[MCA] Anchoring the vtable of CustomBehaviour

[myhsu]

Summary

Put the dtor of mca::CustomBehaviour into the cpp file to avoid undefined vtable when linking libLLVMMCACustomBehaviourAMDGPU as shared library.

Here is the original error message:

FAILED: lib/libLLVMMCACustomBehaviourAMDGPU.so.13git
...
ld.lld: error: undefined symbol: vtable for llvm::mca::CustomBehaviour
>>> referenced by CustomBehaviour.h:64 (llvm-project/llvm/include/llvm/MCA/CustomBehaviour.h:64)
>>>               tools/llvm-mca/lib/AMDGPU/CMakeFiles/LLVMMCACustomBehaviourAMDGPU.dir/AMDGPUCustomBehaviour.cpp.o:(llvm::mca::CustomBehaviour::CustomBehaviour(llvm::MCSubtargetInfo const&, llvm::mca::CircularSourceMgr const&, llvm::MCInstrInfo const&))
>>> referenced by CustomBehaviour.h:66 (llvm-project/llvm/include/llvm/MCA/CustomBehaviour.h:66)
>>>               tools/llvm-mca/lib/AMDGPU/CMakeFiles/LLVMMCACustomBehaviourAMDGPU.dir/AMDGPUCustomBehaviour.cpp.o:(llvm::mca::CustomBehaviour::~CustomBehaviour())
the vtable symbol may be undefined because the class is missing its key function (see https://lld.llvm.org/missingkeyfunction)

[andreadb]

LGTM

[holland11]

+1 Thanks for catching this!

llvm/include/llvm/MCA/CustomBehaviour.h

protected:
   const SourceMgr &SrcMgr;
   const MCInstrInfo &MCII;
 
 public:
   CustomBehaviour(const MCSubtargetInfo &STI, const SourceMgr &SrcMgr,
                   const MCInstrInfo &MCII)
       : STI(STI), SrcMgr(SrcMgr), MCII(MCII) {}
 
-  virtual ~CustomBehaviour() {}
+  virtual ~CustomBehaviour();
 
   // Before the llvm-mca pipeline dispatches an instruction, it first checks
   // for any register or resource dependencies / hazards. If it doesn't find
   // any, this method will be invoked to determine if there are any custom
   // hazards that the instruction needs to wait for.
   // The return value of this method is the number of cycles that the
   // instruction needs to wait for.
   // It's safe to underestimate the number of cycles to wait for since these

llvm/lib/MCA/CustomBehaviour.cpp

 ///
 //===----------------------------------------------------------------------===//
 
 #include "llvm/MCA/CustomBehaviour.h"
 
 namespace llvm {
 namespace mca {
 
+CustomBehaviour::~CustomBehaviour() {}
+
 unsigned CustomBehaviour::checkCustomHazard(ArrayRef<InstRef> IssuedInst,
                                             const InstRef &IR) {
   // 0 signifies that there are no hazards that need to be waited on
   return 0;
 }
 
 } // namespace mca
 } // namespace llvm

llvm/tools/llvm-mca/lib/AMDGPU/CMakeLists.txt

 include_directories(
   ${LLVM_MAIN_SRC_DIR}/lib/Target/AMDGPU
   ${LLVM_BINARY_DIR}/lib/Target/AMDGPU
   )
 
 set(LLVM_LINK_COMPONENTS
   AMDGPU
   Core
+  MCA
   Support
   )
 
 add_llvm_library(LLVMMCACustomBehaviourAMDGPU
   AMDGPUCustomBehaviour.cpp
 
   DEPENDS
   AMDGPUCommonTableGen
   )