Allow zero sizes

Author: rikhuijzer

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

@@ -2849,8 +2849,8 @@ LogicalResult SubViewOp::verify() {
              << offset;
   }
   for (int64_t size : getStaticSizes()) {
-    if (size < 1 && !ShapedType::isDynamic(size))
-      return emitError("expected subview sizes to be positive, but got ")
+    if (size < 0 && !ShapedType::isDynamic(size))
+      return emitError("expected subview sizes to be non-negative, but got ")
              << size;
   }
 
@@ -3103,6 +3103,7 @@ struct SubViewReturnTypeCanonicalizer {
   MemRefType operator()(SubViewOp op, ArrayRef<OpFoldResult> mixedOffsets,
                         ArrayRef<OpFoldResult> mixedSizes,
                         ArrayRef<OpFoldResult> mixedStrides) {
+
     // Infer a memref type without taking into account any rank reductions.
     MemRefType nonReducedType = cast<MemRefType>(SubViewOp::inferResultType(
         op.getSourceType(), mixedOffsets, mixedSizes, mixedStrides));

mlir/test/Dialect/MemRef/invalid.mlir

@@ -620,8 +620,8 @@ func.func @invalid_subview(%input: memref<4x1024xf32>) -> memref<2x256xf32, stri
 // -----
 
 func.func @invalid_subview(%input: memref<4x1024xf32>) -> memref<2x256xf32, strided<[1024, 1], offset: 2304>> {
-  // expected-error@+1 {{expected subview sizes to be positive, but got 0}}
-  %0 = memref.subview %input[2, 256] [0, 256] [1, 1] : memref<4x1024xf32> to memref<2x256xf32, strided<[1024, 1], offset: 2304>>
+  // expected-error@+1 {{expected subview sizes to be non-negative, but got -1}}
+  %0 = memref.subview %input[2, 256] [-1, 256] [1, 1] : memref<4x1024xf32> to memref<2x256xf32, strided<[1024, 1], offset: 2304>>
   return %0 : memref<2x256xf32, strided<[1024, 1], offset: 2304>>
 }