[PATCH 1/2] Add new RTX instruction class FILLER_INSN
Wed Aug 19 17:47:29 GMT 2020
Segher Boessenkool <firstname.lastname@example.org> writes:
> [ Please don't post new patch series as replies to old ]
> On Wed, Jul 22, 2020 at 12:02:33PM +0200, Andrea Corallo wrote:
>> This first patch implements the addition of a new RTX instruction class
>> FILLER_INSN, which has been white listed to allow placement of NOPs
>> outside of a basic block. This is to allow padding after unconditional
>> branches. This is favorable so that any performance gained from
>> diluting branches is not paid straight back via excessive eating of
>> It was deemed that a new RTX class was less invasive than modifying
>> behavior in regards to standard UNSPEC nops.
> Deemed, by whom? There are several people very against it, too. You
> need to modify only one simple behaviour (maybe in a handful of places),
> making a new RTX class for that is excessive.
That's understood and agreed. I haven't posted any new patch on this,
the quoted mail is an old one. I just wanted to discuss how to proceede
this way with my mail of today.
Thanks for your feedback!
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