Re: [PATCH] Fix PR tree-optimization/51315

[Eric Botcazou <ebotcazou at adacore dot com>]

> Shouldn't we go back and unconditionally return false if lhs and (or?) rhs
> are BLKmode?  I suppose they are, in this case.  Or should we truncate
> the alignment from get_object_alignment to TYPE_ALIGN if it is bigger
> than that to avoid this situation?

Sorry, I didn't read your message before sending mine.  Yes, the alignment cap 
appears to be the best solution, but of course TYPE_ALIGN (access->type) won't 
work (that was the original code), so TYPE_ALIGN (TREE_TYPE (access->base)):

Index: tree-sra.c
===================================================================
--- tree-sra.c  (revision 182780)
+++ tree-sra.c  (working copy)
@@ -1124,7 +1124,9 @@ build_accesses_from_assign (gimple stmt)
     {
       lacc->grp_assignment_write = 1;
       if (STRICT_ALIGNMENT
-         && tree_non_aligned_mem_p (rhs, get_object_alignment (lhs)))
+         && tree_non_aligned_mem_p (rhs,
+                                    MIN (TYPE_ALIGN (TREE_TYPE (lacc->base)),
+                                         get_object_alignment (lhs))))
         lacc->grp_unscalarizable_region = 1;
     }

@@ -1135,7 +1137,9 @@ build_accesses_from_assign (gimple stmt)
          && !is_gimple_reg_type (racc->type))
        bitmap_set_bit (should_scalarize_away_bitmap, DECL_UID (racc->base));
       if (STRICT_ALIGNMENT
-         && tree_non_aligned_mem_p (lhs, get_object_alignment (rhs)))
+         && tree_non_aligned_mem_p (lhs,
+                                    MIN (TYPE_ALIGN (TREE_TYPE (racc->base)),
+                                         get_object_alignment (rhs))))
         racc->grp_unscalarizable_region = 1;
     }

-- 
Eric Botcazou