[1/2] Move copy_phi_arg_into_existing_phi to common location and use it

  While improving replace_phi_edge_with_variable for the diamond formed bb
case, I need a way to copy phi entries from one edge to another as I am
removing a forwarding bb inbetween. I was pointed out that jump threading
code had copy_phi_arg_into_existing_phi which I can use.
I also noticed that both gimple_duplicate_sese_tail and
remove_forwarder_block have similar code so it makes sense to use that function
in those two locations too.

OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.

gcc/ChangeLog:

	* tree-cfg.cc (copy_phi_args): New function
	(gimple_duplicate_sese_tail): Use it instead of
	doing it inline.
	* tree-cfg.h (copy_phi_args): New declaration.
	* tree-cfgcleanup.cc (remove_forwarder_block): Use
	copy_phi_args instead of implementing it inline.

gcc/ChangeLog:

	* tree-ssa-threadupdate.cc (copy_phi_arg_into_existing_phi): Move to ...
	* tree-cfg.cc (copy_phi_arg_into_existing_phi): Here and remove static.
	(gimple_duplicate_sese_tail): Use copy_phi_arg_into_existing_phi instead
	of an inline version of it.
	* tree-cfgcleanup.cc (remove_forwarder_block): Likewise.
	* tree-cfg.h (copy_phi_arg_into_existing_phi): New declaration.
---
 gcc/tree-cfg.cc              | 38 +++++++++++++++++++++++++-----------
 gcc/tree-cfg.h               |  1 +
 gcc/tree-cfgcleanup.cc       | 12 ++----------
 gcc/tree-ssa-threadupdate.cc | 25 ------------------------
 4 files changed, 30 insertions(+), 46 deletions(-)
  

On Thu, May 4, 2023 at 1:13 AM Andrew Pinski via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> While improving replace_phi_edge_with_variable for the diamond formed bb
> case, I need a way to copy phi entries from one edge to another as I am
> removing a forwarding bb inbetween. I was pointed out that jump threading
> code had copy_phi_arg_into_existing_phi which I can use.
> I also noticed that both gimple_duplicate_sese_tail and
> remove_forwarder_block have similar code so it makes sense to use that function
> in those two locations too.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.

OK.

