On Mon, Apr 24, 2023 at 11:31 PM Andrew Pinski via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Since the last cleanups, it made easier to see
> that we should split out the store elimination
> worker from tree_ssa_phiopt_worker function.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
OK.
> gcc/ChangeLog:
>
> * tree-ssa-phiopt.cc (tree_ssa_phiopt_worker): Remove
> do_store_elim argument and split that part out to ...
> (store_elim_worker): This new function.
> (pass_cselim::execute): Call store_elim_worker.
> (pass_phiopt::execute): Update call to tree_ssa_phiopt_worker.
> ---
> gcc/tree-ssa-phiopt.cc | 180 ++++++++++++++++++++++++++++-------------
> 1 file changed, 126 insertions(+), 54 deletions(-)
>
> diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
> index 4a3ab8efb71..7f47b32576b 100644
> --- a/gcc/tree-ssa-phiopt.cc
> +++ b/gcc/tree-ssa-phiopt.cc
> @@ -104,27 +104,19 @@ single_non_singleton_phi_for_edges (gimple_seq seq,
> edge e0, edge e1)
> return phi;
> }
>
> -/* The core routine of conditional store replacement and normal
> - phi optimizations. Both share much of the infrastructure in how
> - to match applicable basic block patterns. DO_STORE_ELIM is true
> - when we want to do conditional store replacement, false otherwise.
> +/* The core routine of phi optimizations.
> DO_HOIST_LOADS is true when we want to hoist adjacent loads out
> of diamond control flow patterns, false otherwise. */
> static unsigned int
> -tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool
> early_p)
> +tree_ssa_phiopt_worker (bool do_hoist_loads, bool early_p)
> {
> basic_block bb;
> basic_block *bb_order;
> unsigned n, i;
> bool cfgchanged = false;
> - hash_set<tree> *nontrap = 0;
>
> calculate_dominance_info (CDI_DOMINATORS);
>
> - if (do_store_elim)
> - /* Calculate the set of non-trapping memory accesses. */
> - nontrap = get_non_trapping ();
> -
> /* Search every basic block for COND_EXPR we may be able to optimize.
>
> We walk the blocks in order that guarantees that a block with
> @@ -148,7 +140,7 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool
> do_hoist_loads, bool early_p)
> /* Check to see if the last statement is a GIMPLE_COND. */
> gcond *cond_stmt = safe_dyn_cast <gcond *> (*gsi_last_bb (bb));
> if (!cond_stmt)
> - continue;
> + continue;
>
> e1 = EDGE_SUCC (bb, 0);
> bb1 = e1->dest;
> @@ -158,12 +150,12 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool
> do_hoist_loads, bool early_p)
> /* We cannot do the optimization on abnormal edges. */
> if ((e1->flags & EDGE_ABNORMAL) != 0
> || (e2->flags & EDGE_ABNORMAL) != 0)
> - continue;
> + continue;
>
> /* If either bb1's succ or bb2 or bb2's succ is non NULL. */
> if (EDGE_COUNT (bb1->succs) == 0
> || EDGE_COUNT (bb2->succs) == 0)
> - continue;
> + continue;
>
> /* Find the bb which is the fall through to the other. */
> if (EDGE_SUCC (bb1, 0)->dest == bb2)
> @@ -192,39 +184,6 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool
> do_hoist_loads, bool early_p)
> || (e1->flags & EDGE_FALLTHRU) == 0)
> continue;
>
> - if (do_store_elim)
> - {
> - if (diamond_p)
> - {
> - basic_block bb3 = e1->dest;
> -
> - /* Only handle sinking of store from 2 bbs only,
> - The middle bbs don't need to come from the
> - if always since we are sinking rather than
> - hoisting. */
> - if (EDGE_COUNT (bb3->preds) != 2)
> - continue;
> - if (cond_if_else_store_replacement (bb1, bb2, bb3))
> - cfgchanged = true;
> - continue;
> - }
> -
> - /* Also make sure that bb1 only have one predecessor and that it
> - is bb. */
> - if (!single_pred_p (bb1)
> - || single_pred (bb1) != bb)
> - continue;
> -
> - /* bb1 is the middle block, bb2 the join block, bb the split block,
> - e1 the fallthrough edge from bb1 to bb2. We can't do the
> - optimization if the join block has more than two predecessors.
> */
> - if (EDGE_COUNT (bb2->preds) > 2)
> - continue;
> - if (cond_store_replacement (bb1, bb2, e1, e2, nontrap))
> - cfgchanged = true;
> - continue;
> - }
> -
> if (diamond_p)
> {
> basic_block bb3 = e1->dest;
> @@ -322,18 +281,132 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool
> do_hoist_loads, bool early_p)
>
> free (bb_order);
>
> - if (do_store_elim)
> - delete nontrap;
> + if (cfgchanged)
> + return TODO_cleanup_cfg;
> + return 0;
> +}
> +
> +/* The core routine of conditional store replacement. */
> +static unsigned int
> +store_elim_worker (void)
> +{
> + basic_block bb;
> + basic_block *bb_order;
> + unsigned n, i;
> + bool cfgchanged = false;
> + hash_set<tree> *nontrap = 0;
> +
> + calculate_dominance_info (CDI_DOMINATORS);
> +
> + /* Calculate the set of non-trapping memory accesses. */
> + nontrap = get_non_trapping ();
> +
> + /* Search every basic block for COND_EXPR we may be able to optimize.
