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KMF

Introduction to Xmake v2.5.9’s New Features

xmake is a lightweight cross-platform build tool based on Lua. It uses xmake.lua to maintain project builds. Compared with makefile/CMakeLists.txt, the configuration syntax is more concise and intuitive, it is very friendly to novices, and you can get started quickly in a short time, allowing users to focus more on actual project development.

In this version, we have added a lot of heavyweight new features, such as Nim language project build support as well as Keil MDK, Circle, and Wasi toolchain support.

In addition, we have made major improvements to C++20 Modules, not only supporting the latest gcc-11, clang, and msvc compilers but also automatic analysis of inter-module dependencies to achieve maximum parallel compilation support.

Finally, there is a more useful feature that is Unity Build support, through which we can greatly improve the compilation speed of C++ code.

New Feature Introduction

Nimlang Project Construction

Recently, we have added build support for the Nimlang project. For related issues, see: #1756

Create an Empty Project

We can use the xmake create command to create an empty project.

xmake create -l nim -t console test
xmake create -l nim -t static test
xmake create -l nim -t shared test

Console Program

add_rules("mode.debug", "mode.release")

target("test")
    set_kind("binary")
    add_files("src/main.nim")

$ xmake -v
[33%]: linking.release test
/usr/local/bin/nim c --opt:speed --nimcache:build/.gens/test/macosx/x86_64/release/nimcache -o:b
uild/macosx/x86_64/release/test src/main.nim
[100%]: build ok!

Static Library Program

add_rules("mode.debug", "mode.release")

target("foo")
    set_kind("static")
    add_files("src/foo.nim")

target("test")
    set_kind("binary")
    add_deps("foo")
    add_files("src/main.nim")

$ xmake -v
[33%]: linking.release libfoo.a
/usr/local/bin/nim c --opt:speed --nimcache:build/.gens/foo/macosx/x86_64/release/nimcache --app
:staticlib --noMain --passC:-DNimMain=NimMain_B6D5BD02 --passC:-DNimMainInner=NimMainInner_B6D5B
D02 --passC:-DNimMainModule=NimMainModule_B6D5BD02 --passC:-DPreMain=PreMain_B6D5BD02 --passC:-D
PreMainInner=PreMainInner_B6D5BD02 -o:build/macosx/x86_64/release/libfoo.a src/foo.nim
[66%]: linking.release test
/usr/local/bin/nim c --opt:speed --nimcache:build/.gens/test/macosx/x86_64/release/nimcache --pa
ssL:-Lbuild/macosx/x86_64/release --passL:-lfoo -o:build/macosx/x86_64/release/test src/main.nim
[100%]: build ok!

Dynamic Library Program

add_rules("mode.debug", "mode.release")

target("foo")
    set_kind("shared")
    add_files("src/foo.nim")

target("test")
    set_kind("binary")
    add_deps("foo")
    add_files("src/main.nim")

$ xmake -rv
[33%]: linking.release libfoo.dylib
/usr/local/bin/nim c --opt:speed --nimcache:build/.gens/foo/macosx/x86_64/release/nimcache --app
:lib --noMain -o:build/macosx/x86_64/release/libfoo.dylib src/foo.nim
[66%]: linking.release test
/usr/local/bin/nim c --opt:speed --nimcache:build/.gens/test/macosx/x86_64/release/nimcache --pa
ssL:-Lbuild/macosx/x86_64/release --passL:-lfoo -o:build/macosx/x86_64/release/test src/main.nim
[100%]: build ok!

C Code Mixed Compilation

add_rules("mode.debug", "mode.release")

target("foo")
    set_kind("static")
    add_files("src/*.c")

target("test")
    set_kind("binary")
    add_deps("foo")
    add_files("src/main.nim")

Nimble Dependency Package Integration

For a complete example, see Nimble Package Example

add_rules("mode.debug", "mode.release")

add_requires("nimble::zip >0.3")

target("test")
    set_kind("binary")
    add_files("src/main.nim")
    add_packages("nimble::zip")

main.nim

import zip/zlib

echo zlibVersion()

Native Dependency Package Integration

For a complete example, see Native Package Example

add_rules("mode.debug", "mode.release")

add_requires("zlib")

target("test")
    set_kind("binary")
    add_files("src/main.nim")
    add_packages("zlib")

main.nim

proc zlibVersion(): cstring {.cdecl, importc}

echo zlibVersion()

Unity Build Acceleration

We know that C++ code compilation speed is usually very slow because each code file needs to parse the imported header file.

