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AP_Scripting: more intelligently manage Lua stack 

The Lua stack is guaranteed to have at least LUA_MINSTACK (default 20)
slots upon entry to C. Check to see if we might need more than that
minimum and only in that case call the function to check and resize the
stack. In virtually all cases the check can then be optimized away.

Additionally remove the redundant "Out of stack" message. Lua already
says "stack overflow" and a null message is valid.

Saves ~330B.
This commit is contained in:
Thomas Watson 2024-06-28 13:21:45 -05:00 committed by Andrew Tridgell
parent 7212e35fb0
commit 837b17e82e
2 changed files with 13 additions and 5 deletions
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1
libraries/AP_Scripting/AP_Scripting_helpers.cpp
View File

@ -20,7 +20,6 @@ int lua_new_Parameter(lua_State *L) {
}
// This chunk is the same as the auto generated constructor
luaL_checkstack(L, 2, "Out of stack");
void *ud = lua_newuserdata(L, sizeof(Parameter));
memset(ud, 0, sizeof(Parameter));
new (ud) Parameter();

17
libraries/AP_Scripting/generator/src/main.c
View File

@ -1303,7 +1303,6 @@ void emit_userdata_allocators(void) {
start_dependency(source, node->dependency);
// New method used internally
fprintf(source, "int new_%s(lua_State *L) {\n", node->sanatized_name);
fprintf(source, " luaL_checkstack(L, 2, \"Out of stack\");\n"); // ensure we have sufficent stack to push the return
fprintf(source, " void *ud = lua_newuserdata(L, sizeof(%s));\n", node->name);
fprintf(source, " new (ud) %s();\n", node->name);
fprintf(source, " luaL_getmetatable(L, \"%s\");\n", node->rename ? node->rename : node->name);
@ -1844,9 +1843,20 @@ void emit_singleton_fields() {
int emit_references(const struct argument *arg, const char * tab) {
int arg_index = NULLABLE_ARG_COUNT_BASE + 2;
int return_count = 0;
// count arguments to return so we know if we need to check the stack
const struct argument *count_arg = arg;
while (count_arg != NULL) {
if (count_arg->type.flags & (TYPE_FLAGS_NULLABLE | TYPE_FLAGS_REFERNCE)) {
return_count++;
}
count_arg = count_arg->next;
}
// add one to have a spare stack slot for userdata creation funcs
fprintf(source, "#if %d > LUA_MINSTACK\n", return_count+1);
fprintf(source, "%sluaL_checkstack(L, %d, nullptr);\n", tab, return_count+1);
fprintf(source, "#endif\n\n");
while (arg != NULL) {
if (arg->type.flags & (TYPE_FLAGS_NULLABLE | TYPE_FLAGS_REFERNCE)) {
return_count++;
switch (arg->type.type) {
case TYPE_BOOLEAN:
fprintf(source, "%slua_pushboolean(L, data_%d);\n", tab, arg_index);
@ -2535,7 +2545,7 @@ void emit_loaders(void) {
fprintf(source, "}\n\n");
fprintf(source, "void load_generated_bindings(lua_State *L) {\n");
fprintf(source, " luaL_checkstack(L, 5, \"Out of stack\");\n"); // this is more stack space then we need, but should never fail
fprintf(source, " luaL_checkstack(L, 5, nullptr);\n"); // this is more stack space then we need, but should never fail
fprintf(source, " // userdata metatables\n");
fprintf(source, " for (uint32_t i = 0; i < ARRAY_SIZE(userdata_fun); i++) {\n");
fprintf(source, " luaL_newmetatable(L, userdata_fun[i].name);\n");
@ -2708,7 +2718,6 @@ void emit_argcheck_helper(void) {
fprintf(source, "}\n\n");
fprintf(source, "int new_ap_object(lua_State *L, size_t size, const char * name) {\n");
fprintf(source, " luaL_checkstack(L, 2, \"Out of stack\");\n");
fprintf(source, " lua_newuserdata(L, size);\n");
fprintf(source, " luaL_getmetatable(L, name);\n");
fprintf(source, " lua_setmetatable(L, -2);\n");