Cmake use lld

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Cmake use lld

Posted by: admin February 27, Leave a comment. I installed the LLVM 5. The compilation and execution of a simple program worked perfectly fine screenshot of the respective terminal history. Clang automatically detected the standard lib for Windows within the VS Tools directories and produced an executable output. The next step was setting up a simple build with Ninja screenshot of ninja.

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The build process worked as expected and produced a working executable, just like before. The problems begun when I started to integrate CMake into the process.

My expectation is that CMake produces a ninja build file and runs it, correct? I tried the following CMakeLists file. I guess that the problem is related to CMake calling clang with VS style options using slash instead of preceded by minus, like clang requires. I tried Florians command but omitted the path to ninja for a shorter notation and it turned out to work just fine.

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I ran ninja all to build the executable as Test. I renamed it to Test. So far… success!!! But much more complicated than I expected.

See Passing compiler options cmake. See obsolete, but sometimes useful CMakeForceCompiler module. So probably check with the CMake team or raise an issue to get this scenario officially supported.

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And the last part with a Generic system is probably not the best choice, because it will skip Windows specific settings like the. I was running into similar problems when trying to use clang cmake and msvc together.

As far as I know, you should use clang-cl. However, building still failed for me in x86 configurations due to some linker problems regarding x86 vs x64 library incompatibilities.

Mine looks like this:. I finally found a way to use my favoured tools in a way that pleases me. I did this by adding the following line to the VS Code preferences.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

Skip to content. Permalink Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. Branch: master. Find file Copy path.

Cannot retrieve contributors at this time. Raw Blame History. Check if lld is built as a standalone project. TODO: Figure out a way to get the revision and the repository on windows. Please create a directory and run cmake " "from there, passing the path to this source directory as the last argument. Please delete them. If OFF, just generate build targets. You signed in with another tab or window. Reload to refresh your session.

You signed out in another tab or window. Note: path not really used, except for checking if lit was found. Seek installed Lit. NAMES llvm-lit lit. DOC "Path to lit. Define the default arguments to use with 'lit', and an option for the user.

On Win32 hosts, provide an option to specify the path to the GnuWin32 tools. Determine LLD revision and repository. Replace newline characters with spaces. Remove leading spaces. Remove trailing spaces.This probably works well enough right now due to the fact that the default configuration does not use shared libraries.

Differential D Closed Public. Authored by Eugene. Zelenko on Jul 27PM. I checked this patch on my own build on RHEL 6. Regressions were OK.

Clang/LLVM Support for MSBuild Projects

Diff Detail. Event Timeline. Zelenko updated this revision to Diff Jul 27PM.

cmake use lld

Zelenko updated this object. Zelenko added a reviewer: compnerd. Zelenko added a subscriber: llvm-commits. Why the whitespace removal? This revision now requires changes to proceed. Zelenko added inline comments. I don't see any logic behind. Same for white space below. Is it really necessary? Jul 28PM. Zelenko edited edge metadata. Please undo the whitespace changes, they make the file harder to follow. This revision is now accepted and ready to land. Zelenko added a comment. Will undo white space changes at commit.

Just wanted to make white space consistent.Visual Studio version You may want to use Clang instead if you are developing cross platform code, especially if it already depends on Clang or GCC extensions. Please download the latest Preview to try it out and let us know how it works. It is not installed by default, but if you have installed it before, Clang will automatically be updated to 8. If you want to use your own Clang compiler with Windows instead of the bundled one, you can do that too.

We strongly recommend using the bundled compiler as it will be kept up to date as the STL is updated. The remote machine or WSL will need to have Clang installed.

Some compiler options are not supported by clang-cl e. Using Clang with Linux projects is also as simple as selecting the appropriate platform toolset. For Linux projects, there are two toolsets to choose from. One for using Clang with a WSL instance on the local machine and another for using Clang on a remote machine:. The project properties and nearly all compiler flags are identical. You can also use a custom installation of Clang. On Windows, by default, the built-in version of Clang from the installer will always be used.

However, you can override this behavior on either platform by setting defining a property in your project file:. To do this, you will need to unload your project and edit it. You can add this to any project configurations that you would like to use your custom installation of Clang.

Consider opening a feedback ticket if you find yourself using a particular option this way frequently. Based on demand, we may add it to the property pages. Your feedback is a critical part of ensuring that we can deliver the best experience. Log in to join the discussion. It would make it easier to use the same compiler flags across different platforms. Thanks again and if you have any solutions to the following problems please let me know!

LLD cannot link some binaries build in vcpkg gtest.

cmake use lld

How can I configure the MSBuild project to use link. With CMake there is no issue, since then link.

cmake use lld

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July 11th, Read next Vcpkg: Tara Raj July 19, Terry Mahaffey July 24, An option in the MSBuild project to choose what linker to use would still be appreciated. Link Text. Open link in a new tab. No search term specified. Showing recent items. Search or use up and down arrow keys to select an item.LLD is a linker from the LLVM project that is a drop-in replacement for system linkers and runs much faster than them. It also provides features that are useful for toolchain developers.

