Strip old MachineInstrs *after* we know we can put them back.

Previous patch accidentally decided it couldn't convert a VFP to a
NEON instruction after it had already destroyed the old one. Not a
good move.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163230 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index dc4b67a..f8e554f 100644
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -3479,9 +3479,6 @@
       DstReg = MI->getOperand(0).getReg();
       SrcReg = MI->getOperand(1).getReg();
 
-      for (unsigned i = MI->getDesc().getNumOperands(); i; --i)
-        MI->RemoveOperand(i-1);
-
       DReg = getCorrespondingDRegAndLane(TRI, DstReg, Lane);
 
       // If we insert both a novel <def> and an <undef> on the DReg, we break
@@ -3491,6 +3488,9 @@
       if (!MI->definesRegister(DReg, TRI) && !MI->readsRegister(DReg, TRI))
           break;
 
+      for (unsigned i = MI->getDesc().getNumOperands(); i; --i)
+        MI->RemoveOperand(i-1);
+
       // Convert to %DDst = VSETLNi32 %DDst, %RSrc, Lane, 14, %noreg (; imps)
       // Again DDst may be undefined at the beginning of this instruction.
       MI->setDesc(get(ARM::VSETLNi32));
@@ -3512,9 +3512,6 @@
       DstReg = MI->getOperand(0).getReg();
       SrcReg = MI->getOperand(1).getReg();
 
-      for (unsigned i = MI->getDesc().getNumOperands(); i; --i)
-        MI->RemoveOperand(i-1);
-
       unsigned DstLane = 0, SrcLane = 0, DDst, DSrc;
       DDst = getCorrespondingDRegAndLane(TRI, DstReg, DstLane);
       DSrc = getCorrespondingDRegAndLane(TRI, SrcReg, SrcLane);
@@ -3526,6 +3523,9 @@
       if (!MI->definesRegister(DDst, TRI) && !MI->readsRegister(DDst, TRI))
           break;
 
+      for (unsigned i = MI->getDesc().getNumOperands(); i; --i)
+        MI->RemoveOperand(i-1);
+
       if (DSrc == DDst) {
         // Destination can be:
         //     %DDst = VDUPLN32d %DDst, Lane, 14, %noreg (; implicits)