[PATCH] Fix PR69983

[Richard Biener]

I am testing the following patch to fix PR69983 - SCEV was confused
by a PRE inserted PHI node where it checks for equality of the
evolution of all edges.  After my SCEV fix these have conversions
which are not handled by eq_evolutions_p.

I've noticed the function misses any type compatibility check
and operand_equal_p on INTEGER_CSTs will ignore types.

Also it will give up on SSA names or ADDR_EXPRs which can
occur in both the evolution and init part of SCEVs.  So simply
fall back to operand_equal_p for all bits where we don't expect
any further embeded CHRECs (operand_equal_p does no handle
TREE_CHREC currently).

Bootstrap and regtest running on x86_64-unknown-linux-gnu.

Richard.

2016-03-01  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/69983
        * tree-chrec.c (eq_evolutions_p): Handle conversions, compare
        types and fall back to operand_equal_p.

Index: gcc/tree-chrec.c
===================================================================
*** gcc/tree-chrec.c    (revision 233840)
--- gcc/tree-chrec.c    (working copy)
*************** eq_evolutions_p (const_tree chrec0, cons
*** 1468,1478 ****
    if (chrec0 == chrec1)
      return true;
  
    switch (TREE_CODE (chrec0))
      {
-     case INTEGER_CST:
-       return operand_equal_p (chrec0, chrec1, 0);
- 
      case POLYNOMIAL_CHREC:
        return (CHREC_VARIABLE (chrec0) == CHREC_VARIABLE (chrec1)
              && eq_evolutions_p (CHREC_LEFT (chrec0), CHREC_LEFT (chrec1))
--- 1468,1478 ----
    if (chrec0 == chrec1)
      return true;
  
+   if (! types_compatible_p (TREE_TYPE (chrec0), TREE_TYPE (chrec1)))
+     return false;
+ 
    switch (TREE_CODE (chrec0))
      {
      case POLYNOMIAL_CHREC:
        return (CHREC_VARIABLE (chrec0) == CHREC_VARIABLE (chrec1)
              && eq_evolutions_p (CHREC_LEFT (chrec0), CHREC_LEFT (chrec1))
*************** eq_evolutions_p (const_tree chrec0, cons
*** 1487,1494 ****
          && eq_evolutions_p (TREE_OPERAND (chrec0, 1),
                              TREE_OPERAND (chrec1, 1));
  
      default:
!       return false;
      }
  }
  
--- 1487,1498 ----
          && eq_evolutions_p (TREE_OPERAND (chrec0, 1),
                              TREE_OPERAND (chrec1, 1));
  
+     CASE_CONVERT:
+       return eq_evolutions_p (TREE_OPERAND (chrec0, 0),
+                             TREE_OPERAND (chrec1, 0));
+ 
      default:
!       return operand_equal_p (chrec0, chrec1, 0);
      }
  }