在CMakeList.txt中检测到32位x86处理器？ [英] Detect 32-bit x86 processor in CMakeList.txt?

问题描述

由于缺少 -fPIC 错误 c>。她是ci20 MIPS开发板上的一位：

  ... 
 [92 ％]构建目标cryptopp-object 
扫描目标cryptopp共享的
的依赖关系扫描目标cryptopp-static 
的依赖关系链接CXX静态库libcryptopp.a 
链接CXX共享库libcryptopp。因此
 / usr / bin / ld：CMakeFiles / cryptopp-object.dir / cryptlib.cpp.o：将R_MIPS_HI16相对于
本地符号进行重定位时，不能使用共享对象；用-fPIC 
重新编译CMakeFiles / cryptopp-object.dir / cryptlib.cpp.o：无法读取符号：错误值
 collect2：ld返回1退出状态
  

由于寄存器压力，除32位x86以外，该项目的政策一直对我们PIC有用。这意味着x86_64，ARM-32，Aarch32，Aarch64，MIPS，MIPS64，UltraSparc等将获得PIC。

我相信目标处理器在 CMAKE_SYSTEM_PROCESSOR 。我遇到的问题是文档没有告诉我这些值，因此我无法弄清楚如何制作非32位x86测试。

如何在CMakeList.txt中检测32位x86处理器？

更好的是，我希望看到CMake设置<$ c $的处理器的完整列表。 c> CMAKE_SYSTEM_PROCESSOR 到。

解决方案

我可能会在编译器周围构建一些东西。 / p>

使用现有变量/模块的近似值是：

  include（TestBigEndian）
 
 if（不是WIN32）
 TEST_BIG_ENDIAN（_bigendian）
 if（（（CMAKE_SIZEOF_VOID_P GREATER 4）OR（_bigendian））
消息（
 STATUS正在设置$ {CMAKE_CXX_COMPILE_OPTIONS_PIC} 
对于机器$ {CMAKE_HOST_SYSTEM_PROCESSOR} 
）
 set（CMAKE_POSITION_INDEPENDENT_CODE 1）
 endif（）
 endif（）
  

简而言之，我做了什么：

• WIN32 也适用于64位Windows编译器/环境


• CMAKE_SIZEOF_VOID_P GREATER 4 检查大于32位


• 最后一个是bigg最佳假设：将所有小的字节序处理器作为基于Intel / AMD的


• 使用更通用的 CMAKE_POSITION_INDEPENDENT_CODE 设置 -fPIC

我承认更准确的方法是围绕预定义的宏测试构建一些东西。

编辑：添加了预定义宏检查选项

以下是对预定义宏的更精确的检查：

  include（CheckCXXSourceCompiles）
 
 if（CMAKE_CXX_COMPILE_OPTIONS_PIC）
 set（
 _preDefMacrosX86 
 __i386 __i386__ __i486__ __i586__ __i686__ 
 _M_I86 _M_IX86 __X86__ _X86_ __THW_INTEL__ 
 __I86__ __INTEL__ __386 
）
 set（_} foreach（_宏在列表中_preDefMacrosX86）
 set（
 _code 
 $ {_ code} \n\＃ifdef $ {_ macro} \n\＃error $ {_ macro}已定义\ n\＃endif 
）
 endforeach（）
 CHECK_CXX_SOURCE_COMPILES（ $ {_ code} _canCompileX86DoesFailCheck）
 
 if（（CMAKE_SIZEOF_VOID_P GREATER 4）OR（_canCompileX86Does ））
消息（状态正在设置$ {CMAKE_CXX_COMPILE_OPTIONS_PIC}））
 set（CMAKE_POSITION_INDEPENDENT_CODE 1）
 endif（）
 endif（）
  

参考

• < a href = https://stackoverflow.com/questions/39258250/how-to-detect-if-64-bit-msvc-with-cmake>如何使用cmake检测64位MSVC？


• 检测CPU体系结构的编译时间
  

We are catching errors in our CMake makefiles due to lack of -fPIC. Her's one from a ci20 MIPS dev-board:

...
[ 92%] Built target cryptopp-object
Scanning dependencies of target cryptopp-shared
Scanning dependencies of target cryptopp-static
Linking CXX static library libcryptopp.a
Linking CXX shared library libcryptopp.so
/usr/bin/ld: CMakeFiles/cryptopp-object.dir/cryptlib.cpp.o: relocation R_MIPS_HI16 against
`a local symbol' can not be used when making a shared object; recompile with -fPIC
CMakeFiles/cryptopp-object.dir/cryptlib.cpp.o: could not read symbols: Bad value
collect2: ld returned 1 exit status

The project's policy is to us PIC everywhere except 32-bit x86 due to register pressures. That means x86_64, ARM-32, Aarch32, Aarch64, MIPS, MIPS64, UltraSparc, etc get PIC.

I believe the target processor is provided in CMAKE_SYSTEM_PROCESSOR. The problem I am having is the docs don't tell me the values, so I can't figure out how to craft a "not 32-bit x86" test.

How do I detect 32-bit x86 processor in CMakeList.txt?

Even better, I would like to see a comprehensive list of processors that CMake sets CMAKE_SYSTEM_PROCESSOR to. If anyone has the list, then it would be great to provide it.

解决方案

I probably would build something around the compiler.

A close approximation using existing variables/modules would be:

include(TestBigEndian)

if (NOT WIN32)
    TEST_BIG_ENDIAN(_bigendian)
    if((CMAKE_SIZEOF_VOID_P GREATER 4) OR (_bigendian))
        message(
            STATUS "Setting ${CMAKE_CXX_COMPILE_OPTIONS_PIC} "
                   "for machine ${CMAKE_HOST_SYSTEM_PROCESSOR}"
        )
        set(CMAKE_POSITION_INDEPENDENT_CODE 1)
    endif()
endif()

In short what I have done:

• WIN32 is also valid for 64 Bit Windows compilers/environments
• CMAKE_SIZEOF_VOID_P GREATER 4 checks for "greater then 32 Bit"
• The last is the biggest assumption: take all little endian processors as Intel/AMD based
• Used more generic CMAKE_POSITION_INDEPENDENT_CODE to set -fPIC

I admit a more accurate method would be to build something around a pre-defined macros test.

Edit: Added "Predefined Macros Check" Alternative

Here is the more precise check for predefined macros:

include(CheckCXXSourceCompiles)

if (CMAKE_CXX_COMPILE_OPTIONS_PIC)
    set(
        _preDefMacrosX86 
            __i386 __i386__ __i486__ __i586__ __i686__      
            _M_I86 _M_IX86 __X86__ _X86_ __THW_INTEL__
            __I86__ __INTEL__ __386
    )
    set(_code "void main() {}")
    foreach(_macro IN LISTS _preDefMacrosX86)
        set(
            _code
            "${_code}\n\#ifdef ${_macro}\n\#error ${_macro} is defined\n\#endif"
        )
    endforeach()
    CHECK_CXX_SOURCE_COMPILES("${_code}" _canCompileX86DoesFailCheck)

    if((CMAKE_SIZEOF_VOID_P GREATER 4) OR (_canCompileX86DoesFailCheck))
        message(STATUS "Setting ${CMAKE_CXX_COMPILE_OPTIONS_PIC}")
        set(CMAKE_POSITION_INDEPENDENT_CODE 1)
    endif()
endif()

References

• How to detect if 64 bit MSVC with cmake?
• Detecting CPU architecture compile-time

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