scheduling question

[Vladimir Makarov]

Alex Turjan wrote:
> Hi,
> During scheduling Im confronted with the fact that an instruction is moved
> from the ready list to queued with the cost 2, while according to my
> expectations the insn should have been moved to queued with cost 1.
>
>   
High, Alex.  I could look at this, if you have a test and the problem 
can be reproducable (it is not a new target).
> Did anybody experience similar problem? 
>
> In case an insn is ready but can bot be schedled in the current
> cycle, is it correct (i.e. the generated code is correct) to move the insn
> to the queue list with cost 1 ?; no matter what it the value >=1
> returned by state_transition.
>
>   
No, it is not correct. With the point of resource hazard, it is ok 
because the scheduler checks possibility of insn issuing at given state 
in any way.  But it is wrong with the point of the data delay hazard 
because the scheduler does not check that time when all data for insn 
(INSN_TICK) are ready at given time (INSN_TICK () <= clock_var).  If you 
add checking this in schedule_block and update clock_var until the insn 
is ready plus sort insn according to their INSN_TICK as the first 
priority, you can put all insns into the queue list with cost 1.
> It seams to me that moving from the ready to queue list with cost >=1 is 
> an optimization for compilation time.
>  
>
>   
Not only, please see my comment above.
>
>       
>