CodeGen: Use MachineInstr& in TargetLowering, NFC

This is a mechanical change to make TargetLowering API take MachineInstr&
(instead of MachineInstr*), since the argument is expected to be a valid
MachineInstr.  In one case, changed a parameter from MachineInstr* to
MachineBasicBlock::iterator, since it was used as an insertion point.

As a side effect, this removes a bunch of MachineInstr* to
MachineBasicBlock::iterator implicit conversions, a necessary step
toward fixing PR26753.

llvm-svn: 274287
diff --git a/llvm/lib/CodeGen/ExpandISelPseudos.cpp b/llvm/lib/CodeGen/ExpandISelPseudos.cpp
index 90ddac9..37cbba9 100644
--- a/llvm/lib/CodeGen/ExpandISelPseudos.cpp
+++ b/llvm/lib/CodeGen/ExpandISelPseudos.cpp
@@ -58,8 +58,7 @@
       // If MI is a pseudo, expand it.
       if (MI->usesCustomInsertionHook()) {
         Changed = true;
-        MachineBasicBlock *NewMBB =
-          TLI->EmitInstrWithCustomInserter(MI, MBB);
+        MachineBasicBlock *NewMBB = TLI->EmitInstrWithCustomInserter(*MI, MBB);
         // The expansion may involve new basic blocks.
         if (NewMBB != MBB) {
           MBB = NewMBB;