如何编写特定的多目标并行可构建CMakeLists.txt？

问题描述

这是How to build specific multiple targets parallelly using make?

的相关问题

多个目标Makefile可以与特定的多个目标并行构建。 例如，我有目标a，b和c。

我可以执行以下操作：

make -j2 a b

同时定位目标a和b。

但是，由cmake和CMakeList.txt生成的我的Makefile无法并行工作。

这是我的CMakeLists.txt

CMAKE_MINIMUM_required (VERSION 3.13.0)
PROJECT (para)

ADD_EXECUTABLE (a a.cpp)
ADD_EXECUTABLE (b b.cpp)
ADD_EXECUTABLE (c c.cpp)

a.cpp，b.cpp和c.cpp具有相同的内容

int main() {}

我创建构建目录如下：

mkdir build

然后执行以下cmake：

cd buid
cmake ..

然后使用-j2选项执行make，没有特定的目标。

make -j2
[master][~/work/training/code/cmake/parallel/build]
[ 16%] Building CXX object CMakeFiles/b.dir/b.cpp.o
[ 33%] Building CXX object CMakeFiles/c.dir/c.cpp.o
[ 50%] Linking CXX executable b
[ 66%] Linking CXX executable c
[ 66%] Built target c
[ 66%] Built target b
[ 83%] Building CXX object CMakeFiles/a.dir/a.cpp.o
[100%] Linking CXX executable a
[100%] Built target a

这是预期的结果。两个目标并行建立。

但是，如果我按以下方式通过特定目标，则构建将按顺序进行。

make -j2 a b
[ 50%] Building CXX object CMakeFiles/a.dir/a.cpp.o
[100%] Linking CXX executable a
[100%] Built target a
[ 50%] Building CXX object CMakeFiles/b.dir/b.cpp.o
[100%] Linking CXX executable b
[100%] Built target b

我应该如何编写CMakeLists.txt与特定目标并行构建？

此处是通过上面的cmake和CMakeLists.txt生成的Makefile。

;; This buffer is for text that is not saved,and for Lisp evaluation.
;; To create a file,visit it with C-x C-f and enter text in its buffer.

# CMAKE generated file: DO NOT EDIT!
# Generated by "Unix Makefiles" Generator,CMake Version 3.18

# Default target executed when no arguments are given to make.
default_target: all

.PHONY : default_target

# Allow only one "make -f Makefile2" at a time,but pass parallelism.
.NOTParaLLEL:


#=============================================================================
# Special targets provided by cmake.

# disable implicit rules so canonical targets will work.
.SUFFIXES:


# disable VCS-based implicit rules.
% : %,v


# disable VCS-based implicit rules.
% : RCS/%


# disable VCS-based implicit rules.
% : RCS/%,v


# disable VCS-based implicit rules.
% : SCCS/s.%


# disable VCS-based implicit rules.
% : s.%


.SUFFIXES: .hpux_make_needs_suffix_list


# Command-line flag to silence nested $(MAKE).
$(VERBOSE)MAKESILENT = -s

#Suppress display of executed commands.
$(VERBOSE).SILENT:

# A target that is always out of date.
cmake_force:

.PHONY : cmake_force

#=============================================================================
# Set environment variables for the build.

# The shell in which to execute make rules.
SHELL = /bin/sh

# The CMake executable.
CMAKE_COMMAND = /usr/bin/cmake

# The command to remove a file.
RM = /usr/bin/cmake -E rm -f

# Escaping for special characters.
EQUALS = =

# The top-level source directory on which CMake was run.
CMAKE_SOURCE_DIR = /home/kondo/work/training/code/cmake/parallel

# The top-level build directory on which CMake was run.
CMAKE_BINARY_DIR = /home/kondo/work/training/code/cmake/parallel/build

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edit_cache/fast: edit_cache

.PHONY : edit_cache/fast

# The main all target
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c/fast:
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#=============================================================================
# Target rules for targets named b

# Build rule for target.
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b/fast:
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#=============================================================================
# Target rules for targets named a

# Build rule for target.
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    $(MAKE) $(MAKESILENT) -f CMakeFiles/Makefile2 a
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# fast build rule for target.
a/fast:
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a.o: a.cpp.o

.PHONY : a.o

# target to build an object file
a.cpp.o:
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.PHONY : a.cpp.o

a.i: a.cpp.i

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.PHONY : a.cpp.i

a.s: a.cpp.s

.PHONY : a.s

# target to generate assembly for a file
a.cpp.s:
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.PHONY : a.cpp.s

b.o: b.cpp.o

.PHONY : b.o

# target to build an object file
b.cpp.o:
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b.s: b.cpp.s

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c.o: c.cpp.o

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c.i: c.cpp.i

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    @echo "... rebuild_cache"
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    @echo "... a.s"
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#=============================================================================
# Special targets to cleanup operation of make.

# Special rule to run CMake to check the build system integrity.
# No rule that depends on this can have commands that come from listfiles
# because they might be regenerated.
cmake_check_build_system:
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.PHONY : cmake_check_build_system

解决方法

由cmake生成的顶级Makefile具有.NOPARALLEL:。它防止并行构建。 因此，即使我执行make -j2 a b，也要按顺序构建目标a和b。

cmake还会生成CMakeFiles/Makefile2。从顶层Makefile如下使用：

# The main all target
all: cmake_check_build_system
    $(CMAKE_COMMAND) -E cmake_progress_start /home/kondo/work/training/code/cmake/parallel/build/CMakeFiles /home/kondo/work/training/code/cmake/parallel/build//CMakeFiles/progress.marks
    $(MAKE) $(MAKESILENT) -f CMakeFiles/Makefile2 all
    $(CMAKE_COMMAND) -E cmake_progress_start /home/kondo/work/training/code/cmake/parallel/build/CMakeFiles 0
.PHONY : all

CMakeFiles/Makefile2不会阻止并行构建。

因此，如果我明确使用CMakeFiles/Makefile2，则可以并行构建特定目标。

命令在这里。

make -f CMakeFiles/Makefile2 -j2 a b

谢谢@Tsyvarev，您的评论非常有帮助。