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libclc: Pass system libraries to the linker after llvm libraries
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Authored by tstellar on Apr 20 2020, 9:52 PM.

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Summary

The llvm libraries depend on the symbols in the system libaries, so
the system libraries need to be added after.

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Event Timeline

tstellar created this revision.Apr 20 2020, 9:52 PM
Herald added a project: Restricted Project. · View Herald TranscriptApr 20 2020, 9:52 PM
jvesely accepted this revision.Apr 22 2020, 4:43 PM

was this a problem with using -Wl,--as-needed?

LGTM.

This revision is now accepted and ready to land.Apr 22 2020, 4:43 PM

was this a problem with using -Wl,--as-needed?

LGTM.

No, I was hitting this when using the default build options for both LLVM and libclc.

was this a problem with using -Wl,--as-needed?

LGTM.

No, I was hitting this when using the default build options for both LLVM and libclc.

that's weird. linker shouldn't really drop libraries unless as-needed is used. can you post the falling cmdline?

was this a problem with using -Wl,--as-needed?

LGTM.

No, I was hitting this when using the default build options for both LLVM and libclc.

that's weird. linker shouldn't really drop libraries unless as-needed is used. can you post the falling cmdline?

This is the failing cmdline (from here https://github.com/tstellar/llvm-project/runs/587088911):

/usr/bin/c++ CMakeFiles/prepare_builtins.dir/utils/prepare-builtins.cpp.o -o prepare_builtins -L/home/runner/work/llvm-project/llvm-project/build/lib -Wl,-rpath,/home/runner/work/llvm-project/llvm-project/build/lib -lz -lrt -ldl -ltinfo -lpthread -lm -lxml2 -lLLVMBitWriter -lLLVMAnalysis -lLLVMProfileData -lLLVMObject -lLLVMTextAPI -lLLVMMCParser -lLLVMMC -lLLVMDebugInfoCodeView -lLLVMDebugInfoMSF -lLLVMBitReader -lLLVMCore -lLLVMRemarks -lLLVMBitstreamReader -lLLVMBinaryFormat -lLLVMSupport -lLLVMDemangle

This is the failing cmdline (from here https://github.com/tstellar/llvm-project/runs/587088911):

/usr/bin/c++ CMakeFiles/prepare_builtins.dir/utils/prepare-builtins.cpp.o -o prepare_builtins -L/home/runner/work/llvm-project/llvm-project/build/lib -Wl,-rpath,/home/runner/work/llvm-project/llvm-project/build/lib -lz -lrt -ldl -ltinfo -lpthread -lm -lxml2 -lLLVMBitWriter -lLLVMAnalysis -lLLVMProfileData -lLLVMObject -lLLVMTextAPI -lLLVMMCParser -lLLVMMC -lLLVMDebugInfoCodeView -lLLVMDebugInfoMSF -lLLVMBitReader -lLLVMCore -lLLVMRemarks -lLLVMBitstreamReader -lLLVMBinaryFormat -lLLVMSupport -lLLVMDemangle

Looks like this is caused by Ubuntu enabling -Wl,--as-needed by default (since 11.10) [0]

[0] https://wiki.ubuntu.com/ToolChain/CompilerFlags#A-Wl.2C--as-needed

This revision was automatically updated to reflect the committed changes.