Hello,
(sorry for the broken thread, for some reason I haven't received any email
from gcc since about 10am, I'll investigate later)
+/* x & ~(x & y) -> x & ~y */
+(simplify
+ (bit_and:c @0 (bit_not (bit_and:c@2 @0 @1)))
+ (if (TREE_CODE (@2) != SSA_NAME || has_single_use (@2))
+ (bit_and @0 (bit_not @1))))
Wouldn't it make more sense to put @2 on bit_not? If bit_and is used
multiple times, the transformation is neutral so it should be done as a
canonicalization. On the other hand, if bit_not is used multiple times,
the transformation adds an extra bit_not (which might be free when there
is an andn insn). So I believe the 2 main options are:
- move @2 on the bit_not
- don't test has_single_use at all
--
Marc Glisse
