[Bug target/55752] __builtin_ia32_ldmxcsr / __builtin_ia32_stmxcsr are not scheduling barriers

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55752

--- Comment #1 from Uros Bizjak <ubizjak at gmail dot com> 2012-12-20 12:59:40 UTC ---
The RTXes that corresponds to builtins are all declared unspec_volatile.
According to the comment in sched-deps.c, around line 2723, it is assumed that
unspec_volatile clobbers all registers.