Inline plpgsql's exec_stmt() into exec_stmts().

This saves one level of C function call per plpgsql statement executed,
and permits a tiny additional optimization of not saving and restoring
estate->err_stmt for each statement in a block.  The net effect seems
nearly un-measurable on x86_64, but there's a clear win on aarch64,
amounting to two or three percent in a loop over a few simple plpgsql
statements.

To do this, we have to get rid of the other existing call sites for
exec_stmt().  Replace them with exec_toplevel_block(), which is just
defined to do what exec_stmts() does, but for a single
PLpgSQL_stmt_block statement.  Hard-wiring the expectation of which
statement type applies here allows us to skip the dispatch switch,
making this not much uglier than the previous factorization.

Amit Khandekar, tweaked a bit by me

Discussion: https://postgr.es/m/CAJ3gD9eBNrmUD7WBBLG8ohaZ485H9y+4eihQTgr+K8Lhka3vcQ@mail.gmail.com

diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index f41d675d656342a3045da52f5049b8db68d240b3..54900e01c8f59bc2e3141c29fd8fa161c805daca 100644 (file)
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -260,12 +260,12 @@ static MemoryContext get_stmt_mcontext(PLpgSQL_execstate *estate);
 static void push_stmt_mcontext(PLpgSQL_execstate *estate);
 static void pop_stmt_mcontext(PLpgSQL_execstate *estate);
 
+static int exec_toplevel_block(PLpgSQL_execstate *estate,
+                               PLpgSQL_stmt_block *block);
 static int exec_stmt_block(PLpgSQL_execstate *estate,
                            PLpgSQL_stmt_block *block);
 static int exec_stmts(PLpgSQL_execstate *estate,
                       List *stmts);
-static int exec_stmt(PLpgSQL_execstate *estate,
-                     PLpgSQL_stmt *stmt);
 static int exec_stmt_assign(PLpgSQL_execstate *estate,
                             PLpgSQL_stmt_assign *stmt);
 static int exec_stmt_perform(PLpgSQL_execstate *estate,
@@ -599,11 +599,9 @@ plpgsql_exec_function(PLpgSQL_function *func, FunctionCallInfo fcinfo,
     * Now call the toplevel block of statements
     */
    estate.err_text = NULL;
-   estate.err_stmt = (PLpgSQL_stmt *) (func->action);
-   rc = exec_stmt(&estate, (PLpgSQL_stmt *) func->action);
+   rc = exec_toplevel_block(&estate, func->action);
    if (rc != PLPGSQL_RC_RETURN)
    {
-       estate.err_stmt = NULL;
        estate.err_text = NULL;
        ereport(ERROR,
                (errcode(ERRCODE_S_R_E_FUNCTION_EXECUTED_NO_RETURN_STATEMENT),
@@ -613,7 +611,6 @@ plpgsql_exec_function(PLpgSQL_function *func, FunctionCallInfo fcinfo,
    /*
     * We got a return value - process it
     */
-   estate.err_stmt = NULL;
    estate.err_text = gettext_noop("while casting return value to function's return type");
 
    fcinfo->isnull = estate.retisnull;
@@ -1015,18 +1012,15 @@ plpgsql_exec_trigger(PLpgSQL_function *func,
     * Now call the toplevel block of statements
     */
    estate.err_text = NULL;
-   estate.err_stmt = (PLpgSQL_stmt *) (func->action);
-   rc = exec_stmt(&estate, (PLpgSQL_stmt *) func->action);
+   rc = exec_toplevel_block(&estate, func->action);
    if (rc != PLPGSQL_RC_RETURN)
    {
-       estate.err_stmt = NULL;
        estate.err_text = NULL;
        ereport(ERROR,
                (errcode(ERRCODE_S_R_E_FUNCTION_EXECUTED_NO_RETURN_STATEMENT),
                 errmsg("control reached end of trigger procedure without RETURN")));
    }
 
-   estate.err_stmt = NULL;
    estate.err_text = gettext_noop("during function exit");
 
    if (estate.retisset)
@@ -1176,18 +1170,15 @@ plpgsql_exec_event_trigger(PLpgSQL_function *func, EventTriggerData *trigdata)
     * Now call the toplevel block of statements
     */
    estate.err_text = NULL;
-   estate.err_stmt = (PLpgSQL_stmt *) (func->action);
-   rc = exec_stmt(&estate, (PLpgSQL_stmt *) func->action);
+   rc = exec_toplevel_block(&estate, func->action);
    if (rc != PLPGSQL_RC_RETURN)
    {
-       estate.err_stmt = NULL;
        estate.err_text = NULL;
        ereport(ERROR,
                (errcode(ERRCODE_S_R_E_FUNCTION_EXECUTED_NO_RETURN_STATEMENT),
                 errmsg("control reached end of trigger procedure without RETURN")));
    }
 
