Re: [PATCH][LRA] Fix PR87899: r264897 cause mis-compiled native arm-linux-gnueabihf toolchain

[Renlin Li <renlin.li@foss.arm.com>]

Hi Peter,

I could verify that, your patch fixes all the ICEs I saw with arm-linux-gnueabihf toolchain!
There are some differences on the test results, because I compare the latest results with something which is old.

I haven't test it on bare-metal toolchain yet. But will do to ensure all related issues are fixed.

Thanks for fixing it!

Regards,
Renlin



On 11/12/2018 08:25 PM, Peter Bergner wrote:
> On 11/12/18 6:25 AM, Renlin Li wrote:
>> I tried to build a native arm-linuxeabihf toolchain with the patch.
>> But I got the following ICE:
> 
> Ok, the issue was a problem in handling the src reg from a register copy.
> I thought I could just remove it from the dead_set, but forgot that the
> updating of the program points looks at whether the pseudo is live or
> not.  The change below on top of the previous patch fixes the ICE for me.
> I now add the src reg back into pseudos_live before we process the insn's
> input operands so it doesn't trigger a new program point being added.
> 
> Renlin and Jeff, can you apply this patch on top of the previous one
> and see whether that is better?
> 
> Thanks.
> 
> Peter
> 
> 
> --- gcc/lra-lives.c.orig	2018-11-12 14:15:18.257657911 -0600
> +++ gcc/lra-lives.c	2018-11-12 14:08:55.978795092 -0600
> @@ -934,6 +934,18 @@
>   	  || sparseset_contains_pseudos_p (start_dying))
>   	next_program_point (curr_point, freq);
>   
> +      /* If we removed the source reg from a simple register copy from the
> +	 live set above, then add it back now so we don't accidentally add
> +	 it to the start_living set below.  */
> +      if (ignore_reg != NULL_RTX)
> +	{
> +	  int ignore_regno = REGNO (ignore_reg);
> +	  if (HARD_REGISTER_NUM_P (ignore_regno))
> +	    SET_HARD_REG_BIT (hard_regs_live, ignore_regno);
> +	  else
> +	    sparseset_set_bit (pseudos_live, ignore_regno);
> +	}
> +
>         sparseset_clear (start_living);
>   
>         /* Mark each used value as live.	*/
> @@ -959,11 +971,6 @@
>   
>         sparseset_and_compl (dead_set, start_living, start_dying);
>   
> -      /* If we removed the source reg from a simple register copy from the
> -	 live set, then it will appear to be dead, but it really isn't.  */
> -      if (ignore_reg != NULL_RTX)
> -	sparseset_clear_bit (dead_set, REGNO (ignore_reg));
> -
>         sparseset_clear (start_dying);
>   
>         /* Mark early clobber outputs dead.  */
>