time: Avoid alignment gaps in __tzfile_read

By ordering the suballocations by decreasing alignment, alignment
gaps can be avoided.

Also use __glibc_unlikely for reading the transitions and type
indexes.  In the 8-byte case, two reads are now needed because the
transitions and type indexes are no longer adjacent.  The separate
call to __fread_unlocked does not matter from a performance point of
view because __tzfile_read is only invoked rarely.

1 files changed, 5 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index bc1b17f..0c9a4e8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2019-02-04  Florian Weimer  <fweimer@redhat.com>
+
+	* time/tzfile.c (__tzfile_read): Reorder suballocations to avoid
+	alignment gaps.
+
 2019-02-03  Florian Weimer  <fweimer@redhat.com>
 
 	* time/tzfile.c (__tzfile_read): Use struct alloc_buffer and its