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LibJS: Avoid string trimming in GlobalObject.parseInt() when possible

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In the common case, parseInt() is being called with strings that don't
have leading whitespace. By checking for that first, we can avoid the
cost of trimming and multiple malloc/GC allocations.
This commit is contained in:
Andreas Kling 2024-05-07 12:27:03 +02:00
commit 3170ad2ee3
Notes: sideshowbarker 2024-07-17 21:16:31 +09:00
1 changed files with 7 additions and 1 deletions
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8
Userland/Libraries/LibJS/Runtime/GlobalObject.cpp
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@ -303,7 +303,13 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::parse_int)
auto input_string = TRY(string.to_string(vm));
// 2. Let S be ! TrimString(inputString, start).
auto trimmed_string = MUST(trim_string(vm, PrimitiveString::create(vm, move(input_string)), TrimMode::Left));
String trimmed_string;
// OPTIMIZATION: We can skip the trimming step when the value already starts with an alphanumeric ASCII character.
if (input_string.is_empty() || is_ascii_alphanumeric(input_string.bytes_as_string_view()[0])) {
trimmed_string = input_string;
} else {
trimmed_string = MUST(trim_string(vm, PrimitiveString::create(vm, move(input_string)), TrimMode::Left));
}
// 3. Let sign be 1.
auto sign = 1;