With Unity Build, we accelerate the compilation of the project by combining multiple cpp files into one. The main benefit is to reduce the repetitive work of parsing and compiling the contents of the header files contained in multiple source files. The contents of the header files usually account for most of the code in the source file after preprocessing.

Unity build also reduces the overhead caused by having a large number of small source files by reducing the number of object files created and processed by the compilation chain and allows inter-procedural analysis and optimization across files that form a unified build task (similar to optimization during effect linking ).

It can greatly improve the compilation speed of C/C++ code, usually by 30%. However, depending on the complexity of the project, the benefits it brings depend on the situation of the project.

xmake has also supported this build mode in v2.5.9. For related issues, see #1019.

How to Enable?

We provide two built-in rules to handle Unity Build for C and C++ code respectively.

add_rules("c.unity_build")
add_rules("c++.unity_build")

Batch Mode

By default, as long as the above rules are set, Unity Build in Batch mode will be enabled, that is, xmake will automatically organize and merge according to the project code files.

target("test")
    set_kind("binary")
    add_includedirs("src")
    add_rules("c++.unity_build", {batchsize = 2})
    add_files("src/*.c", "src/*.cpp")

We can additionally specify the size of each merged Batch by setting the {batchsize = 2} parameter to the rule, which means that every two C++ files are automatically merged and compiled.

The compilation effect is roughly as follows:

$ xmake -r
[11%]: ccache compiling.release build/.gens/test/unity_build/unity_642A245F.cpp
[11%]: ccache compiling.release build/.gens/test/unity_build/unity_bar.cpp
[11%]: ccache compiling.release build/.gens/test/unity_build/unity_73161A20.cpp
[11%]: ccache compiling.release build/.gens/test/unity_build/unity_F905F036.cpp
[11%]: ccache compiling.release build/.gens/test/unity_build/unity_foo.cpp
[11%]: ccache compiling.release build/.gens/test/unity_build/main.c
[77%]: linking.release test
[100%]: build ok

Since we only enabled the Unity Build of C++, the C code is still compiled one by one normally. In addition, in the Unity Build mode, we can still speed up the parallel compilation as much as possible without conflicting each other.

If the batchsize parameter is not set, all files will be merged into one file for compilation by default.

Group Mode

If the automatic merging effect of the above Batch mode is not satisfactory, we can also use custom grouping to manually configure which files are merged together to participate in the compilation, which makes users more flexible and controllable.

target("test")
    set_kind("binary")
    add_rules("c++.unity_build", {batchsize = 0}) - disable batch mode
    add_files("src/*.c", "src/*.cpp")
    add_files("src/foo/*.c", {unity_group = "foo"})
    add_files("src/bar/*.c", {unity_group = "bar"})

We use {unity_group = "foo"} to specify the name of each group and which files are included. The files in each group will be merged into one code file separately.

In addition, batchsize = 0 also forcibly disables the Batch mode, that is, if there is no unity_group grouped code files, we will still compile them separately, and will not automatically turn on automatic merging.

Batch and Group Mixed Mode

As long as we change the above batchsize = 0 to a value other than 0, we can let the remaining code files continue to open the Batch mode in the grouping mode to automatically merge and compile.

target("test")
    set_kind("binary")
    add_includedirs("src")
    add_rules("c++.unity_build", {batchsize = 2})
    add_files("src/*.c", "src/*.cpp")
    add_files("src/foo/*.c", {unity_group = "foo"})
    add_files("src/bar/*.c", {unity_group = "bar"})

Ignore the Specified File

If it is in Batch mode because it is an automatic merge operation, all files will be merged by default, but if some code files do not want to participate in the merge, then we can also ignore them through {unity_ignored = true}.

target("test")
    set_kind("binary")
    add_includedirs("src")
    add_rules("c++.unity_build", {batchsize = 2})
    add_files("src/*.c", "src/*.cpp")
    add_files("src/test/*.c", {unity_ignored = true}) - ignore these files

Unique ID

Although the benefits of Unity Build are good, we still encounter some unexpected situations. For example, in our two code files, under the global namespace, there are global variables and functions with the same name.

Then, merge compilation will bring about compilation conflicts, and the compiler usually reports global variable redefinition errors.

