Fix wrong number of operands error with default operands

[arsenm]

Summary

If a value was provided for some of the defaulted operands,
this wouldn't work.

e.g. inst x, y, defaulted_z, defaulted_w

If a value was provided for z and / or w,
these overriding value operands would be skipped,
never incrementing ChildNo and would hit the "too many operands"
error below. Only check for d

utils/TableGen/CodeGenDAGPatterns.cpp

if (getOperator()->getName() == "INSERT_SUBREG") {
         }
       }
     }
 
     unsigned ChildNo = 0;
     for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) {
       Record *OperandNode = Inst.getOperand(i);
 
+      // Verify that we didn't run out of provided operands.
+      if (ChildNo >= getNumChildren()) {
+        // If we have advanced past the number of provided operands, check if we
+        // have a default operand that will be acceptable instead.
+
         // If the instruction expects a predicate or optional def operand, we
         // codegen this by setting the operand to it's default value if it has a
         // non-empty DefaultOps field.
         if (OperandNode->isSubClassOf("OperandWithDefaultOps") &&
             !CDP.getDefaultOperand(OperandNode).DefaultOps.empty())
           continue;
 
-      // Verify that we didn't run out of provided operands.
-      if (ChildNo >= getNumChildren()) {
         emitTooFewOperandsError(TP, getOperator()->getName(), getNumChildren());
         return false;
       }
 
       TreePatternNode *Child = getChild(ChildNo++);
       unsigned ChildResNo = 0;  // Instructions always use res #0 of their op.
 
       // If the operand has sub-operands, they may be provided by distinct