Internally, LLD consists of several different linkers. The ELF port is the one that will be described in this document. The Mach-O port is built based on a different architecture than the others.

Building with CMake, Ninja and Clang on Windows

We are currently working closely with the FreeBSD project to make LLD default system linker in future versions of the operating system, so we are serious about addressing compatibility issues. For the details, see FreeBSD quarterly status report. LLD is very fast. When you link a large program on a multicore machine, you can expect that LLD runs more than twice as fast as the GNU gold linker. Your mileage may vary, though. MIPS seems decent too.

It is always a cross-linker, meaning that it always supports all the above targets however it was built. This should make it easy to use our linker as part of a cross-compile toolchain. You can embed LLD in your program to eliminate dependencies on external linkers.

It is small. Link-time optimization LTO is supported by default. Essentially, all you have to do to do LTO is to pass the -flto option to clang.

Then clang creates object files not in the native object file format but in LLVM bitcode format. Because in this way LLD can see the entire program, it can do the whole program optimization. Some very old features for ancient Unix systems pres or even before that have been removed. Some default settings have been tuned for the 21st century.

For example, the stack is marked as non-executable by default to tighten security.

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This is a link time comparison on a 2-socket core thread Xeon E 2. We ran gold and lld with or without multi-threading support. To disable multi-threading, we added -no-threads to the command lines. As you can see, lld is significantly faster than GNU linkers. Note that this is just a benchmark result of our environment. LLD is installed as ld. On Unix, linkers are invoked by compiler drivers, so you are not expected to use that command directly.

There are a few ways to tell compiler drivers to use ld. The easiest way to do that is to overwrite the default linker. LLD leaves its name and version number to a. If you are in doubt whether you are successfully using LLD or not, run readelf --string-dump.

It is a bit outdated but the fundamental concepts remain valid.LTO Link Time Optimization achieves better runtime performance through whole-program analysis and cross-module optimization. However, monolithic LTO implements this by merging all input into a single module, which is not scalable in time or memory, and also prevents fast incremental compiles. The ThinLTO bitcode is augmented with a compact summary of the module.

During the link step, only the summaries are read and merged into a combined summary index, which includes an index of function locations for later cross-module function importing. Fast and efficient whole-program analysis is then performed on the combined summary index. However, all transformations, including function importing, occur later when the modules are optimized in fully parallel backends. So the usage model is not affected as the distinction between the fast serial thin link step and the backends is transparent to the user.

While tuning is still in progress, results in the blog post show that ThinLTO already performs well compared to LTO, in many cases matching the performance improvement. The 3. However, ThinLTO is under active development, and new features, improvements and bugfixes are being added for the next release.

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As mentioned earlier, by default the linkers will launch the ThinLTO backend threads in parallel, passing the resulting native object files back to the linker for the final native link. As such, the usage model the same as non-LTO. See the instructions for the LLVM gold plugin. By default, the ThinLTO link step will launch as many threads in parallel as there are cores.

For machines with hyper-threading, this is the total number of virtual cores. For some applications and machine configurations this may be too aggressive, in which case the amount of parallelism can be reduced to N via:.

ThinLTO supports fast incremental builds through the use of a cache, which currently must be enabled through a linker option. To help keep the size of the cache under control, ThinLTO supports cache pruning. The cache policy must be specified with a linker option. A policy string is a series of key-value pairs separated by : characters.

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Possible key-value pairs are:. Set to to indicate no limit, 50 to indicate that the cache size will not be left over half the available disk space. A value over is invalid. A value of 0 disables the percentage size-based pruning. A value over the amount of available space on the disk will be reduced to the amount of available space.

A value of 0 disables the byte size-based pruning. The default is no byte size-based pruning. Note that ThinLTO will apply both size-based pruning policies simultaneously, and changing one does not affect the other. Set to 0 to indicate no limit. The default is files.Toolchain files are CMake files that customize the behavior of the toolchain for cross-compiling.

For a list of supported arguments, see the Toolchain Arguments section. Use of the CMake toolchain file is automatic when using externalNativeBuild. When building with CMake outside of Gradle, the toolchain file itself and its arguments must be passed to CMake.

For example:. The following arguments can be passed to the CMake toolchain file.

cmake use lld

If building with Gradle, add arguments to android. If building from the command line, pass arguments to CMake with -D. The target ABI. Gradle provides this argument automatically. Do not explicitly set this argument in your build. CMake builds for a single target per build. It is recommended to use different build directories for each ABI to avoid collisions between builds. Specifies whether to generate arm or thumb instructions for armeabi-v7a.

Has no effect for other ABIs. For more information, see the Android ABIs documentation. Enables or disables NEON for armeabi-v7a. For more information, see the Neon documentation. Selects which linker to use. Specifies the minimum API level supported by the application or library. This value corresponds to the application's minSdkVersion.

When using the Android Gradle Plugin, this value is automatically set to match the application's minSdkVersion and should not be set manually. Note that some releases received an API increase without a letter increase.


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