> +
> + We walk the blocks in order that guarantees that a block with
> + a single predecessor is processed before the predecessor.
> + This ensures that we collapse inner ifs before visiting the
> + outer ones, and also that we do not try to visit a removed
> + block. */
> + bb_order = single_pred_before_succ_order ();
> + n = n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS;
> +
> + for (i = 0; i < n; i++)
> + {
> + basic_block bb1, bb2;
> + edge e1, e2;
> + bool diamond_p = false;
> +
> + bb = bb_order[i];
> +
> + /* Check to see if the last statement is a GIMPLE_COND. */
> + gcond *cond_stmt = safe_dyn_cast <gcond *> (*gsi_last_bb (bb));
> + if (!cond_stmt)
> + continue;
> +
> + e1 = EDGE_SUCC (bb, 0);
> + bb1 = e1->dest;
> + e2 = EDGE_SUCC (bb, 1);
> + bb2 = e2->dest;
> +
> + /* We cannot do the optimization on abnormal edges. */
> + if ((e1->flags & EDGE_ABNORMAL) != 0
> + || (e2->flags & EDGE_ABNORMAL) != 0)
> + continue;
> +
> + /* If either bb1's succ or bb2 or bb2's succ is non NULL. */
> + if (EDGE_COUNT (bb1->succs) == 0
> + || EDGE_COUNT (bb2->succs) == 0)
> + continue;
> +
> + /* Find the bb which is the fall through to the other. */
> + if (EDGE_SUCC (bb1, 0)->dest == bb2)
> + ;
> + else if (EDGE_SUCC (bb2, 0)->dest == bb1)
> + {
> + std::swap (bb1, bb2);
> + std::swap (e1, e2);
> + }
> + else if (EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest
> + && single_succ_p (bb2))
> + {
> + diamond_p = true;
> + e2 = EDGE_SUCC (bb2, 0);
> + /* Make sure bb2 is just a fall through. */
> + if ((e2->flags & EDGE_FALLTHRU) == 0)
> + continue;
> + }
> + else
> + continue;
> +
> + e1 = EDGE_SUCC (bb1, 0);
> +
> + /* Make sure that bb1 is just a fall through. */
> + if (!single_succ_p (bb1)
> + || (e1->flags & EDGE_FALLTHRU) == 0)
> + continue;
> +
> + if (diamond_p)
> + {
> + basic_block bb3 = e1->dest;
> +
> + /* Only handle sinking of store from 2 bbs only,
> + The middle bbs don't need to come from the
> + if always since we are sinking rather than
> + hoisting. */
> + if (EDGE_COUNT (bb3->preds) != 2)
> + continue;
> + if (cond_if_else_store_replacement (bb1, bb2, bb3))
> + cfgchanged = true;
> + continue;
> + }
> +
> + /* Also make sure that bb1 only have one predecessor and that it
> + is bb. */
> + if (!single_pred_p (bb1)
> + || single_pred (bb1) != bb)
> + continue;
> +
> + /* bb1 is the middle block, bb2 the join block, bb the split block,
> + e1 the fallthrough edge from bb1 to bb2. We can't do the
> + optimization if the join block has more than two predecessors. */
> + if (EDGE_COUNT (bb2->preds) > 2)
> + continue;
> + if (cond_store_replacement (bb1, bb2, e1, e2, nontrap))
> + cfgchanged = true;
> + }
> +
> + free (bb_order);
> +
> + delete nontrap;
> /* If the CFG has changed, we should cleanup the CFG. */
> - if (cfgchanged && do_store_elim)
> + if (cfgchanged)
> {
> /* In cond-store replacement we have added some loads on edges
> and new VOPS (as we moved the store, and created a load). */
> gsi_commit_edge_inserts ();
> return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals;
> }
> - else if (cfgchanged)
> - return TODO_cleanup_cfg;
> return 0;
> }
>
> @@ -4257,8 +4330,7 @@ public:
> bool gate (function *) final override { return flag_ssa_phiopt; }
> unsigned int execute (function *) final override
> {
> - return tree_ssa_phiopt_worker (false,
> - !early_p ? gate_hoist_loads () : false,
> + return tree_ssa_phiopt_worker (!early_p ? gate_hoist_loads () : false,
> early_p);
> }
>
> @@ -4360,7 +4432,7 @@ pass_cselim::execute (function *)
> An interfacing issue of find_data_references_in_bb. */
> loop_optimizer_init (LOOPS_NORMAL);
> scev_initialize ();
> - todo = tree_ssa_phiopt_worker (true, false, false);
> + todo = store_elim_worker ();
> scev_finalize ();
> loop_optimizer_finalize ();
> return todo;
> --
> 2.39.1
>
