prepend（）是CMake的内置函数还是宏？

我试图阅读Pytorch的源代码，却被它的CMake文件卡住了

正如您在文件中看到的：

##############################################################################
#宏以更新缓存选项。
宏（caffe2_更新_选项变量值）
if（CAFFE2\U CMAKE\U大楼\U带主回购）
get_属性（uu帮助_字符串缓存${variable}属性帮助字符串）
set（${variable}${value}CACHE BOOL${{uuuu help\u string}FORCE）
else（）
集合（${variable}${value}）
endif（）
endmacro（）
##############################################################################
#添加依赖于源的接口库定义。
#
#要解释这个宏存在的原因，最简单的方法可能是描述
#如果没有这个宏，情况会是什么样子。
#
#让我们假设我们想要静态链接到火炬。我们已经定义了
#cmake的一个图书馆叫torch，我们可能认为
#目标链接库（我的应用程序公共火炬）。这将导致
#链接器参数“libtorch.a”正在传递给链接器。
#
#不幸的是，这个链接命令是错误的！我们有静电干扰
#libtorch.a中的初始值设定项会被
#默认链接设置。我们真正需要的是你
#做-Wl，-整个档案，libtorch.a-Wl，-没有整个档案要确保
#我们保留所有符号，即使它们（看起来）没有被使用。
#
#caffe2_接口_库所做的是创建一个接口库
#这间接地依赖于真实的库，但建立了链接
#参数，以便获得所需的所有额外链接设置。
#结果不是一个“真正的”库，因此我们必须手动创建
#从原始目标复制必要的属性。
#
#（上面的讨论是关于静态库的，但是类似的
#动态库会出现这样的情况：如果没有从中使用符号
#一个动态库，它将被删减，除非您是--不需要）
宏（caffe2_接口_库SRC DST）
添加库（${DST}接口）
添加依赖项（${DST}${SRC}）
#根据源库和编译器的性质，
#确定所需的编译标志。
get_target_属性（uu src_target_type${src}type）
#根据源库的类型，我们将设置
#特定SRC库的link命令。
if（${u\u src\u target\u type}STREQUAL“STATIC\u LIBRARY”）
#对于静态库，我们需要添加整个静态标志。
如果（苹果）
目标链接库(
${DST}接口-Wl，-力荷载，$）
elseif（MSVC）
#在MSVC中，我们将在默认情况下添加整个存档。
目标链接库(
${DST}接口-wholerchive:$）
else（）
#假设其他一切都像gcc
目标链接库（${DST}接口
“-Wl，--整个档案，$-Wl，--没有整个档案”）
endif（）
#链接src目标的所有接口链接库。
#对于静态库，我们需要显式地依赖于所有库
#是源库的从属库。请注意，我们不能
#使用填充的接口链接库属性，因为如果
#依赖库不是目标，cmake创建$wrapper
#然后就找不到目标“src”。有关更多讨论，请查看
#   https://gitlab.kitware.com/cmake/cmake/issues/15415
#   https://cmake.org/pipermail/cmake-developers/2013-May/019019.html
#具体如下
#
# """
#对于静态库，我们可以定义PUBLIC/PRIVATE/INTERFACE键
#为链接而忽略，并且它始终填充两个链接库
#链接\接口\库。请注意，对于静态库
#链接库属性将不用于除生成顺序之外的任何内容
#依赖关系。
# """
目标链接库（${DST}接口
$)
elseif（${u_src_target_type}STREQUAL“共享_库”）
如果（${CMAKE\u CXX\u COMPILER\u ID}）匹配“GNU”）
目标链接库（${DST}接口
“-Wl，--不需要，$-Wl，--需要时”）
else（）
目标链接库（${DST}接口${SRC}）
endif（）
#链接src目标的所有接口链接库。
#对于共享库，我们可以简单地依赖于接口链接库
#目标的属性。
目标链接库（${DST}接口
$)
else（）
消息（致命错误）
您犯了一个CMake生成文件错误：目标“${SRC}
必须是静态\u库或共享\u库的类型。但是
“我得到了“${uuu src\u target\u type}”。”
endif（）
#对于所有其他接口属性，请手动从源目标继承。
设置_目标_属性（${DST}属性
接口\u编译\u定义
$
接口\编译\选项
$
接口包括目录
$
接口\系统\包括\目录
$)
endmacro（）
##############################################################################
#使用相对路径指定的源创建Caffe2二进制目标。
#用法：
#caffe2_二进制_目标（目标_名称_或_src[][…）
#如果只指定了target\u name\u或\u src，则此目标是使用单个
#源文件和目标名称是文件名中的autogen。否则
#目标名称由第一个参数给出，其余为源文件
#建立目标。
函数（caffe2\u二进制\u目标\u名称\u或\u src）
# https://cmake.org/cmake/help/latest/command/function.html
#检查ARGC是否大于#是确保
#该ARGV#作为额外参数传递给函数。
如果（ARGC大于1）
set（uuu target${target_name_u或_src}）
前置（${CMAKE\u CURRENT\u SOURCE\u DIR}/“${ARGN}”）
else（）
获取\u文件名\u组件（\u目标${target\u name\u或\u src}name\u WE）
前置（uu srcs“${CMAKE\u CURRENT\u SOURCE\u DIR}/“${target\u name\u或_src}”）
恩迪夫(
##############################################################################
# Macro to update cached options.
macro (caffe2_update_option variable value)
  if(CAFFE2_CMAKE_BUILDING_WITH_MAIN_REPO)
    get_property(__help_string CACHE ${variable} PROPERTY HELPSTRING)
    set(${variable} ${value} CACHE BOOL ${__help_string} FORCE)
  else()
    set(${variable} ${value})
  endif()
endmacro()


