Re: [PATCH][8/n] Remove GENERIC stmt combining from SCCVN

[Eric Botcazou]

> The following moves some bitwise patterns from the match-and-simplify
> branch, extending them with proper conditional converts and removing
> the corresponding patterns from fold-const.c

There is a pasto/thinko in the last pattern:

/* Convert ~X ^ C to X ^ ~C.  */
(simplify
 (bit_xor (convert? (bit_not @0)) INTEGER_CST@1)
 (bit_xor (convert @0) (bit_not @1)))

That's incorrect if the types don't have the same precision, as in the other 
cases, and is responsible for PR tree-optimization/66757.

Tested on x86_64-suse-linux, OK for the mainline?


2015-07-05 Eric Botcazou  <ebotca...@adacore.com>

        PR tree-optimization/66757
        * match.pd: Add missing condition to ~X ^ C -> X ^ ~C.

2015-07-05 Eric Botcazou  <ebotca...@adacore.com>

        * gcc.c-torture/execute/pr66757.c: New test.

-- 
Eric Botcazou
Index: match.pd
===================================================================
--- match.pd	(revision 225410)
+++ match.pd	(working copy)
@@ -444,7 +444,8 @@ (define_operator_list CBRT BUILT_IN_CBRT
 /* Convert ~X ^ C to X ^ ~C.  */
 (simplify
  (bit_xor (convert? (bit_not @0)) INTEGER_CST@1)
- (bit_xor (convert @0) (bit_not @1)))
+ (if (tree_nop_conversion_p (type, TREE_TYPE (@0)))
+  (bit_xor (convert @0) (bit_not @1))))
 
 /* Fold (X & Y) ^ Y as ~X & Y.  */
 (simplify

/* PR tree-optimization/66757 */
/* Testcase by Zhendong Su <s...@cs.ucdavis.edu> */

int a, b;

int
main (void)
{
  unsigned int t = (unsigned char) (~b); 

  if ((t ^ 1) / 255)
    __builtin_abort (); 

  return 0;
}