On Mon, Jun 22, 2026 at 1:05 AM Andrew Pinski
<[email protected]> wrote:
>
> While working on related code I noticed that we can keep
> the vops up todate so rename ssa does not need to do anything here.
> This manually updates the 2 inserted statements, the load on the edge
> and the store in the join bb. This should be a small compile
> time optimization.
>
> Boostrapped and tested on x86_64-linux-gnu.
OK. (can we remove TODO_update_ssa{_only_virtuals,} after this?)
Richard.
> gcc/ChangeLog:
>
> * tree-ssa-phiopt.cc (cond_store_replacement): Update
> the vuse on the new load and the vuse/vdef on the new
> store.
>
> Signed-off-by: Andrew Pinski <[email protected]>
> ---
> gcc/tree-ssa-phiopt.cc | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
> index ebdff20b69b..b18e5aa9c06 100644
> --- a/gcc/tree-ssa-phiopt.cc
> +++ b/gcc/tree-ssa-phiopt.cc
> @@ -3167,9 +3167,12 @@ cond_store_replacement (basic_block middle_bb,
> basic_block join_bb, edge e0,
>
> /* 2) Insert a load from the memory of the store to the temporary
> on the edge which did not contain the store. */
> + gphi *vphi = get_virtual_phi (join_bb);
> name = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
> new_stmt = gimple_build_assign (name, lhs);
> gimple_set_location (new_stmt, locus);
> + /* Set the vuse for the new load. */
> + gimple_set_vuse (new_stmt, gimple_phi_arg_def (vphi, e1->dest_idx));
> lhs = unshare_expr (lhs);
> {
> /* Set the no-warning bit on the rhs of the load to avoid uninit
> @@ -3189,6 +3192,15 @@ cond_store_replacement (basic_block middle_bb,
> basic_block join_bb, edge e0,
>
> new_stmt = gimple_build_assign (lhs, gimple_phi_result (newphi));
>
> + /* Update the vdef for the new store statement. */
> + tree newvphilhs = make_ssa_name (gimple_vop (cfun));
> + tree vdef = gimple_phi_result (vphi);
> + gimple_set_vuse (new_stmt, newvphilhs);
> + gimple_set_vdef (new_stmt, vdef);
> + gimple_phi_set_result (vphi, newvphilhs);
> + SSA_NAME_DEF_STMT (vdef) = new_stmt;
> + update_stmt (vphi);
> +
> /* 4) Insert that PHI node. */
> gsi = gsi_after_labels (join_bb);
> gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
> --
> 2.43.0
>
