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[dart2wasm] Simplify UTF-8 decoder flag scanning

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Simplify the VM-specific `scan` function that assumes an instruction
called `Utf8ScanInstr` and scans the input in chunks to be able to use
the instruction. Instead scan the whole input in one loop.

Change-Id: I9c796e0728e46687653b623effb214ebc93cc01c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/395960
Commit-Queue: Ömer Ağacan <omersa@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
This commit is contained in:
Ömer Sinan Ağacan
2024-11-18 13:30:17 +00:00
committed by Commit Queue
parent 3b707d5e72
commit 47681c79c8
1 changed files with 0 additions and 21 deletions
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sdk/lib/_internal/wasm/lib/convert_patch.dart
-21
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@@ -1980,13 +1980,6 @@ class _Utf8Decoder {
82, 82, 98, 98, 98, 98, 98, 98, 98, 98, 98, 98, 98,
]);
/// Max chunk to scan at a time.
///
/// Avoids staying away from safepoints too long.
/// The Utf8ScanInstr relies on this being small enough to ensure the
/// decoded length stays within Smi range.
static const int scanChunkSize = 65536;
/// Reset the decoder to a state where it is ready to decode a new string but
/// will not skip a leading BOM. Used by the fused UTF-8 / JSON decoder.
void reset() {
@@ -1995,20 +1988,6 @@ class _Utf8Decoder {
}
int scan(Uint8List bytes, int start, int end) {
// Assumes 0 <= start <= end <= bytes.length
int size = 0;
_scanFlags = 0;
int localStart = start;
while (end - localStart > scanChunkSize) {
int localEnd = localStart + scanChunkSize;
size += _scan(bytes, localStart, localEnd);
localStart = localEnd;
}
size += _scan(bytes, localStart, end);
return size;
}
int _scan(Uint8List bytes, int start, int end) {
int size = 0;
int flags = 0;
for (int i = start; i < end; i++) {