[PATCH] D61583: [ELF] Create Undefined for local STT_SECTION symbol if the section is discarded

Thu Jun 6 19:26:12 PDT 2019

sfertile added a comment.

In D61583#1533390 <https://reviews.llvm.org/D61583#1533390>, @MaskRay wrote:

> @sfertile I'm confused with the recent revert and revert of revert.. The problem this change caused should have been fixed by D62840 <https://reviews.llvm.org/D62840>. Did you find other problems? (The `warn()` can be deleted if you suspect there is somethin

The multistage power-pc build bot is broken

  69.906 [3746/40/441] Linking CXX executable bin/llvm-tblgen
  FAILED: bin/llvm-tblgen 
  : && /home/buildbots/ppc64le-lld-multistage-test/ppc64le-lld-multistage-test/install/stage1/bin/clang++  -fPIC -fvisibility-inlines-hidden -Werror -Werror=date-time -Werror=unguarded-availability-new -std=c++11 -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -fdiagnostics-color -ffunction-sections -fdata-sections -O3  -fuse-ld=lld -Wl,--color-diagnostics -Wl,-allow-shlib-undefined    -Wl,-O3 -Wl,--gc-sections utils/TableGen/CMakeFiles/llvm-tblgen.dir/AsmMatcherEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/AsmWriterEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/AsmWriterInst.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/Attributes.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/CallingConvEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeEmitterGen.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenDAGPatterns.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenHwModes.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenInstruction.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenMapTable.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenRegisters.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenSchedule.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenTarget.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/DAGISelEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/DAGISelMatcherEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/DAGISelMatcherGen.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/DAGISelMatcherOpt.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/DAGISelMatcher.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/DFAPacketizerEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/DisassemblerEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/ExegesisEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/FastISelEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/FixedLenDecoderEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/GlobalISelEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/InfoByHwMode.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/InstrInfoEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/InstrDocsEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/IntrinsicEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/OptParserEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/PredicateExpander.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/PseudoLoweringEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/RISCVCompressInstEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/RegisterBankEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/RegisterInfoEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/SDNodeProperties.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/SearchableTableEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/SubtargetEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/SubtargetFeatureInfo.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/TableGen.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/Types.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/X86DisassemblerTables.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/X86EVEX2VEXTablesEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/X86FoldTablesEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/X86ModRMFilters.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/X86RecognizableInstr.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/WebAssemblyDisassemblerEmitter.cpp.o utils/TableGen/CMakeFiles/llvm-tblgen.dir/CTagsEmitter.cpp.o  -o bin/llvm-tblgen  -Wl,-rpath,"\$ORIGIN/../lib" lib/libLLVMSupport.a lib/libLLVMTableGen.a -lpthread lib/libLLVMSupport.a -lz -lrt -ldl -ltinfo -lpthread -lm lib/libLLVMDemangle.a && :
  ld.lld: error: relocation refers to a discarded section: .rodata._ZNK4llvm3MVT13getSizeInBitsEv
  >>> defined in utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenRegisters.cpp.o
  >>> referenced by CodeGenRegisters.cpp
  >>>               utils/TableGen/CMakeFiles/llvm-tblgen.dir/CodeGenRegisters.cpp.o:(.toc+0x0)

  ld.lld: error: relocation refers to a discarded section: .rodata._ZNK4llvm3MVT13getSizeInBitsEv
  >>> defined in utils/TableGen/CMakeFiles/llvm-tblgen.dir/GlobalISelEmitter.cpp.o
  >>> referenced by GlobalISelEmitter.cpp
  >>>               utils/TableGen/CMakeFiles/llvm-tblgen.dir/GlobalISelEmitter.cpp.o:(.toc+0x20)

  ld.lld: error: relocation refers to a discarded section: .rodata._ZNK4llvm3MVT20getVectorElementTypeEv
  >>> defined in utils/TableGen/CMakeFiles/llvm-tblgen.dir/GlobalISelEmitter.cpp.o
  >>> referenced by GlobalISelEmitter.cpp
  >>>               utils/TableGen/CMakeFiles/llvm-tblgen.dir/GlobalISelEmitter.cpp.o:(.toc+0x28)

  ld.lld: error: relocation refers to a discarded section: .rodata._ZNK4llvm3MVT20getVectorElementTypeEv
  >>> defined in utils/TableGen/CMakeFiles/llvm-tblgen.dir/IntrinsicEmitter.cpp.o
  >>> referenced by IntrinsicEmitter.cpp
  >>>               utils/TableGen/CMakeFiles/llvm-tblgen.dir/IntrinsicEmitter.cpp.o:(.toc+0x38)

  ld.lld: error: relocation refers to a discarded section: .rodata._ZNK4llvm3MVT13getSizeInBitsEv
  >>> defined in utils/TableGen/CMakeFiles/llvm-tblgen.dir/IntrinsicEmitter.cpp.o
  >>> referenced by IntrinsicEmitter.cpp
  >>>               utils/TableGen/CMakeFiles/llvm-tblgen.dir/IntrinsicEmitter.cpp.o:(.toc+0x40)

  ld.lld: error: relocation refers to a discarded section: .rodata._ZN4llvm4yaml11needsQuotesENS_9StringRefE
  >>> defined in lib/libLLVMSupport.a(Timer.cpp.o)
  >>> referenced by Timer.cpp
  >>>               Timer.cpp.o:(.toc+0x30) in archive lib/libLLVMSupport.a
  clang-9: error: linker command failed with exit code 1 (use -v to see invocation)

The build monitor narrowed it down to this patch so I was pulling it to turn the bot back to green until we can figure out why this patch only causes a problem on PowerPC.  I don't think there is anything necessarily wrong with the warning. but I do think we need to see if we are discarding the same sections before/after this patch. I'm not familiar with when/why we discard sections but it seems quite odd to me we are discarding a section with relocations referencing it.

Repository:
  rLLD LLVM Linker

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D61583/new/

https://reviews.llvm.org/D61583