On Tue, 28 May 2024 17:30:24 GMT, Scott Gibbons <sgibb...@openjdk.org> wrote:
>> src/hotspot/cpu/x86/c2_stubGenerator_x86_64_string.cpp line 278: >> >>> 276: __ bind(L_nextCheck); >>> 277: __ testq(haystack_len_p, haystack_len_p); >>> 278: __ je(L_zeroCheckFailed); >> >> This check could be removed as the next check covers this one. > > No. This is checking for a zero length haystack. The following compare > checks for needle length longer than haystack, regardless of the value in > each. The comparison is signed, so a haystack length of 0 with a needle > length of -1 will pass the following test and assume validity. But we have already checked for needle length to be greater than 0 in the following lines: __ cmpq(needle_len_p, 0); __ jg_b(L_nextCheck); ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1617857240
