Properly register the ARMConstantIslands pass with PassRegistry

[rmaprath]

Summary

This pass is currently not registered properly with the PassRegistry, making
it invisible for llc options like -stop-after and -run-pass.

I need this pass to be available for those options for a follow-up patch.

[john.brawn]

lib/Target/ARM/ARM.h

57

This variable isn't used for anything, and I don't see why you declare it.

[rmaprath]

Address review comments: Get rid of the unnecessary pass id definition in the llvm namespace.

[rmaprath]

Abandoning: @jmolloy has committed a semantically equivalent patch: https://reviews.llvm.org/rL294948

lib/Target/ARM/ARM.h

 
 void computeBlockSize(MachineFunction *MF, MachineBasicBlock *MBB,
                       BasicBlockInfo &BBI);
 std::vector<BasicBlockInfo> computeAllBlockSizes(MachineFunction *MF);
 
 void initializeARMLoadStoreOptPass(PassRegistry &);
 void initializeARMPreAllocLoadStoreOptPass(PassRegistry &);
 
+extern char &ARMConstantIslandsID;
+void initializeARMConstantIslandsPass(PassRegistry &);
 } // end namespace llvm
 
 #endif // LLVM_LIB_TARGET_ARM_ARM_H

lib/Target/ARM/ARMConstantIslandPass.cpp

 #include <iterator>
 #include <new>
 #include <utility>
 #include <vector>
 
 using namespace llvm;
 
 #define DEBUG_TYPE "arm-cp-islands"
+#define ARM_CONSTANT_ISLANDS_PASS_NAME \
+  "ARM constant island placement and branch shortening pass"
 
 STATISTIC(NumCPEs,       "Number of constpool entries");
 STATISTIC(NumSplit,      "Number of uncond branches inserted");
 STATISTIC(NumCBrFixed,   "Number of cond branches fixed");
 STATISTIC(NumUBrFixed,   "Number of uncond branches fixed");
 STATISTIC(NumTBs,        "Number of table branches generated");
 STATISTIC(NumT2CPShrunk, "Number of Thumb2 constantpool instructions shrunk");
 STATISTIC(NumT2BrShrunk, "Number of Thumb2 immediate branches shrunk");
public:
     bool runOnMachineFunction(MachineFunction &MF) override;
 
     MachineFunctionProperties getRequiredProperties() const override {
       return MachineFunctionProperties().set(
           MachineFunctionProperties::Property::NoVRegs);
     }
 
     StringRef getPassName() const override {
-      return "ARM constant island placement and branch shortening pass";
+      return ARM_CONSTANT_ISLANDS_PASS_NAME;
     }
 
   private:
     void doInitialConstPlacement(std::vector<MachineInstr *> &CPEMIs);
     void doInitialJumpTablePlacement(std::vector<MachineInstr *> &CPEMIs);
     bool BBHasFallthrough(MachineBasicBlock *MBB);
     CPEntry *findConstPoolEntry(unsigned CPI, const MachineInstr *CPEMI);
     unsigned getCPELogAlign(const MachineInstr *CPEMI);
private:
     bool isOffsetInRange(unsigned UserOffset, unsigned TrialOffset,
                          unsigned Disp, bool NegativeOK, bool IsSoImm = false);
     bool isOffsetInRange(unsigned UserOffset, unsigned TrialOffset,
                          const CPUser &U) {
       return isOffsetInRange(UserOffset, TrialOffset,
                              U.getMaxDisp(), U.NegOk, U.IsSoImm);
     }
   };
+} // end anonymous namespace
 
-  char ARMConstantIslands::ID = 0;
-
-} // end anonymous namespace
+char &llvm::ARMConstantIslandsID = ARMConstantIslands::ID;
+INITIALIZE_PASS(ARMConstantIslands, DEBUG_TYPE, ARM_CONSTANT_ISLANDS_PASS_NAME,
+                false, false)
 
 /// verify - check BBOffsets, BBSizes, alignment of islands
 void ARMConstantIslands::verify() {
 #ifndef NDEBUG
   assert(std::is_sorted(MF->begin(), MF->end(),
                         [this](const MachineBasicBlock &LHS,
                                const MachineBasicBlock &RHS) {
                           return BBInfo[LHS.getNumber()].postOffset() <

lib/Target/ARM/ARMTargetMachine.cpp

extern "C" void LLVMInitializeARMTarget() {
   RegisterTargetMachine<ARMBETargetMachine> Y(getTheARMBETarget());
   RegisterTargetMachine<ThumbLETargetMachine> A(getTheThumbLETarget());
   RegisterTargetMachine<ThumbBETargetMachine> B(getTheThumbBETarget());
 
   PassRegistry &Registry = *PassRegistry::getPassRegistry();
   initializeGlobalISel(Registry);
   initializeARMLoadStoreOptPass(Registry);
   initializeARMPreAllocLoadStoreOptPass(Registry);
+  initializeARMConstantIslandsPass(Registry);
 }
 
 static std::unique_ptr<TargetLoweringObjectFile> createTLOF(const Triple &TT) {
   if (TT.isOSBinFormatMachO())
     return llvm::make_unique<TargetLoweringObjectFileMachO>();
   if (TT.isOSWindows())
     return llvm::make_unique<TargetLoweringObjectFileCOFF>();
   return llvm::make_unique<ARMElfTargetObjectFile>();