1 files changed, 10 insertions, 13 deletions
diff --git a/llvm/lib/Target/ARM/ARMLoadStoreOptimizer.cpp b/llvm/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
index ed9d30c3c3ab..6121055eb021 100644
--- a/llvm/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
@@ -2062,17 +2062,6 @@ bool ARMLoadStoreOpt::MergeReturnIntoLDM(MachineBasicBlock &MBB) {
       MO.setReg(ARM::PC);
       PrevMI.copyImplicitOps(*MBB.getParent(), *MBBI);
       MBB.erase(MBBI);
-      // We now restore LR into PC so it is not live-out of the return block
-      // anymore: Clear the CSI Restored bit.
-      MachineFrameInfo &MFI = MBB.getParent()->getFrameInfo();
-      // CSI should be fixed after PrologEpilog Insertion
-      assert(MFI.isCalleeSavedInfoValid() && "CSI should be valid");
-      for (CalleeSavedInfo &Info : MFI.getCalleeSavedInfo()) {
-        if (Info.getReg() == ARM::LR) {
-          Info.setRestored(false);
-          break;
-        }
-      }
       return true;
     }
   }
@@ -2120,14 +2109,22 @@ bool ARMLoadStoreOpt::runOnMachineFunction(MachineFunction &Fn) {
   isThumb2 = AFI->isThumb2Function();
   isThumb1 = AFI->isThumbFunction() && !isThumb2;
 
-  bool Modified = false;
+  bool Modified = false, ModifiedLDMReturn = false;
   for (MachineBasicBlock &MBB : Fn) {
     Modified |= LoadStoreMultipleOpti(MBB);
     if (STI->hasV5TOps() && !AFI->shouldSignReturnAddress())
-      Modified |= MergeReturnIntoLDM(MBB);
+      ModifiedLDMReturn |= MergeReturnIntoLDM(MBB);
     if (isThumb1)
       Modified |= CombineMovBx(MBB);
   }
+  Modified |= ModifiedLDMReturn;
+
+  // If we merged a BX instruction into an LDM, we need to re-calculate whether
+  // LR is restored. This check needs to consider the whole function, not just
+  // the instruction(s) we changed, because there may be other BX returns which
+  // still need LR to be restored.
+  if (ModifiedLDMReturn)
+    ARMFrameLowering::updateLRRestored(Fn);
 
   Allocator.DestroyAll();
   return Modified;