Refactor PIM/Common (splitting in files, adding helpers, adding brief

docs)

src/PIM/Common/IR/WeightUtils.hpp

@@ -0,0 +1,29 @@
+#pragma once
+
+#include "mlir/IR/Operation.h"
+#include "mlir/IR/Value.h"
+
+#include "llvm/ADT/STLFunctionalExtras.h"
+#include "llvm/ADT/StringRef.h"
+
+inline constexpr llvm::StringRef PimWeightAlwaysAttrName = "weightAlways";
+
+namespace onnx_mlir {
+
+bool hasWeightAlways(mlir::Operation* op);
+
+/// Tags an op as producing a value that should stay materialized as a reusable
+/// weight across later PIM lowering/codegen stages.
+void markWeightAlways(mlir::Operation* op);
+
+bool isSpatialMvmVmmWeightUse(mlir::OpOperand& use);
+
+/// Returns true when a value flows only into Spatial weighted MVM/VMM operands,
+/// allowing later passes to preserve it as a dedicated weight-like object.
+bool hasOnlySpatialMvmVmmWeightUses(mlir::Value value);
+
+/// Visits weight operands consumed by Pim core ops/core batches so downstream
+/// passes can identify globals that must remain weight-backed.
+void walkPimMvmVmmWeightUses(mlir::Operation* root, llvm::function_ref<void(mlir::OpOperand&)> callback);
+
+} // namespace onnx_mlir