[fixup] Fix an assertion

`computeStrides` does not acccess the first element of `sizes`

Author: momchil-velikov

mlir/include/mlir/Dialect/Utils/IndexingUtils.h

@@ -40,7 +40,7 @@ class ArrayAttr;
 /// Assuming `sizes` is `[s0, .. sn]`, return the vector<int64_t>
 ///   `[s1 * ... * sn, s2 * ... * sn, ..., sn, 1]`.
 ///
-/// `sizes` elements are asserted to be non-negative.
+/// `sizes` elements `s1` to `sn` are asserted to be non-negative.
 ///
 /// Return an empty vector if `sizes` is empty.
 SmallVector<int64_t> computeSuffixProduct(ArrayRef<int64_t> sizes);

mlir/lib/Dialect/Utils/IndexingUtils.cpp

@@ -69,7 +69,8 @@ SmallVector<ExprType> delinearizeImpl(ExprType linearIndex,
 //===----------------------------------------------------------------------===//
 
 SmallVector<int64_t> mlir::computeSuffixProduct(ArrayRef<int64_t> sizes) {
-  assert(llvm::all_of(sizes, [](int64_t s) { return s >= 0; }) &&
+  assert((sizes.size() == 0 ||
+          llvm::all_of(sizes.drop_front(), [](int64_t s) { return s >= 0; })) &&
          "sizes must be nonnegative");
   int64_t unit = 1;
   return ::computeSuffixProductImpl(sizes, unit);