How to forbid register allocator to overlap bewteen DEST and SOURCE

[jiejie_rong]

Hi,

GCC seems to overlap register bewteen DEST and SOURCE in different 
machine mode,

Is there any target hooks to control this feature ?

I use  ‘&’ to forbid register allocator to overlap 
bewteen DEST and SOURCE,

but there are some redundancy instructions in the result code :(

Thanks a lot

—Jojo

Re: How to forbid register allocator to overlap bewteen DEST and SOURCE

[jiejie_rong]

Hi,

Thanks for your reply :)

Maybe there are some register limits in reload pass with my case like 


We need to expand to ‘mov’ and ‘madd’ first to get suitable registers.

—Jojo
在 2020年7月3日 +0800 AM5:35，Jim Wilson ，写道：
> On Wed, Jul 1, 2020 at 8:40 PM  wrote:
> > GCC seems to overlap register bewteen DEST and SOURCE in different machine 
> > mode,
> > Is there any target hooks to control this feature ?
> > I use  ‘&’ to forbid register allocator to overlap 
> > bewteen DEST and SOURCE,
> > but there are some redundancy instructions in the result code :(
>
> & is the correct solution in general.
>
> Presumably this is about your draft v0.7.1 vector port. This port
> uses an unspec in every pattern. This limits the compiler's ability
> to optimize code. You might get better results if you eliminated as
> many of the unspecs as you can.
>
> You might want to check TARGET_MODES_TIEABLE_P though this is mostly
> about casts and moves not register allocation.
>
> Jim

Split generated insn-emit.c

[jiejie_rong]

Hi,

The size of generated file like insn-emit.c is very huge
if we add lots of define_expand patten or define_insn patten.

It’s present easily when there are much more intrinsic interfaces
it costs much more time to create toolchain with compiling these files 
:(

Does anyone have method to split the generated file to small pieces ?
Or any hints to modify GCC toolchain creation process ?

Thanks,

—Jojo