[PATCH] Fix PR80181

[PATCH] Fix PR80181

[Richard Biener]

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2017-03-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/80181
	* tree-ssa-ccp.c (likely_value): UNDEFINED ^ X is UNDEFINED.

	* gcc.dg/torture/pr80181.c: New testcase.

Index: gcc/tree-ssa-ccp.c
===================================================================
*** gcc/tree-ssa-ccp.c	(revision 246490)
--- gcc/tree-ssa-ccp.c	(working copy)
*************** likely_value (gimple *stmt)
*** 741,749 ****
  	case PLUS_EXPR:
  	case MINUS_EXPR:
  	case POINTER_PLUS_EXPR:
  	  /* Not MIN_EXPR, MAX_EXPR.  One VARYING operand may be selected.
  	     Not bitwise operators, one VARYING operand may specify the
! 	     result completely.  Not logical operators for the same reason.
  	     Not COMPLEX_EXPR as one VARYING operand makes the result partly
  	     not UNDEFINED.  Not *DIV_EXPR, comparisons and shifts because
  	     the undefined operand may be promoted.  */
--- 741,751 ----
  	case PLUS_EXPR:
  	case MINUS_EXPR:
  	case POINTER_PLUS_EXPR:
+ 	case BIT_XOR_EXPR:
  	  /* Not MIN_EXPR, MAX_EXPR.  One VARYING operand may be selected.
  	     Not bitwise operators, one VARYING operand may specify the
! 	     result completely.
! 	     Not logical operators for the same reason, apart from XOR.
  	     Not COMPLEX_EXPR as one VARYING operand makes the result partly
  	     not UNDEFINED.  Not *DIV_EXPR, comparisons and shifts because
  	     the undefined operand may be promoted.  */
Index: gcc/testsuite/gcc.dg/torture/pr80181.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr80181.c	(nonexistent)
--- gcc/testsuite/gcc.dg/torture/pr80181.c	(working copy)
***************
*** 0 ****
--- 1,19 ----
+ /* { dg-do compile } */
+ 
+ int
+ nr (void)
+ {
+ }
+ 
+ void
+ it (int dl)
+ {
+   int vp = 0;
+ 
+   for (;;)
+     {
+       dl = vp ^ nr ();
+       dl ^= vp;
+       vp = 1;
+     }
+ }