[backport from gcc-4.7/trunk r184619 <mikpe@it.uu.se>]

gcc/

2012-02-28  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/52402
	* ipa-prop.c (ipa_modify_call_arguments): Properly use
	mis-aligned types when creating the accesses at the call site.

gcc/testsuite/

2012-02-28  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/52402
	* gcc.dg/torture/pr52402.c: New testcase.

--- gcc-4.6.3/gcc/ipa-prop.c.~1~	2011-12-13 23:03:05.000000000 +0100
+++ gcc-4.6.3/gcc/ipa-prop.c	2012-03-04 18:23:01.000000000 +0100
@@ -2428,9 +2428,27 @@ ipa_modify_call_arguments (struct cgraph
 		}
 	    }
 
-	  expr = fold_build2_loc (loc, MEM_REF, adj->type, base, off);
-	  if (adj->by_ref)
-	    expr = build_fold_addr_expr (expr);
+	  if (!adj->by_ref)
+	    {
+	      tree type = adj->type;
+	      unsigned int align;
+	      unsigned HOST_WIDE_INT misalign;
+	      align = get_pointer_alignment_1 (base, &misalign);
+	      misalign += (double_int_sext (tree_to_double_int (off),
+					    TYPE_PRECISION (TREE_TYPE (off))).low
+			   * BITS_PER_UNIT);
+	      misalign = misalign & (align - 1);
+	      if (misalign != 0)
+		align = (misalign & -misalign);
+	      if (align < TYPE_ALIGN (type))
+		type = build_aligned_type (type, align);
+	      expr = fold_build2_loc (loc, MEM_REF, type, base, off);
+	    }
+	  else
+	    {
+	      expr = fold_build2_loc (loc, MEM_REF, adj->type, base, off);
+	      expr = build_fold_addr_expr (expr);
+	    }
 
 	  expr = force_gimple_operand_gsi (&gsi, expr,
 					   adj->by_ref
--- gcc-4.6.3/gcc/testsuite/gcc.dg/torture/pr52402.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.6.3/gcc/testsuite/gcc.dg/torture/pr52402.c	2012-03-04 18:23:01.000000000 +0100
@@ -0,0 +1,28 @@
+/* { dg-do run } */
+
+typedef int v4si __attribute__((vector_size(16)));
+struct T { v4si i[2]; int j; } __attribute__((packed));
+
+static v4si __attribute__((noinline))
+foo (struct T t)
+{
+  return t.i[0];
+}
+
+static struct T *__attribute__((noinline))
+init ()
+{
+  char *p = __builtin_malloc (sizeof (struct T) + 1);
+  p++;
+  __builtin_memset (p, 1, sizeof (struct T));
+  return (struct T *)p;
+}
+
+int main()
+{
+  struct T *p;
+  p = init ();
+  if (foo (*p)[0] != 0x01010101)
+    __builtin_abort ();
+  return 0;
+}