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Clang linker options

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Clang/LLVM support in Visual Studio projects

Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. When you use cc 1 to link a program, it will invoke a default linker command. I'm interested mostly in gcc and clang. I'm not looking for methods that involve running the various compilation steps separately e. But that doesn't work for gcc or clang. Update with one possible motivation : To easily test with a different linker than the default linker.

clang linker options

For example, it would be nice to be able to do this:. Instead, you have to do generate the object file, run cc -v to figure out the arguments to ldmanually run the ld you want with those arguments:.

As you can see, that's not easy. Note there is documentation in the gcc info page about how collect2 looks for a linker program. But according to those docs, the first place it looks is not an environment variable or something you can specify on the command line e.

The docs say it looks first for a "a hard coded linker file name". If that documentation is correct, to coerce it not to use that linker i. Update 2 : Using -B seems to work well enough for my needs.

See below where I posted an answer. I can't accept my own answer, but I would if I could - it seems to solve the issue well. This works for some versions of gcc [1] and for clang currently undocumented - in man pages of at least clang 3. Note that this will cause cc to search for other tools e. This is documented as far back as at least gcc 2.

I don't know how compatible the behavior of -B is for clang. As mentioned, it's not currently documented in the clang man page. But it worked well enough to allow me to select an alternate linker as shown above. You could also use that and point at a wrapper script that alters what program the compiler is calling.

So if your gcc was not configured with '--with-ld', then it will eventually search in the path specified by -B if it doesn't find real-ld first. If your gcc was configured with --with-ldthen the -B option will not help you specify an alternate linker of your choosing. The -fuse-ld flag also works with clang on my system. GCC uses internally spec files to decide how the gcc program behaves, in particular how it is linking and with what linker. Or use the -T option of gcc which explicitly passes it to ld to give a linker script.

Also, by strace 1 -ing some gcc command, you'll find out that it tries to access e. Learn more. Asked 3 years, 5 months ago. Active 4 months ago. Viewed 8k times. Juan Juan 4 4 silver badges 19 19 bronze badges. No XY problem here.

Just testing against a different version of the linker.These options come into play when the compiler links object files into an executable output file.

They are meaningless if the compiler is not doing a link step. A file name that does not end in a special recognized suffix is considered to name an object file or library. Object files are distinguished from libraries by the linker according to the file contents. If linking is done, these object files are used as input to the linker. If any of these options is used, then the linker is not run, and object file names should not be used as arguments.

See Overall Options. This option controls code generation of the link-time optimizer. By default the linker output is automatically determined by the linker plugin.

For debugging the compiler and if incremental linking with a non-LTO object file is desired, it may be useful to control the type manually. In this case -fpic and -fpie are both disabled. In this case -fpic or -fPIC is preserved, but not enabled automatically. This allows to build shared libraries without position-independent code on architectures where this is possible, i.

The sections containing intermediate code for link-time optimization are merged, pre-optimized, and output to the resulting object file. In addition, if -ffat-lto-objects is specified, binary code is produced for future non-LTO linking. The object file produced by incremental linking is smaller than a static library produced from the same object files. At link time the result of incremental linking also loads faster than a static library assuming that the majority of objects in the library are used.

When multiple object files are linked together the resulting code is better optimized than with link-time optimizations disabled for example, cross-module inlining happensbut most of benefits of whole program optimizations are lost.

During the incremental link by -r the linker plugin defaults to rel. To maintain whole program optimization, it is recommended to link such objects into static library instead. Alternatively it is possible to use H. Search the library named library when linking. The second alternative with the library as a separate argument is only for POSIX compliance and is not recommended. The -l option is passed directly to the linker by GCC.

Refer to your linker documentation for exact details. The general description below applies to the GNU linker. The linker searches a standard list of directories for the library. The directories searched include several standard system directories plus any that you specify with -L. Static libraries are archives of object files, and have file names like lib library. Some targets also support shared libraries, which typically have names like lib library.

If both static and shared libraries are found, the linker gives preference to linking with the shared library unless the -static option is used.For details on how to specify each option on the command line or in Visual Studio, see the documentation for that option.

You can use the comment pragma to specify some linker options. You may also leave feedback directly on GitHub.

Skip to main content. Exit focus mode. The following table lists options for LINK. Linker options listed alphabetically Option Purpose Specifies a response file. You can use this option multiple times to specify more than one manifest input file. NET Framework assembly. Yes No. Any additional feedback? Skip Submit. Send feedback about This product This page. This page. Submit feedback. There are no open issues. View on GitHub. Is this page helpful? Adds the DebuggableAttribute to a managed image.

