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Eliminate @memcpy from Str.trim functions

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Richard Feldman 2022-07-18 10:28:30 -04:00
parent b6b66b883a
commit 7e446d1b0d
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GPG Key ID: 7E4127D1E4241798
1 changed files with 34 additions and 28 deletions
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62
crates/compiler/builtins/bitcode/src/str.zig
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@ -1977,23 +1977,26 @@ pub fn strTrim(string: RocStr) callconv(.C) RocStr {
const small_or_shared = new_len <= SMALL_STR_MAX_LENGTH or !string.isRefcountOne();
if (small_or_shared) {
return RocStr.init(string.asU8ptr() + leading_bytes, new_len);
}
} else {
// nonempty, large, and unique: shift everything over in-place if necessary.
// Note: must use memmove over memcpy, because the bytes definitely overlap!
if (leading_bytes > 0) {
// Zig doesn't seem to have `memmove` in the stdlib anymore; this is based on:
// https://github.com/ziglang/zig/blob/52ba2c3a43a88a4db30cff47f2f3eff8c3d5be19/lib/std/special/c.zig#L115
// Copyright Andrew Kelley, MIT licensed.
const src = bytes_ptr + leading_bytes;
var index: usize = 0;
// nonempty, large, and unique:
if (leading_bytes > 0) {
var i: usize = 0;
while (i < new_len) : (i += 1) {
const dest = bytes_ptr + i;
const source = dest + leading_bytes;
@memcpy(dest, source, 1);
while (index != new_len) : (index += 1) {
bytes_ptr[index] = src[index];
}
}
var new_string = string;
new_string.str_len = new_len;
return new_string;
}
var new_string = string;
new_string.str_len = new_len;
return new_string;
}
return RocStr.empty();
@ -2014,23 +2017,26 @@ pub fn strTrimLeft(string: RocStr) callconv(.C) RocStr {
const small_or_shared = new_len <= SMALL_STR_MAX_LENGTH or !string.isRefcountOne();
if (small_or_shared) {
return RocStr.init(string.asU8ptr() + leading_bytes, new_len);
}
} else {
// nonempty, large, and unique: shift everything over in-place if necessary.
// Note: must use memmove over memcpy, because the bytes definitely overlap!
if (leading_bytes > 0) {
// Zig doesn't seem to have `memmove` in the stdlib anymore; this is based on:
// https://github.com/ziglang/zig/blob/52ba2c3a43a88a4db30cff47f2f3eff8c3d5be19/lib/std/special/c.zig#L115
// Copyright Andrew Kelley, MIT licensed.
const src = bytes_ptr + leading_bytes;
var index: usize = 0;
// nonempty, large, and unique:
if (leading_bytes > 0) {
var i: usize = 0;
while (i < new_len) : (i += 1) {
const dest = bytes_ptr + i;
const source = dest + leading_bytes;
@memcpy(dest, source, 1);
while (index != new_len) : (index += 1) {
bytes_ptr[index] = src[index];
}
}
var new_string = string;
new_string.str_len = new_len;
return new_string;
}
var new_string = string;
new_string.str_len = new_len;
return new_string;
}
return RocStr.empty();