[Bug target/59968] Unused BT patterns

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59968

--- Comment #3 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to H.J. Lu from comment #0)
> There are some BT patterns in i386 guarded with
> TARGET_USE_BT.  But there are no testcases to show
> if they are used at all.

testsuite/gcc.target/i386/bt-*.c

> Also BT instructions supports memory destination.
> But BT patterns only allow register destination.

bt with a memory operand is slow. The bitpos argument is not limited to operand
size, and is primarily used for locked memory access.

BTW:

$ objdump -d cc1 | grep "bt " | wc -l
1228