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Optimize big_int_from_string usage for small integers

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gingerBill
2026-06-09 15:50:39 +01:00
parent a34b03aced
commit bcff6688a1
2 changed files with 84 additions and 30 deletions
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109
src/big_int.cpp
View File

@@ -208,45 +208,93 @@ gb_internal void big_int_from_string(BigInt *dst, String const &s, bool *success
len -= 2;
}
// NOTE(bill): Try a fast path for small integers rather than relying on
// big integer arithmetic straightaway
isize max_len = 0;
switch (base) {
case 2: max_len = 63; break;
case 8: max_len = 21; break;
case 10: max_len = 18; break;
case 12: max_len = 17; break;
case 16: max_len = 15; break;
}
BigInt b = {};
big_int_from_u64(&b, base);
defer (big_int_dealloc(&b));
mp_zero(dst);
BigInt digit = {};
defer (big_int_dealloc(&digit));
defer (if (b.dp) big_int_dealloc(&b));
isize i = 0;
for (; i < len; i++) {
Rune r = cast(Rune)text[i];
if (len < max_len) {
u64 value = 0;
if (r == '-') {
if (is_negative) {
// NOTE(Jeroen): Can't have a doubly negative number.
*success = false;
return;
for (; i < len; i++) {
Rune r = cast(Rune)text[i];
if (r == '-') {
if (is_negative) {
// NOTE(Jeroen): Can't have a doubly negative number.
*success = false;
return;
}
is_negative = true;
continue;
}
is_negative = true;
continue;
}
if (r == '_') {
continue;
}
u64 v = u64_digit_value(r);
if (v >= base) {
// NOTE(Jeroen): Can still be a valid integer if the next character is an `e` or `E`.
if (r != 'e' && r != 'E') {
*success = false;
if (r == '_') {
continue;
}
break;
u64 v = u64_digit_value(r);
if (v >= base) {
// NOTE(Jeroen): Can still be a valid integer if the next character is an `e` or `E`.
if (r != 'e' && r != 'E') {
*success = false;
}
break;
}
value *= base;
value += v;
}
big_int_from_u64(&digit, v);
big_int_mul_eq(dst, &b);
big_int_add_eq(dst, &digit);
big_int_from_u64(dst, value);
} else {
big_int_from_u64(&b, base);
mp_zero(dst);
BigInt digit = {};
defer (big_int_dealloc(&digit));
for (; i < len; i++) {
Rune r = cast(Rune)text[i];
if (r == '-') {
if (is_negative) {
// NOTE(Jeroen): Can't have a doubly negative number.
*success = false;
return;
}
is_negative = true;
continue;
}
if (r == '_') {
continue;
}
u64 v = u64_digit_value(r);
if (v >= base) {
// NOTE(Jeroen): Can still be a valid integer if the next character is an `e` or `E`.
if (r != 'e' && r != 'E') {
*success = false;
}
break;
}
big_int_from_u64(&digit, v);
big_int_mul_eq(dst, &b);
big_int_add_eq(dst, &digit);
}
}
if (i < len && (text[i] == 'e' || text[i] == 'E')) {
i += 1;
GB_ASSERT(base == 10);
@@ -284,6 +332,9 @@ gb_internal void big_int_from_string(BigInt *dst, String const &s, bool *success
BigInt tmp = {};
mp_init(&tmp);
defer (big_int_dealloc(&tmp));
if (b.dp == nullptr) {
big_int_from_u64(&b, base);
}
big_int_exp_u64(&tmp, &b, exp, success);
big_int_mul_eq(dst, &tmp);
}

5
src/parser.cpp
View File

@@ -792,17 +792,20 @@ gb_internal Ast *ast_uninit(AstFile *f, Token token) {
gb_internal ExactValue exact_value_from_token(AstFile *f, Token const &token) {
String s = token.string;
string_interner_insert(s);
switch (token.kind) {
case Token_Rune:
if (!unquote_string(ast_allocator(f), &s, 0)) {
syntax_error(token, "Invalid rune literal");
return {};
}
string_interner_insert(s);
break;
case Token_String:
if (!unquote_string(ast_allocator(f), &s, 0, s.text[0] == '`')) {
syntax_error(token, "Invalid string literal");
return {};
}
string_interner_insert(s);
break;
}
ExactValue value = exact_value_from_basic_literal(token.kind, s);