[gcc r13-6902] bootstrap/84402 - improve (match ...) code generation

[gcc r13-6902] bootstrap/84402 - improve (match ...) code generation

[Richard Biener]

https://gcc.gnu.org/g:75cda3be0232f745cda4e177d514f6900390af0b

commit r13-6902-g75cda3be0232f745cda4e177d514f6900390af0b
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Mar 28 12:42:14 2023 +0200

    bootstrap/84402 - improve (match ...) code generation
    
    The following avoids duplicating matching code for (match ...)
    in match.pd when possible.  That's more easily possible for
    (match ...) than simplify because we do not need to handle
    common matches (those would be diagnosed only during compiling)
    nor is the result able to inspect the active operator.
    
    Specifically this reduces the size of the generated matches for
    the atomic ops as noted in PR108129.
    
    gimple-match.cc shrinks from 245k lines to 209k lines with this patch.
    
            PR bootstrap/84402
            PR tree-optimization/108129
            * genmatch.cc (lower_for): For (match ...) delay
            substituting into the match operator if possible.
            (dt_operand::gen_gimple_expr): For user_id look at the
            first substitute for determining how to access operands.
            (dt_operand::gen_generic_expr): Likewise.
            (dt_node::gen_kids): Properly sort user_ids according
            to their substitutes.
            (dt_node::gen_kids_1): Code-generate user_id matching.

Diff:
---
 gcc/genmatch.cc | 65 ++++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 53 insertions(+), 12 deletions(-)

diff --git a/gcc/genmatch.cc b/gcc/genmatch.cc
index 43bd0212d0e..4fab4135347 100644
--- a/gcc/genmatch.cc
+++ b/gcc/genmatch.cc
@@ -1464,7 +1464,7 @@ lower_for (simplify *sin, vec<simplify *>& simplifiers)
       vec<user_id *>& ids = for_vec[fi];
       unsigned n_ids = ids.length ();
       unsigned max_n_opers = 0;
-      bool can_delay_subst = (sin->kind == simplify::SIMPLIFY);
+      bool can_delay_subst = true;
       for (unsigned i = 0; i < n_ids; ++i)
 	{
 	  if (ids[i]->substitutes.length () > max_n_opers)
@@ -1504,6 +1504,9 @@ lower_for (simplify *sin, vec<simplify *>& simplifiers)
 	    else
 	      can_delay_subst = false;
 	}
+      if (sin->kind == simplify::MATCH
+	  && can_delay_subst)
+	continue;
 
       unsigned worklist_end = worklist.length ();
       for (unsigned si = worklist_start; si < worklist_end; ++si)
@@ -1527,7 +1530,9 @@ lower_for (simplify *sin, vec<simplify *>& simplifiers)
 		      break;
 		    }
 		  subst.quick_push (std::make_pair (id, oper));
-		  match_op = replace_id (match_op, id, oper);
+		  if (sin->kind == simplify::SIMPLIFY
+		      || !can_delay_subst)
+		    match_op = replace_id (match_op, id, oper);
 		  if (result_op
 		      && !can_delay_subst)
 		    result_op = replace_id (result_op, id, oper);
@@ -2824,6 +2829,9 @@ dt_operand::gen_gimple_expr (FILE *f, int indent, int depth)
   unsigned n_ops = e->ops.length ();
   unsigned n_braces = 0;
 
+  if (user_id *u = dyn_cast <user_id *> (id))
+    id = u->substitutes[0];
+
   for (unsigned i = 0; i < n_ops; ++i)
     {
       char child_opname[20];
@@ -2905,14 +2913,18 @@ unsigned
 dt_operand::gen_generic_expr (FILE *f, int indent, const char *opname)
 {
   expr *e = static_cast<expr *> (op);
+  id_base *id = e->operation;
   unsigned n_ops = e->ops.length ();
 
+  if (user_id *u = dyn_cast <user_id *> (id))
+    id = u->substitutes[0];
+
   for (unsigned i = 0; i < n_ops; ++i)
     {
       char child_opname[20];
       gen_opname (child_opname, i);
 