##############################################################################
# Add an interface library definition that is dependent on the source.
#
# It's probably easiest to explain why this macro exists, by describing
# what things would look like if we didn't have this macro.
#
# Let's suppose we want to statically link against torch.  We've defined
# a library in cmake called torch, and we might think that we just
# target_link_libraries(my-app PUBLIC torch).  This will result in a
# linker argument 'libtorch.a' getting passed to the linker.
#
# Unfortunately, this link command is wrong!  We have static
# initializers in libtorch.a that would get improperly pruned by
# the default link settings.  What we actually need is for you
# to do -Wl,--whole-archive,libtorch.a -Wl,--no-whole-archive to ensure
# that we keep all symbols, even if they are (seemingly) not used.
#
# What caffe2_interface_library does is create an interface library
# that indirectly depends on the real library, but sets up the link
# arguments so that you get all of the extra link settings you need.
# The result is not a "real" library, and so we have to manually
# copy over necessary properties from the original target.
#
# (The discussion above is about static libraries, but a similar
# situation occurs for dynamic libraries: if no symbols are used from
# a dynamic library, it will be pruned unless you are --no-as-needed)
macro(caffe2_interface_library SRC DST)
  add_library(${DST} INTERFACE)
  add_dependencies(${DST} ${SRC})
  # Depending on the nature of the source library as well as the compiler,
  # determine the needed compilation flags.
  get_target_property(__src_target_type ${SRC} TYPE)
  # Depending on the type of the source library, we will set up the
  # link command for the specific SRC library.
  if (${__src_target_type} STREQUAL "STATIC_LIBRARY")
    # In the case of static library, we will need to add whole-static flags.
    if(APPLE)
      target_link_libraries(
          ${DST} INTERFACE -Wl,-force_load,$<TARGET_FILE:${SRC}>)
    elseif(MSVC)
      # In MSVC, we will add whole archive in default.
      target_link_libraries(
          ${DST} INTERFACE -WHOLEARCHIVE:$<TARGET_FILE:${SRC}>)
    else()
      # Assume everything else is like gcc
      target_link_libraries(${DST} INTERFACE
          "-Wl,--whole-archive,$<TARGET_FILE:${SRC}> -Wl,--no-whole-archive")
    endif()
    # Link all interface link libraries of the src target as well.
    # For static library, we need to explicitly depend on all the libraries
    # that are the dependent library of the source library. Note that we cannot
    # use the populated INTERFACE_LINK_LIBRARIES property, because if one of the
    # dependent library is not a target, cmake creates a $<LINK_ONLY:src> wrapper
    # and then one is not able to find target "src". For more discussions, check
    #   https://gitlab.kitware.com/cmake/cmake/issues/15415
    #   https://cmake.org/pipermail/cmake-developers/2013-May/019019.html
    # Specifically the following quote
    #
    # """
    # For STATIC libraries we can define that the PUBLIC/PRIVATE/INTERFACE keys
    # are ignored for linking and that it always populates both LINK_LIBRARIES
    # LINK_INTERFACE_LIBRARIES.  Note that for STATIC libraries the
    # LINK_LIBRARIES property will not be used for anything except build-order
    # dependencies.
    # """
    target_link_libraries(${DST} INTERFACE
        $<TARGET_PROPERTY:${SRC},LINK_LIBRARIES>)
  elseif(${__src_target_type} STREQUAL "SHARED_LIBRARY")
    if("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU")
      target_link_libraries(${DST} INTERFACE
          "-Wl,--no-as-needed,$<TARGET_FILE:${SRC}> -Wl,--as-needed")
    else()
      target_link_libraries(${DST} INTERFACE ${SRC})
    endif()
    # Link all interface link libraries of the src target as well.
    # For shared libraries, we can simply depend on the INTERFACE_LINK_LIBRARIES
    # property of the target.
    target_link_libraries(${DST} INTERFACE
        $<TARGET_PROPERTY:${SRC},INTERFACE_LINK_LIBRARIES>)
  else()
    message(FATAL_ERROR
        "You made a CMake build file error: target " ${SRC}
        " must be of type either STATIC_LIBRARY or SHARED_LIBRARY. However, "
        "I got " ${__src_target_type} ".")
  endif()
  # For all other interface properties, manually inherit from the source target.
  set_target_properties(${DST} PROPERTIES
    INTERFACE_COMPILE_DEFINITIONS
    $<TARGET_PROPERTY:${SRC},INTERFACE_COMPILE_DEFINITIONS>
    INTERFACE_COMPILE_OPTIONS
    $<TARGET_PROPERTY:${SRC},INTERFACE_COMPILE_OPTIONS>
    INTERFACE_INCLUDE_DIRECTORIES
    $<TARGET_PROPERTY:${SRC},INTERFACE_INCLUDE_DIRECTORIES>
    INTERFACE_SYSTEM_INCLUDE_DIRECTORIES
    $<TARGET_PROPERTY:${SRC},INTERFACE_SYSTEM_INCLUDE_DIRECTORIES>)
endmacro()


