[Lldb-commits] [lldb] [lldb][DataFormatter] VectorType: fix format for arrays with size not a power-of-2 (PR #68907)

[Adrian Prantl via lldb-commits]

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@@ -169,21 +169,49 @@ static lldb::Format GetItemFormatForFormat(lldb::Format format,
   }
 }
 
-static size_t CalculateNumChildren(
-    CompilerType container_type, CompilerType element_type,
-    lldb_private::ExecutionContextScope *exe_scope =
-        nullptr // does not matter here because all we trade in are basic types
-    ) {
-  std::optional<uint64_t> container_size =
-      container_type.GetByteSize(exe_scope);
-  std::optional<uint64_t> element_size = element_type.GetByteSize(exe_scope);
-
-  if (container_size && element_size && *element_size) {
-    if (*container_size % *element_size)
-      return 0;
-    return *container_size / *element_size;
-  }
-  return 0;
+/// \brief Returns the number of elements stored in a container
+/// (with element type 'container_elem_type') as if it had elements
+/// of type 'element_type'.
+///
+/// For example, a container of type
+/// `uint8_t __attribute__((vector_size(16)))` has 16 elements.
+/// But calling `CalculateNumChildren` with an 'element_type'
+/// of `float` (4-bytes) will return `4` because we are interpreting
+/// the byte-array as a `float32[]`.
+///
+/// \param[in] container_elem_type The type of the elements stored
+/// in the container we are calculating the children of.
+///
+/// \param[in] num_elements Number of 'container_elem_type's our
+/// container stores.
+///
+/// \param[in] element_type The type of elements we interpret
+/// container_type to contain for the purposes of calculating
+/// the number of children.
+///
+/// If size of the container is not a multiple of 'element_type'
+/// returns 0.
+///
+/// On error, returns 0.
+static size_t CalculateNumChildren(CompilerType container_elem_type,
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adrian-prantl wrote:

Could you, just out of principle, return optional<size_t> here even if you the use it with getValueOr(0) at the call site?

https://github.com/llvm/llvm-project/pull/68907