https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55177
--- Comment #20 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So the original testcase shows there are missing other bitop related
optimizations on the tree level and conversions.
I have two patches which fix the original issue.
The first patch also fixes:
unsigned foo(unsigned x, int b)
{
int a = x;
a &= b;
x = a;
x |= b;
return x;
}
--- CUT ---
The problem here is:
a_3 = (int) x_2(D);
a_5 = a_3 & b_4(D);
x_6 = (unsigned int) a_5;
is not optimized to:
_7 = (unsigned int) b_4(D);
x_6 = _6 & x_2(D);
Which shows up in testcase in comment #0:
_2 = __builtin_bswap32 (x.0_1);
a_6 = (int) _2;
a_7 = a_6 & 1515936861;
a.1_3 = (unsigned int) a_7;
_4 = __builtin_bswap32 (a.1_3);
Fixing the bitop with convert, we get rid of the two byteswaps in comment #0.
diff --git a/gcc/match.pd b/gcc/match.pd
index 363006e28fd..d0258a19534 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1393,7 +1393,12 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* Or if the precision of TO is not the same as the precision
of its mode. */
|| !type_has_mode_precision_p (type)))
- (convert (bitop @0 (convert @1))))))
+ (convert (bitop @0 (convert @1)))))
+ (simplify
+ (convert (bitop:c (nop_convert @0) @1))
+ (if (tree_nop_conversion_p (type, TREE_TYPE (@1))
+ && types_match (type, TREE_TYPE (@0)))
+ (bitop @0 (convert @1)))))
(for bitop (bit_and bit_ior)
rbitop (bit_ior bit_and)