##############################################################################
# Creating a Caffe2 binary target with sources specified with relative path.
# Usage:
#   caffe2_binary_target(target_name_or_src <src1> [<src2>] [<src3>] ...)
# If only target_name_or_src is specified, this target is build with one single
# source file and the target name is autogen from the filename. Otherwise, the
# target name is given by the first argument and the rest are the source files
# to build the target.
function(caffe2_binary_target target_name_or_src)
  # https://cmake.org/cmake/help/latest/command/function.html
  # Checking that ARGC is greater than # is the only way to ensure
  # that ARGV# was passed to the function as an extra argument.
  if (ARGC GREATER 1)
    set(__target ${target_name_or_src})
    prepend(__srcs "${CMAKE_CURRENT_SOURCE_DIR}/" "${ARGN}")
  else()
    get_filename_component(__target ${target_name_or_src} NAME_WE)
    prepend(__srcs "${CMAKE_CURRENT_SOURCE_DIR}/" "${target_name_or_src}")
  endif()
  add_executable(${__target} ${__srcs})
  target_link_libraries(${__target} ${Caffe2_MAIN_LIBS})
  # If we have Caffe2_MODULES defined, we will also link with the modules.
  if (DEFINED Caffe2_MODULES)
    target_link_libraries(${__target} ${Caffe2_MODULES})
  endif()
  if (USE_TBB)
    target_include_directories(${__target} PUBLIC ${TBB_ROOT_DIR}/include)
  endif()
  install(TARGETS ${__target} DESTINATION bin)
endfunction()

function(caffe2_hip_binary_target target_name_or_src)
  if (ARGC GREATER 1)
    set(__target ${target_name_or_src})
    prepend(__srcs "${CMAKE_CURRENT_SOURCE_DIR}/" "${ARGN}")
  else()
    get_filename_component(__target ${target_name_or_src} NAME_WE)
    prepend(__srcs "${CMAKE_CURRENT_SOURCE_DIR}/" "${target_name_or_src}")
  endif()

  caffe2_binary_target(${target_name_or_src})

  target_compile_options(${__target} PRIVATE ${HIP_CXX_FLAGS})
  target_include_directories(${__target} PRIVATE ${Caffe2_HIP_INCLUDE})
endfunction()

##############################################################################
# Multiplex between loading executables for CUDA versus HIP (AMD Software Stack).
# Usage:
#   torch_cuda_based_add_executable(cuda_target)
#
macro(torch_cuda_based_add_executable cuda_target)
  IF (USE_ROCM)
    hip_add_executable(${cuda_target} ${ARGN})
  ELSEIF(USE_CUDA)
    cuda_add_executable(${cuda_target} ${ARGN})
  ELSE()

  ENDIF()
endmacro()


##############################################################################
# Multiplex between adding libraries for CUDA versus HIP (AMD Software Stack).
# Usage:
#   torch_cuda_based_add_library(cuda_target)
#
macro(torch_cuda_based_add_library cuda_target)
  IF (USE_ROCM)
    hip_add_library(${cuda_target} ${ARGN})
  ELSEIF(USE_CUDA)
    cuda_add_library(${cuda_target} ${ARGN})
  ELSE()
  ENDIF()
endmacro()