In order to solve this problem, we need to make some modifications to the user code, and then cooperate with the build tool to solve it.

For example, our foo.cpp and bar.cpp both have global variable i.

foo.cpp

namespace {
    int i = 42;
}

int foo()
{
    return i;
}

bar.cpp

namespace {
    int i = 42;
}

int bar()
{
    return i;
}

Then, our merge compilation will conflict, and we can introduce a Unique ID to isolate the global anonymous space.

foo.cpp

namespace MY_UNITY_ID {
    int i = 42;
}

int foo()
{
    return MY_UNITY_ID::i;
}

bar.cpp

namespace MY_UNITY_ID {
    int i = 42;
}

int bar()
{
    return MY_UNITY_ID::i;
}

Next, we also need to ensure that after the code is merged, the definitions of MY_UNITY_ID in foo and bar are completely different, and a unique ID value can be calculated according to the file name, which does not conflict with each other, which is to achieve the following merge effect:

#define MY_UNITY_ID <hash(foo.cpp)>
#include "foo.c"
#undef MY_UNITY_ID
#define MY_UNITY_ID <hash(bar.cpp)>
#include "bar.c"
#undef MY_UNITY_ID

This may seem troublesome, but the user does not need to care about these, xmake will automatically process them when merging, the user only needs to specify the name of the Unique ID, for example, the following:

target("test")
    set_kind("binary")
    add_includedirs("src")
    add_rules("c++.unity_build", {batchsize = 2, uniqueid = "MY_UNITY_ID"})
    add_files("src/*.c", "src/*.cpp")

Dealing with global variables, as well as global macro definitions with the same name, functions, etc., can be used in this way to avoid conflicts.

C++20 Modules

xmake uses .mpp as the default module extension, but also supports .ixx, .cppm, .mxx and other extensions.

In the early days, xmake experimentally supported C++ Modules TS, but at that time, gcc could not support it well, and the dependencies between modules were not supported either.

Recently, we have made a lot of improvements to xmake. We have fully supported the C++20 Modules construction support of gcc-11/clang/msvc, and can automatically analyze the dependencies between modules to maximize parallel compilation.

At the same time, the new version of clang/msvc has also been better handled.

set_languages("c++20")
target("test")
    set_kind("binary")
    add_files("src/*.cpp", "src/*.mpp")

For more examples, see: C++ Modules

Lua5.4 Runtime Support

In the last version, we added support for the Lua5.3 runtime. In this version, we further upgraded the Lua runtime to 5.4. Compared with 5.3, the runtime performance and memory utilization have been greatly improved.

However, the current default runtime of xmake is still luajit, and it is expected that version 2.6.1 (that is, the next version) will officially switch to Lua5.4 as the default runtime.

Although the Lua runtime is switched, it is completely unaware of the user side and fully compatible with the existing project configuration, because xmake originally provides a layer of encapsulation for the exposed API. The interfaces that have compatibility issues between Lua versions, such as setfenv, ffi, etc., are hidden internally and are not exposed to users.

Keil MDK Toolchain Support

In this version, we also added Keil/MDK embedded compilation toolchain support, related example projects.

xmake will automatically detect the compiler installed by Keil/MDK, related issues #1753.

Compile with armcc

$ xmake f -p cross -a cortex-m3 --toolchain=armcc -c
$ xmake

Compile with armclang

$ xmake f -p cross -a cortex-m3 --toolchain=armclang -c
$ xmake

Console Program

target("hello")
    add_deps("foo")
    add_rules("mdk.console")
    add_files("src/*.c", "src/*.s")
    add_defines("__EVAL", "__MICROLIB")
    add_includedirs("src/lib/cmsis")

Static Library Program

add_rules("mode.debug", "mode.release")

target("foo")
    add_rules("mdk.static")
    add_files("src/foo/*.c")

Wasi Toolchain Support

We previously supported the emcc toolchain of the wasm platform to build the wasm program, and here, we added another Wasm toolchain with WASI enabled to replace emcc.

$ xmake f -p wasm --toolchain=wasi
$ xmake

Circle Toolchain Support

We also added support for the circle compiler, which is a new C++20 compiler with some interesting compile-time meta-programming features. Those who are interested can check it out on the official website.

