1 files changed, 25 insertions, 1 deletions
diff --git a/llvm/lib/Target/AArch64/AArch64CollectLOH.cpp b/llvm/lib/Target/AArch64/AArch64CollectLOH.cpp
index efdb1131abc9..ac243347b24d 100644
--- a/llvm/lib/Target/AArch64/AArch64CollectLOH.cpp
+++ b/llvm/lib/Target/AArch64/AArch64CollectLOH.cpp
@@ -419,13 +419,37 @@ static void handleADRP(const MachineInstr &MI, AArch64FunctionInfo &AFI,
         ++NumADRPToLDR;
       }
       break;
-    case MCLOH_AdrpAddLdr:
+    case MCLOH_AdrpAddLdr: {
+      // There is a possibility that the linker may try to rewrite:
+      // adrp x0, @sym@PAGE
+      // add x1, x0, @sym@PAGEOFF
+      // [x0 = some other def]
+      // ldr x2, [x1]
+      //    ...into...
+      // adrp x0, @sym
+      // nop
+      // [x0 = some other def]
+      // ldr x2, [x0]
+      // ...if the offset to the symbol won't fit within a literal load.
+      // This causes the load to use the result of the adrp, which in this
+      // case has already been clobbered.
+      // 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))
+        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"