-   estate.err_stmt = NULL;
    estate.err_text = gettext_noop("during function exit");
 
    /*
@@ -1584,6 +1575,40 @@ exception_matches_conditions(ErrorData *edata, PLpgSQL_condition *cond)
 }
 
 
+/* ----------
+ * exec_toplevel_block         Execute the toplevel block
+ *
+ * This is intentionally equivalent to executing exec_stmts() with a
+ * list consisting of the one statement.  One tiny difference is that
+ * we do not bother to save the entry value of estate->err_stmt;
+ * that's assumed to be NULL.
+ * ----------
+ */
+static int
+exec_toplevel_block(PLpgSQL_execstate *estate, PLpgSQL_stmt_block *block)
+{
+   int         rc;
+
+   estate->err_stmt = (PLpgSQL_stmt *) block;
+
+   /* Let the plugin know that we are about to execute this statement */
+   if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->stmt_beg)
+       ((*plpgsql_plugin_ptr)->stmt_beg) (estate, (PLpgSQL_stmt *) block);
+
+   CHECK_FOR_INTERRUPTS();
+
+   rc = exec_stmt_block(estate, block);
+
+   /* Let the plugin know that we have finished executing this statement */
+   if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->stmt_end)
+       ((*plpgsql_plugin_ptr)->stmt_end) (estate, (PLpgSQL_stmt *) block);
+
+   estate->err_stmt = NULL;
+
+   return rc;
+}
+
+
 /* ----------
  * exec_stmt_block         Execute a block of statements
  * ----------
@@ -1917,6 +1942,7 @@ exec_stmt_block(PLpgSQL_execstate *estate, PLpgSQL_stmt_block *block)
 static int
 exec_stmts(PLpgSQL_execstate *estate, List *stmts)
 {
+   PLpgSQL_stmt *save_estmt = estate->err_stmt;
    ListCell   *s;
 
    if (stmts == NIL)
@@ -1933,162 +1959,150 @@ exec_stmts(PLpgSQL_execstate *estate, List *stmts)
    foreach(s, stmts)
    {
        PLpgSQL_stmt *stmt = (PLpgSQL_stmt *) lfirst(s);
-       int         rc = exec_stmt(estate, stmt);
-
-       if (rc != PLPGSQL_RC_OK)
-           return rc;
-   }
+       int         rc;
 
-   return PLPGSQL_RC_OK;
-}
+       estate->err_stmt = stmt;
 
+       /* Let the plugin know that we are about to execute this statement */
+       if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->stmt_beg)
+           ((*plpgsql_plugin_ptr)->stmt_beg) (estate, stmt);
 
-/* ----------
- * exec_stmt           Distribute one statement to the statements
- *             type specific execution function.
- * ----------
- */
-static int
-exec_stmt(PLpgSQL_execstate *estate, PLpgSQL_stmt *stmt)
-{
-   PLpgSQL_stmt *save_estmt;
-   int         rc = -1;
-
-   save_estmt = estate->err_stmt;
-   estate->err_stmt = stmt;
+       CHECK_FOR_INTERRUPTS();
 
-   /* Let the plugin know that we are about to execute this statement */
-   if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->stmt_beg)
-       ((*plpgsql_plugin_ptr)->stmt_beg) (estate, stmt);
+       switch (stmt->cmd_type)
+       {
+           case PLPGSQL_STMT_BLOCK:
+               rc = exec_stmt_block(estate, (PLpgSQL_stmt_block *) stmt);
+               break;
 
-   CHECK_FOR_INTERRUPTS();
+           case PLPGSQL_STMT_ASSIGN:
+               rc = exec_stmt_assign(estate, (PLpgSQL_stmt_assign *) stmt);
+               break;
 
-   switch (stmt->cmd_type)
-   {
-       case PLPGSQL_STMT_BLOCK:
-           rc = exec_stmt_block(estate, (PLpgSQL_stmt_block *) stmt);
-           break;
+           case PLPGSQL_STMT_PERFORM:
+               rc = exec_stmt_perform(estate, (PLpgSQL_stmt_perform *) stmt);
+               break;
 
-       case PLPGSQL_STMT_ASSIGN:
-           rc = exec_stmt_assign(estate, (PLpgSQL_stmt_assign *) stmt);
-           break;
+           case PLPGSQL_STMT_CALL:
+               rc = exec_stmt_call(estate, (PLpgSQL_stmt_call *) stmt);
+               break;
 
-       case PLPGSQL_STMT_PERFORM:
-           rc = exec_stmt_perform(estate, (PLpgSQL_stmt_perform *) stmt);
-           break;
+           case PLPGSQL_STMT_GETDIAG:
+               rc = exec_stmt_getdiag(estate, (PLpgSQL_stmt_getdiag *) stmt);
+               break;
 