$ xmake f --toolchain=circle
$ xmake

Gcc-8/9/10/11 Specific Version Support

If the user additionally installs a specific version of the gcc tool chain such as gcc-11, gcc-10, the local gcc program may be named /usr/bin/gcc-11.

One way is to switch by specifying the configuration one by one through xmake f --cc=gcc-11 --cxx=gcc-11 --ld=g++-11, but it is very cumbersome.

Therefore, xmake also provides a faster switching method:

$ xmake f --toolchain=gcc-11 -c
$ xmake

You only need to specify the version name corresponding to gcc-11 to quickly switch the entire gcc tool chain.

C++17/20 Compiler Feature Detection

xmake provides the check_features auxiliary interface to detect compiler features.

includes("check_features.lua")

target("test")
    set_kind("binary")
    add_files("*.c")
    add_configfiles("config.h.in")
    configvar_check_features("HAS_CONSTEXPR", "cxx_constexpr")
    configvar_check_features("HAS_CONSEXPR_AND_STATIC_ASSERT", {"cxx_constexpr", "c_static_assert"}, {languages = "c++11"})

config.h.in

${define HAS_CONSTEXPR}
${define HAS_CONSEXPR_AND_STATIC_ASSERT}

config.h

/* #undef HAS_CONSTEXPR */
#define HAS_CONSEXPR_AND_STATIC_ASSERT 1

In version 2.5.9, we added c++17 feature detection:

Feature name
cxx_aggregate_bases
cxx_aligned_new
cxx_capture_star_this
cxx_constexpr
cxx_deduction_guides
cxx_enumerator_attributes
cxx_fold_expressions
cxx_guaranteed_copy_elision
cxx_hex_float
cxx_if_constexpr
cxx_inheriting_constructors
cxx_inline_variables
cxx_namespace_attributes
cxx_noexcept_function_type
cxx_nontype_template_args
cxx_nontype_template_parameter_auto
cxx_range_based_for
cxx_static_assert
cxx_structured_bindings
cxx_template_template_args
cxx_variadic_using

Also added c++20 feature detection:

Feature name
cxx_aggregate_paren_init
cxx_char8_t
cxx_concepts
cxx_conditional_explicit
cxx_consteval
cxx_constexpr
cxx_constexpr_dynamic_alloc
cxx_constexpr_in_decltype
cxx_constinit
cxx_deduction_guides
cxx_designated_initializers
cxx_generic_lambdas
cxx_impl_coroutine
cxx_impl_destroying_delete
cxx_impl_three_way_comparison
cxx_init_captures
cxx_modules
cxx_nontype_template_args
cxx_using_enum

Xrepo Package Virtual Environment Management

Enter the Virtual Environment

The xrepo package management tool that comes with xmake can now well support package virtual machine environment management, similar to nixos’ nixpkgs.

We can customize some package configurations by adding the xmake.lua file in the current directory, and then enter the specific package virtual environment.

add_requires("zlib 1.2.11")
add_requires("python 3.x", "luajit")

$ xrepo env shell
> python --version
> luajit --version

We can also configure and load the corresponding toolchain environment in xmake.lua, for example, load the VS compilation environment.

Manage Virtual Environments

We can use the following command to register the specified virtual environment configuration globally to the system for quick switching.

$ xrepo env --add /tmp/base.lua

At this time, we have saved a global virtual environment called base, and we can view it through the list command.

$ xrepo env --list
/Users/ruki/.xmake/envs:
  -base
envs(1) found!

We can also delete it.

$ xrepo env --remove base

Switch Global Virtual Environment

If we register multiple virtual environments, we can also switch them quickly.

$ xrepo env -b base shell
> python --version

Or directly load the specified virtual environment to run specific commands

$ xrepo env -b base python --version

xrepo env -b/--bind is to bind the specified virtual environment. For more details, see: #1762

Header Only Target Type

For the target, we added the headeronly target type. For this type of target program, we will not actually compile them because it has no source files to be compiled.

But it contains a list of header files, which are usually used for the installation of headeronly library projects, the generation of file lists for IDE projects, and the generation of cmake/pkgconfig import files during the installation phase.

E.g:

add_rules("mode.release", "mode.debug")

target("foo")
    set_kind("headeronly")
    add_headerfiles("src/foo.h")
    add_rules("utils.install.cmake_importfiles")
    add_rules("utils.install.pkgconfig_importfiles")

For more details, please see: #1747

Find Packages From CMake

Now, cmake is the de facto standard, so the find_package provided by CMake can already find a large number of libraries and modules. We fully reuse this part of cmake’s ecology to expand xmake’s integration of packages.

