File vrp.patch of Package gcc41

While working on improving tree-vrp's ability to discover
non-null ranges and half-ranges I discovered that it was
mis-handling TRUTH_XOR_EXPR.

The current code will incorrectly handle

[0, 1] TRUTH_XOR [0, 1] 

The obvious result should be [0, 1], but due to a bug in 
extract_range_from_binary_expr, we instead get [0, 0].

Long term it's not clear to me that we get any significant
benefit from handling TRUTH_XXX_EXPRs in tree-vrp.c.  If we
do nothing we should be getting [0, 1].  The only time we
can do better is when one of the operands is known true or
known false.  And those kind of cases should really be 
encoded into fold-const.c rather than in each optimizer.

Anyway, this patch removes the buggy handling of TRUTH_XOR_EXPR.

Bootstrapped and regression tested on i686-pc-linux-gnu.  I've
also verified this fixes the bootstrap failure when the VRP
enhancements to find more non-null and half ranges.

	* tree-vrp.c (extract_range_from_binary_expr): Remove handling of
	TRUTH_XOR_EPR.

Index: gcc/tree-vrp.c
===================================================================
*** gcc/tree-vrp.c	(revision 110916)
--- gcc/tree-vrp.c	(working copy)
*************** extract_range_from_binary_expr (value_ra
*** 1278,1285 ****
        && code != TRUTH_ANDIF_EXPR
        && code != TRUTH_ORIF_EXPR
        && code != TRUTH_AND_EXPR
!       && code != TRUTH_OR_EXPR
!       && code != TRUTH_XOR_EXPR)
      {
        set_value_range_to_varying (vr);
        return;
--- 1278,1284 ----
        && code != TRUTH_ANDIF_EXPR
        && code != TRUTH_ORIF_EXPR
        && code != TRUTH_AND_EXPR
!       && code != TRUTH_OR_EXPR)
      {
        set_value_range_to_varying (vr);
        return;
*************** extract_range_from_binary_expr (value_ra
*** 1365,1372 ****
    if (code == TRUTH_ANDIF_EXPR
        || code == TRUTH_ORIF_EXPR
        || code == TRUTH_AND_EXPR
!       || code == TRUTH_OR_EXPR
!       || code == TRUTH_XOR_EXPR)
      {
        /* If one of the operands is zero, we know that the whole
  	 expression evaluates zero.  */
--- 1364,1370 ----
    if (code == TRUTH_ANDIF_EXPR
        || code == TRUTH_ORIF_EXPR
        || code == TRUTH_AND_EXPR
!       || code == TRUTH_OR_EXPR)
      {
        /* If one of the operands is zero, we know that the whole
  	 expression evaluates zero.  */