Filter: Implement soft scopes

Soft scopes are anonymous scopes that most likely do not contain any
symbol, so allocating regular scope is postponed when it is really
needed.
This commit is contained in:
Ondrej Zajicek (work) 2022-03-06 16:37:30 +01:00 committed by Ondrej Zajicek
parent 26bc4f9904
commit 946cedfcfe
3 changed files with 64 additions and 5 deletions

View file

@ -574,6 +574,8 @@ check_eof(void)
return 0; return 0;
} }
static inline void cf_swap_soft_scope(void);
static struct symbol * static struct symbol *
cf_new_symbol(const byte *c) cf_new_symbol(const byte *c)
{ {
@ -583,6 +585,8 @@ cf_new_symbol(const byte *c)
if (l > SYM_MAX_LEN) if (l > SYM_MAX_LEN)
cf_error("Symbol too long"); cf_error("Symbol too long");
cf_swap_soft_scope();
s = cfg_allocz(sizeof(struct symbol) + l + 1); s = cfg_allocz(sizeof(struct symbol) + l + 1);
*s = (struct symbol) { .scope = conf_this_scope, .class = SYM_VOID, }; *s = (struct symbol) { .scope = conf_this_scope, .class = SYM_VOID, };
strcpy(s->name, c); strcpy(s->name, c);
@ -656,8 +660,8 @@ cf_localize_symbol(struct symbol *sym)
return sym; return sym;
/* If the scope is the current, it is already defined in this scope. */ /* If the scope is the current, it is already defined in this scope. */
if (sym->scope == conf_this_scope) if (cf_symbol_is_local(sym))
cf_error("Symbol already defined"); cf_error("Symbol '%s' already defined", sym->name);
/* Not allocated here yet, doing it now. */ /* Not allocated here yet, doing it now. */
return cf_new_symbol(sym->name); return cf_new_symbol(sym->name);
@ -787,12 +791,60 @@ cf_push_scope(struct symbol *sym)
void void
cf_pop_scope(void) cf_pop_scope(void)
{ {
ASSERT(!conf_this_scope->soft_scopes);
conf_this_scope->active = 0; conf_this_scope->active = 0;
conf_this_scope = conf_this_scope->next; conf_this_scope = conf_this_scope->next;
ASSERT(conf_this_scope); ASSERT(conf_this_scope);
} }
/**
* cf_push_soft_scope - enter new soft scope
*
* If we want to enter a new anonymous scope that most likely will not contain
* any symbols, we can use cf_push_soft_scope() insteas of cf_push_scope().
* Such scope will be converted to a regular scope on first use.
*/
void
cf_push_soft_scope(void)
{
if (conf_this_scope->soft_scopes < 0xfe)
conf_this_scope->soft_scopes++;
else
cf_push_scope(NULL);
}
/**
* cf_pop_soft_scope - leave a soft scope
*
* Leave a soft scope entered by cf_push_soft_scope().
*/
void
cf_pop_soft_scope(void)
{
if (conf_this_scope->soft_scopes)
conf_this_scope->soft_scopes--;
else
cf_pop_scope();
}
/**
* cf_swap_soft_scope - convert soft scope to regular scope
*
* Soft scopes cannot hold symbols, so they must be converted to regular scopes
* on first use. It is done automatically by cf_new_symbol().
*/
static inline void
cf_swap_soft_scope(void)
{
if (conf_this_scope->soft_scopes)
{
conf_this_scope->soft_scopes--;
cf_push_scope(NULL);
}
}
/** /**
* cf_symbol_class_name - get name of a symbol class * cf_symbol_class_name - get name of a symbol class
* @sym: symbol * @sym: symbol

View file

@ -133,7 +133,8 @@ struct sym_scope {
struct sym_scope *next; /* Next on scope stack */ struct sym_scope *next; /* Next on scope stack */
struct symbol *name; /* Name of this scope */ struct symbol *name; /* Name of this scope */
uint slots; /* Variable slots */ uint slots; /* Variable slots */
int active; /* Currently entered */ byte active; /* Currently entered */
byte soft_scopes; /* Number of soft scopes above */
}; };
struct bytestring { struct bytestring {
@ -190,6 +191,9 @@ struct symbol *cf_get_symbol(const byte *c);
struct symbol *cf_default_name(char *template, int *counter); struct symbol *cf_default_name(char *template, int *counter);
struct symbol *cf_localize_symbol(struct symbol *sym); struct symbol *cf_localize_symbol(struct symbol *sym);
static inline int cf_symbol_is_local(struct symbol *sym)
{ return (sym->scope == conf_this_scope) && !conf_this_scope->soft_scopes; }
/** /**
* cf_define_symbol - define meaning of a symbol * cf_define_symbol - define meaning of a symbol
* @sym: symbol to be defined * @sym: symbol to be defined
@ -213,6 +217,9 @@ struct symbol *cf_localize_symbol(struct symbol *sym);
void cf_push_scope(struct symbol *); void cf_push_scope(struct symbol *);
void cf_pop_scope(void); void cf_pop_scope(void);
void cf_push_soft_scope(void);
void cf_pop_soft_scope(void);
char *cf_symbol_class_name(struct symbol *sym); char *cf_symbol_class_name(struct symbol *sym);
/* Parser */ /* Parser */

View file

@ -116,7 +116,7 @@ add_num_const(char *name, int val, const char *file, const uint line)
struct f_val *v = cfg_alloc(sizeof(struct f_val)); struct f_val *v = cfg_alloc(sizeof(struct f_val));
*v = (struct f_val) { .type = T_INT, .val.i = val }; *v = (struct f_val) { .type = T_INT, .val.i = val };
struct symbol *sym = cf_get_symbol(name); struct symbol *sym = cf_get_symbol(name);
if (sym->class && (sym->scope == conf_this_scope)) if (sym->class && cf_symbol_is_local(sym))
cf_error("Error reading value for %s from %s:%d: already defined", name, file, line); cf_error("Error reading value for %s from %s:%d: already defined", name, file, line);
cf_define_symbol(sym, SYM_CONSTANT | T_INT, val, v); cf_define_symbol(sym, SYM_CONSTANT | T_INT, val, v);