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[cmake] Explicitly mark libraries defined in lib/ as "Component Libraries"
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Authored by tstellar on Wed, Nov 13, 6:46 AM.

Details

Summary

Most libraries are defined in the lib/ directory but there are also a
few libraries defined in tools/ e.g. libLLVM, libLTO. I'm defining
"Component Libraries" as libraries defined in lib/ that may be included in
libLLVM.so. Explicitly marking the libraries in lib/ as component
libraries allows us to remove some fragile checks that attempt to
differentiate between lib/ libraries and tools/ libraires:

  1. In tools/llvm-shlib, because

llvm_map_components_to_libnames(LIB_NAMES "all") returned a list of
all libraries defined in the whole project, there was custom code
needed to filter out libraries defined in tools/, none of which should
be included in libLLVM.so. This code assumed that any library
defined as static was from lib/ and everything else should be
excluded.

With this change, llvm_map_components_to_libnames(LIB_NAMES, "all")
only returns libraries that have been added to the LLVM_COMPONENT_LIBS
global cmake property, so this custom filtering logic can be removed.
Doing this also fixes the build with BUILD_SHARED_LIBS=ON
and LLVM_BUILD_LLVM_DYLIB=ON.

  1. There was some code in llvm_add_library that assumed that

libraries defined in lib/ would not have LLVM_LINK_COMPONENTS or
ARG_LINK_COMPONENTS set. This is only true because libraries
defined lib lib/ use LLVMBuild.txt and don't set these values.
This code has been fixed now to check if the library has been
explicitly marked as a component library, which should now make it
easier to remove LLVMBuild at some point in the future.

I have tested this patch on Windows, MacOS and Linux with release builds
and the following combinations of CMake options:

  • "" (No options)
  • -DLLVM_BUILD_LLVM_DYLIB=ON
  • -DLLVM_LINK_LLVM_DYLIB=ON
  • -DBUILD_SHARED_LIBS=ON
  • -DBUILD_SHARED_LIBS=ON -DLLVM_BUILD_LLVM_DYLIB=ON
  • -DBUILD_SHARED_LIBS=ON -DLLVM_LINK_LLVM_DYLIB=ON

Diff Detail

Event Timeline

tstellar created this revision.Wed, Nov 13, 6:46 AM
beanz accepted this revision.Wed, Nov 13, 11:23 AM

This looks like a great cleanup to me.

This revision is now accepted and ready to land.Wed, Nov 13, 11:23 AM
This revision was automatically updated to reflect the committed changes.