Do not override explicit alignment on user-defined sections.

http://gcc.gnu.org/PR53708
http://gcc.gnu.org/viewcvs?view=revision&revision=193121


--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -4574,6 +4574,13 @@ vect_can_force_dr_alignment_p (const_tree decl, unsigned int alignment)
   if (TREE_ASM_WRITTEN (decl))
     return false;
 
+  /* Do not override explicit alignment set by the user when an explicit
+     section name is also used.  This is a common idiom used by many
+     software projects.  */
+  if (DECL_SECTION_NAME (decl) != NULL_TREE
+      && !DECL_HAS_IMPLICIT_SECTION_NAME_P (decl))
+    return false;
+
   if (TREE_STATIC (decl))
     return (alignment <= MAX_OFILE_ALIGNMENT);
   else