[mlir][LLVM] Add OpBuilder for opaque pointer GEPs without struct indices

[zero9178]

Summary

An OpBuilder already exists for GEPs that does not have any struct indices for existing typed pointers, but no such builder exists for GEPs utilizing opaque pointers that has an explicit basePtrType

[zero9178]

Friendly ping :)

mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td

def LLVM_GEPOp : LLVM_Op<"getelementptr", [NoSideEffect]> {
   let skipDefaultBuilders = 1;
   let builders = [
     OpBuilder<(ins "Type":$resultType, "Value":$basePtr, "ValueRange":$indices,
                CArg<"ArrayRef<NamedAttribute>", "{}">:$attributes)>,
     OpBuilder<(ins "Type":$resultType, "Value":$basePtr, "ValueRange":$indices,
                "ArrayRef<int32_t>":$structIndices,
                CArg<"ArrayRef<NamedAttribute>", "{}">:$attributes)>,
     OpBuilder<(ins "Type":$resultType, "Type":$basePtrType, "Value":$basePtr,
+               "ValueRange":$indices,
+               CArg<"ArrayRef<NamedAttribute>", "{}">:$attributes)>,
+    OpBuilder<(ins "Type":$resultType, "Type":$basePtrType, "Value":$basePtr,
                "ValueRange":$indices, "ArrayRef<int32_t>":$structIndices,
                CArg<"ArrayRef<NamedAttribute>", "{}">:$attributes)>
   ];
   let llvmBuilder = [{
     SmallVector<llvm::Value *> indices;
     indices.reserve($structIndices.size());
     unsigned operandIdx = 0;
     for (int32_t structIndex : $structIndices.getValues<int32_t>()) {

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

static Type extractVectorElementType(Type type) {
   if (auto scalableVectorType = type.dyn_cast<LLVMScalableVectorType>())
     return scalableVectorType.getElementType();
   if (auto fixedVectorType = type.dyn_cast<LLVMFixedVectorType>())
     return fixedVectorType.getElementType();
   return type;
 }
 
 void GEPOp::build(OpBuilder &builder, OperationState &result, Type resultType,
+                  Type elementType, Value basePtr, ValueRange indices,
+                  ArrayRef<NamedAttribute> attributes) {
+  build(builder, result, resultType, elementType, basePtr, indices,
+        SmallVector<int32_t>(indices.size(), kDynamicIndex), attributes);
+}
+
+void GEPOp::build(OpBuilder &builder, OperationState &result, Type resultType,
                   Value basePtr, ValueRange indices,
                   ArrayRef<int32_t> structIndices,
                   ArrayRef<NamedAttribute> attributes) {
   auto ptrType =
       extractVectorElementType(basePtr.getType()).cast<LLVMPointerType>();
   assert(!ptrType.isOpaque() &&
          "expected non-opaque pointer, provide elementType explicitly when "
          "opaque pointers are used");