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From: "wschmidt at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/58041] Unaligned access to arrays in packed structure
Date: Thu, 01 Aug 2013 18:32:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58041

--- Comment #15 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
Bernd, Mikael, Martin:  Could you please test this on your respective targets?

Index: gcc/gimple-ssa-strength-reduction.c
===================================================================
--- gcc/gimple-ssa-strength-reduction.c    (revision 201413)
+++ gcc/gimple-ssa-strength-reduction.c    (working copy)
@@ -845,6 +845,8 @@ slsr_process_ref (gimple gs)
   int unsignedp, volatilep;
   double_int index;
   slsr_cand_t c;
+  unsigned HOST_WIDE_INT misalign;
+  unsigned align;

   if (gimple_vdef (gs))
     ref_expr = gimple_assign_lhs (gs);
@@ -857,6 +859,16 @@ slsr_process_ref (gimple gs)
       && DECL_BIT_FIELD (TREE_OPERAND (ref_expr, 1))))
     return;

+  /* If this reference doesn't meet alignment restrictions, don't
+     make it a candidate.  */
+  get_object_alignment_1 (ref_expr, &align, &misalign);
+
+  if (misalign != 0)
+    align = (misalign & -misalign);
+
+  if (align < TYPE_ALIGN (TREE_TYPE (ref_expr)))
+    return;
+
   base = get_inner_reference (ref_expr, &bitsize, &bitpos, &offset, &mode,
                   &unsignedp, &volatilep, false);
   index = double_int::from_uhwi (bitpos);

Thanks,
Bill