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Diffstat (limited to 'gcc/doc/gty.texi')
| -rw-r--r-- | gcc/doc/gty.texi | 32 |
1 files changed, 0 insertions, 32 deletions
diff --git a/gcc/doc/gty.texi b/gcc/doc/gty.texi index d32ac00e48e..e50eef66b3e 100644 --- a/gcc/doc/gty.texi +++ b/gcc/doc/gty.texi @@ -382,38 +382,6 @@ of pointers. @code{reorder} functions can be expensive. When possible, it is better to depend on properties of the data, like an ID number or the hash of a string instead. -@findex variable_size -@item variable_size - -The type machinery expects the types to be of constant size. When this -is not true, for example, with structs that have array fields or unions, -the type machinery cannot tell how many bytes need to be allocated at -each allocation. The @code{variable_size} is used to mark such types. -The type machinery then provides allocators that take a parameter -indicating an exact size of object being allocated. Note that the size -must be provided in bytes whereas the @code{length} option works with -array lengths in number of elements. - -For example, -@smallexample -struct GTY((variable_size)) sorted_fields_type @{ - int len; - tree GTY((length ("%h.len"))) elts[1]; -@}; -@end smallexample - -Then the objects of @code{struct sorted_fields_type} are allocated in GC -memory as follows: -@smallexample - field_vec = ggc_alloc_sorted_fields_type (size); -@end smallexample - -If @var{field_vec->elts} stores @var{n} elements, then @var{size} -could be calculated as follows: -@smallexample - size_t size = sizeof (struct sorted_fields_type) + n * sizeof (tree); -@end smallexample - @findex atomic @item atomic |