From: Phillip Wood Date: Tue, 20 Jan 2026 16:32:41 GMT Subject: Re: [PATCH 06/10] xdiff: cleanup xdl_trim_ends() Message-ID: <2b6592f6-1d20-4cdd-8af7-f524920ad1a7@gmail.com> In-Reply-To: <65da408da9589420ec341368d0853e6183aee922.1767379944.git.gitgitgadget@gmail.com> On 02/01/2026 18:52, Ezekiel Newren via GitGitGadget wrote: > From: Ezekiel Newren > > This patch is best viewed with a before and after of the whole > function. > > Rather than using 2 pointers and walking them. Use direct indexing with > local variables of what is being compared to make it easier to follow > along. I think using direct indexing makes things clearer, but I'm not sure this is a faithful conversion (see below). > diff --git a/xdiff/xprepare.c b/xdiff/xprepare.c > index 0acb3437d4..06b6a6f804 100644 > --- a/xdiff/xprepare.c > +++ b/xdiff/xprepare.c > @@ -340,29 +340,29 @@ cleanup: > /* > * Early trim initial and terminal matching records. > */ > -static int xdl_trim_ends(xdfenv_t *xe) { > - long i, lim; > - xrecord_t *recs1, *recs2; > - > - recs1 = xe->xdf1.recs; > - recs2 = xe->xdf2.recs; > - for (i = 0, lim = (long)XDL_MIN(xe->xdf1.nrec, xe->xdf2.nrec); i < lim; > - i++, recs1++, recs2++) > - if (recs1->minimal_perfect_hash != recs2->minimal_perfect_hash) > +static void xdl_trim_ends(xdfenv_t *xe) > +{ > + size_t lim = XDL_MIN(xe->xdf1.nrec, xe->xdf2.nrec); > + > + for (size_t i = 0; i < lim; i++) { > + size_t mph1 = xe->xdf1.recs[i].minimal_perfect_hash; > + size_t mph2 = xe->xdf2.recs[i].minimal_perfect_hash; > + if (mph1 != mph2) { > + xe->xdf1.dstart = xe->xdf2.dstart = (ssize_t)i; The type of dstart is ptrdiff_t, not ssize_t. The original set dstart and dend unconditionally but here they are not set if all the lines match. Thanks Phillip > + lim -= i; > break; > + } > + } > > - xe->xdf1.dstart = xe->xdf2.dstart = i; > - > - recs1 = xe->xdf1.recs + xe->xdf1.nrec - 1; > - recs2 = xe->xdf2.recs + xe->xdf2.nrec - 1; > - for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--) > - if (recs1->minimal_perfect_hash != recs2->minimal_perfect_hash) > + for (size_t i = 0; i < lim; i++) { > + size_t mph1 = xe->xdf1.recs[xe->xdf1.nrec - 1 - i].minimal_perfect_hash; > + size_t mph2 = xe->xdf2.recs[xe->xdf2.nrec - 1 - i].minimal_perfect_hash; > + if (mph1 != mph2) { > + xe->xdf1.dend = xe->xdf1.nrec - 1 - i; > + xe->xdf2.dend = xe->xdf2.nrec - 1 - i; > break; > - > - xe->xdf1.dend = (long)xe->xdf1.nrec - i - 1; > - xe->xdf2.dend = (long)xe->xdf2.nrec - i - 1; > - > - return 0; > + } > + } > } > >