2012-12-07 Martin Jambor <mjambor@suse.cz>

	PR tree-optimization/55590
	* tree-sra.c (build_ref_for_offset): Use get_object_alignment_1 to
	get base alignment.

	* testsuite/gcc.target/i386/pr55590-1.c: New test.
	* testsuite/gcc.target/i386/pr55590-2.c: Likewise.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@194300 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 6 insertions, 18 deletions

diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
index 4580ad22e64..21d8a514117 100644
--- a/gcc/tree-sra.c
+++ b/gcc/tree-sra.c
@@ -1423,7 +1423,10 @@ make_fancy_name (tree expr)
    EXP_TYPE at the given OFFSET.  If BASE is something for which
    get_addr_base_and_unit_offset returns NULL, gsi must be non-NULL and is used
    to insert new statements either before or below the current one as specified
-   by INSERT_AFTER.  This function is not capable of handling bitfields.  */
+   by INSERT_AFTER.  This function is not capable of handling bitfields.
+
+   BASE must be either a declaration or a memory reference that has correct
+   alignment ifformation embeded in it (e.g. a pre-existing one in SRA).  */
 
 tree
 build_ref_for_offset (location_t loc, tree base, HOST_WIDE_INT offset,
@@ -1437,7 +1440,7 @@ build_ref_for_offset (location_t loc, tree base, HOST_WIDE_INT offset,
   unsigned int align;
 
   gcc_checking_assert (offset % BITS_PER_UNIT == 0);
-
+  get_object_alignment_1 (base, &align, &misalign);
   base = get_addr_base_and_unit_offset (base, &base_offset);
 
   /* get_addr_base_and_unit_offset returns NULL for references with a variable
@@ -1476,22 +1479,7 @@ build_ref_for_offset (location_t loc, tree base, HOST_WIDE_INT offset,
       base = build_fold_addr_expr (unshare_expr (base));
     }
 
-  /* If prev_base were always an originally performed access
-     we can extract more optimistic alignment information
-     by looking at the access mode.  That would constrain the
-     alignment of base + base_offset which we would need to
-     adjust according to offset.  */
-  if (!get_pointer_alignment_1 (base, &align, &misalign))
-    {
-      gcc_assert (misalign == 0);
-      if (TREE_CODE (prev_base) == MEM_REF
-	  || TREE_CODE (prev_base) == TARGET_MEM_REF)
-	align = TYPE_ALIGN (TREE_TYPE (prev_base));
-    }
-  misalign += (tree_to_double_int (off)
-	       .sext (TYPE_PRECISION (TREE_TYPE (off))).low
-	       * BITS_PER_UNIT);
-  misalign = misalign & (align - 1);
+  misalign = (misalign + offset) & (align - 1);
   if (misalign != 0)
     align = (misalign & -misalign);
   if (align < TYPE_ALIGN (exp_type))