expression eval: Fix EEOP_JSON_CONSTRUCTOR and EEOP_JSONEXPR size.

The new expression step types increased the size of ExprEvalStep by ~4 for all
types of expression steps, slowing down expression evaluation noticeably. Move
them out of line.

There's other issues with these expression steps, but addressing them is
largely independent of this aspect.

Author: Andres Freund <andres@anarazel.de>
Reviewed-By: Andrew Dunstan <andrew@dunslane.net>
Discussion: https://postgr.es/m/20220616233130.rparivafipt6doj3@alap3.anarazel.de
Backpatch: 15-

1 files changed, 62 insertions, 49 deletions

diff --git a/src/include/executor/execExpr.h b/src/include/executor/execExpr.h
index e34db8c93cb..fa2d9be4c99 100644
--- a/src/include/executor/execExpr.h
+++ b/src/include/executor/execExpr.h
@@ -22,6 +22,8 @@ struct ExprEvalStep;
 struct SubscriptingRefState;
 struct ScalarArrayOpExprHashTable;
 struct JsonbValue;
+struct JsonExprState;
+struct JsonConstructorExprState;
 
 /* Bits in ExprState->flags (see also execnodes.h for public flag bits): */
 /* expression's interpreter has been initialized */
@@ -676,16 +678,7 @@ typedef struct ExprEvalStep
 		/* for EEOP_JSON_CONSTRUCTOR */
 		struct
 		{
-			JsonConstructorExpr *constructor;
-			Datum	   *arg_values;
-			bool	   *arg_nulls;
-			Oid		   *arg_types;
-			struct
-			{
-				int			category;
-				Oid			outfuncid;
-			}		   *arg_type_cache; /* cache for datum_to_json[b]() */
-			int			nargs;
+			struct JsonConstructorExprState *jcstate;
 		}			json_constructor;
 
 		/* for EEOP_IS_JSON */
@@ -697,45 +690,7 @@ typedef struct ExprEvalStep
 		/* for EEOP_JSONEXPR */
 		struct
 		{
-			JsonExpr   *jsexpr; /* original expression node */
-
-			struct
-			{
-				FmgrInfo	func;	/* typinput function for output type */
-				Oid			typioparam;
-			}			input;	/* I/O info for output type */
-
-			NullableDatum
-					   *formatted_expr, /* formatted context item value */
-					   *res_expr,	/* result item */
-					   *coercion_expr,	/* input for JSON item coercion */
-					   *pathspec;	/* path specification value */
-
-			ExprState  *result_expr;	/* coerced to output type */
-			ExprState  *default_on_empty;	/* ON EMPTY DEFAULT expression */
-			ExprState  *default_on_error;	/* ON ERROR DEFAULT expression */
-			List	   *args;	/* passing arguments */
-
-			void	   *cache;	/* cache for json_populate_type() */
-
-			struct JsonCoercionsState
-			{
-				struct JsonCoercionState
-				{
-					JsonCoercion *coercion; /* coercion expression */
-					ExprState  *estate; /* coercion expression state */
-				}			null,
-							string,
-				numeric    ,
-							boolean,
-							date,
-							time,
-							timetz,
-							timestamp,
-							timestamptz,
-							composite;
-			}			coercions;	/* states for coercion from SQL/JSON item
-									 * types directly to the output type */
+			struct JsonExprState *jsestate;
 		}			jsonexpr;
 
 	}			d;
@@ -782,6 +737,64 @@ typedef struct SubscriptExecSteps
 	ExecEvalSubroutine sbs_fetch_old;	/* fetch old value for assignment */
 } SubscriptExecSteps;
 
+/* EEOP_JSON_CONSTRUCTOR state, too big to inline */
+typedef struct JsonConstructorExprState
+{
+	JsonConstructorExpr *constructor;
+	Datum	   *arg_values;
+	bool	   *arg_nulls;
+	Oid		   *arg_types;
+	struct
+	{
+		int			category;
+		Oid			outfuncid;
+	}		   *arg_type_cache; /* cache for datum_to_json[b]() */
+	int			nargs;
+} JsonConstructorExprState;
+
+/* EEOP_JSONEXPR state, too big to inline */
+typedef struct JsonExprState
+{
+	JsonExpr   *jsexpr;			/* original expression node */
+
+	struct
+	{
+		FmgrInfo	func;		/* typinput function for output type */
+		Oid			typioparam;
+	}			input;			/* I/O info for output type */
+
+	NullableDatum
+			   *formatted_expr, /* formatted context item value */
+			   *res_expr,		/* result item */
+			   *coercion_expr,	/* input for JSON item coercion */
+			   *pathspec;		/* path specification value */
+
+	ExprState  *result_expr;	/* coerced to output type */
+	ExprState  *default_on_empty;	/* ON EMPTY DEFAULT expression */
+	ExprState  *default_on_error;	/* ON ERROR DEFAULT expression */
+	List	   *args;			/* passing arguments */
+
+	void	   *cache;			/* cache for json_populate_type() */
+
+	struct JsonCoercionsState
+	{
+		struct JsonCoercionState
+		{
+			JsonCoercion *coercion; /* coercion expression */
+			ExprState  *estate; /* coercion expression state */
+		}			null,
+					string,
+		numeric    ,
+					boolean,
+					date,
+					time,
+					timetz,
+					timestamp,
+					timestamptz,
+					composite;
+	}			coercions;		/* states for coercion from SQL/JSON item
+								 * types directly to the output type */
+} JsonExprState;
 
 /* functions in execExpr.c */
 extern void ExprEvalPushStep(ExprState *es, const ExprEvalStep *s);