[PATCH] D75425: [docs] Added solutions to slow build under common problems

[Evan LeClercq via Phabricator via llvm-commits]

e-leclercq updated this revision to Diff 250986.
e-leclercq added a comment.

Made the recommended changes: explained what the split dwarf option does, included more information on parallel link jobs,  replaced the enable lld option with more information under the use linker option, added more information to the build type including the MinSizeRel setting, added some common projects as examples under the enable projects option, and changed the formatting of clang static analyzer, so that it is now correct.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D75425/new/

https://reviews.llvm.org/D75425

Files:
  llvm/docs/GettingStarted.rst


Index: llvm/docs/GettingStarted.rst
===================================================================
--- llvm/docs/GettingStarted.rst
+++ llvm/docs/GettingStarted.rst
@@ -1098,6 +1098,58 @@
 general questions about LLVM, please consult the `Frequently Asked
 Questions <FAQ.html>`_ page.
 
+If you are having problems with limited memory and build time, please try 
+building with ninja instead of make. Please consider configuring the 
+following options with cmake:
+ 
+ * -G Ninja
+   Setting this option will allow you to build with ninja instead of make.
+
+ * -DLLVM_USE_LINKER
+   Setting this option to either gold or lld will significantly improve 
+   performance. In the case that you are compiling lld, you may wish to use the 
+   gold linker as a faster alternative.
+
+ * -DCMAKE_BUILD_TYPE  
+   This option defaults to Debug; however, this may consume more memory during 
+   the linking phase. So, you may wish to use the build type Release. Another 
+   build type you may wish to consider is release-with-asserts which compiles at 
+   nearly the same rate as the Release build; however, it may not be as easy
+   to debug. MinSizeRel is another build type you may wish to consider, if you 
+   are still having problems with slow build time.
+
+ * -DLLVM_PARALLEL_LINK_JOBS  
+   Set this equal to number of jobs you wish to run simultaneously. This is 
+   similar to the -j option used with make, but only for link jobs. This option 
+   is of course only meaningful if you plan to build with ninja. You may wish to 
+   use a very low number of jobs, as this will greatly reduce the amount memory 
+   used during the build process. If you have limited memory, you may wish to 
+   set this to 1.
+ 
+ * -DLLVM_TARGETS_TO_BUILD  
+   Set this equal to the target you wish to build. You may wish to set this to 
+   X86; however, you will find a full list of targets within the 
+   llvm-project/llvm/lib/Target directory. 
+
+ * -DLLVM_OPTIMIZED_TABLEGEN  
+   Set this to ON to generate a fully optimized tablegen during build. This will 
+   significantly improve your build time.
+
+ * -DLLVM_ENABLE_PROJECTS  
+   Set this equal to the projects you wish to compile (e.g. clang, lld, etc.) If 
+   compiling more than one project, deliniate the list with a semicolon. Should 
+   you run into issues with the semicolon, try surrounding it with single quotes.  
+ 
+ * -DCLANG_ENABLE_STATIC_ANALYZER  
+   Set this option to OFF if you do not require the clang static analyzer. This 
+   should improve your build time significantly.
+ 
+ * -DLLVM_USE_SPLIT_DWARF
+   Consider setting this to ON if you require a debug build, as this will ease 
+   memory pressure on the linker. This will make linking much faster, as the 
+   binaries will not contain any of the debug information; however, this will 
+   generate the debug information in the form of a DWARF object file.
+
 .. _links:
 
 Links


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