Re: Fix PR 49014

[Bernd Schmidt <bernds@codesourcery.com>]

On 07/01/11 16:50, Andrey Belevantsev wrote:
> On 26.05.2011 17:32, Andrey Belevantsev wrote:
>> On 25.05.2011 19:31, Bernd Schmidt wrote:
>>> On 05/25/2011 03:29 PM, Andrey Belevantsev wrote:
>>>> I think the hook is a better idea than the attribute because nobody
>>>> will
>>>> care to mark all offending insns with an attribute.
>>>
>>> I don't know. IIRC when I looked at sh or whatever the broken port was,
>>> it was only two insns - there would still be some value in being able to
>>> assert that all other insns have a reservation.
>> OK, I will take a look on x86-64 and will get back with more information.
>>
>> Andrey
> So, I have made an attempt to bootstrap on x86-64 with the extra assert
> in selective scheduling that assumes the DFA state always changes when
> issuing a recog_memoized >=0 insn (patch attached).  Indeed, there are
> just a few general insns that don't have proper reservations.  However,
> it was a surprise to me to see that almost any insn with SSE registers
> fails this assert and thus does not get properly scheduled.

Probably because it's picking a scheduling description for an old CPU?
With "-mcpu=pentium" probably none of the newer patterns has a reservation.

That may scupper any plans to use this attribute on i386.

> Overall, the work on fixing those seems doable, it took just a day to
> get the compiler bootstrapped (of course, the testsuite may bring much
> more issues).  So, if there is an agreement on marking a few offending
> insns with the new attribute, we can proceed with the help of somebody
> from the x86 land on fixing those and researching for other targets.

+    (set (attr "nondfa_insn") (if_then_else (eq_attr "alternative"
"3,4,5,6") (const_int 1) (const_int 0)))

I think this shouldn't use (const_int x); you want to be able to write
 (set_attr "nondfa_insn" "0,0,0,1,1,1,1")


Bernd