From 7f3c7464b47448e609adfddf3787857c626194c2 Mon Sep 17 00:00:00 2001
From: NiccoloN <niccolo.nicolosi@gmail.com>
Date: Fri, 22 May 2026 22:16:19 +0200
Subject: [PATCH] update cost model of batch lanes to consider only a slice of
 the shared batch input

---
 .../Scheduling/ComputeGraph.cpp               | 55 +++++++++++++++++--
 1 file changed, 49 insertions(+), 6 deletions(-)

diff --git a/src/PIM/Dialect/Spatial/Transforms/MergeComputeNodes/Scheduling/ComputeGraph.cpp b/src/PIM/Dialect/Spatial/Transforms/MergeComputeNodes/Scheduling/ComputeGraph.cpp
index b3831f6..6ca07f3 100644
--- a/src/PIM/Dialect/Spatial/Transforms/MergeComputeNodes/Scheduling/ComputeGraph.cpp
+++ b/src/PIM/Dialect/Spatial/Transforms/MergeComputeNodes/Scheduling/ComputeGraph.cpp
@@ -7,7 +7,7 @@
 #include "llvm/Support/Casting.h"
 
 #include <algorithm>
-#include <limits>
+#include <iterator>
 #include <optional>
 #include <queue>
 #include <utility>
@@ -64,6 +64,49 @@ bool isUsedAsWeightOnly(Operation* producerOp) {
   return true;
 }
 
+bool isLaneOffset(OpFoldResult offset, Value laneArg) {
+  auto offsetValue = llvm::dyn_cast<Value>(offset);
+  return offsetValue == laneArg;
+}
+
+std::optional<Weight> getBatchProjectedInputTransferCost(SpatComputeBatch batch, Value input) {
+  auto inputIt = llvm::find(batch.getInputs(), input);
+  if (inputIt == batch.getInputs().end())
+    return std::nullopt;
+
+  size_t inputIndex = std::distance(batch.getInputs().begin(), inputIt);
+  std::optional<BlockArgument> inputArg = batch.getInputArgument(inputIndex);
+  std::optional<BlockArgument> laneArg = batch.getLaneArgument();
+  if (!inputArg || !laneArg)
+    return std::nullopt;
+
+  Weight projectedCost = 0;
+  for (Operation* user : inputArg->getUsers()) {
+    auto extract = dyn_cast<tensor::ExtractSliceOp>(user);
+    if (!extract || extract.getSource() != *inputArg)
+      return std::nullopt;
+    if (extract.getMixedOffsets().empty() || !isLaneOffset(extract.getMixedOffsets().front(), *laneArg))
+      return std::nullopt;
+
+    auto resultType = dyn_cast<ShapedType>(extract.getResult().getType());
+    if (!resultType || !resultType.hasStaticShape())
+      return std::nullopt;
+    projectedCost = checkedAdd(projectedCost, static_cast<Weight>(getSizeInBytes(resultType)));
+  }
+
+  if (projectedCost == 0)
+    return std::nullopt;
+  return projectedCost;
+}
+
+Weight getInputTransferCost(const ComputeInstance& consumerInstance, Value input) {
+  auto inputType = cast<ShapedType>(input.getType());
+  if (auto batch = dyn_cast<SpatComputeBatch>(consumerInstance.op))
+    if (std::optional<Weight> projectedCost = getBatchProjectedInputTransferCost(batch, input))
+      return *projectedCost;
+  return static_cast<Weight>(getSizeInBytes(inputType));
+}
+
 std::vector<ComputeGraphEdge> aggregateEdges(llvm::ArrayRef<ComputeGraphEdge> edges) {
   llvm::DenseMap<std::pair<size_t, size_t>, Weight> edgeWeights;
   for (const ComputeGraphEdge& edge : edges) {
@@ -136,15 +179,16 @@ ComputeGraph buildComputeGraph(Operation* entryOp) {
 
   llvm::SmallVector<ComputeGraphEdge, 16> rawEdges;
   for (const auto& [targetIndex, node] : llvm::enumerate(graph.nodes)) {
-    for (Value input : getComputeInstanceInputs(node.instance)) {
+    llvm::SmallVector<Value, 4> inputs = getComputeInstanceInputs(node.instance);
+    for (Value input : inputs) {
+      Weight transferCost = getInputTransferCost(node.instance, input);
       if (auto producerBatch = dyn_cast_or_null<SpatComputeBatch>(input.getDefiningOp());
           producerBatch && producerBatch.getNumResults() != 0 && !isa<SpatComputeBatch>(node.instance.op)) {
         for (uint32_t lane = 0; lane < static_cast<uint32_t>(producerBatch.getLaneCount()); ++lane) {
           auto producerIt = graph.instanceToIndex.find(getBatchChunkForLane(producerBatch, lane));
           if (producerIt == graph.instanceToIndex.end())
             continue;
-          rawEdges.push_back(
-            {producerIt->second, targetIndex, static_cast<Weight>(getSizeInBytes(cast<ShapedType>(input.getType())))});
+          rawEdges.push_back({producerIt->second, targetIndex, transferCost});
         }
         continue;
       }
@@ -155,8 +199,7 @@ ComputeGraph buildComputeGraph(Operation* entryOp) {
       auto producerIt = graph.instanceToIndex.find(*producerInstance);
       if (producerIt == graph.instanceToIndex.end())
         continue;
-      rawEdges.push_back(
-        {producerIt->second, targetIndex, static_cast<Weight>(getSizeInBytes(cast<ShapedType>(input.getType())))});
+      rawEdges.push_back({producerIt->second, targetIndex, transferCost});
     }
   }