[SelectionDAG] Update check in createOperands to reflect max() is a valid value.

[fhahn]

Summary

The value returned by max() is the last valid value, adjust the
comparison accordingly.

The code added in D55073 creates TokenFactors with max() operands.

[lebedev.ri]

Can any test case be added here, or would it be just too big to realistically test?

[fhahn]

In D56738#1358379, @lebedev.ri wrote:

Can any test case be added here, or would it be just too big to realistically test?

I have a file triggering the assert, but I think the cases where it is triggered require 64k load/stores in a single BB. But maybe there is another way to construct a node with more than 64k operands?

[aemerson]

In D56738#1358417, @fhahn wrote:

In D56738#1358379, @lebedev.ri wrote:

Can any test case be added here, or would it be just too big to realistically test?

I have a file triggering the assert, but I think the cases where it is triggered require 64k load/stores in a single BB. But maybe there is another way to construct a node with more than 64k operands?

I couldn't find a way to generate the test myself without writing a huge one. LGTM.

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

SDNode *SelectionDAG::isConstantFPBuildVectorOrConstantFP(SDValue N) {
   if (ISD::isBuildVectorOfConstantFPSDNodes(N.getNode()))
     return N.getNode();
 
   return nullptr;
 }
 
 void SelectionDAG::createOperands(SDNode *Node, ArrayRef<SDValue> Vals) {
   assert(!Node->OperandList && "Node already has operands");
-  assert(std::numeric_limits<decltype(SDNode::NumOperands)>::max() >
+  assert(std::numeric_limits<decltype(SDNode::NumOperands)>::max() >=
              Vals.size() &&
          "too many operands to fit into SDNode");
   SDUse *Ops = OperandRecycler.allocate(
       ArrayRecycler<SDUse>::Capacity::get(Vals.size()), OperandAllocator);
 
   bool IsDivergent = false;
   for (unsigned I = 0; I != Vals.size(); ++I) {
     Ops[I].setUser(Node);