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Merged
merged 1 commit into from
Aug 25, 2025
Merged

Use string interning for identifier deduplication #260

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10 changes: 10 additions & 0 deletions src/defs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -224,6 +224,16 @@ typedef struct {
int count;
} token_buffer_t;

/* String pool for identifier deduplication */
typedef struct {
hashmap_t *strings; /* Map string -> interned string */
} string_pool_t;

/* String literal pool for deduplicating string constants */
typedef struct {
hashmap_t *literals; /* Map string literal -> ELF data offset */
} string_literal_pool_t;

/* builtin types */
typedef enum {
TYPE_void = 0,
Expand Down
72 changes: 66 additions & 6 deletions src/globals.c
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,9 @@

#include "defs.h"

/* Forward declaration for string interning */
char *intern_string(char *str);

/* Lexer */
char token_str[MAX_TOKEN_LEN];
token_t next_token;
Expand Down Expand Up @@ -673,7 +676,8 @@ void add_alias(char *alias, char *value)
printf("Failed to allocate alias_t\n");
return;
}
strcpy(al->alias, alias);
/* Use interned string for alias name */
strcpy(al->alias, intern_string(alias));
hashmap_put(ALIASES_MAP, alias, al);
}
strcpy(al->value, value);
Expand Down Expand Up @@ -707,7 +711,8 @@ macro_t *add_macro(char *name)
printf("Failed to allocate macro_t\n");
return NULL;
}
strcpy(ma->name, name);
/* Use interned string for macro name */
strcpy(ma->name, intern_string(name));
hashmap_put(MACROS_MAP, name, ma);
}
ma->disabled = false;
Expand All @@ -733,6 +738,41 @@ bool remove_macro(char *name)
}

void error(char *msg);

/* String pool global */
string_pool_t *string_pool;
string_literal_pool_t *string_literal_pool;

/* Safe string interning that works with self-hosting */
char *intern_string(char *str)
{
char *existing;
char *interned;
int len;

/* Safety: return original if NULL */
if (!str)
return NULL;

/* Safety: can't intern before initialization */
if (!GENERAL_ARENA || !string_pool)
return str;

/* Check if already interned */
existing = hashmap_get(string_pool->strings, str);
if (existing)
return existing;

/* Allocate and store new string */
len = strlen(str) + 1;
interned = arena_alloc(GENERAL_ARENA, len);
strcpy(interned, str);

hashmap_put(string_pool->strings, interned, interned);

return interned;
}

int find_macro_param_src_idx(char *name, block_t *parent)
{
macro_t *macro = parent->macro;
Expand Down Expand Up @@ -761,7 +801,8 @@ type_t *add_type(void)
type_t *add_named_type(char *name)
{
type_t *type = add_type();
strcpy(type->type_name, name);
/* Use interned string for type name */
strcpy(type->type_name, intern_string(name));
return type;
}

Expand All @@ -773,7 +814,8 @@ void add_constant(char alias[], int value)
return;
}

strcpy(constant->alias, alias);
/* Use interned string for constant name */
strcpy(constant->alias, intern_string(alias));
constant->value = value;
hashmap_put(CONSTANTS_MAP, alias, constant);
}
Expand Down Expand Up @@ -877,7 +919,8 @@ func_t *add_func(char *func_name, bool synthesize)

func = arena_alloc_func();
hashmap_put(FUNC_MAP, func_name, func);
strcpy(func->return_def.var_name, func_name);
/* Use interned string for function name */
strcpy(func->return_def.var_name, intern_string(func_name));
func->stack_size = 4;

if (synthesize)
Expand Down Expand Up @@ -1042,7 +1085,7 @@ void add_insn(block_t *block,
n->idx = 0;

if (str)
strcpy(n->str, str);
strcpy(n->str, intern_string(str));
else
n->str[0] = '\0';

Expand Down Expand Up @@ -1151,6 +1194,16 @@ void global_init(void)
TYPES = arena_alloc(GENERAL_ARENA, MAX_TYPES * sizeof(type_t));
PH2_IR_FLATTEN =
arena_alloc(GENERAL_ARENA, MAX_IR_INSTR * sizeof(ph2_ir_t *));

/* Initialize string pool for identifier deduplication */
string_pool = arena_alloc(GENERAL_ARENA, sizeof(string_pool_t));
string_pool->strings = hashmap_create(512);

/* Initialize string literal pool for deduplicating string constants */
string_literal_pool =
arena_alloc(GENERAL_ARENA, sizeof(string_literal_pool_t));
string_literal_pool->literals = hashmap_create(256);
Comment on lines +1198 to +1205
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@ChAoSUnItY ChAoSUnItY Aug 25, 2025

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It seems hashmap won't be freed after in global_release?

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@jserv jserv Aug 25, 2025

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It seems hashmap won't be freed after in global_release?

Yes, the hashmaps for string pools were not being freed in global_release().
Fixed now by adding proper cleanup for both string pool hashmaps.


