revert: re PR tree-optimization/80492 (Wrong code when unrolling a loop with…

revert: re PR tree-optimization/80492 (Wrong code when unrolling a loop with inline asm and local regs)

2017-05-03  Richard Biener  <rguenther@suse.de>

	Revert
	PR tree-optimization/80492
	* tree-ssa-alias.c (decl_refs_may_alias_p): Handle
	compare_base_decls returning dont-know properly.

From-SVN: r247543

gcc/ChangeLog

+2017-05-03  Richard Biener  <rguenther@suse.de>
+
+	Revert
+	PR tree-optimization/80492
+	* tree-ssa-alias.c (decl_refs_may_alias_p): Handle
+	compare_base_decls returning dont-know properly.
+
 2017-05-03  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
 	* config/arm/iterators.md (CCSI): New mode iterator.

gcc/tree-ssa-alias.c

@@ -1096,16 +1096,13 @@ decl_refs_may_alias_p (tree ref1, tree base1,
 {
   gcc_checking_assert (DECL_P (base1) && DECL_P (base2));
 
-  int cmp = compare_base_decls (base1, base2);
-
   /* If both references are based on different variables, they cannot alias.  */
-  if (cmp == 0)
+  if (compare_base_decls (base1, base2) == 0)
     return false;
 
   /* If both references are based on the same variable, they cannot alias if
      the accesses do not overlap.  */
-  if (cmp == 1
-      && !ranges_overlap_p (offset1, max_size1, offset2, max_size2))
+  if (!ranges_overlap_p (offset1, max_size1, offset2, max_size2))
     return false;
 
   /* For components with variable position, the above test isn't sufficient,