Save one syscache lookup when examining volatility or strictness of

OpExpr and related nodes.  We're going to have to set the opfuncid of
such nodes eventually (if we haven't already), so we might as well
exploit the opportunity to cache the function OID.  Buys back some
of the extra planner overhead noted by Guillaume Smet, though I still
need to fool with equivclass.c to really respond to that.

src/backend/optimizer/util/clauses.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.251 2007/11/15 21:14:36 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.252 2007/11/22 19:09:23 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -715,7 +715,8 @@ contain_mutable_functions_walker(Node *node, void *context)
 	{
 		OpExpr	   *expr = (OpExpr *) node;
 
-		if (op_volatile(expr->opno) != PROVOLATILE_IMMUTABLE)
+		set_opfuncid(expr);
+		if (func_volatile(expr->opfuncid) != PROVOLATILE_IMMUTABLE)
 			return true;
 		/* else fall through to check args */
 	}
@@ -723,7 +724,8 @@ contain_mutable_functions_walker(Node *node, void *context)
 	{
 		DistinctExpr *expr = (DistinctExpr *) node;
 
-		if (op_volatile(expr->opno) != PROVOLATILE_IMMUTABLE)
+		set_opfuncid((OpExpr *) expr);	/* rely on struct equivalence */
+		if (func_volatile(expr->opfuncid) != PROVOLATILE_IMMUTABLE)
 			return true;
 		/* else fall through to check args */
 	}
@@ -731,7 +733,8 @@ contain_mutable_functions_walker(Node *node, void *context)
 	{
 		ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
 
-		if (op_volatile(expr->opno) != PROVOLATILE_IMMUTABLE)
+		set_sa_opfuncid(expr);
+		if (func_volatile(expr->opfuncid) != PROVOLATILE_IMMUTABLE)
 			return true;
 		/* else fall through to check args */
 	}
@@ -767,7 +770,8 @@ contain_mutable_functions_walker(Node *node, void *context)
 	{
 		NullIfExpr *expr = (NullIfExpr *) node;
 
-		if (op_volatile(expr->opno) != PROVOLATILE_IMMUTABLE)
+		set_opfuncid((OpExpr *) expr);	/* rely on struct equivalence */
+		if (func_volatile(expr->opfuncid) != PROVOLATILE_IMMUTABLE)
 			return true;
 		/* else fall through to check args */
 	}
@@ -826,7 +830,8 @@ contain_volatile_functions_walker(Node *node, void *context)
 	{
 		OpExpr	   *expr = (OpExpr *) node;
 
-		if (op_volatile(expr->opno) == PROVOLATILE_VOLATILE)
+		set_opfuncid(expr);
+		if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
 			return true;
 		/* else fall through to check args */
 	}
@@ -834,7 +839,8 @@ contain_volatile_functions_walker(Node *node, void *context)
 	{
 		DistinctExpr *expr = (DistinctExpr *) node;
 
-		if (op_volatile(expr->opno) == PROVOLATILE_VOLATILE)
+		set_opfuncid((OpExpr *) expr);	/* rely on struct equivalence */
+		if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
 			return true;
 		/* else fall through to check args */
 	}
@@ -842,7 +848,8 @@ contain_volatile_functions_walker(Node *node, void *context)
 	{
 		ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
 
-		if (op_volatile(expr->opno) == PROVOLATILE_VOLATILE)
+		set_sa_opfuncid(expr);
+		if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
 			return true;
 		/* else fall through to check args */
 	}
@@ -878,7 +885,8 @@ contain_volatile_functions_walker(Node *node, void *context)
 	{
 		NullIfExpr *expr = (NullIfExpr *) node;
 
-		if (op_volatile(expr->opno) == PROVOLATILE_VOLATILE)
+		set_opfuncid((OpExpr *) expr);	/* rely on struct equivalence */
+		if (func_volatile(expr->opfuncid) == PROVOLATILE_VOLATILE)
 			return true;
 		/* else fall through to check args */
 	}
@@ -951,7 +959,8 @@ contain_nonstrict_functions_walker(Node *node, void *context)
 	{
 		OpExpr	   *expr = (OpExpr *) node;
 
-		if (!op_strict(expr->opno))
+		set_opfuncid(expr);
+		if (!func_strict(expr->opfuncid))
 			return true;
 		/* else fall through to check args */
 	}
@@ -1091,7 +1100,8 @@ find_nonnullable_rels_walker(Node *node, bool top_level)
 	{
 		OpExpr	   *expr = (OpExpr *) node;
 
-		if (op_strict(expr->opno))
+		set_opfuncid(expr);
+		if (func_strict(expr->opfuncid))
 			result = find_nonnullable_rels_walker((Node *) expr->args, false);
 	}
 	else if (IsA(node, ScalarArrayOpExpr))
@@ -1228,7 +1238,8 @@ is_strict_saop(ScalarArrayOpExpr *expr, bool falseOK)
 	Node	   *rightop;
 
 	/* The contained operator must be strict. */
-	if (!op_strict(expr->opno))
+	set_sa_opfuncid(expr);
+	if (!func_strict(expr->opfuncid))
 		return false;
 	/* If ANY and falseOK, that's all we need to check. */
 	if (expr->useOr && falseOK)