On Tue, 11 Jun 2024 11:35:28 GMT, Shaojin Wen <d...@openjdk.org> wrote:
>> After PR https://github.com/openjdk/jdk/pull/16245, C2 optimizes stores into >> primitive arrays by combining values into larger stores. >> >> This PR rewrites the code of appendNull and append(boolean) methods so that >> these two methods can be optimized by C2. > > Shaojin Wen has updated the pull request incrementally with one additional > commit since the last revision: > > revert _putCharStringU will perform MergeStore but with bounds checking. Can the C2 optimizer perform MergeStore without bounds checking in this case? StringUTF16.putChar does not have a bounds check, so there should be no bounds check after MergeStore? class AbstractStringBuilder { private AbstractStringBuilder appendNull() { // ... StringUTF16.putCharsAt(val, count, 'n', 'u', 'l', 'l'); // ... } } class StringUTF16 { public static void putCharsAt(byte[] value, int i, char c1, char c2, char c3, char c4) { putChar(value, i , c1); putChar(value, i + 1, c2); putChar(value, i + 2, c3); putChar(value, i + 3, c4); } @IntrinsicCandidate // intrinsic performs no bounds checks static void putChar(byte[] val, int index, int c) { assert index >= 0 && index < length(val) : "Trusted caller missed bounds check"; index <<= 1; val[index++] = (byte)(c >> HI_BYTE_SHIFT); val[index] = (byte)(c >> LO_BYTE_SHIFT); } } ------------- PR Comment: https://git.openjdk.org/jdk/pull/19626#issuecomment-2163132228