-       case PLPGSQL_STMT_CALL:
-           rc = exec_stmt_call(estate, (PLpgSQL_stmt_call *) stmt);
-           break;
+           case PLPGSQL_STMT_IF:
+               rc = exec_stmt_if(estate, (PLpgSQL_stmt_if *) stmt);
+               break;
 
-       case PLPGSQL_STMT_GETDIAG:
-           rc = exec_stmt_getdiag(estate, (PLpgSQL_stmt_getdiag *) stmt);
-           break;
+           case PLPGSQL_STMT_CASE:
+               rc = exec_stmt_case(estate, (PLpgSQL_stmt_case *) stmt);
+               break;
 
-       case PLPGSQL_STMT_IF:
-           rc = exec_stmt_if(estate, (PLpgSQL_stmt_if *) stmt);
-           break;
+           case PLPGSQL_STMT_LOOP:
+               rc = exec_stmt_loop(estate, (PLpgSQL_stmt_loop *) stmt);
+               break;
 
-       case PLPGSQL_STMT_CASE:
-           rc = exec_stmt_case(estate, (PLpgSQL_stmt_case *) stmt);
-           break;
+           case PLPGSQL_STMT_WHILE:
+               rc = exec_stmt_while(estate, (PLpgSQL_stmt_while *) stmt);
+               break;
 
-       case PLPGSQL_STMT_LOOP:
-           rc = exec_stmt_loop(estate, (PLpgSQL_stmt_loop *) stmt);
-           break;
+           case PLPGSQL_STMT_FORI:
+               rc = exec_stmt_fori(estate, (PLpgSQL_stmt_fori *) stmt);
+               break;
 
-       case PLPGSQL_STMT_WHILE:
-           rc = exec_stmt_while(estate, (PLpgSQL_stmt_while *) stmt);
-           break;
+           case PLPGSQL_STMT_FORS:
+               rc = exec_stmt_fors(estate, (PLpgSQL_stmt_fors *) stmt);
+               break;
 
-       case PLPGSQL_STMT_FORI:
-           rc = exec_stmt_fori(estate, (PLpgSQL_stmt_fori *) stmt);
-           break;
+           case PLPGSQL_STMT_FORC:
+               rc = exec_stmt_forc(estate, (PLpgSQL_stmt_forc *) stmt);
+               break;
 
-       case PLPGSQL_STMT_FORS:
-           rc = exec_stmt_fors(estate, (PLpgSQL_stmt_fors *) stmt);
-           break;
+           case PLPGSQL_STMT_FOREACH_A:
+               rc = exec_stmt_foreach_a(estate, (PLpgSQL_stmt_foreach_a *) stmt);
+               break;
 
-       case PLPGSQL_STMT_FORC:
-           rc = exec_stmt_forc(estate, (PLpgSQL_stmt_forc *) stmt);
-           break;
+           case PLPGSQL_STMT_EXIT:
+               rc = exec_stmt_exit(estate, (PLpgSQL_stmt_exit *) stmt);
+               break;
 
-       case PLPGSQL_STMT_FOREACH_A:
-           rc = exec_stmt_foreach_a(estate, (PLpgSQL_stmt_foreach_a *) stmt);
-           break;
+           case PLPGSQL_STMT_RETURN:
+               rc = exec_stmt_return(estate, (PLpgSQL_stmt_return *) stmt);
+               break;
 
-       case PLPGSQL_STMT_EXIT:
-           rc = exec_stmt_exit(estate, (PLpgSQL_stmt_exit *) stmt);
-           break;
+           case PLPGSQL_STMT_RETURN_NEXT:
+               rc = exec_stmt_return_next(estate, (PLpgSQL_stmt_return_next *) stmt);
+               break;
 
-       case PLPGSQL_STMT_RETURN:
-           rc = exec_stmt_return(estate, (PLpgSQL_stmt_return *) stmt);
-           break;
+           case PLPGSQL_STMT_RETURN_QUERY:
+               rc = exec_stmt_return_query(estate, (PLpgSQL_stmt_return_query *) stmt);
+               break;
 
-       case PLPGSQL_STMT_RETURN_NEXT:
-           rc = exec_stmt_return_next(estate, (PLpgSQL_stmt_return_next *) stmt);
-           break;
+           case PLPGSQL_STMT_RAISE:
+               rc = exec_stmt_raise(estate, (PLpgSQL_stmt_raise *) stmt);
+               break;
 
-       case PLPGSQL_STMT_RETURN_QUERY:
-           rc = exec_stmt_return_query(estate, (PLpgSQL_stmt_return_query *) stmt);
-           break;
+           case PLPGSQL_STMT_ASSERT:
+               rc = exec_stmt_assert(estate, (PLpgSQL_stmt_assert *) stmt);
+               break;
 
