[ARM] Add dependency on GlobalISel for unit tests to fix shared libs build

[nemanjai]

Summary

The shared libraries build fails due to a missing dependency. This just adds it. It is NFC otherwise.

[rovka]

Could you be a little more specific? I just ran a build with BUILD_SHARED_LIBS=ON and it seemed to work.

unittests/CodeGen/CMakeLists.txt

12

Why is this necessary? There's a subdirectory for GlobalISel, if some unit test in here is pulling in GlobalISel it's worth investigating why.

unittests/Target/ARM/CMakeLists.txt

15

Nit; These lists are sorted alphabetically.

[nemanjai]

unittests/CodeGen/CMakeLists.txt

12

Sorry, I probably should have added that to the description. It is missing vtables for two classes.

unittests/Target/ARM/CMakeFiles/ARMTests.dir/MachineInstrTest.cpp.o:(.toc+0x0): undefined reference to `vtable for llvm::RegisterBankInfo'
unittests/Target/ARM/CMakeFiles/ARMTests.dir/MachineInstrTest.cpp.o:(.toc+0x8): undefined reference to `vtable for llvm::LegalizerInfo'

Build info:
GCC build compiler: 7.3.1
CMake vars: -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_ASSERTIONS=ON -DBUILD_SHARED_LIBS=ON
OS: Ubuntu 16.04.6

unittests/Target/ARM/CMakeLists.txt

15

Oops, sorry about that. I'll reorder them.

[nemanjai]

Added the library in its correct slot alphabetically.

[peter.smith]

The references are coming from ARMSubtarget which is instantiated in MachineInstrTest.cpp. These have in the ARMSubtarget.h header file:

/// GlobalISel related APIs.
std::unique_ptr<CallLowering> CallLoweringInfo;
std::unique_ptr<InstructionSelector> InstSelector;
std::unique_ptr<LegalizerInfo> Legalizer;
std::unique_ptr<RegisterBankInfo> RegBankInfo;

There are code-generation differences in GCC and Clang. GCC generates the destructors for RegBankInfo and Legalizer in Comdat groups and calls them from the destructor of ArmSubTargetInfo, whereas LLVM does not. I don't intuitively know why there is this difference in code-generation.

In the static build libLLVMGlobalISel.a is included in the link line whereas it isn't for the shared build. I think that unless there is a good reason for GCC not to output the destructors then it is worth adding GlobalIsel.

[nemanjai]

In D69064#1714348, @peter.smith wrote:

The references are coming from ARMSubtarget which is instantiated in MachineInstrTest.cpp. These have in the ARMSubtarget.h header file:

/// GlobalISel related APIs.
std::unique_ptr<CallLowering> CallLoweringInfo;
std::unique_ptr<InstructionSelector> InstSelector;
std::unique_ptr<LegalizerInfo> Legalizer;
std::unique_ptr<RegisterBankInfo> RegBankInfo;

There are code-generation differences in GCC and Clang. GCC generates the destructors for RegBankInfo and Legalizer in Comdat groups and calls them from the destructor of ArmSubTargetInfo, whereas LLVM does not. I don't intuitively know why there is this difference in code-generation.

In the static build libLLVMGlobalISel.a is included in the link line whereas it isn't for the shared build. I think that unless there is a good reason for GCC not to output the destructors then it is worth adding GlobalIsel.

We don't really have control over how the GCC build compiler works, so I really think we should go ahead with this patch. This is particularly important since the PPC bot has also been failing for 3 days or so with the same error (caused by r374887):
http://lab.llvm.org:8011/builders/clang-ppc64le-linux-multistage/builds/10972

I initially didn't realize that this is causing build bot breaks, so I plan to commit this patch today to get the bot back to green.

unittests/CodeGen/CMakeLists.txt

8

This one is actually not needed. Just the other one. So on the commit, I'll commit just the change in unittests/Target/ARM.

[rovka]

Thanks, LGTM then!

unittests/CodeGen/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   ${LLVM_TARGETS_TO_BUILD}
   Analysis
   AsmParser
   AsmPrinter
   CodeGen
   Core
   MC
   SelectionDAG
   Support
   Target
+  GlobalISel
   )
 
 add_llvm_unittest(CodeGenTests
   AArch64SelectionDAGTest.cpp
   DIEHashTest.cpp
   LowLevelTypeTest.cpp
   MachineInstrBundleIteratorTest.cpp
   MachineInstrTest.cpp
   MachineOperandTest.cpp
   ScalableVectorMVTsTest.cpp
   TypeTraitsTest.cpp
   TargetOptionsTest.cpp
   )
 
 add_subdirectory(GlobalISel)

unittests/Target/ARM/CMakeLists.txt

 include_directories(
   ${LLVM_MAIN_SRC_DIR}/lib/Target/ARM
   ${LLVM_BINARY_DIR}/lib/Target/ARM
   )
 
 set(LLVM_LINK_COMPONENTS
   ARMCodeGen
   ARMDesc
   ARMInfo
   CodeGen
   MC
   SelectionDAG
   Support
   Target
+  GlobalISel
 )
 
 add_llvm_unittest(ARMTests
   MachineInstrTest.cpp
   )