[Mlir-commits] [mlir] [mlir][vector] Fix fold result for empty vector.mask with no results (PR #180345)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir-vector

Author: Longsheng Mou (CoTinker)

<details>
<summary>Changes</summary>

This PR fixes `foldEmptyMaskOp` to return `failure` when folding an empty vector.mask whose terminatorhas no operands. Previously this case returned success without producing any folded results, which violates the folding contract. Fixes #<!-- -->177825.

---
Full diff: https://github.com/llvm/llvm-project/pull/180345.diff


2 Files Affected:

- (modified) mlir/lib/Dialect/Vector/IR/VectorOps.cpp (+1-1) 
- (modified) mlir/test/Conversion/ArithToEmitC/arith-to-emitc.mlir (+11) 


``````````diff
diff --git a/mlir/lib/Dialect/Vector/IR/VectorOps.cpp b/mlir/lib/Dialect/Vector/IR/VectorOps.cpp
index 613adeb5eeaaf..089f41142dfd5 100644
--- a/mlir/lib/Dialect/Vector/IR/VectorOps.cpp
+++ b/mlir/lib/Dialect/Vector/IR/VectorOps.cpp
@@ -7614,7 +7614,7 @@ static LogicalResult foldEmptyMaskOp(MaskOp maskOp, MaskOp::FoldAdaptor adaptor,
   auto terminator = cast<vector::YieldOp>(block->front());
   if (terminator.getNumOperands() == 0) {
     // `vector.mask` has no results, just remove the `vector.mask`.
-    return success();
+    return failure();
   }
 
   // `vector.mask` has results, propagate the results.
diff --git a/mlir/test/Conversion/ArithToEmitC/arith-to-emitc.mlir b/mlir/test/Conversion/ArithToEmitC/arith-to-emitc.mlir
index 319dfc31ab637..5655c76d37faf 100644
--- a/mlir/test/Conversion/ArithToEmitC/arith-to-emitc.mlir
+++ b/mlir/test/Conversion/ArithToEmitC/arith-to-emitc.mlir
@@ -772,3 +772,14 @@ func.func @arith_truncf(%arg0: f64) -> f16 {
 
   return %truncd1 : f16
 }
+
+// -----
+
+// Ensure that vector.mask with an empty mask does not cause issues.
+
+// CHECK-LABEL: empty_vector_mask
+func.func @empty_vector_mask(%mask : vector<8xi1>) {
+  // CHECK: vector.mask
+  vector.mask %mask { vector.yield } : vector<8xi1>
+  return
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/180345