-      if (e->operation->kind == id_base::CODE)
+      if (id->kind == id_base::CODE)
 	fprintf_indent (f, indent, "tree %s = TREE_OPERAND (%s, %u);\n",
 			child_opname, opname, i);
       else
@@ -2964,10 +2976,21 @@ dt_node::gen_kids (FILE *f, int indent, bool gimple, int depth)
 		preds.safe_push (op);
 	      else
 		{
-		  if (gimple && !e->is_generic)
-		    gimple_exprs.safe_push (op);
+		  user_id *u = dyn_cast <user_id *> (e->operation);
+		  if (u && u->substitutes[0]->kind == id_base::FN)
+		    {
+		      if (gimple)
+			fns.safe_push (op);
+		      else
+			generic_fns.safe_push (op);
+		    }
 		  else
-		    generic_exprs.safe_push (op);
+		    {
+		      if (gimple && !e->is_generic)
+			gimple_exprs.safe_push (op);
+		      else
+			generic_exprs.safe_push (op);
+		    }
 		}
 	    }
 	  else if (op->op->type == operand::OP_PREDICATE)
@@ -3064,11 +3087,19 @@ dt_node::gen_kids_1 (FILE *f, int indent, bool gimple, int depth,
 	  for (unsigned i = 0; i < exprs_len; ++i)
 	    {
 	      expr *e = as_a <expr *> (gimple_exprs[i]->op);
-	      id_base *op = e->operation;
-	      if (*op == CONVERT_EXPR || *op == NOP_EXPR)
-		fprintf_indent (f, indent, "CASE_CONVERT:\n");
+	      if (user_id *u = dyn_cast <user_id *> (e->operation))
+		{
+		  for (auto id : u->substitutes)
+		    fprintf_indent (f, indent, "case %s:\n", id->id);
+		}
 	      else
-		fprintf_indent (f, indent, "case %s:\n", op->id);
+		{
+		  id_base *op = e->operation;
+		  if (*op == CONVERT_EXPR || *op == NOP_EXPR)
+		    fprintf_indent (f, indent, "CASE_CONVERT:\n");
+		  else
+		    fprintf_indent (f, indent, "case %s:\n", op->id);
+		}
 	      fprintf_indent (f, indent, "  {\n");
 	      gimple_exprs[i]->gen (f, indent + 4, true, depth);
 	      fprintf_indent (f, indent, "    break;\n");
@@ -3093,7 +3124,11 @@ dt_node::gen_kids_1 (FILE *f, int indent, bool gimple, int depth,
 	  for (unsigned i = 0; i < fns_len; ++i)
 	    {
 	      expr *e = as_a <expr *>(fns[i]->op);
-	      fprintf_indent (f, indent, "case %s:\n", e->operation->id);
+	      if (user_id *u = dyn_cast <user_id *> (e->operation))
+		for (auto id : u->substitutes)
+		  fprintf_indent (f, indent, "case %s:\n", id->id);
+	      else
+		fprintf_indent (f, indent, "case %s:\n", e->operation->id);
 	      /* We need to be defensive against bogus prototypes allowing
 		 calls with not enough arguments.  */
 	      fprintf_indent (f, indent,
@@ -3140,7 +3175,13 @@ dt_node::gen_kids_1 (FILE *f, int indent, bool gimple, int depth,
 	/* Already handled above.  */
 	continue;
       else
-	fprintf_indent (f, indent, "case %s:\n", op->id);
+	{
+	  if (user_id *u = dyn_cast <user_id *> (op))
+	    for (auto id : u->substitutes)
+	      fprintf_indent (f, indent, "case %s:\n", id->id);
+	  else
+	    fprintf_indent (f, indent, "case %s:\n", op->id);
+	}
       fprintf_indent (f, indent, "  {\n");
       generic_exprs[i]->gen (f, indent + 4, gimple, depth);
       fprintf_indent (f, indent, "    break;\n");