFIX "")endif()SET(OpenBLAS_INCLUDE_DIRS ${_IMPORT_PREFIX}/include)# 判断编译器类型，MSVC下置为import library(.dll.a) ,否则(MinGW)置为.dllif(MSVC)    SET(OpenBLAS_LIBRARIES ${_IMPORT_PREFIX}/lib/libopenblas.dll.a)else(MSVC)    SET(OpenBLAS_LIBRARIES ${_IMPORT_PREFIX}/bin/libopenblas.dll)endif(MSVC)SET(openblas_is_dynamic true)# if OpenBlas_USE_STATIC is true,force to use static library with MinGWif(openblas_is_dynamic)    # 使用MinGW编译时,如果定义了OpenBlas_USE_STATIC,则置为静态库    if(EXISTS "${_IMPORT_PREFIX}/lib/libopenblas.a" AND OpenBlas_USE_STATIC AND NOT MSVC)        SET(OpenBLAS_LIBRARIES ${_IMPORT_PREFIX}/lib/libopenblas.a)    endif()endif(openblas_is_dynamic)unset(openblas_is_dynamic)unset(_IMPORT_PREFIX)

完整代码

修改后的OpenBLAS Makefile.install完整代码参见 ：

https://code.csdn.net/10km/caffe-static/tree/master/patch/OpenBLAS-0.2.18/Makefile.install

后记

本文对 Makefile.install的修改已经申请 Pull Request ,如果被接受，后续OpenBLAS的版本就不需要这样手工修改了。
https://github.com/xianyi/OpenBLAS/pull/1231