[Mlir-commits] [mlir] [mlir][vector] Fix for WarpOpScfForOp failure when scf.for has results that are unused. (PR #141853)

[Jianhui Li]

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@@ -1554,22 +1554,37 @@ struct WarpOpScfForOp : public WarpDistributionPattern {
     llvm::SmallSetVector<Value, 32> escapingValues;
     SmallVector<Type> inputTypes;
     SmallVector<Type> distTypes;
+    auto collectEscapingValues = [&](Value value) {
+      if (!escapingValues.insert(value))
+        return;
+      Type distType = value.getType();
+      if (auto vecType = dyn_cast<VectorType>(distType)) {
+        AffineMap map = distributionMapFn(value);
+        distType = getDistributedType(vecType, map, warpOp.getWarpSize());
+      }
+      inputTypes.push_back(value.getType());
+      distTypes.push_back(distType);
+    };
+
     mlir::visitUsedValuesDefinedAbove(
         forOp.getBodyRegion(), [&](OpOperand *operand) {
           Operation *parent = operand->get().getParentRegion()->getParentOp();
           if (warpOp->isAncestor(parent)) {
-            if (!escapingValues.insert(operand->get()))
-              return;
-            Type distType = operand->get().getType();
-            if (auto vecType = dyn_cast<VectorType>(distType)) {
-              AffineMap map = distributionMapFn(operand->get());
-              distType = getDistributedType(vecType, map, warpOp.getWarpSize());
-            }
-            inputTypes.push_back(operand->get().getType());
-            distTypes.push_back(distType);
+            collectEscapingValues(operand->get());
           }
         });
 
+    // Any forOp result that is not already yielded by the warpOp
+    // region is also considered escaping and must be returned by the
+    // original warpOp.
+    for (OpResult forResult : forOp.getResults()) {
+      // Check if this forResult is already yielded by the yield op.
+      if (llvm::is_contained(yield->getOperands(), forResult)) {
+        continue;
+      }
+      collectEscapingValues(forResult);
+    }
+
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Jianhui-Li wrote:

If the code is to add the initial value of the loop-carried variables to the new warp op's result -

Instead collect the loop result and fixup latter, can we directly collect "forOp.getInitArgs()" as escaping value - since these are escaping value of the for statement, but not captured by the original code which only scan the loop body. 

https://github.com/llvm/llvm-project/pull/141853