re PR middle-end/70424 (Pointer derived from integer gets reduced alignment)

2016-03-29  Richard Biener  <rguenther@suse.de>

	PR middle-end/70424
	* ipa-prop.c (ipa_compute_jump_functions_for_edge): Always
	use alignment returned by get_pointer_alignment_1 if it is
	bigger than BITS_PER_UNIT.
	* builtins.c (get_pointer_alignment_1): Do not return true
	for alignment extracted from SSA info.

From-SVN: r234517

gcc/ChangeLog

+2016-03-29  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/70424
+	* ipa-prop.c (ipa_compute_jump_functions_for_edge): Always
+	use alignment returned by get_pointer_alignment_1 if it is
+	bigger than BITS_PER_UNIT.
+	* builtins.c (get_pointer_alignment_1): Do not return true
+	for alignment extracted from SSA info.
+
 2016-03-28  James Bowman  <james.bowman@ftdichip.com>
 
 	* config/ft32/ft32.opt (mnodiv): New.

gcc/builtins.c

@@ -463,7 +463,7 @@ get_pointer_alignment_1 (tree exp, unsigned int *alignp,
 	  if (*alignp == 0)
 	    *alignp = 1u << (HOST_BITS_PER_INT - 1);
 	  /* We cannot really tell whether this result is an approximation.  */
-	  return true;
+	  return false;
 	}
       else
 	{

gcc/ipa-prop.c

@@ -1639,11 +1639,11 @@ ipa_compute_jump_functions_for_edge (struct ipa_func_body_info *fbi,
 	  unsigned HOST_WIDE_INT hwi_bitpos;
 	  unsigned align;
 
-	  if (get_pointer_alignment_1 (arg, &align, &hwi_bitpos)
+	  get_pointer_alignment_1 (arg, &align, &hwi_bitpos);
+	  if (align > BITS_PER_UNIT
 	      && align % BITS_PER_UNIT == 0
 	      && hwi_bitpos % BITS_PER_UNIT == 0)
 	    {
-	      gcc_checking_assert (align != 0);
 	      jfunc->alignment.known = true;
 	      jfunc->alignment.align = align / BITS_PER_UNIT;
 	      jfunc->alignment.misalign = hwi_bitpos / BITS_PER_UNIT;