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

[Kyrill Tkachov]

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.

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