[gcc r14-303] PHIOPT: Split out store elimination from phiopt

[gcc r14-303] PHIOPT: Split out store elimination from phiopt

[Andrew Pinski]

https://gcc.gnu.org/g:b9fedabe381cce0b375383a746ab9fe983596bd9

commit r14-303-gb9fedabe381cce0b375383a746ab9fe983596bd9
Author: Andrew Pinski <apinski@marvell.com>
Date:   Mon Apr 24 09:28:25 2023 -0700

    PHIOPT: Split out store elimination from phiopt
    
    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.
    
    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.

Diff:
---
 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 3b15ffcb0fc..9e8f7671345 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;
 }
 
@@ -4248,8 +4321,7 @@ 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);
     }
 
@@ -4351,7 +4423,7 @@ 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;