AMDGPU: Handle invariant when lowering global loads (#168914)

Global with invariant should be treated identically to
constant.

Author: arsenm

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

@@ -11944,7 +11944,7 @@ SDValue SITargetLowering::LowerLOAD(SDValue Op, SelectionDAG &DAG) const {
       AS == AMDGPUAS::CONSTANT_ADDRESS_32BIT ||
       (AS == AMDGPUAS::GLOBAL_ADDRESS &&
        Subtarget->getScalarizeGlobalBehavior() && Load->isSimple() &&
-       isMemOpHasNoClobberedMemOperand(Load))) {
+       (Load->isInvariant() || isMemOpHasNoClobberedMemOperand(Load)))) {
     if ((!Op->isDivergent() || AMDGPU::isUniformMMO(MMO)) &&
         Alignment >= Align(4) && NumElements < 32) {
       if (MemVT.isPow2VectorType() ||