Revert parts of the change for PR25130.

	* cse.c (exp_equiv_p): For MEMs, if for_gcse, only compare
	MEM_ALIAS_SET.

From-SVN: r161534

gcc/ChangeLog

@@ -5,6 +5,10 @@
 	(maddhisi4): Renamed from mulhisi3addsi.  Operands renumbered.
 	(maddhidi4): Likewise.
 
+	Revert parts of the change for PR25130.
+	* cse.c (exp_equiv_p): For MEMs, if for_gcse, only compare
+	MEM_ALIAS_SET.
+
 2010-06-29  Nathan Froyd  <froydnj@codesourcery.com>
 
 	* calls.c, dse.c, expr.c, function.c: Call targetm.calls.function_arg,

gcc/cse.c

@@ -2669,26 +2669,16 @@ exp_equiv_p (const_rtx x, const_rtx y, int validate, bool for_gcse)
     case MEM:
       if (for_gcse)
 	{
+	  /* Can't merge two expressions in different alias sets, since we
+	     can decide that the expression is transparent in a block when
+	     it isn't, due to it being set with the different alias set.  */
+	  if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
+	    return 0;
+
 	  /* A volatile mem should not be considered equivalent to any
 	     other.  */
 	  if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
 	    return 0;
-
-	  /* Can't merge two expressions in different alias sets, since we
-	     can decide that the expression is transparent in a block when
-	     it isn't, due to it being set with the different alias set.
-
-	     Also, can't merge two expressions with different MEM_ATTRS.
-	     They could e.g. be two different entities allocated into the
-	     same space on the stack (see e.g. PR25130).  In that case, the
-	     MEM addresses can be the same, even though the two MEMs are
-	     absolutely not equivalent.
-
-	     But because really all MEM attributes should be the same for
-	     equivalent MEMs, we just use the invariant that MEMs that have
-	     the same attributes share the same mem_attrs data structure.  */
-	  if (MEM_ATTRS (x) != MEM_ATTRS (y))
-	    return 0;
 	}
       break;