Re: help needed on gcc instruction scheduling with unspec_volatile()

[Ian Lance Taylor <iant at google dot com>]

raja.saleru@iap-online.com writes:

> In gcc, while instruction scheduling can it be possible to suspend the
> scheduling for some instructions ? or

No.  You can turn off instruction scheduling for the entire
compilation.  You can use #pragma GCC optimize to turn scheduling off
for a specific function.  But there is no way to turn it off for some
instructions within a function but not others.


> Is there a way to make the instruction has to allocate to run without
> using the scheduler for particular instruction ?

I don't understand the question.


> Currently there is RTL template in machine description unspec_volatile().
> If the instruction is scheduled using this, does this make the instruction
> out of scope of scheduler ?

Nothing is out of scope of the scheduler.  Using unspec_volatile in
the RTL template makes the instruction a scheduling barrier and a
memory barrier.

Ian