comments, reject 0-poerand version

Author: Hardcode84

mlir/include/mlir/Dialect/MemRef/IR/MemRefOps.td

@@ -187,16 +187,16 @@ def DistinctObjectsOp : MemRef_Op<"distinct_objects", [
     ]> {
   let summary = "assumption that acesses to specific memrefs will never alias";
   let description = [{
-      The `distinct_objects` operation takes a list of memrefs and returns a list of
-      memrefs of the same types, with the additional assumption that accesses to
-      these memrefs will never alias with each other. This means that loads and
-      stores to different memrefs in the list can be safely reordered.
-
-      If the memrefs do alias, the behavior is undefined. This operation doesn't
-      affect the semantics of a program where the non-aliasing assumption holds
-      true. It is intended for optimization purposes, allowing the compiler to
-      generate more efficient code based on the non-aliasing assumption. The
-      optimization is best-effort.
+      The `distinct_objects` operation takes a list of memrefs and returns the same
+      memrefs, with the additional assumption that accesses to them will never
+      alias with each other. This means that loads and stores to different
+      memrefs in the list can be safely reordered.
+
+      If the memrefs do alias, the load/store behavior is undefined. This
+      operation doesn't affect the semantics of a valid program. It is
+      intended for optimization purposes, allowing the compiler to generate more
+      efficient code based on the non-aliasing assumption. The optimization is
+      best-effort.
 
       Example:
 

mlir/lib/Conversion/MemRefToLLVM/MemRefToLLVM.cpp

@@ -476,10 +476,12 @@ struct DistinctObjectsOpLowering
   matchAndRewrite(memref::DistinctObjectsOp op, OpAdaptor adaptor,
                   ConversionPatternRewriter &rewriter) const override {
     ValueRange operands = adaptor.getOperands();
-    if (operands.empty()) {
-      rewriter.eraseOp(op);
+    if (operands.size() <= 1) {
+      // Fast path.
+      rewriter.replaceOp(op, operands);
       return success();
     }
+
     Location loc = op.getLoc();
     SmallVector<Value> ptrs;
     for (auto [origOperand, newOperand] :

mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp

@@ -549,6 +549,10 @@ OpFoldResult AssumeAlignmentOp::fold(FoldAdaptor adaptor) {
 LogicalResult DistinctObjectsOp::verify() {
   if (getOperandTypes() != getResultTypes())
     return emitOpError("operand types and result types must match");
+
+  if (getOperandTypes().empty())
+    return emitOpError("expected at least one operand");
+
   return success();
 }
 

mlir/test/Conversion/MemRefToLLVM/memref-to-llvm.mlir

@@ -214,6 +214,17 @@ func.func @distinct_objects(%arg0: memref<?xf16>, %arg1: memref<?xf32>, %arg2: m
 
 // -----
 
+// ALL-LABEL: func @distinct_objects_noop
+//  ALL-SAME:   (%[[ARG0:.*]]: memref<?xf16>)
+func.func @distinct_objects_noop(%arg0: memref<?xf16>) -> memref<?xf16> {
+// 1-operand version is noop
+//  ALL-NEXT:   return %[[ARG0]]
+  %1 = memref.distinct_objects %arg0 : memref<?xf16>
+  return %1 : memref<?xf16>
+}
+
+// -----
+
 // CHECK-LABEL: func @assume_alignment_w_offset
 // CHECK-INTERFACE-LABEL: func @assume_alignment_w_offset
 func.func @assume_alignment_w_offset(%0 : memref<4x4xf16, strided<[?, ?], offset: ?>>) {

mlir/test/Dialect/MemRef/invalid.mlir

@@ -1172,8 +1172,16 @@ func.func @expand_shape_invalid_output_shape(
 
 // -----
 
-func.func @Invalid_distinct_objects(%arg0: memref<?xf32>, %arg1: memref<?xi32>) -> (memref<?xi32>, memref<?xf32>) {
+func.func @distinct_objects_types_mismatch(%arg0: memref<?xf32>, %arg1: memref<?xi32>) -> (memref<?xi32>, memref<?xf32>) {
   // expected-error @+1 {{operand types and result types must match}}
   %0, %1 = "memref.distinct_objects"(%arg0, %arg1) : (memref<?xf32>, memref<?xi32>) -> (memref<?xi32>, memref<?xf32>)
   return %0, %1 : memref<?xi32>, memref<?xf32>
 }
+
+// -----
+
+func.func @distinct_objects_0_operands() {
+  // expected-error @+1 {{expected at least one operand}}
+  "memref.distinct_objects"() : () -> ()
+  return
+}