When folding memory operands, preserve existing MachineMemOperands.

This comes into play with patchpoint, which can fold multiple
operands. Since the patchpoint is already treated as a call, the
machine mem operands won't affect anything, and there's nothing to
test. But we still want to do the right thing here to be sure that our
MIs obey the rules.

llvm-svn: 194750

llvm/lib/CodeGen/TargetInstrInfo.cpp

@@ -364,6 +364,7 @@ TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI,
 
   // Ask the target to do the actual folding.
   if (MachineInstr *NewMI = foldMemoryOperandImpl(MF, MI, Ops, FI)) {
+    NewMI->setMemRefs(MI->memoperands_begin(), MI->memoperands_end());
     // Add a memory operand, foldMemoryOperandImpl doesn't do that.
     assert((!(Flags & MachineMemOperand::MOStore) ||
             NewMI->mayStore()) &&
@@ -424,9 +425,19 @@ TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI,
   NewMI = MBB.insert(MI, NewMI);
 
   // Copy the memoperands from the load to the folded instruction.
-  NewMI->setMemRefs(LoadMI->memoperands_begin(),
-                    LoadMI->memoperands_end());
-
+  if (MI->memoperands_empty()) {
+    NewMI->setMemRefs(LoadMI->memoperands_begin(),
+                      LoadMI->memoperands_end());
+  }
+  else {
+    // Handle the rare case of folding multiple loads.
+    NewMI->setMemRefs(MI->memoperands_begin(),
+                      MI->memoperands_end());
+    for (MachineInstr::mmo_iterator I = LoadMI->memoperands_begin(),
+           E = LoadMI->memoperands_end(); I != E; ++I) {
+      NewMI->addMemOperand(MF, *I);
+    }
+  }
   return NewMI;
 }