Don't use MCInstrDesc flags for implicit operands.

When a MachineInstr is constructed, its implicit operands are added
first, then the explicit operands are inserted before the implicits.

MCInstrDesc has oprand flags like early clobber and operand ties that
apply to the explicit operands.

Don't look at those flags when the implicit operands are first added in
the explicit operands's positions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162910 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/MachineInstr.cpp

@@ -721,19 +721,24 @@ void MachineInstr::addOperand(const MachineOperand &Op) {
     // Add the new operand to RegInfo.
     if (RegInfo)
       RegInfo->addRegOperandToUseList(&Operands[OpNo]);
-    // Set the IsTied bit if MC indicates this use is tied to a def.
-    if (Operands[OpNo].isUse()) {
-      int DefIdx = MCID->getOperandConstraint(OpNo, MCOI::TIED_TO);
-      if (DefIdx != -1) {
-        MachineOperand &DefMO = getOperand(DefIdx);
-        assert(DefMO.isDef() && "Use tied to operand that isn't a def");
-        DefMO.IsTied = true;
-        Operands[OpNo].IsTied = true;
+    // The MCID operand information isn't accurate until we start adding
+    // explicit operands. The implicit operands are added first, then the
+    // explicits are inserted before them.
+    if (!isImpReg) {
+      // Set the IsTied bit if MC indicates this use is tied to a def.
+      if (Operands[OpNo].isUse()) {
+        int DefIdx = MCID->getOperandConstraint(OpNo, MCOI::TIED_TO);
+        if (DefIdx != -1) {
+          MachineOperand &DefMO = getOperand(DefIdx);
+          assert(DefMO.isDef() && "Use tied to operand that isn't a def");
+          DefMO.IsTied = true;
+          Operands[OpNo].IsTied = true;
+        }
       }
+      // If the register operand is flagged as early, mark the operand as such.
+      if (MCID->getOperandConstraint(OpNo, MCOI::EARLY_CLOBBER) != -1)
+        Operands[OpNo].setIsEarlyClobber(true);
     }
-    // If the register operand is flagged as early, mark the operand as such.
-    if (MCID->getOperandConstraint(OpNo, MCOI::EARLY_CLOBBER) != -1)
-      Operands[OpNo].setIsEarlyClobber(true);
   }
 
   // Re-add all the implicit ops.