[llvm] [LOH] Don't emit AdrpAddStr when register could be clobbered (PR #142849)

[Kyungwoo Lee via llvm-commits]

================
@@ -432,28 +443,24 @@ static void handleADRP(const MachineInstr &MI, AArch64FunctionInfo &AFI,
       // FIXME: Implement proper liveness tracking for all registers. For now,
       // don't emit the LOH if there are any instructions between the add and
       // the ldr.
-      MachineInstr *AddMI = const_cast<MachineInstr *>(Info.MI1);
-      const MachineInstr *LdrMI = Info.MI0;
-      auto AddIt = MachineBasicBlock::iterator(AddMI);
-      auto EndIt = AddMI->getParent()->end();
-      if (AddMI->getIterator() == EndIt || LdrMI != &*next_nodbg(AddIt, EndIt))
+      if (!areInstructionsConsecutive(Info.MI1, Info.MI0))
         break;
-
       LLVM_DEBUG(dbgs() << "Adding MCLOH_AdrpAddLdr:\n"
                         << '\t' << MI << '\t' << *Info.MI1 << '\t'
                         << *Info.MI0);
       AFI.addLOHDirective(MCLOH_AdrpAddLdr, {&MI, Info.MI1, Info.MI0});
       ++NumADDToLDR;
       break;
-    }
     case MCLOH_AdrpAddStr:
-      if (Info.MI1 != nullptr) {
-        LLVM_DEBUG(dbgs() << "Adding MCLOH_AdrpAddStr:\n"
-                          << '\t' << MI << '\t' << *Info.MI1 << '\t'
-                          << *Info.MI0);
-        AFI.addLOHDirective(MCLOH_AdrpAddStr, {&MI, Info.MI1, Info.MI0});
-        ++NumADDToSTR;
-      }
+      if (!Info.MI1)
----------------
kyulee-com wrote:

This check already exists. I'm curious why this check is not needed for AdrpAddLdr. Can we conservatively integrate a null-check for both MI0 and MI1 inside `areInstructionsConsecutive()`, return false if either one is null?

https://github.com/llvm/llvm-project/pull/142849