AMDGPU/SI: Report SIFixSGPRLiveRanges changed function

[• tstellarAMD]

LGTM. Does anything ever check the this return value?

[arsenm]

In D12258#233309, @tstellarAMD wrote:

LGTM. Does anything ever check the this return value?

I think the pass manager checks this for whether to print the function after the pass runs when debugging

[arsenm]

246056

lib/Target/AMDGPU/SIFixSGPRLiveRanges.cpp

FunctionPass *llvm::createSIFixSGPRLiveRangesPass() {
   return new SIFixSGPRLiveRanges();
 }
 
 bool SIFixSGPRLiveRanges::runOnMachineFunction(MachineFunction &MF) {
   MachineRegisterInfo &MRI = MF.getRegInfo();
   const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
   const SIRegisterInfo *TRI = static_cast<const SIRegisterInfo *>(
       MF.getSubtarget().getRegisterInfo());
+  bool MadeChange = false;
 
   MachinePostDominatorTree *PDT = &getAnalysis<MachinePostDominatorTree>();
   std::vector<std::pair<unsigned, LiveRange *>> SGPRLiveRanges;
 
   LiveIntervals *LIS = &getAnalysis<LiveIntervals>();
   LiveVariables *LV = getAnalysisIfAvailable<LiveVariables>();
   MachineBasicBlock *Entry = MF.begin();
 
for (std::pair<unsigned, LiveRange*> RegLR : SGPRLiveRanges) {
 
       // FIXME: Need to figure out how to update LiveRange here so this pass
       // will be able to preserve LiveInterval analysis.
       MachineInstr *NCDSGPRUse =
         BuildMI(*NCD, NCD->getFirstNonPHI(), DebugLoc(),
                 TII->get(AMDGPU::SGPR_USE))
         .addReg(Reg, RegState::Implicit);
 
+      MadeChange = true;
+
       SlotIndex SI = LIS->InsertMachineInstrInMaps(NCDSGPRUse);
       LIS->extendToIndices(*LR, SI.getRegSlot());
 
       if (LV) {
         // TODO: This won't work post-SSA
         LV->HandleVirtRegUse(Reg, NCD, NCDSGPRUse);
       }
 
       DEBUG(NCDSGPRUse->dump());
     }
   }
 
-  return false;
+  return MadeChange;
 }