On Tue, 28 May 2024 21:17:07 GMT, Scott Gibbons <sgibb...@openjdk.org> wrote:
>> src/hotspot/cpu/x86/c2_stubGenerator_x86_64_string.cpp line 488: >> >>> 486: __ cmpq(r11, nMinusK); >>> 487: __ ja_b(L_return); >>> 488: __ movq(rax, r11); >> >> At places where we know that return value in r11 is correct, we dont need to >> checkRange so this could have its own label. > > Disabling causes the test to succeed, so we're not finding matches beyond the > end of the string, correct? Are we confident that this test passing can > warrant removing the range check? @sviswa7 ? Removed. >> src/hotspot/cpu/x86/c2_stubGenerator_x86_64_string.cpp line 621: >> >>> 619: __ addq(hsPtrRet, index); >>> 620: __ movq(r11, hsPtrRet); >>> 621: __ jmp(L_checkRangeAndReturn); >> >> Why do we have to checkRange here, would it not be always correct? It so we >> could return r11 directly (by moving into rax). > > There are cases where r11 could have a value that, when added to (k - 1) > would go past the end of the haystack. I did all in my power to ensure that > it doesn't but there's no test I know of to ensure that condition. I would > recommend leaving this in for now. Removed checkRangeAndReturn ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1617956870 PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1617956635