> gcc/ChangeLog:
>
>         * tree-cfg.cc (copy_phi_args): New function
>         (gimple_duplicate_sese_tail): Use it instead of
>         doing it inline.
>         * tree-cfg.h (copy_phi_args): New declaration.
>         * tree-cfgcleanup.cc (remove_forwarder_block): Use
>         copy_phi_args instead of implementing it inline.
>
> gcc/ChangeLog:
>
>         * tree-ssa-threadupdate.cc (copy_phi_arg_into_existing_phi): Move to ...
>         * tree-cfg.cc (copy_phi_arg_into_existing_phi): Here and remove static.
>         (gimple_duplicate_sese_tail): Use copy_phi_arg_into_existing_phi instead
>         of an inline version of it.
>         * tree-cfgcleanup.cc (remove_forwarder_block): Likewise.
>         * tree-cfg.h (copy_phi_arg_into_existing_phi): New declaration.
> ---
>  gcc/tree-cfg.cc              | 38 +++++++++++++++++++++++++-----------
>  gcc/tree-cfg.h               |  1 +
>  gcc/tree-cfgcleanup.cc       | 12 ++----------
>  gcc/tree-ssa-threadupdate.cc | 25 ------------------------
>  4 files changed, 30 insertions(+), 46 deletions(-)
>
> diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
> index 4927fc0a8d9..a94dc3c2eea 100644
> --- a/gcc/tree-cfg.cc
> +++ b/gcc/tree-cfg.cc
> @@ -6802,6 +6802,32 @@ bb_part_of_region_p (basic_block bb, basic_block* bbs, unsigned n_region)
>    return false;
>  }
>
> +
> +/* For each PHI in BB, copy the argument associated with SRC_E to TGT_E.
> +   Assuming the argument exists, just does not have a value.  */
> +
> +void
> +copy_phi_arg_into_existing_phi (edge src_e, edge tgt_e)
> +{
> +  int src_idx = src_e->dest_idx;
> +  int tgt_idx = tgt_e->dest_idx;
> +
> +  /* Iterate over each PHI in e->dest.  */
> +  for (gphi_iterator gsi = gsi_start_phis (src_e->dest),
> +                          gsi2 = gsi_start_phis (tgt_e->dest);
> +       !gsi_end_p (gsi);
> +       gsi_next (&gsi), gsi_next (&gsi2))
> +    {
> +      gphi *src_phi = gsi.phi ();
> +      gphi *dest_phi = gsi2.phi ();
> +      tree val = gimple_phi_arg_def (src_phi, src_idx);
> +      location_t locus = gimple_phi_arg_location (src_phi, src_idx);
> +
> +      SET_PHI_ARG_DEF (dest_phi, tgt_idx, val);
> +      gimple_phi_arg_set_location (dest_phi, tgt_idx, locus);
> +    }
> +}
> +
>  /* Duplicates REGION consisting of N_REGION blocks.  The new blocks
>     are stored to REGION_COPY in the same order in that they appear
>     in REGION, if REGION_COPY is not NULL.  ENTRY is the entry to
> @@ -6847,9 +6873,6 @@ gimple_duplicate_sese_tail (edge entry, edge exit,
>    gimple_stmt_iterator gsi;
>    edge sorig, snew;
>    basic_block exit_bb;
> -  gphi_iterator psi;
> -  gphi *phi;
> -  tree def;
>    class loop *target, *aloop, *cloop;
>
>    gcc_assert (EDGE_COUNT (exit->src->succs) == 2);
> @@ -6947,14 +6970,7 @@ gimple_duplicate_sese_tail (edge entry, edge exit,
>         gcc_assert (single_succ_edge (region_copy[i]));
>         e = redirect_edge_and_branch (single_succ_edge (region_copy[i]), exit_bb);
>         PENDING_STMT (e) = NULL;
> -       for (psi = gsi_start_phis (exit_bb);
> -            !gsi_end_p (psi);
> -            gsi_next (&psi))
> -         {
> -           phi = psi.phi ();
> -           def = PHI_ARG_DEF (phi, nexits[0]->dest_idx);
> -           add_phi_arg (phi, def, e, gimple_phi_arg_location_from_edge (phi, e));
> -         }
> +       copy_phi_arg_into_existing_phi (nexits[0], e);
>        }
>    e = redirect_edge_and_branch (nexits[1], nexits[0]->dest);
>    PENDING_STMT (e) = NULL;
> diff --git a/gcc/tree-cfg.h b/gcc/tree-cfg.h
> index 9b56a68fe9d..9a1605be305 100644
> --- a/gcc/tree-cfg.h
> +++ b/gcc/tree-cfg.h
> @@ -113,6 +113,7 @@ extern basic_block gimple_switch_default_bb (function *, gswitch *);
>  extern edge gimple_switch_edge (function *, gswitch *, unsigned);
>  extern edge gimple_switch_default_edge (function *, gswitch *);
>  extern bool cond_only_block_p (basic_block);
> +extern void copy_phi_arg_into_existing_phi (edge, edge);
>
>  /* Return true if the LHS of a call should be removed.  */
>
> diff --git a/gcc/tree-cfgcleanup.cc b/gcc/tree-cfgcleanup.cc
> index 42b25312122..193d87e3278 100644
> --- a/gcc/tree-cfgcleanup.cc
> +++ b/gcc/tree-cfgcleanup.cc
> @@ -610,17 +610,9 @@ remove_forwarder_block (basic_block bb)
>
>        if (s == e)
>         {
> -         /* Create arguments for the phi nodes, since the edge was not
> +         /* Copy arguments for the phi nodes, since the edge was not
>              here before.  */
> -         for (gphi_iterator psi = gsi_start_phis (dest);
> -              !gsi_end_p (psi);
> -              gsi_next (&psi))
> -           {
> -             gphi *phi = psi.phi ();
> -             location_t l = gimple_phi_arg_location_from_edge (phi, succ);
> -             tree def = gimple_phi_arg_def (phi, succ->dest_idx);
> -             add_phi_arg (phi, unshare_expr (def), s, l);
> -           }
> +         copy_phi_arg_into_existing_phi (succ, s);
>         }
>      }
>
> diff --git a/gcc/tree-ssa-threadupdate.cc b/gcc/tree-ssa-threadupdate.cc
> index 33a91063638..d5416b21a78 100644
> --- a/gcc/tree-ssa-threadupdate.cc
> +++ b/gcc/tree-ssa-threadupdate.cc
> @@ -511,31 +511,6 @@ fwd_jt_path_registry::lookup_redirection_data (edge e, insert_option insert)
>      }
>  }
>
> -/* Similar to copy_phi_args, except that the PHI arg exists, it just
> -   does not have a value associated with it.  */
> -
> -static void
> -copy_phi_arg_into_existing_phi (edge src_e, edge tgt_e)
> -{
> -  int src_idx = src_e->dest_idx;
> -  int tgt_idx = tgt_e->dest_idx;
> -
> -  /* Iterate over each PHI in e->dest.  */
> -  for (gphi_iterator gsi = gsi_start_phis (src_e->dest),
> -                          gsi2 = gsi_start_phis (tgt_e->dest);
> -       !gsi_end_p (gsi);
> -       gsi_next (&gsi), gsi_next (&gsi2))
> -    {
> -      gphi *src_phi = gsi.phi ();
> -      gphi *dest_phi = gsi2.phi ();
> -      tree val = gimple_phi_arg_def (src_phi, src_idx);
> -      location_t locus = gimple_phi_arg_location (src_phi, src_idx);
> -
> -      SET_PHI_ARG_DEF (dest_phi, tgt_idx, val);
> -      gimple_phi_arg_set_location (dest_phi, tgt_idx, locus);
> -    }
> -}
> -
>  /* Given ssa_name DEF, backtrack jump threading PATH from node IDX
>     to see if it has constant value in a flow sensitive manner.  Set
>     LOCUS to location of the constant phi arg and return the value.
> --
> 2.31.1
>