On Thu, 21 Aug 2014, Richard Biener wrote:
2014-08-21 Richard Biener <rguent...@suse.de>
* match.pd ((T1)(~(T2) X) -> ~(T1) X): Paste all comment
from fold-const.c, fix simplification result.
Index: gcc/match.pd
===================================================================
--- gcc/match.pd (revision 214268)
+++ gcc/match.pd (working copy)
@@ -109,7 +109,9 @@ along with GCC; see the file COPYING3.
/* From fold_unary. */
-/* (T1)(~(T2) X) -> ~(T1) X */
+/* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
+ of the same precision, and X is an integer type not narrower than
+ types T1 or T2, i.e. the cast (T2)X isn't an extension. */
(simplify
(convert (bit_not@0 (convert @1)))
(if (INTEGRAL_TYPE_P (type)
@@ -117,7 +119,7 @@ along with GCC; see the file COPYING3.
&& TYPE_PRECISION (type) == TYPE_PRECISION (TREE_TYPE (@0))
&& INTEGRAL_TYPE_P (TREE_TYPE (@1))
&& TYPE_PRECISION (type) <= TYPE_PRECISION (TREE_TYPE (@1)))
- (bit_not (convert (bit_not @0)))))
+ (bit_not (convert @0))))
Er, I think you mean:
(bit_not (convert @1))
Your pattern (bit_not (convert (bit_not @0))) was valid, @0 is the
bit_not, so it simplifies, but that was a pretty unreadable way to write
it, and I was scared that you had done it on purpose to help the machinery
guess the type. Glad to see that the simple version is ok.
--
Marc Glisse
