Re: [PATCH] Properly release VOP of inlined call stmt

[Jeff Law <law at redhat dot com>]

On 02/17/14 06:42, Richard Biener wrote:
> This makes us release the virtual SSA name associated with a call that
> is inlined.  This removes some garbage that is otherwise kept live
> duing early opts (and thus reduces whole-program footprint).
>
> With this patch and the separately posted ipa-prop change I can
> bootstrap & regtest with
>
> Index: gcc/tree-ssa.c
> ===================================================================
> --- gcc/tree-ssa.c      (revision 207783)
> +++ gcc/tree-ssa.c      (working copy)
> @@ -741,6 +741,16 @@ verify_def (basic_block bb, basic_block
>         goto err;
>       }
>
> +  if (bb == NULL
> +      /* ???  Too many latent cases in the main opt pipeline.  But it's
> +         worth to fix all cases before inlining as that reduces the
> +        amount of garbage kept live.  */
> +      && !cfun->after_inlining)
> +    {
> +      error ("removed STMT failed to release SSA name");
> +      goto err;
> +    }
> +
>     if (definition_block[SSA_NAME_VERSION (ssa_name)])
>       {
>         error ("SSA_NAME created in two different blocks %i and %i",
>
> applied.
>
> Bootstrapped and tested (with the above applied) on
> x86_64-unknown-linux-gnu.  Ok?
>
> Thanks,
> Richard.
>
> 2014-02-17  Richard Biener  <rguenther@suse.de>
>
> 	* tree-inline.c (expand_call_inline): Release the virtual
> 	operand defined by the call we are about to inline.
OK.

ISTM that we ought to define stage4 as explicitly including this kind of 
stuff in addition to regression fixing.  Not sure exactly what wording 
we'd want to use though.

If you wanted to really go nuts, install a mark hook on for the RTL GGC 
routines that flags when a deleted insn is still reachable ;-)  It's 
obviously not OK for the tree, but good for finding leaking deleted insns.

Jeff