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Zig builtins: set small string flag on empty string

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Brian Carroll 2021-12-16 14:36:48 +00:00
parent 33277144d6
commit a481e34f31
1 changed files with 9 additions and 12 deletions
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21
compiler/builtins/bitcode/src/str.zig
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@ -16,7 +16,7 @@ const InPlace = enum(u8) {
};
const SMALL_STR_MAX_LENGTH = small_string_size - 1;
const small_string_size = 2 * @sizeOf(usize);
const small_string_size = @sizeOf(RocStr);
const blank_small_string: [@sizeOf(RocStr)]u8 = init_blank_small_string(small_string_size);
fn init_blank_small_string(comptime n: usize) [n]u8 {
@ -37,8 +37,9 @@ pub const RocStr = extern struct {
pub const alignment = @alignOf(usize);
pub inline fn empty() RocStr {
const small_str_flag: isize = std.math.minInt(isize);
return RocStr{
.str_len = 0,
.str_len = @bitCast(usize, small_str_flag),
.str_bytes = null,
};
}
@ -80,7 +81,7 @@ pub const RocStr = extern struct {
}
pub fn deinit(self: RocStr) void {
if (!self.isSmallStr() and !self.isEmpty()) {
if (!self.isSmallStr()) {
utils.decref(self.str_bytes, self.str_len, RocStr.alignment);
}
}
@ -142,7 +143,7 @@ pub const RocStr = extern struct {
}
pub fn clone(in_place: InPlace, str: RocStr) RocStr {
if (str.isSmallStr() or str.isEmpty()) {
if (str.isSmallStr()) {
// just return the bytes
return str;
} else {
@ -214,7 +215,8 @@ pub const RocStr = extern struct {
}
pub fn isEmpty(self: RocStr) bool {
return self.len() == 0;
comptime const empty_len = RocStr.empty().str_len;
return self.str_len == empty_len;
}
// If a string happens to be null-terminated already, then we can pass its
@ -294,11 +296,6 @@ pub const RocStr = extern struct {
}
pub fn isUnique(self: RocStr) bool {
// the empty string is unique (in the sense that copying it will not leak memory)
if (self.isEmpty()) {
return true;
}
// small strings can be copied
if (self.isSmallStr()) {
return true;
@ -321,8 +318,8 @@ pub const RocStr = extern struct {
// Since this conditional would be prone to branch misprediction,
// make sure it will compile to a cmov.
// return if (self.isSmallStr() or self.isEmpty()) (&@bitCast([@sizeOf(RocStr)]u8, self)) else (@ptrCast([*]u8, self.str_bytes));
if (self.isSmallStr() or self.isEmpty()) {
// return if (self.isSmallStr()) (&@bitCast([@sizeOf(RocStr)]u8, self)) else (@ptrCast([*]u8, self.str_bytes));
if (self.isSmallStr()) {
const as_int = @ptrToInt(&self);
const as_ptr = @intToPtr([*]u8, as_int);
return as_ptr;