We can use find_package("cmake::xxx") to find some packages with cmake, xmake will automatically generate a cmake script to call cmake’s find_package to find some packages and get the bread information.

E.g:

$ xmake l find_package cmake::ZLIB
{
  links = {
    "z"
  },
  includedirs = {
    "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.
15.sdk/usr/include"
  },
  linkdirs = {
    "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.
15.sdk/usr/lib"
  }
}
$ xmake l find_package cmake::LibXml2
{
  links = {
    "xml2"
  },
  includedirs = {
    "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/libxml2"
  },
  linkdirs = {
    "/usr/lib"
  }
}

Specify Version

find_package("cmake::OpenCV", {required_version = "4.1.1"})

Specified Components

find_package("cmake::Boost", {components = {"regex", "system"}})

Default Switch

find_package("cmake::Boost", {components = {"regex", "system"}, presets = {Boost_USE_STATIC_LIB = true}})
set(Boost_USE_STATIC_LIB ON) - will be used in FindBoost.cmake
find_package(Boost REQUIRED COMPONENTS regex system)

Set Environment Variables

find_package("cmake::OpenCV", {envs = {CMAKE_PREFIX_PATH = "xxx"}})

Specify Custom FindFoo.cmake Module Script directory

mydir/cmake_modules/FindFoo.cmake

find_package("cmake::Foo", {moduledirs = "mydir/cmake_modules"})

Package Dependency Integration

package("xxx")
    on_fetch(function (package, opt)
         return package:find_package("cmake::xxx", opt)
    end)
package_end()

add_requires("xxx")

Package Dependency Integration (Optional Component)

package("boost")
    add_configs("regex", {description = "Enable regex.", default = false, type = "boolean"})
    on_fetch(function (package, opt)
         opt.components = {}
         if package:config("regex") then
             table.insert(opt.components, "regex")
         end
         return package:find_package("cmake::Boost", opt)
    end)
package_end()

add_requires("boost", {configs = {regex = true}})

Related issues: #1632

Add Custom Commands to CMakelists.txt

We have further improved the cmake generator. Now you can serialize the custom script in rule into a list of commands and generate them together to CMakelists.txt

However, currently, only the serialization of batchcmds series scripts can be supported.

rule("foo")
    after_buildcmd(function (target, batchcmds, opt)
        batchcmds:show("hello xmake!")
        batchcmds:cp("xmake.lua", "/tmp/")
        - batchcmds:execv("echo", {"hello", "world!"})
        - batchcmds:runv("echo", {"hello", "world!"})
    end)

target("test")
    set_kind("binary")
    add_rules("foo")
    add_files("src/*.c")

It will generate CMakelists.txt similar to the following

# ...
add_custom_command(TARGET test
    POST_BUILD
    COMMAND echo hello xmake!
    VERBATIM
)
add_custom_command(TARGET test
    POST_BUILD
    COMMAND cp xmake.lua /tmp/
    VERBATIM
)
target_sources(test PRIVATE
    src/main.c
)

However, the actual effect of cmake’s ADD_CUSTOM_COMMAND PRE_BUILD differs greatly on different generators, which cannot meet our needs, so we have done a lot of processing to support it.

Related issues: #1735

Changelog

New Features

  • #1736: Support wasi-sdk toolchain
  • Support Lua 5.4 runtime
  • Add gcc-8, gcc-9, gcc-10, gcc-11 toolchains
  • #1623: Support find_package from cmake
  • #1747: Add set_kind("headeronly") for target to install files for headeronly library
  • #1019: Support Unity build
  • #1438: Support code amalgamation, xmake l cli.amalgamate
  • #1765: Support nim language
  • #1762: Manage and switch the given package envs for xrepo env
  • #1767: Support Circle compiler
  • #1753: Support armcc/armclang toolchains for Keil/MDK
  • #1774: Add table.contains api
  • #1735: Add custom command in cmake generator

Changes

  • #1528: Check c++17/20 features
  • #1729: Improve C++20 modules for clang/gcc/msvc, support inter-module dependency compilation and parallel optimization
  • #1779: Remove builtin -Gd for ml.exe/x86
  • #1781: Improve get.sh installation script to support nixos

Credit: Source link

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