##############################################################################
# Get the NVCC arch flags specified by TORCH_CUDA_ARCH_LIST and CUDA_ARCH_NAME.
# Usage:
#   torch_cuda_get_nvcc_gencode_flag(variable_to_store_flags)
#
macro(torch_cuda_get_nvcc_gencode_flag store_var)
  # setting nvcc arch flags
  if ((NOT EXISTS ${TORCH_CUDA_ARCH_LIST}) AND (DEFINED ENV{TORCH_CUDA_ARCH_LIST}))
    message(WARNING
        "In the future we will require one to explicitly pass "
        "TORCH_CUDA_ARCH_LIST to cmake instead of implicitly setting it as an "
        "env variable. This will become a FATAL_ERROR in future version of "
        "pytorch.")
    set(TORCH_CUDA_ARCH_LIST $ENV{TORCH_CUDA_ARCH_LIST})
  endif()
  if (EXISTS ${CUDA_ARCH_NAME})
    message(WARNING
        "CUDA_ARCH_NAME is no longer used. Use TORCH_CUDA_ARCH_LIST instead. "
        "Right now, CUDA_ARCH_NAME is ${CUDA_ARCH_NAME} and "
        "TORCH_CUDA_ARCH_LIST is ${TORCH_CUDA_ARCH_LIST}.")
    set(TORCH_CUDA_ARCH_LIST TORCH_CUDA_ARCH_LIST ${CUDA_ARCH_NAME})
  endif()

  # Invoke cuda_select_nvcc_arch_flags from proper cmake FindCUDA.
  cuda_select_nvcc_arch_flags(${store_var} ${TORCH_CUDA_ARCH_LIST})
endmacro()


##############################################################################
# Add standard compile options.
# Usage:
#   torch_compile_options(lib_name)
function(torch_compile_options libname)
  set_property(TARGET ${libname} PROPERTY CXX_STANDARD 14)

  if (NOT INTERN_BUILD_MOBILE OR NOT BUILD_CAFFE2_MOBILE)
    # until they can be unified, keep these lists synced with setup.py
    if(MSVC)

      if (MSVC_Z7_OVERRIDE)
        set(MSVC_DEBINFO_OPTION "/Z7")
      else()
        set(MSVC_DEBINFO_OPTION "/Zi")
      endif()

      target_compile_options(${libname} PUBLIC
        ${MSVC_RUNTIME_LIBRARY_OPTION}
        ${MSVC_DEBINFO_OPTION}
        /EHa
        /DNOMINMAX
        /wd4267
        /wd4251
        /wd4522
        /wd4522
        /wd4838
        /wd4305
        /wd4244
        /wd4190
        /wd4101
        /wd4996
        /wd4275
        /bigobj
        )
    else()
      target_compile_options(${libname} PUBLIC
        #    -std=c++14
        -Wall
        -Wextra
        -Wno-unused-parameter
        -Wno-missing-field-initializers
        -Wno-write-strings
        -Wno-unknown-pragmas
        # Clang has an unfixed bug leading to spurious missing braces
        # warnings, see https://bugs.llvm.org/show_bug.cgi?id=21629
        -Wno-missing-braces
        )

      if(NOT APPLE)
        target_compile_options(${libname} PRIVATE
          # Considered to be flaky.  See the discussion at
          # https://github.com/pytorch/pytorch/pull/9608
          -Wno-maybe-uninitialized)
      endif()

    endif()

    if (MSVC)
    elseif (WERROR)
      target_compile_options(${libname} PRIVATE -Werror -Wno-strict-overflow)
    endif()
  endif()

  if (NOT WIN32 AND NOT USE_ASAN)
    # Enable hidden visibility by default to make it easier to debug issues with
    # TORCH_API annotations. Hidden visibility with selective default visibility
    # behaves close enough to Windows' dllimport/dllexport.
    #
    # Unfortunately, hidden visibility messes up some ubsan warnings because
    # templated classes crossing library boundary get duplicated (but identical)
    # definitions. It's easier to just disable it.
    target_compile_options(${libname} PRIVATE "-fvisibility=hidden")
  endif()

  # Use -O2 for release builds (-O3 doesn't improve perf, and -Os results in perf regression)
  target_compile_options(${libname} PRIVATE "$<$<OR:$<CONFIG:Release>,$<CONFIG:RelWithDebInfo>>:-O2>")

  # ---[ Check if warnings should be errors.
  # TODO: Dedupe with WERROR check above
  if (WERROR)
    target_compile_options(${libname} PRIVATE -Werror)
  endif()
endfunction()


##############################################################################
# Set standard target properties.
# Usage:
#   torch_set_target_props(lib_name)
function(torch_set_target_props libname)
  if(MSVC AND AT_MKL_MT)
    set_target_properties(${libname} PROPERTIES LINK_FLAGS_RELEASE "/NODEFAULTLIB:${VCOMP_LIB}")
    set_target_properties(${libname} PROPERTIES LINK_FLAGS_DEBUG "/NODEFAULTLIB:${VCOMP_LIB}")
    set_target_properties(${libname} PROPERTIES STATIC_LIBRARY_FLAGS "/NODEFAULTLIB:${VCOMP_LIB}")
  endif()
endfunction()

list(PREPEND <list> [<element> ...])