-       case PLPGSQL_STMT_RAISE:
-           rc = exec_stmt_raise(estate, (PLpgSQL_stmt_raise *) stmt);
-           break;
+           case PLPGSQL_STMT_EXECSQL:
+               rc = exec_stmt_execsql(estate, (PLpgSQL_stmt_execsql *) stmt);
+               break;
 
-       case PLPGSQL_STMT_ASSERT:
-           rc = exec_stmt_assert(estate, (PLpgSQL_stmt_assert *) stmt);
-           break;
+           case PLPGSQL_STMT_DYNEXECUTE:
+               rc = exec_stmt_dynexecute(estate, (PLpgSQL_stmt_dynexecute *) stmt);
+               break;
 
-       case PLPGSQL_STMT_EXECSQL:
-           rc = exec_stmt_execsql(estate, (PLpgSQL_stmt_execsql *) stmt);
-           break;
+           case PLPGSQL_STMT_DYNFORS:
+               rc = exec_stmt_dynfors(estate, (PLpgSQL_stmt_dynfors *) stmt);
+               break;
 
-       case PLPGSQL_STMT_DYNEXECUTE:
-           rc = exec_stmt_dynexecute(estate, (PLpgSQL_stmt_dynexecute *) stmt);
-           break;
+           case PLPGSQL_STMT_OPEN:
+               rc = exec_stmt_open(estate, (PLpgSQL_stmt_open *) stmt);
+               break;
 
-       case PLPGSQL_STMT_DYNFORS:
-           rc = exec_stmt_dynfors(estate, (PLpgSQL_stmt_dynfors *) stmt);
-           break;
+           case PLPGSQL_STMT_FETCH:
+               rc = exec_stmt_fetch(estate, (PLpgSQL_stmt_fetch *) stmt);
+               break;
 
-       case PLPGSQL_STMT_OPEN:
-           rc = exec_stmt_open(estate, (PLpgSQL_stmt_open *) stmt);
-           break;
+           case PLPGSQL_STMT_CLOSE:
+               rc = exec_stmt_close(estate, (PLpgSQL_stmt_close *) stmt);
+               break;
 
-       case PLPGSQL_STMT_FETCH:
-           rc = exec_stmt_fetch(estate, (PLpgSQL_stmt_fetch *) stmt);
-           break;
+           case PLPGSQL_STMT_COMMIT:
+               rc = exec_stmt_commit(estate, (PLpgSQL_stmt_commit *) stmt);
+               break;
 
-       case PLPGSQL_STMT_CLOSE:
-           rc = exec_stmt_close(estate, (PLpgSQL_stmt_close *) stmt);
-           break;
+           case PLPGSQL_STMT_ROLLBACK:
+               rc = exec_stmt_rollback(estate, (PLpgSQL_stmt_rollback *) stmt);
+               break;
 
-       case PLPGSQL_STMT_COMMIT:
-           rc = exec_stmt_commit(estate, (PLpgSQL_stmt_commit *) stmt);
-           break;
+           case PLPGSQL_STMT_SET:
+               rc = exec_stmt_set(estate, (PLpgSQL_stmt_set *) stmt);
+               break;
 
-       case PLPGSQL_STMT_ROLLBACK:
-           rc = exec_stmt_rollback(estate, (PLpgSQL_stmt_rollback *) stmt);
-           break;
+           default:
+               /* point err_stmt to parent, since this one seems corrupt */
+               estate->err_stmt = save_estmt;
+               elog(ERROR, "unrecognized cmd_type: %d", stmt->cmd_type);
+               rc = -1;        /* keep compiler quiet */
+       }
 
-       case PLPGSQL_STMT_SET:
-           rc = exec_stmt_set(estate, (PLpgSQL_stmt_set *) stmt);
-           break;
+       /* Let the plugin know that we have finished executing this statement */
+       if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->stmt_end)
+           ((*plpgsql_plugin_ptr)->stmt_end) (estate, stmt);
 
-       default:
+       if (rc != PLPGSQL_RC_OK)
+       {
            estate->err_stmt = save_estmt;
-           elog(ERROR, "unrecognized cmd_type: %d", stmt->cmd_type);
-   }
-
-   /* Let the plugin know that we have finished executing this statement */
-   if (*plpgsql_plugin_ptr && (*plpgsql_plugin_ptr)->stmt_end)
-       ((*plpgsql_plugin_ptr)->stmt_end) (estate, stmt);
+           return rc;
+       }
+   }                           /* end of loop over statements */
 
    estate->err_stmt = save_estmt;
-
-   return rc;
+   return PLPGSQL_RC_OK;
 }