Sets number of cl. Specifies whether to generate an executable image that's rebased at load time by using the address space layout randomization ASLR feature. Both of these options specify generation of a.

Specifies a manifest input file for the linker to process and embed in the binary. Marks an executable as verified to be compatible with the Windows Data Execution Prevention feature. Partially signs a Windows Runtime Metadata.You can use Visual Studio version To configure a Visual Studio project to use Clang, right-click on the project node in Solution Explorer and choose Properties.

Typically, you should first choose All configurations at the top of the dialog. If you are using the Clang tools that are bundled with Visual Studio, no additional steps are required. For Windows projects, Visual Studio by default invokes Clang in clang-cl mode and links with the Microsoft implementation of the Standard Library. By default, clang-cl.

The project properties and nearly all compiler flags are identical. You can add it to the root solution folder to apply it to all projects in the solution. The file should look like this but substitute your actual path :. After you have set up a Clang configuration, right-click again on the project node and choose Reload project.

You can now build and debug the project using the Clang tools. Visual Studio detects that you are using the Clang compiler and provides IntelliSense, highlighting, navigation, and other editing features. Errors and warnings are displayed in the Output Window. The project property pages for a Clang configuration are very similar to those for MSVC, although some compiler-dependent features such as Edit and Continue are not available for Clang configurations. When debugging, you can use breakpoints, memory and data visualization, and most other debugging features.

You may also leave feedback directly on GitHub. Skip to main content. Exit focus mode. Configure a Windows project to use Clang tools To configure a Visual Studio project to use Clang, right-click on the project node in Solution Explorer and choose Properties. The project properties and nearly all compiler flags are identical To configure a Visual Studio Linux project to use Clang: Right-click on the project node in Solution Explorer and choose Properties.

Press OK. Is this page helpful? Yes No. Any additional feedback? Skip Submit. Send feedback about This product This page. This page. Submit feedback. There are no open issues. View on GitHub.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Update: After setting path for llvm-ld it partially works. I mean if I perform clang C:myFile. But it still fails for clang myFile. How I run clang correctly for acceptig full debug info and preventing clang errors. I think you need to install a linker. GNU ld will be fine; you should be able to install it via your package manager.

Learn more. Asked 8 years, 8 months ago.

clang linker options

Active 8 years, 8 months ago. Viewed 14k times. I tried clang myFile. Yakov Yakov 7, 23 23 gold badges 88 88 silver badges bronze badges.

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You need a linker. Stupid site. Active Oldest Votes. I use clang with llvm - is there anothe option for the linker? Yakov: either ld or gold, both should work. Aug 9 '11 at Suppose I installed llvm-ld or GNU-ld either-ld. I have llvm-ld exe. It was added to path. But I still get the same error. Yakov: You should run it with -v to have more details about your error, and post relevant information here.May be specified more than once.

Enable builtin include directories even when -nostdinc is used before or after -ibuiltininc. Using -nobuiltininc after the option disables it. Flags controlling the behavior of Clang during compilation. These flags have no effect during actions that do not perform compilation.

Require member pointer base types to be complete if they would be significant under the Microsoft ABI.

Linker options

Disable auto-generation of preprocessed source files and a script for reproduction during a clang crash. Enable ODR indicator globals to avoid false ODR violation reports in partially sanitized programs at the cost of an increase in binary size. This option is currently unused. Strip or keep only, if negative a given number of path components when emitting check metadata. Turn on runtime checks for various forms of undefined or suspicious behavior.

See user manual for available checks. Print supported cpu models for the given target if target is not specified, it will print the supported cpus for the default target. Flags controlling how include s are resolved to files. Restrict all prior -I flags to double-quoted inclusion and remove current directory from include path.

Specify the mapping of module name to precompiled module file, or load a module file if name is omitted. Flags controlling generation of a dependency file for make -like build systems.

Flags controlling which warnings, errors, and remarks Clang will generate. See the full list of warning and remark flags. Report transformation analysis from optimization passes whose name matches the given POSIX regular expression. Report missed transformations by optimization passes whose name matches the given POSIX regular expression. Report transformations performed by optimization passes whose name matches the given POSIX regular expression. Generate instrumented code to collect context sensitive execution counts into default.

Form fused FP ops e. Directly create compilation output files.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. 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.

clang linker options

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. 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.

Navigation index next lld Home. Quick search. GNU ld would have been slower than this if it had these options. Noticed that the new linker is much faster than the MSVC linker. October Succeeded to self-host the ELF port.


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