SOURCE = strbuf_create(MAX_SOURCE);
FUNC_MAP = hashmap_create(DEFAULT_FUNCS_SIZE);
INCLUSION_MAP = hashmap_create(DEFAULT_INCLUSIONS_SIZE);
Expand Down Expand Up @@ -1273,6 +1326,13 @@ void global_release(void)
lexer_cleanup();

hashmap_free(MACROS_MAP);

/* Free string interning hashmaps */
if (string_pool && string_pool->strings)
hashmap_free(string_pool->strings);
if (string_literal_pool && string_literal_pool->literals)
hashmap_free(string_literal_pool->literals);

arena_free(BLOCK_ARENA);
arena_free(INSN_ARENA);
arena_free(BB_ARENA);
Expand Down
26 changes: 15 additions & 11 deletions src/parser.c
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Original file line number Diff line number Diff line change
Expand Up @@ -554,7 +554,7 @@ bool read_preproc_directive(void)
while (lex_peek(T_identifier, alias)) {
lex_expect(T_identifier);
strcpy(macro->param_defs[macro->num_param_defs++].var_name,
alias);
intern_string(alias));
lex_accept(T_comma);
}
if (lex_accept(T_elipsis))
Expand Down Expand Up @@ -1192,14 +1192,18 @@ void read_inner_var_decl(var_t *vd, int anon, int is_param)
/* is it function pointer declaration? */
if (lex_accept(T_open_bracket)) {
func_t func;
char temp_name[MAX_VAR_LEN];
lex_expect(T_asterisk);
lex_ident(T_identifier, vd->var_name);
lex_ident(T_identifier, temp_name);
strcpy(vd->var_name, intern_string(temp_name));
lex_expect(T_close_bracket);
read_parameter_list_decl(&func, 1);
vd->is_func = true;
} else {
if (anon == 0) {
lex_ident(T_identifier, vd->var_name);
char temp_name[MAX_VAR_LEN];
lex_ident(T_identifier, temp_name);
strcpy(vd->var_name, intern_string(temp_name));
if (!lex_peek(T_open_bracket, NULL) && !is_param) {
if (vd->is_global) {
opstack_push(vd);
Expand Down Expand Up @@ -2078,7 +2082,7 @@ void read_expr_operand(block_t *parent, basic_block_t **bb)
/* indirective function pointer assignment */
vd = require_var(parent);
vd->is_func = true;
strcpy(vd->var_name, token);
strcpy(vd->var_name, intern_string(token));
opstack_push(vd);
}
} else if (lex_accept(T_open_curly)) {
Expand Down Expand Up @@ -4431,7 +4435,7 @@ void read_global_statement(void)
if (!type)
type = add_type();

strcpy(type->type_name, token);
strcpy(type->type_name, intern_string(token));
type->base_type = TYPE_struct;

lex_expect(T_open_curly);
Expand Down Expand Up @@ -4469,7 +4473,7 @@ void read_global_statement(void)
if (!type)
type = add_type();

strcpy(type->type_name, token);
strcpy(type->type_name, intern_string(token));
type->base_type = TYPE_union;

lex_expect(T_open_curly);
Expand Down Expand Up @@ -4520,7 +4524,7 @@ void read_global_statement(void)
} while (lex_accept(T_comma));
lex_expect(T_close_curly);
lex_ident(T_identifier, token);
strcpy(type->type_name, token);
strcpy(type->type_name, intern_string(token));
lex_expect(T_semicolon);
} else if (lex_accept(T_struct)) {
int i = 0, size = 0, has_struct_def = 0;
Expand All @@ -4535,7 +4539,7 @@ void read_global_statement(void)
if (!tag) {
tag = add_type();
tag->base_type = TYPE_struct;
strcpy(tag->type_name, token);
strcpy(tag->type_name, intern_string(token));
}
}

Expand Down Expand Up @@ -4574,7 +4578,7 @@ void read_global_statement(void)
strcpy(token, tag->type_name);
memcpy(tag, type, sizeof(type_t));
tag->base_type = TYPE_struct;
strcpy(tag->type_name, token);
strcpy(tag->type_name, intern_string(token));
} else {
/* If it is a forward declaration, build a connection between
* structure tag and alias. In 'find_type', it will retrieve
Expand All @@ -4597,7 +4601,7 @@ void read_global_statement(void)
if (!tag) {
tag = add_type();
tag->base_type = TYPE_union;
strcpy(tag->type_name, token);
strcpy(tag->type_name, intern_string(token));
}
}

Expand Down Expand Up @@ -4640,7 +4644,7 @@ void read_global_statement(void)
strcpy(token, tag->type_name);
memcpy(tag, type, sizeof(type_t));
tag->base_type = TYPE_union;
strcpy(tag->type_name, token);
strcpy(tag->type_name, intern_string(token));
} else {
/* If it is a forward declaration, build a connection between
* union tag and alias. In 'find_type', it will retrieve
Expand Down