[PATCH][ARM] Restrict MAX_CONDITIONAL_EXECUTE when -mrestrict-it is in place

[Kyrill Tkachov]

Ping.
https://gcc.gnu.org/ml/gcc-patches/2015-05/msg02405.html

Thanks,
Kyrill
On 27/05/15 11:25, Kyrill Tkachov wrote:
> Ping.
>
> Here is the rebased (and retested) patch after Christian's series.
>
> Thanks,
> Kyrill
>
> On 18/05/15 11:26, Kyrill Tkachov wrote:
>> Hi all,
>>
>> When using the short Thumb2 IT blocks we want to also restrict ifcvt so that it will not end up generating a number of back-to-back cond_execs
>> that will later end up being back to back single-instruction IT blocks. Branching over them should be a better choice.
>>
>> This patch implements that by setting max_insns_skipped to 1 when arm_restrict_it.
>>
>> With this patch, I've seen GCC replace a number of sequences in places like SPEC2006 from:
>>        it    eq
>>        moveq    r1, r5
>>        it    ne
>>        movne    r1, r10
>>        it    eq
>>        moveq    r8, r4
>>
>> to a branch over them.
>>
>> Bootstrapped and tested on arm.
>> Ok for trunk?
>>
>> Thanks,
>> Kyrill
>>
>> 2015-05-18  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
>>
>>        * config/arm/arm.c (arm_option_params_internal): When optimising
>>        for speed set max_insns_skipped when arm_restrict_it.
>>
>> 2015-05-18  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
>>
>>        * gcc.target/arm/short-it-ifcvt-1.c: New test.
>>        * gcc.target/arm/short-it-ifcvt-2.c: Likewise.